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bypassing electrolytic caps

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Anonymous
July 22, 2004 7:23:27 PM

Archived from groups: rec.audio.pro (More info?)

I'm about to recap my board (Soundcraft 200B) which is getting hissy on some
channels, and in researching options I found some discussion of bypassing
electrolytic capacitors with film caps in parallel.

The textbooks I've been using to teach myself basic electronics don't
discuss this practice, so before I go ordering a bunch of components I may
not even need, I have a few questions:

1. The benefit of bypassing electrolytic caps is typically in improved high
frequency response because the lower value film cap will pass higher
frequencies better than the higher value one, and vice versa? There's a
counter argument about phase shift--how much is that worth worrying about?

2. Are there places where this isn't useful/helpful/worth dealing with? I'm
guessing that the 47uf phantom blocking caps would benefit, but what about
interstage coupling, etc?

3. The value of the film cap should be 10% of the electrolytic. How critical
is that value?

4. In an existing design, you just connect both caps at the same point,
soldering the film cap to the point where the electrolytic attaches to the
circuit board? In this case there's room on the other side of the circuit
board. Since all the points on each side of a parallel network are
electrically the same point, this would work, right?

Thanks!

-jw
Anonymous
July 22, 2004 7:23:28 PM

Archived from groups: rec.audio.pro (More info?)

John Washburn <johnwashburn99@nyc.rr.com> wrote:
>
>1. The benefit of bypassing electrolytic caps is typically in improved high
>frequency response because the lower value film cap will pass higher
>frequencies better than the higher value one, and vice versa? There's a
>counter argument about phase shift--how much is that worth worrying about?

The electrolytic can be looked at as a capacitor with a resistor and an
inductor in series with it. The parasitic resistance and inductance are
a problem at high frequencies. The smaller value film cap will provide
a lower-impedance path to shunt those high frequencies around.

I don't know what the phase shift counter-argument is. It will indeed
change the phase characteristics of the circuit, but it will improve them.
This could be a problem in some high-feedback circuits that are designed
around particular electrolytics, but it should not be an issue in well-designed
gear.

>2. Are there places where this isn't useful/helpful/worth dealing with? I'm
>guessing that the 47uf phantom blocking caps would benefit, but what about
>interstage coupling, etc?

Certainly it's a good idea for interstage coupling. On a single-ended circuit
it's even a good idea for supply decoupling caps.

>3. The value of the film cap should be 10% of the electrolytic. How critical
>is that value?

Not very. It's a reasonable ballpark, though, but use whatever you have
on the sjunkbox.

>4. In an existing design, you just connect both caps at the same point,
>soldering the film cap to the point where the electrolytic attaches to the
>circuit board? In this case there's room on the other side of the circuit
>board. Since all the points on each side of a parallel network are
>electrically the same point, this would work, right?

Yes. Or (with an axial electrolytic) you can piggyback them on the same
side.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 22, 2004 7:23:28 PM

Archived from groups: rec.audio.pro (More info?)

"John Washburn" <johnwashburn99@nyc.rr.com> wrote in message
news:p ZQLc.56238$4h7.6769465@twister.nyc.rr.com

> I'm about to recap my board (Soundcraft 200B) which is getting hissy
> on some channels, and in researching options I found some discussion
> of bypassing electrolytic capacitors with film caps in parallel.

Recapping can be a darn good idea when you have problems like these. Did I
ever tell you about the time I thought my stereo receiver was losing its
bass, and I found that virtually every electrolytic coupling cap had lost
90% of its nameplate capacitance. Boy, did it sound better after I did THAT.

> The textbooks I've been using to teach myself basic electronics don't
> discuss this practice, so before I go ordering a bunch of components
> I may not even need, I have a few questions:

> 1. The benefit of bypassing electrolytic caps is typically in
> improved high frequency response because the lower value film cap
> will pass higher frequencies better than the higher value one, and
> vice versa? There's a counter argument about phase shift--how much is
> that worth worrying about?

I don't know of a counter argument based on phase shift.

There is a counter argument based on common sense - why do something that
has no tangible benefits? The answer to that challenge is that there may
sometimes be some tangible benefits. But not always.

The stated purposes for adding these caps relates to two well-known
effects - series inductance and dielectric absorption.

Every electrolytic capacitor, no every capacitor effectively has a little
inductor that is effectively in series with it. One historical way to
quantify this inductance is to give the frequency where this inductance
resonates the capacitance of the capacitor. Above this frequency, the
capacitor has lost its capacitive effects due to the series inductance. I
was surprised to learn that the self-resonant frequency of a common
wire-leaded 0.1 uF ceramic capacitor might be like 150 MHz. The major
source of inductance in that case was simply the lead wires.

At times the series inductance of a part may include more than just the lead
inductance, as the part itself may have appreciable inductance inside.
Aluminum electrolytic and larger film capacitors are commonly made up of
sheets of insulation and foil wound up in a roll. This is an obvious
opportunity to unintentionally introduce inductance. OTOH, a skillful
designer can work with the geometry and largely avoid excess inductance.
There are such things as low ESR and low ESL electrolytic capacitors. Most
of them end up in non-audio applications or in power supplies and power
amps.

Dielectric absorption is a more recent issue for audio, maybe 30 years old.
Dielectric absorption refers to the tendency of dielectric materials to
experience longer-term changes, and produce a capacitor that acts like it
has a larger capacitor in series with a large resistor, connected across the
capacitor's terminals.

In such cases quantification is off the essence. It's easy to say that "The
benefit of bypassing electrolytic caps is typically in
improved high frequency response", but what constitutes high frequencies,
and what constitutes a useful improvement?

These days it is relatively easy to make incredibly accurate frequency
response measurements, within a hundredth of a dB or better. Yet, AFAIK
nobody has ever produced an measurement of say a good commercial mic preamp
(to eliminate contrived situations), and showed that its frequency response
in the audio range was significantly improved by paralleling all of the
electrolytics with film caps.

If you run the numbers, you find out the reason why - series inductance in
most elecrolytics isn't a problem, and those few cases where it is, it gets
dealt with in the original design. Why? Because most ESL creates impedance
in the audio range that are a few ohms or less, and most coupling capacitors
drive resistances that are a thousand ohms or more - typically ten thousand
ohms or more. One ohm series reactance versus a ten thousand ohm load leads
to a loss of less than a thousandth of a dB.

If you understand dielectric absorption well, you just might hurt yourself
laughing when someone suggests that you address DA in a large electrolytic
by paralleling it with a film cap. Remember, we earlier found that DA was
due to a phantom capacitance that is in parallel with the cap. It's darn
hard to reduce parallel capacitance due to DA by *adding* parallel
capacitors, is it not?

> 2. Are there places where this isn't useful/helpful/worth dealing
> with? I'm guessing that the 47uf phantom blocking caps would benefit,
> but what about interstage coupling, etc?

Educate yourself. Learn how to make accurate frequency response of audio
gear, which is pretty cheap and easy to do these days. Then tack in some
parallel caps, and see what happens. What does it take to make accurate FR
measurements of audio gear? A PC with even a mediocre sound card and a
freebie piece of software called "Audio Rightmark".

What about all those deadly earnest listening tests where capacitor upgrades
saved some precious piece of legacy gear from the scrap heap? Well, either
the caps that were there to start with, had dried out and stopped being the
caps their nameplate described, or well unhh have you ever heard of
expectation effects, or placebo effects?

Let me tell you about all the DBTs that conclusively showed an audible
difference due to paralleling an electrolytic in a well-designed,
well-maintained piece of electronic equipment. () That was quick, now wasn't
it?

> 3. The value of the film cap should be 10% of the electrolytic. How
> critical is that value?

Depends on the application, but in the current context the value is so non
critical that you often find that adding it or removing it has no effect.

> 4. In an existing design, you just connect both caps at the same
> point, soldering the film cap to the point where the electrolytic
> attaches to the circuit board? In this case there's room on the other
> side of the circuit board. Since all the points on each side of a
> parallel network are electrically the same point, this would work,
> right?

Right, and that is why paralleling caps with film caps does nothing useful
for DA.
Related resources
Anonymous
July 22, 2004 7:57:54 PM

Archived from groups: rec.audio.pro (More info?)

"John Washburn" <johnwashburn99@nyc.rr.com> wrote in message
news:p ZQLc.56238$4h7.6769465@twister.nyc.rr.com...
> I'm about to recap my board (Soundcraft 200B) which is getting hissy on
some
> channels, and in researching options I found some discussion of bypassing
> electrolytic capacitors with film caps in parallel.
>
> The textbooks I've been using to teach myself basic electronics don't
> discuss this practice, so before I go ordering a bunch of components I may
> not even need, I have a few questions:
>
> 1. The benefit of bypassing electrolytic caps is typically in improved
high
> frequency response because the lower value film cap will pass higher
> frequencies better than the higher value one, and vice versa?

Not really. The bypassed electrolytic has lower impedance at high
frequencies than the electrolytic by itself. In power supply caps that
translates to better filtering of high-frequency components, including RFI.
When the electrolytic is a coupling cap, the impedance at the highest audio
frequencies, even unbypassed, is low enough not to matter. The putative
advantage of bypassing audio coupling caps is that the bypass cap, being
film, suffers less from dielectric absorption, particularly at high
frequencies. My own experience is that bypassing electrolytic coupling caps
indeed reduces the amount of audible high-frequency "hash" on things like
sibilants, but not as well as replacing the electrolytics with film caps. Of
course, this often isn't possible due to space limitations.

>There's a
> counter argument about phase shift--how much is that worth worrying about?

Not at all; my tests show *less* phase shift in a bypassed cap assembly than
in an unbypassed electrolytic.

> 2. Are there places where this isn't useful/helpful/worth dealing with?
I'm
> guessing that the 47uf phantom blocking caps would benefit, but what about
> interstage coupling, etc?

Interstage coupling with electrolytics is already problematic, as typically
the (polarized) electrolytic is used without a DC voltage across it, a
perfect example of bad design. Bypassing is a good idea; connecting up a
*pair* of electrolytics with a resistor to the power supply may be better:
+ +
-----||---------||------
|
1 Meg
|
V+

You then bypass the nose-to-nose electrolytics with a film cap. Note that
the effective capacitance is half of the capacitance of each electrolytic,
so that if you used 100uF caps the combined capacitance would be 500uF.

All this is awkward and space-consuming, yes.

> 3. The value of the film cap should be 10% of the electrolytic. How
critical
> is that value?

That's a good value, but there will be measurable benefits to high-frequency
impedance even bypassing a 1000uF electrolytic with a 0.1uF-1uF film cap.
Typical electrolytics have their resonant point (the frequency where they
stop being capacitors and turn into inductors) anywhere from around 6kHz
(3300uF caps) to 30kHz (100uF caps). Small film caps remain capacitative up
to the 200kHz region (0.47uF), 600kHz region (0.1uF) or well into the
megahertz region (.01uF caps, ceramic discs).

More specific data coming up in an article for audioXpress, probably about a
year from now.

> 4. In an existing design, you just connect both caps at the same point,
> soldering the film cap to the point where the electrolytic attaches to the
> circuit board? In this case there's room on the other side of the circuit
> board. Since all the points on each side of a parallel network are
> electrically the same point, this would work, right?

Right.

Peace,
Paul
Anonymous
July 22, 2004 7:57:55 PM

Archived from groups: rec.audio.pro (More info?)

You then bypass the nose-to-nose electrolytics with a film cap. Note that
> the effective capacitance is half of the capacitance of each electrolytic,
> so that if you used 100uF caps the combined capacitance would be 50uF.

500 was a typo.....
July 22, 2004 9:02:42 PM

Archived from groups: rec.audio.pro (More info?)

>
> Every electrolytic capacitor, no every capacitor effectively has a little
> inductor that is effectively in series with it. One historical way to
> quantify this inductance is to give the frequency where this inductance
> resonates the capacitance of the capacitor. Above this frequency, the
> capacitor has lost its capacitive effects due to the series inductance. I
> was surprised to learn that the self-resonant frequency of a common
> wire-leaded 0.1 uF ceramic capacitor might be like 150 MHz. The major
> source of inductance in that case was simply the lead wires.
>

The inductance is negligble at audio frequency.

At RF it may be an issue.

If you don't beleive me, try it, hook up a scope or whatever you trust
and look at a 2 kHz square wave signal, a two tone signal or whatever
you think is a good test, and then add the parallel cap. After the DC
settles down, see if there is any difference at all. I doubt it.

I'm sure the golden ears will disagree.

Mark
Anonymous
July 22, 2004 9:03:41 PM

Archived from groups: rec.audio.pro (More info?)

"Eric K. Weber" <eric-nospam@webermusic.com> wrote in message
news:XfSLc.33$Xt6.11593@news.uswest.net...
> You then bypass the nose-to-nose electrolytics with a film cap. Note that
> > the effective capacitance is half of the capacitance of each
electrolytic,
> > so that if you used 100uF caps the combined capacitance would be 50uF.
>
> 500 was a typo.....

Quite right; thank you!

Peace,
PPPPPPaul
Anonymous
July 22, 2004 11:32:51 PM

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey" wrote:
> John Washburn wrote:
> >
> >1. The benefit of bypassing electrolytic caps is typically in improved
high
> >frequency response because the lower value film cap will pass higher
> >frequencies better than the higher value one, and vice versa? There's a
> >counter argument about phase shift--how much is that worth worrying
about?
>
> The electrolytic can be looked at as a capacitor with a resistor and an
> inductor in series with it. The parasitic resistance and inductance are
> a problem at high frequencies. The smaller value film cap will provide
> a lower-impedance path to shunt those high frequencies around.

Makes perfect sense.

>
> I don't know what the phase shift counter-argument is. It will indeed
> change the phase characteristics of the circuit, but it will improve them.
> This could be a problem in some high-feedback circuits that are designed
> around particular electrolytics, but it should not be an issue in
well-designed
> gear.

Well... now I can't find it (naturally). Something to do with multiple
resonances causing smearing? Isn't that why 10% is the recommended value--so
the the resonance of the bypass cap is preportional to the cap being
bypassed?


>
> >2. Are there places where this isn't useful/helpful/worth dealing with?
I'm
> >guessing that the 47uf phantom blocking caps would benefit, but what
about
> >interstage coupling, etc?
>
> Certainly it's a good idea for interstage coupling. On a single-ended
circuit
> it's even a good idea for supply decoupling caps.

Great. Thanks!

-jw
Anonymous
July 22, 2004 11:44:42 PM

Archived from groups: rec.audio.pro (More info?)

"Paul Stamler" wrote:
> "John Washburn" wrote:

> > I'm about to recap my board (Soundcraft 200B) which is getting hissy on
> some
> > channels, and in researching options I found some discussion of
bypassing
> > electrolytic capacitors with film caps in parallel.
> >
> > The textbooks I've been using to teach myself basic electronics don't
> > discuss this practice, so before I go ordering a bunch of components I
may
> > not even need, I have a few questions:
> >
> > 1. The benefit of bypassing electrolytic caps is typically in improved
> high
> > frequency response because the lower value film cap will pass higher
> > frequencies better than the higher value one, and vice versa?
>
> Not really. The bypassed electrolytic has lower impedance at high
> frequencies than the electrolytic by itself. In power supply caps that
> translates to better filtering of high-frequency components, including
RFI.
> When the electrolytic is a coupling cap, the impedance at the highest
audio
> frequencies, even unbypassed, is low enough not to matter. The putative
> advantage of bypassing audio coupling caps is that the bypass cap, being
> film, suffers less from dielectric absorption, particularly at high
> frequencies.

Interesting.


My own experience is that bypassing electrolytic coupling caps
> indeed reduces the amount of audible high-frequency "hash" on things like
> sibilants, but not as well as replacing the electrolytics with film caps.
Of
> course, this often isn't possible due to space limitations.

Right. When there's 100uf coupling caps, there doesn't seem to be much
choice.


>
> >There's a
> > counter argument about phase shift--how much is that worth worrying
about?
>
> Not at all; my tests show *less* phase shift in a bypassed cap assembly
than
> in an unbypassed electrolytic.
>
> > 2. Are there places where this isn't useful/helpful/worth dealing with?
> I'm
> > guessing that the 47uf phantom blocking caps would benefit, but what
about
> > interstage coupling, etc?
>
> Interstage coupling with electrolytics is already problematic, as
typically
> the (polarized) electrolytic is used without a DC voltage across it, a
> perfect example of bad design. Bypassing is a good idea; connecting up a
> *pair* of electrolytics with a resistor to the power supply may be better:
> + +
> -----||---------||------
> |
> 1 Meg
> |
> V+
>
> You then bypass the nose-to-nose electrolytics with a film cap. Note that
> the effective capacitance is half of the capacitance of each electrolytic,
> so that if you used 100uF caps the combined capacitance would be 500uF.
>
> All this is awkward and space-consuming, yes.

Right. It looks like there is DC at most of the stages, so hopefully this
won't be necessary. In any case, I need to learn more before I can really
sus it to the point of actually redesigning the circuit that much.

>
> > 3. The value of the film cap should be 10% of the electrolytic. How
> critical
> > is that value?
>
> That's a good value, but there will be measurable benefits to
high-frequency
> impedance even bypassing a 1000uF electrolytic with a 0.1uF-1uF film cap.
> Typical electrolytics have their resonant point (the frequency where they
> stop being capacitors and turn into inductors) anywhere from around 6kHz
> (3300uF caps) to 30kHz (100uF caps). Small film caps remain capacitative
up
> to the 200kHz region (0.47uF), 600kHz region (0.1uF) or well into the
> megahertz region (.01uF caps, ceramic discs).

That certainly would seem to simplify things. Thanks!

-jw
Anonymous
July 22, 2004 11:55:18 PM

Archived from groups: rec.audio.pro (More info?)

"Arny Krueger" wrote:
> "John Washburn" wrote:
>
> > I'm about to recap my board (Soundcraft 200B) which is getting hissy
> > on some channels, and in researching options I found some discussion
> > of bypassing electrolytic capacitors with film caps in parallel.
>
> Recapping can be a darn good idea when you have problems like these. Did I
> ever tell you about the time I thought my stereo receiver was losing its
> bass, and I found that virtually every electrolytic coupling cap had lost
> 90% of its nameplate capacitance. Boy, did it sound better after I did
THAT.

I do seem to remember seeing something about that in my research. I don't
think my console is that far gone, but maybe it's on it's way, since it's
almost 20 years old.


>
> > The textbooks I've been using to teach myself basic electronics don't
> > discuss this practice, so before I go ordering a bunch of components
> > I may not even need, I have a few questions:
>
> > 1. The benefit of bypassing electrolytic caps is typically in
> > improved high frequency response because the lower value film cap
> > will pass higher frequencies better than the higher value one, and
> > vice versa? There's a counter argument about phase shift--how much is
> > that worth worrying about?
>
> I don't know of a counter argument based on phase shift.

I can't find it now. I don't think it was a big discussion...


>
> There is a counter argument based on common sense - why do something that
> has no tangible benefits? The answer to that challenge is that there may
> sometimes be some tangible benefits. But not always.
>
> The stated purposes for adding these caps relates to two well-known
> effects - series inductance and dielectric absorption.

<interesting discussion of series inductance and dielectric absorption
snipped>

>
> > 2. Are there places where this isn't useful/helpful/worth dealing
> > with? I'm guessing that the 47uf phantom blocking caps would benefit,
> > but what about interstage coupling, etc?
>
> Educate yourself.

I'm all about that...

Learn how to make accurate frequency response of audio
> gear, which is pretty cheap and easy to do these days. Then tack in some
> parallel caps, and see what happens. What does it take to make accurate FR
> measurements of audio gear? A PC with even a mediocre sound card and a
> freebie piece of software called "Audio Rightmark".

Downloaded. My laptop's feeble built-in soundcard probably isn't up to the
task, but I suppose there's still something I can learn there.

>
> What about all those deadly earnest listening tests where capacitor
upgrades
> saved some precious piece of legacy gear from the scrap heap? Well, either
> the caps that were there to start with, had dried out and stopped being
the
> caps their nameplate described, or well unhh have you ever heard of
> expectation effects, or placebo effects?

Naturally.

>
> Let me tell you about all the DBTs that conclusively showed an audible
> difference due to paralleling an electrolytic in a well-designed,
> well-maintained piece of electronic equipment. () That was quick, now
wasn't
> it?

Well, that could also be to do with lack of data, right? If there's no one
to conduct a DBT, it doesn't mean that there wasn't actual benefit derived.
(Nor does it mean there was, either).


> > 3. The value of the film cap should be 10% of the electrolytic. How
> > critical is that value?
>
> Depends on the application, but in the current context the value is so non
> critical that you often find that adding it or removing it has no effect.

Well, I suppose then, the task is to proceed with a vigilant ear.


> > 4. In an existing design, you just connect both caps at the same
> > point, soldering the film cap to the point where the electrolytic
> > attaches to the circuit board? In this case there's room on the other
> > side of the circuit board. Since all the points on each side of a
> > parallel network are electrically the same point, this would work,
> > right?
>
> Right, and that is why paralleling caps with film caps does nothing useful
> for DA.

But it could help with series inductance?

Thanks!

-jw
Anonymous
July 22, 2004 11:55:19 PM

Archived from groups: rec.audio.pro (More info?)

"John Washburn" <johnwashburn99@nyc.rr.com> wrote in message
news:GYULc.56247$4h7.6784516@twister.nyc.rr.com

> "Arny Krueger" wrote:

>> "John Washburn" wrote:

>>> I'm about to recap my board (Soundcraft 200B) which is getting hissy
>>> on some channels, and in researching options I found some discussion
>>> of bypassing electrolytic capacitors with film caps in parallel.

>> Recapping can be a darn good idea when you have problems like these.
>> Did I ever tell you about the time I thought my stereo receiver was
>> losing its bass, and I found that virtually every electrolytic
>> coupling cap had lost 90% of its nameplate capacitance. Boy, did it
>> sound better after I did THAT.

> I do seem to remember seeing something about that in my research. I
> don't think my console is that far gone, but maybe it's on it's way,
> since it's almost 20 years old.

There's another anecdote about a certain high end console manufacturer who
built a number of high end consoles with Philips electolytics. Three years
later they were all ready for recapping.

>>
>>> 2. Are there places where this isn't useful/helpful/worth dealing
>>> with? I'm guessing that the 47uf phantom blocking caps would
>>> benefit, but what about interstage coupling, etc?
>>
>> Educate yourself.
>
> I'm all about that...
>
> Learn how to make accurate frequency response of audio
>> gear, which is pretty cheap and easy to do these days. Then tack in
>> some parallel caps, and see what happens. What does it take to make
>> accurate FR measurements of audio gear? A PC with even a mediocre
>> sound card and a freebie piece of software called "Audio Rightmark".
>
> Downloaded. My laptop's feeble built-in soundcard probably isn't up
> to the task, but I suppose there's still something I can learn there.

First loop the card from in to out to establish your base line. The insert
the UUT into the loop, and measure again. Take the difference.

>> Let me tell you about all the DBTs that conclusively showed an
>> audible difference due to paralleling an electrolytic in a
>> well-designed, well-maintained piece of electronic equipment. ()
>> That was quick, now wasn't it?

> Well, that could also be to do with lack of data, right? If there's
> no one to conduct a DBT, it doesn't mean that there wasn't actual
> benefit derived. (Nor does it mean there was, either).

Note that I never said that none were tried.

;-)

>>> 4. In an existing design, you just connect both caps at the same
>>> point, soldering the film cap to the point where the electrolytic
>>> attaches to the circuit board? In this case there's room on the
>>> other side of the circuit board. Since all the points on each side
>>> of a parallel network are electrically the same point, this would
>>> work, right?
>>
>> Right, and that is why paralleling caps with film caps does nothing
>> useful for DA.
>
> But it could help with series inductance?

If there was a significant problem, for sure!
Anonymous
July 22, 2004 11:55:20 PM

Archived from groups: rec.audio.pro (More info?)

All theory aside, I've never liked the 'sound' of bypassed coupling
caps and have always ended up removing them.

Frank /~ http://newmex.com/f10
@/



On Thu, 22 Jul 2004 16:38:32 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>"John Washburn" <johnwashburn99@nyc.rr.com> wrote in message
>news:GYULc.56247$4h7.6784516@twister.nyc.rr.com
>
>> "Arny Krueger" wrote:
>
>>> "John Washburn" wrote:
>
>>>> I'm about to recap my board (Soundcraft 200B) which is getting hissy
>>>> on some channels, and in researching options I found some discussion
>>>> of bypassing electrolytic capacitors with film caps in parallel.
>
>>> Recapping can be a darn good idea when you have problems like these.
>>> Did I ever tell you about the time I thought my stereo receiver was
>>> losing its bass, and I found that virtually every electrolytic
>>> coupling cap had lost 90% of its nameplate capacitance. Boy, did it
>>> sound better after I did THAT.
>
>> I do seem to remember seeing something about that in my research. I
>> don't think my console is that far gone, but maybe it's on it's way,
>> since it's almost 20 years old.
>
>There's another anecdote about a certain high end console manufacturer who
>built a number of high end consoles with Philips electolytics. Three years
>later they were all ready for recapping.
>
>>>
>>>> 2. Are there places where this isn't useful/helpful/worth dealing
>>>> with? I'm guessing that the 47uf phantom blocking caps would
>>>> benefit, but what about interstage coupling, etc?
>>>
>>> Educate yourself.
>>
>> I'm all about that...
>>
>> Learn how to make accurate frequency response of audio
>>> gear, which is pretty cheap and easy to do these days. Then tack in
>>> some parallel caps, and see what happens. What does it take to make
>>> accurate FR measurements of audio gear? A PC with even a mediocre
>>> sound card and a freebie piece of software called "Audio Rightmark".
>>
>> Downloaded. My laptop's feeble built-in soundcard probably isn't up
>> to the task, but I suppose there's still something I can learn there.
>
>First loop the card from in to out to establish your base line. The insert
>the UUT into the loop, and measure again. Take the difference.
>
>>> Let me tell you about all the DBTs that conclusively showed an
>>> audible difference due to paralleling an electrolytic in a
>>> well-designed, well-maintained piece of electronic equipment. ()
>>> That was quick, now wasn't it?
>
>> Well, that could also be to do with lack of data, right? If there's
>> no one to conduct a DBT, it doesn't mean that there wasn't actual
>> benefit derived. (Nor does it mean there was, either).
>
>Note that I never said that none were tried.
>
>;-)
>
>>>> 4. In an existing design, you just connect both caps at the same
>>>> point, soldering the film cap to the point where the electrolytic
>>>> attaches to the circuit board? In this case there's room on the
>>>> other side of the circuit board. Since all the points on each side
>>>> of a parallel network are electrically the same point, this would
>>>> work, right?
>>>
>>> Right, and that is why paralleling caps with film caps does nothing
>>> useful for DA.
>>
>> But it could help with series inductance?
>
>If there was a significant problem, for sure!
>
Anonymous
July 23, 2004 12:18:52 AM

Archived from groups: rec.audio.pro (More info?)

"Mark" <makolber@yahoo.com> wrote in message
news:3367f36e.0407221602.29239d34@posting.google.com

>> Every electrolytic capacitor, no every capacitor effectively has a
>> little inductor that is effectively in series with it. One
>> historical way to quantify this inductance is to give the frequency
>> where this inductance resonates the capacitance of the capacitor.
>> Above this frequency, the capacitor has lost its capacitive effects
>> due to the series inductance. I was surprised to learn that the
>> self-resonant frequency of a common wire-leaded 0.1 uF ceramic
>> capacitor might be like 150 MHz. The major source of inductance in
>> that case was simply the lead wires.

> The inductance is negligible at audio frequency.

I agree that is almost always the case. That's why I wrote:

"If you run the numbers, you find out the reason why - series inductance in
most electrolytic isn't a problem, and those few cases where it is, it gets
dealt with in the original design. Why? Because most ESL creates impedance
in the audio range that are a few ohms or less, and most coupling capacitors
drive resistances that are a thousand ohms or more - typically ten thousand
ohms or more. One ohm series reactance versus a ten thousand ohm load leads
to a loss of less than a thousandth of a dB."

> At RF it may be an issue.

> If you don't believe me, try it, hook up a scope or whatever you trust
> and look at a 2 kHz square wave signal, a two tone signal or whatever
> you think is a good test, and then add the parallel cap. After the DC
> settles down, see if there is any difference at all. I doubt it.

If it was a problem in most audio circuits, it would show up as a measurable
difference in frequency response. If it were a problem in bypassing
applications, it would show up as instability and ringing, or at least a
noisy power supply line.

> I'm sure the golden ears will disagree.

They have been disagreeing for about 30 years. Most of the weirdness that is
going down today, traces back to Marsh and Jung.
Anonymous
July 23, 2004 1:55:39 AM

Archived from groups: rec.audio.pro (More info?)

Frank Vuotto <deepthrob@hotmail.com> wrote:
>All theory aside, I've never liked the 'sound' of bypassed coupling
>caps and have always ended up removing them.

What have you been using for bypass caps?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 23, 2004 1:57:50 AM

Archived from groups: rec.audio.pro (More info?)

Mark <makolber@yahoo.com> wrote:
>The inductance is negligble at audio frequency.
>
>At RF it may be an issue.
>
>If you don't beleive me, try it, hook up a scope or whatever you trust
>and look at a 2 kHz square wave signal, a two tone signal or whatever
>you think is a good test, and then add the parallel cap. After the DC
>settles down, see if there is any difference at all. I doubt it.

BUT be sure to run everything open-loop when you do this.

It would also be interesting to see if there is a difference in intermod
distortion doing this.

>I'm sure the golden ears will disagree.

It sounds different. I'm not sure _what_ that means, though.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 23, 2004 3:15:58 AM

Archived from groups: rec.audio.pro (More info?)

On 22 Jul 2004 21:55:39 -0400, kludge@panix.com (Scott Dorsey) wrote:

>Frank Vuotto <deepthrob@hotmail.com> wrote:

>>All theory aside, I've never liked the 'sound' of bypassed coupling
>>caps and have always ended up removing them.
>

>What have you been using for bypass caps?
>--scott

The last time I played with bypassing it was with an ST70 with the
Triode Electronics front end (my home amp). I tried .01/.005/.001
Rel-Caps (no, not at the same time) over .22 Hovland Musicaps or
Wonder Infini Caps.


Frank /~ http://newmex.com/f10
@/
Anonymous
July 23, 2004 6:47:50 AM

Archived from groups: rec.audio.pro (More info?)

On Thu, 22 Jul 2004 20:18:52 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>> I'm sure the golden ears will disagree.
>
>They have been disagreeing for about 30 years. Most of the weirdness that is
>going down today, traces back to Marsh and Jung.

Your point about the dissipation factor (non)advantage of bypassing
is very well taken. I'd suggest that the same applies for distortion
products, given the relative sizes of the cap's.

Where we perpetually differ is in weighting the relative importance
of incremental improvements. I would draw the conclusion that the
best solution is to not use electrolytic coupling cap's, period.

You would, I believe, conclude that their errors fall under a data
noise threshold, and folks should just get on with their biz.

I'd go so far as to say that "Most of the progress that is going down
today traces back to Marsh and Jung."

I wouldn't however say that you're wrong, cause you're not.

Chris Hornbeck
"Vote or Die" - P. Diddy
Anonymous
July 23, 2004 6:56:13 AM

Archived from groups: rec.audio.pro (More info?)

"Chris Hornbeck" <chrishornbeckremovethis@att.net> wrote in message
news:e9u0g0phntrki6b8j41nm2a7e5fnhgu1fm@4ax.com

> On Thu, 22 Jul 2004 20:18:52 -0400, "Arny Krueger" <arnyk@hotpop.com>
> wrote:

>>> I'm sure the golden ears will disagree.

>> They have been disagreeing for about 30 years. Most of the weirdness
>> that is going down today, traces back to Marsh and Jung.

> Your point about the dissipation factor (non)advantage of bypassing
> is very well taken. I'd suggest that the same applies for distortion
> products, given the relative sizes of the cap's.

Well yes. The distortion products come from running unbiased electrolytics.
One of the best working solutions is to bias them by some means, one of
which was discussed by Paul Stamler. This issue was well-known long before
Marsh and Jung. For example I believe it was mentioned by Howard Tremaine in
his Audio Encyclopedia's First Edition around 1962.

> Where we perpetually differ is in weighting the relative importance
> of incremental improvements. I would draw the conclusion that the
> best solution is to not use electrolytic coupling cap's, period.

I draw a similar conclusion - electrolytics are clearly a convenient evil.

> You would, I believe, conclude that their errors fall under a data
> noise threshold, and folks should just get on with their biz.

No, I conclude that electrolytics first and foremost disappoint because they
are steadily loosing their capacitance, whether slow or fast. No small shunt
capacitor or other trick helps with that basic problem. Electrolytic caps
seem to first show up in electronics gear in the 1930s. Their life
characteristics have not really improved that much since then. They have
gotten a whole lot smaller, though. People have been trying to avoid
electrolytics about as long as they have existed. The alternatives are
always much larger and more expensive.

> I'd go so far as to say that "Most of the progress that is going down
> today traces back to Marsh and Jung."

There has been very little progress due to Marsh and Jung because they
completely blew 50% of their analysis by misinterpreting the meaning and
proper treatment of DA. They mislead themselves and their followers by
basing far-reaching conclusions on highly unreliable listening tests.

I would suggest that the long-term solution to the electrolytic capacitor
has been digital audio. It forces them out of the signal path and relegates
them to the power supply and related circuitry.

> I wouldn't however say that you're wrong, cause you're not.

Thank you.
Anonymous
July 23, 2004 11:59:57 AM

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey"


> The electrolytic can be looked at as a capacitor with a resistor and an
> inductor in series with it.


** The "inductance problem" associated with electros is another idiotic
myth - they have no more inductance than a length of wire the same as the
length of the cap.



> The parasitic resistance and inductance are a problem at high frequencies.


** Resistance is an issue to be considered at any frequency - but the
miniscule inductance is not a problem in audio circuits.


> The smaller value film cap will provide a lower-impedance path to shunt
those high frequencies around.


** That is a false over generalisation - only in a few cases ( with
very low value electros ) will the film cap have a lower impedance at 20 kHz
than the electro does.


Examples:

A 47 uF, 63 volt electro has a series impedance of around 0.5 ohms at 20
kHz and above.

A 1 uF film cap does not have an impedance of 0.5 ohms until the
frequency is 320 kHz !!!





............... Phil
Anonymous
July 23, 2004 1:15:19 PM

Archived from groups: rec.audio.pro (More info?)

In article <3n51g09laamce56d0n62fjqt5qe3v6djbn@4ax.com>,
Frank Vuotto <deepthrob@hotmail.com> wrote:
>On 22 Jul 2004 21:55:39 -0400, kludge@panix.com (Scott Dorsey) wrote:
>
>>Frank Vuotto <deepthrob@hotmail.com> wrote:
>
>>>All theory aside, I've never liked the 'sound' of bypassed coupling
>>>caps and have always ended up removing them.
>
>>What have you been using for bypass caps?
>
>The last time I played with bypassing it was with an ST70 with the
>Triode Electronics front end (my home amp). I tried .01/.005/.001
>Rel-Caps (no, not at the same time) over .22 Hovland Musicaps or
>Wonder Infini Caps.

That would indeed not sound good. The Hovland caps aren't electrolytics
and don't have the problems that electrolytics have. Adding bypass caps
to them is solving a problem that doesn't exist.

Try 'em on the coupling caps in an ST420 and you might change your mind.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 23, 2004 5:44:45 PM

Archived from groups: rec.audio.pro (More info?)

On 23 Jul 2004 09:15:19 -0400, Scott Dorsey <kludge@panix.com> wrote:
> In article <3n51g09laamce56d0n62fjqt5qe3v6djbn@4ax.com>,
> Frank Vuotto <deepthrob@hotmail.com> wrote:
>>On 22 Jul 2004 21:55:39 -0400, kludge@panix.com (Scott Dorsey) wrote:
>>
>>>Frank Vuotto <deepthrob@hotmail.com> wrote:
>>
>>>>All theory aside, I've never liked the 'sound' of bypassed coupling
>>>>caps and have always ended up removing them.
>>
>>>What have you been using for bypass caps?
>>
>>The last time I played with bypassing it was with an ST70 with the
>>Triode Electronics front end (my home amp). I tried .01/.005/.001
>>Rel-Caps (no, not at the same time) over .22 Hovland Musicaps or
>>Wonder Infini Caps.
>

Is it feasible to replace aluminum electrolytics with Tantalum
electrolytics in audio circuits?
Anonymous
July 23, 2004 5:44:46 PM

Archived from groups: rec.audio.pro (More info?)

U-CDK_CHARLES\\Charles <cdkrug@aol.com> wrote:
>
>Is it feasible to replace aluminum electrolytics with Tantalum
>electrolytics in audio circuits?

Often, but why would you want to?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 23, 2004 7:36:34 PM

Archived from groups: rec.audio.pro (More info?)

On Fri, 23 Jul 2004 02:56:13 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>"Chris Hornbeck" <chrishornbeckremovethis@att.net> wrote in message
>news:e9u0g0phntrki6b8j41nm2a7e5fnhgu1fm@4ax.com

>> Your point about the dissipation factor (non)advantage of bypassing
>> is very well taken. I'd suggest that the same applies for distortion
>> products, given the relative sizes of the cap's.
>
>Well

Obviously I misspoke. I meant to say DA (non)advantage. But you knew
that.

Thanks for your comments,

Chris Hornbeck
"Vote or Die" - P. Diddy
Anonymous
July 23, 2004 7:42:15 PM

Archived from groups: rec.audio.pro (More info?)

On 23 Jul 2004 10:21:17 -0400, Scott Dorsey <kludge@panix.com> wrote:
> U-CDK_CHARLES\\Charles <cdkrug@aol.com> wrote:
>>
>>Is it feasible to replace aluminum electrolytics with Tantalum
>>electrolytics in audio circuits?
>

Don't they last longer?
Anonymous
July 23, 2004 7:42:16 PM

Archived from groups: rec.audio.pro (More info?)

U-CDK_CHARLES\\Charles <cdkrug@aol.com> wrote:
>On 23 Jul 2004 10:21:17 -0400, Scott Dorsey <kludge@panix.com> wrote:
>> U-CDK_CHARLES\\Charles <cdkrug@aol.com> wrote:
>>>
>>>Is it feasible to replace aluminum electrolytics with Tantalum
>>>electrolytics in audio circuits?
>
>Don't they last longer?

Not really, and when they do fail, they tend to fail into dead shorts
which is a bad thing in some applications. The reason tantalums get
used in place of aluminum types is mostly because of the smaller physical
size and the better high frequency performance. These days the high
frequency performance of the aluminums is getting considerably better than
it used to be, though.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 23, 2004 8:17:41 PM

Archived from groups: rec.audio.pro (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in message
news:VZmdnQjBQoj9xJ3c4p2dnA@comcast.com...

> If it was a problem in most audio circuits, it would show up as a
measurable
> difference in frequency response. If it were a problem in bypassing
> applications, it would show up as instability and ringing, or at least a
> noisy power supply line.

Instability is precisely the reason I began investigating bypassing. I've
had a couple of circuits go oscillating off into the stratosphere because of
inadequate or badly-thought-out bypassing. Doing it right cleaned them up.

Peace,
Paul
Anonymous
July 23, 2004 8:21:36 PM

Archived from groups: rec.audio.pro (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in message
news:WcednUkCZpHiK53cRVn-sA@comcast.com...

> I would suggest that the long-term solution to the electrolytic capacitor
> has been digital audio. It forces them out of the signal path and
relegates
> them to the power supply and related circuitry.

Naw; most digital audio, unless it's completely synthetic, started out as
waves in the air, went through at least one microphone, mike pre and A/D
converter. In all of those places electrolytics can show up and do their
dastardly deeds. It's possible to design in ways that don't use them except
in the power supply, but most manufacturers don't.

Peace,
Paul
Anonymous
July 23, 2004 9:22:52 PM

Archived from groups: rec.audio.pro (More info?)

"Arny Krueger" <arnyk@hotpop.com
>
> No, I conclude that electrolytics first and foremost disappoint because
they
> are steadily loosing their capacitance, whether slow or fast. No small
shunt
> capacitor or other trick helps with that basic problem.


** That just aint true. Electros hold their original capacitance value over
their whole life. Only when most of the electrolyte has been lost does the
ESR value rise significantly followed finally by a loss of capacitance.
This process takes decades unless the cap is subjected to high temps on a
continuous basis.

This is proven by the fact that an ESR tester ( as used by nearly all
service techs theses days ) will locate a bad electro *long before*
capacitance tests on the same cap show a loss of microfarads.

For coupling audio circuits where there is no DC bias it is best to use
bi-polar electros - even with significant AC voltage across them at low
audio frequencies they show no tendency to produce harmonics.






........... Phil
Anonymous
July 23, 2004 9:22:53 PM

Archived from groups: rec.audio.pro (More info?)

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:2mbsmcFl00dkU1@uni-berlin.de
> "Arny Krueger" <arnyk@hotpop.com
>>
>> No, I conclude that electrolytics first and foremost disappoint
>> because they are steadily loosing their capacitance, whether slow or
>> fast. No small shunt capacitor or other trick helps with that basic
>> problem.

> ** That just aint true. Electros hold their original capacitance
> value over their whole life.

Doesn't explain the distribution of capacitance values I've seen in failed
parts. For example one batch of failing 10 uF parts had degraded to values
that ranged from about 6 uF to 1 uF after about 4 years.

Perhaps steadily is a bad choice of words, but there is an ongoing loss.

>Only when most of the electrolyte has
> been lost does the ESR value rise significantly followed finally by a
> loss of capacitance. This process takes decades unless the cap is
> subjected to high temps on a continuous basis.

On a good day the process can take decades, but there are clearly such
things as defective electrolytics that die in a few years. The last failing
ones I identified were the analog output coupling caps on a Sony CD player.
Both parts failed. Ironically, they had markings that were obviously
designed to impress audiophiles. The good news was that I had shifted to
using the digital output.

It strikes me that bipolar caps might have about twice the failure rate
because the ones I've taken apart were really two components in one outer
package.
Anonymous
July 23, 2004 9:54:26 PM

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey" <kludge@panix.com> wrote in message
news:cdonqe$ec6$1@panix2.panix.com...
> John Washburn <johnwashburn99@nyc.rr.com> wrote:
> >
> >1. The benefit of bypassing electrolytic caps is typically in
improved high
> >frequency response because the lower value film cap will pass
higher
> >frequencies better than the higher value one, and vice versa?
There's a
> >counter argument about phase shift--how much is that worth worrying
about?
>
> The electrolytic can be looked at as a capacitor with a resistor and
an
> inductor in series with it. The parasitic resistance and inductance
are
> a problem at high frequencies. The smaller value film cap will
provide
> a lower-impedance path to shunt those high frequencies around.

The series resistance forms a zero in the loop response of a circuit.
Although the value of the resistor is poorly controlled, it may be a
necessary component to prevent the circuit from oscillating at a high
frequency. Bypassing the electrolytic with a capacitor may cause such
oscillation. This is not some far out theoretical nonsense. It
happens. It's happened to me!

Norm Strong
Anonymous
July 23, 2004 9:54:27 PM

Archived from groups: rec.audio.pro (More info?)

normanstrong <normanstrong@comcast.net> wrote:
>
>The series resistance forms a zero in the loop response of a circuit.
>Although the value of the resistor is poorly controlled, it may be a
>necessary component to prevent the circuit from oscillating at a high
>frequency. Bypassing the electrolytic with a capacitor may cause such
>oscillation. This is not some far out theoretical nonsense. It
>happens. It's happened to me!

Yes, absolutely! I mentioned this as being an issue with high feedback
circuits, didn't I? It may well be necessary to alter compensation networks
when this happens.

This is especially a big issue with circuits that have low phase margins to
begin with, like some equalizers. I think the Gately EQ modules were my
first introduction to this problem.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 23, 2004 10:02:12 PM

Archived from groups: rec.audio.pro (More info?)

"Arny Krueger" <
> "Phil Allison" <

> >> No, I conclude that electrolytics first and foremost disappoint
> >> because they are steadily loosing their capacitance, whether slow or
> >> fast. No small shunt capacitor or other trick helps with that basic
> >> problem.
>
> > ** That just aint true. Electros hold their original capacitance
> > value over their whole life.
>
> Doesn't explain the distribution of capacitance values I've seen in failed
> parts.


** When electro caps fail, for whatever reason, they have certainly reached
the end of their life.

Think it through - Arny.


> For example one batch of failing 10 uF parts had degraded to values
> that ranged from about 6 uF to 1 uF after about 4 years.


** This has no bearing on my post.

Electros will do that if the manufacture is flawed ( ie bad seals will let
the electrolyte escape) or they are subjected to constant high temps for
years.


> Perhaps steadily is a bad choice of words, but there is an ongoing loss.


** No there is not.

You are using the fallacy of arguing from the particular to the general.


>
> >Only when most of the electrolyte has
> > been lost does the ESR value rise significantly followed finally by a
> > loss of capacitance. This process takes decades unless the cap is
> > subjected to high temps on a continuous basis.
>
>
> On a good day the process can take decades, but there are clearly such
> things as defective electrolytics that die in a few years.


** Faulty ones may even explode or leak liquid electrolyte - but this is
rare.

You are using the fallacy of arguing from the particular to the general



> It strikes me that bipolar caps might have about twice the failure rate
> because the ones I've taken apart were really two components in one outer
> package.


** That is not the usual way they are made. The normal life span is the
same as for other electros.




.............. Phil
Anonymous
July 24, 2004 9:39:45 AM

Archived from groups: rec.audio.pro (More info?)

Phil Allison wrote:

> "Scott Dorsey"
>
> > The electrolytic can be looked at as a capacitor with a resistor and an
> > inductor in series with it.
>
> ** The "inductance problem" associated with electros is another idiotic
> myth - they have no more inductance than a length of wire the same as the
> length of the cap.

Over-simplification.

Any *wound* component such as an electrolytic capacitor has true inductance -
and it *isn't* the 'length of the cap' for typical wound designs.

It's necessary to consider the length of the foil !

Many other designs of capacitor ( e.g plate ) avoid this by construction.

Many popular capacitors e.g wound mylar also have significant inductance w.r.t
their 'planar' equivalents.

Do please consider capacitor construction techniques !



Graham
Anonymous
July 24, 2004 9:39:46 AM

Archived from groups: rec.audio.pro (More info?)

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:4101E811.ED48169A@hotmail.com
> Phil Allison wrote:

>> "Scott Dorsey"

>>> The electrolytic can be looked at as a capacitor with a resistor
>>> and an inductor in series with it.

>> ** The "inductance problem" associated with electros is another
>> idiotic myth - they have no more inductance than a length of wire
>> the same as the length of the cap.

> Over-simplification.

Agreed.

> Any *wound* component such as an electrolytic capacitor has true
> inductance - and it *isn't* the 'length of the cap' for typical
> wound designs.

> It's necessary to consider the length of the foil !

Agreed.

Right up front, an electrolytic will have less inductance than a film
capacitor, all other things being equal, because the length of the foil in
the electrolytic will be shorter, because the electrolytic has far higher
capacitance per given area of dielectric.

Then you have to consider the operation of the capacitor over the length of
the foil. A capacitor with a roll of foil a foot long does not require that
all signals traverse the entire length of the foil as they would with an
inductor. The foil stack is terminated at one end. The highest frequencies
will traverse the dielectric with low loss close to the termination point,
because they need the least capacitance to traverse the dielectric.

Finally, you have to consider how much inductance there actually is and how
significant it is to audio, even when the foil strips inside the capacitor
are long. For many years AM radios, which have IF stages that run at about
half a megahertz (455 KHz), used paper capacitors for bypass capacitors.
When I was a boy, I would sometimes cut them apart and unroll foot after
foot of thin strips of aluminum foil. But, they still did their job at half
a megahertz. When we talk about coupling capacitors we're talking audio,
which involves frequencies that are a minimum of 22 times lower than AM
radio IF stages. In fact it was not uncommon to find tubed AM radios that
were built with nothing but air, paper and electrolytic capacitors. No
mica(other than tiny trimmers), no ceramic, and certainly no plastic film.

> Many other designs of capacitor ( e.g plate ) avoid this by construction.

So can electrolytics. For example some tantalum electrolytic capacitors
don't have long strips of foil. Instead, some of them are composed of a
porous slug.

While tantalum capacitors can introduce a lot of distortion when there is no
DC voltage across them, a SS amplifier or preamplifier with a single power
supply can do a pretty good job of ensuring that every capacitor does have
significant amounts of DC across it. A single unbiased tantalum capacitor
can cause on the order of one percent nonlinear distortion. But I've seen SS
equipment with properly biased tantalum coupling capacitors that had no
more distortion than it did with aluminum electrolytics - less than 0.05%
and with many cascaded stages.

> Many popular capacitors e.g wound Mylar also have significant
> inductance w.r.t their 'planar' equivalents.

Agreed.

> Do please consider capacitor construction techniques !

Just another situation where all generalizations are false because of the
diversity of the technology.
Anonymous
July 24, 2004 1:19:12 PM

Archived from groups: rec.audio.pro (More info?)

Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
>
>Any comment regarding the solid aluminium electrolytic type e.g as made by
>Philips - now BC Components ? Nothing to dry out !

Sanyo first started making them, and BC is now making them as well. The
problem with this technology seems to be the same as with the dry slug
tantalum technology, that when they do finally fail they fail into a
dead short.

The Sanyo data sheets specifically say not to use the solid aluminums as
audio coupling capacitors, and this has to either be because of the failure
mode as a short or because they are worried about zero-bias coupling
applications. The Sanyo rep didn't know which one it was.

B&D Electronics sells the Sanyos really cheap and I keep meaning to buy
a bag of them and see how they sound. DA at high frequencies is excellent.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 24, 2004 3:05:50 PM

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey" <kludge@panix.com> wrote in message
news:cdtnkg$ma7$1@panix3.panix.com

DA at high frequencies is excellent.


Just a friendly reminder that DA is always modeled as a big parasitic
capacitor with a big parasitic resistor in series with it. The resulting
time constant is therefore big, so the frequencies it affects in analog
circuitry are low.

Perhaps you meant DF or ESL?
Anonymous
July 24, 2004 6:52:49 PM

Archived from groups: rec.audio.pro (More info?)

"Pooh Bear"
> Phil Allison wrote:
> > "Scott Dorsey"
> >
> > > The electrolytic can be looked at as a capacitor with a resistor and
an
> > > inductor in series with it.
> >
> > ** The "inductance problem" associated with electros is another
idiotic
> > myth - they have no more inductance than a length of wire the same as
the
> > length of the cap.
>
>
> Over-simplification.


** Nope - but Pooh face is about to post a *whole bunch* of them.


> Any *wound* component


** A "wound component " is a coil or transformer.


> such as an electrolytic capacitor has true inductance -
> and it *isn't* the 'length of the cap' for typical wound designs.


** Yes it is.

>
> It's necessary to consider the length of the foil !
>

** Nope - just the width or distance between the wire leads for an axial
type.

Radials may have a little more as one lead completes the return to the
base.


> Many popular capacitors e.g wound mylar also have significant inductance
w.r.t
> their 'planar' equivalents.

> Do please consider capacitor construction techniques !


** The problem is that Pooh face has not.

He just blows it out his bum as usual.





......... Phil
Anonymous
July 24, 2004 9:10:11 PM

Archived from groups: rec.audio.pro (More info?)

On Sat, 24 Jul 2004 11:05:50 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>Just a friendly reminder that DA is always modeled as a big parasitic
>capacitor with a big parasitic resistor in series with it. The resulting
>time constant is therefore big, so the frequencies it affects in analog
>circuitry are low.

I do wonder about how realistic that model is. Wouldn't the model
need to include a battery?

Chris Hornbeck
"Vote or Die" - P. Diddy
Anonymous
July 24, 2004 9:10:12 PM

Archived from groups: rec.audio.pro (More info?)

"Chris Hornbeck" <chrishornbeckremovethis@att.net> wrote in message
news:kk55g09s8nruu3r28mtjroht173mb4aspe@4ax.com
> On Sat, 24 Jul 2004 11:05:50 -0400, "Arny Krueger" <arnyk@hotpop.com>
> wrote:
>
>> Just a friendly reminder that DA is always modeled as a big parasitic
>> capacitor with a big parasitic resistor in series with it. The
>> resulting time constant is therefore big, so the frequencies it
>> affects in analog circuitry are low.
>
> I do wonder about how realistic that model is. Wouldn't the model
> need to include a battery?

Actually, the more refined model includes more capacitors and more
resistors.

Here's one of the more acessible discussions of the DA issue, from an analog
design perspective:

http://www.national.com/rap/Application/0,1570,28,00.ht...

Here's a sequel article by the same guy, relating DA to audio:

http://www.elecdesign.com/Articles/ArticleID/6096/6096....
Anonymous
July 24, 2004 11:55:18 PM

Archived from groups: rec.audio.pro (More info?)

On Sat, 24 Jul 2004 14:50:19 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>Here's one of the more acessible discussions of the DA issue, from an analog
>design perspective:
>
>http://www.national.com/rap/Application/0,1570,28,00.ht...
>
>Here's a sequel article by the same guy, relating DA to audio:
>
>http://www.elecdesign.com/Articles/ArticleID/6096/6096....

Thanks for the references. I'd never heard the term "soakage"
before. And the heating effects are certainly provocative.

Chris Hornbeck
"Vote or Die" - P. Diddy
Anonymous
July 25, 2004 5:27:28 AM

Archived from groups: rec.audio.pro (More info?)

On Thu, 22 Jul 2004 15:57:54 GMT, "Paul Stamler"
<pstamlerhell@pobox.com> wrote:

>"John Washburn" <johnwashburn99@nyc.rr.com> wrote in message
>news:p ZQLc.56238$4h7.6769465@twister.nyc.rr.com...

>>...

>> 1. The benefit of bypassing electrolytic caps is typically in improved
>high
>> frequency response because the lower value film cap will pass higher
>> frequencies better than the higher value one, and vice versa?
>
>Not really. The bypassed electrolytic has lower impedance at high
>frequencies than the electrolytic by itself. In power supply caps that
>translates to better filtering of high-frequency components, including RFI.
>When the electrolytic is a coupling cap, the impedance at the highest audio
>frequencies, even unbypassed, is low enough not to matter. The putative
>advantage of bypassing audio coupling caps is that the bypass cap, being
>film, suffers less from dielectric absorption, particularly at high
>frequencies.

Arny is saying essentially the same thing in this thread, that one
alleged source of problems, perhaps the main problem, with
electrolytics in audio is dielectric absorption. He goes on to
describe an equivalent circuit consisting of several other capacitors
with high-value resistors in series, all across this otherwise-perfect
capacitor (there's a hand-drawn circuit in Bob Pease's article on
soakage). It seems to me that this would have no audible effect in a
coupling capacitor in an audio circuit (OTOH it has obvious negative
effects for a capacitor in a sample-and-hold circuit). My reasoning
for this is that all these capacitors and resistors in this dielectric
absorption model are perfectly linear and can at worst affect phase
shift, and even then to a very small degree.
I suspect the "problem" you hear is actual nonlinearity in the
capacitor that causes harmonic distortion in the signal. I've seen at
least one frequency-response curve of harmonic distortion caused by an
electrolytic, on Douglas Self's webpage "Distortion in Power
Amplifiers."
When bypassed with a film cap, the distorting element (the
electrolytic) is to an extent "shorted out" with a more linear
reactance. As an analogy, two back-to-back diodes used to couple a
signal will give a lot of distortion, but if a small-value resistor is
placed across them, the peak voltage across them may drop to where the
diodes don't conduct appreciably, virtually eliminating the
distortion.

>My own experience is that bypassing electrolytic coupling caps
>indeed reduces the amount of audible high-frequency "hash" on things like
>sibilants, but not as well as replacing the electrolytics with film caps. Of
>course, this often isn't possible due to space limitations.

This argues against the dielectric absorption cause. If in a
sample-and-hold you parallel an electrolytic with a film cap 1/10th
its value, you only reduce the effect of dielectric absorption by 10
percent. I presume you're claiming that the amount of bad stuff you
hear is reduced by more than 10 percent when a 1/10th-value film cap
is put in parallel with an electrolytic.

It might be interesting to create a physical equivalent to an
electrolytic capacitor and its dielectric absorption using film caps
and resistors (as in Pease's schematic). I suspect, for those who can
reliably hear a difference, that the "model" cap will sound like a
film cap rather than like an electrolytic.

>... { more good discussion such as... }

>> 3. The value of the film cap should be 10% of the electrolytic. How
>critical
>> is that value?
>
>That's a good value, but there will be measurable benefits to high-frequency
>impedance even bypassing a 1000uF electrolytic with a 0.1uF-1uF film cap.

>Peace,
>Paul
Anonymous
July 25, 2004 5:35:33 AM

Archived from groups: rec.audio.pro (More info?)

On Fri, 23 Jul 2004 18:02:12 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

>
>"Arny Krueger" <
>> "Phil Allison" <
>
>> >> No, I conclude that electrolytics first and foremost disappoint
>> >> because they are steadily loosing their capacitance, whether slow or
>> >> fast. No small shunt capacitor or other trick helps with that basic
>> >> problem.
>>
>> > ** That just aint true. Electros hold their original capacitance
>> > value over their whole life.
>>
>> Doesn't explain the distribution of capacitance values I've seen in failed
>> parts.
>
>
>** When electro caps fail, for whatever reason, they have certainly reached
>the end of their life.

Is that how the manufacturers define it? So infant mortality means
"We waranty our parts for life, but these have obviously reached the
END of their lives, so they're not covered under warranty." Sounds
circular to me.

> Think it through - Arny.

Trollin, trollin, trollin...
Anonymous
July 25, 2004 8:54:51 AM

Archived from groups: rec.audio.pro (More info?)

"Ben Bradley" <ben_nospam_bradley@mindspring.com> wrote in message
news:r0e6g0dehopukffg3e7hv6rt8ms1psk0an@4ax.com

> I suspect the "problem" you hear is actual nonlinearity in the
> capacitor that causes harmonic distortion in the signal. I've seen at
> least one frequency-response curve of harmonic distortion caused by an
> electrolytic, on Douglas Self's webpage "Distortion in Power
> Amplifiers."

This curve is in item 5.8 of the page posted at

http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm#5

It shows a rise in distortion from about 0.0004% THD at 150 Hz to 0.04% THD
at 10 Hz, presetned in the context of an analysis of a power amp design that
Self calls "blameless". The part in question is a 47uF 25V capacitor driving
8 Vrms into a 680 Ohm load The details suggest that this is in fact not an
analysis of the power amp design being discussed, but rather a 5532 op
amp-based circuit. The point that is being made is that there is a
distortion mechanism in at least some electrolytic caps when a large signal
voltage appears across the dielectric. By definiition, this does not happen
with coupling caps and in-band signals. However, it might happen with
out-of-band subsonic signals.

I should add that hearing 0.04% nonlinear distortion is highly unlikely. But
this distortioin might be larger with other capacitors. It might build up
over multiple stages. Were the capacitor in question a tantalum capacitor
the distortion might be 10 times or more larger. Bottom line, don't use
electrolytic caps in frequency-response determining networks. Two words come
to mind: loudspeaker crossovers.

> When bypassed with a film cap, the distorting element (the
> electrolytic) is to an extent "shorted out" with a more linear
> reactance.

The film cap in quesiton would be a sight to see, because it would have to
be considerably larger than 47 uF, because this is a low frequency effect
caused by the fact that the 47 uF cap has considerable reactance (362 ohms)
at 10 Hz.

In fact, one working solution would be to use a larger electrolytic
capacitor. However, in the stated application (Sallen and Key Filter) this
would be inapporpriate n because it would profoundly change how the Sallen
and Key filter worked! OTOH, were this a coupling cap, the use of a larger
electrolytic capacitor would be appropriate and have the desired result (low
distortion).

> As an analogy, two back-to-back diodes used to couple a
> signal will give a lot of distortion, but if a small-value resistor is
> placed across them, the peak voltage across them may drop to where the
> diodes don't conduct appreciably, virtually eliminating the
> distortion.

In this case, the "small value resistor" would be a capacitor with reactance
of considerably less than 363 ohms at 10 Hz. In a coupling application I
would recommend a 4700 uF capactor. Now if you wish to implement this with a
film cap... ;-).

I believe that author's point is that electrolytics are highly questionable
components for frequency-sensitive networks where it is reasonable to expect
that a large voltage will be dropped across the capacitor in normal
operation.

>> My own experience is that bypassing electrolytic coupling caps
>> indeed reduces the amount of audible high-frequency "hash" on things
>> like sibilants, but not as well as replacing the electrolytics with
>> film caps. Of course, this often isn't possible due to space
>> limitations.

> This argues against the dielectric absorption cause. If in a
> sample-and-hold you parallel an electrolytic with a film cap 1/10th
> its value, you only reduce the effect of dielectric absorption by 10
> percent. I presume you're claiming that the amount of bad stuff you
> hear is reduced by more than 10 percent when a 1/10th-value film cap
> is put in parallel with an electrolytic.

It also argues against the effect that Self is pointing out in
http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm#5 and the solution
proposed in the previous paragraph.

> It might be interesting to create a physical equivalent to an
> electrolytic capacitor and its dielectric absorption using film caps
> and resistors (as in Pease's schematic). I suspect, for those who can
> reliably hear a difference, that the "model" cap will sound like a
> film cap rather than like an electrolytic.

Agreed.
Anonymous
July 25, 2004 9:51:00 AM

Archived from groups: rec.audio.pro (More info?)

On Sun, 25 Jul 2004 01:27:28 -0400, Ben Bradley
<ben_nospam_bradley@mindspring.com> wrote:

> It seems to me that this would have no audible effect in a
>coupling capacitor in an audio circuit (OTOH it has obvious negative
>effects for a capacitor in a sample-and-hold circuit). My reasoning
>for this is that all these capacitors and resistors in this dielectric
>absorption model are perfectly linear and can at worst affect phase
>shift, and even then to a very small degree.

OTOH this model is speculative at best and wasn't presented
in an audio context. It's certainly an interesting starting
point though.

> I suspect the "problem" you hear is actual nonlinearity in the
>capacitor that causes harmonic distortion in the signal. I've seen at
>least one frequency-response curve of harmonic distortion caused by an
>electrolytic, on Douglas Self's webpage "Distortion in Power
>Amplifiers."
> When bypassed with a film cap, the distorting element (the
>electrolytic) is to an extent "shorted out" with a more linear
>reactance.

This conclusion is troublesome to me. Relative sizes of cap's,
parasitic series elements, etc.


> This argues against the dielectric absorption cause. If in a
>sample-and-hold you parallel an electrolytic with a film cap 1/10th
>its value, you only reduce the effect of dielectric absorption by 10
>percent.

Yeah, in fact I would suggest, less.

> It might be interesting to create a physical equivalent to an
>electrolytic capacitor and its dielectric absorption using film caps
>and resistors (as in Pease's schematic). I suspect, for those who can
>reliably hear a difference, that the "model" cap will sound like a
>film cap rather than like an electrolytic.

Again, this model is only very weakly appropriate.

Pease's mention of thermal effects is quite .... something ....

Chris Hornbeck
"Vote or Die" - P. Diddy
Anonymous
July 25, 2004 9:51:01 AM

Archived from groups: rec.audio.pro (More info?)

"Chris Hornbeck" <chrishornbeckremovethis@att.net> wrote in message
news:0ph6g05ucvhke7loof5u0bbr4drugsqau2@4ax.com
> On Sun, 25 Jul 2004 01:27:28 -0400, Ben Bradley
> <ben_nospam_bradley@mindspring.com> wrote:
>
>> It seems to me that this would have no audible effect in a
>> coupling capacitor in an audio circuit (OTOH it has obvious negative
>> effects for a capacitor in a sample-and-hold circuit). My reasoning
>> for this is that all these capacitors and resistors in this
>> dielectric absorption model are perfectly linear and can at worst
>> affect phase shift, and even then to a very small degree.
>
> OTOH this model is speculative at best and wasn't presented
> in an audio context. It's certainly an interesting starting
> point though.

Actually, it is described in exactly an audio context in
http://www.elecdesign.com/Articles/ArticleID/6096/6096....

"Tom Nousaine (who did ABX testing on speaker cables) says the golden-ears
cannot hear a difference, in truly blind tests. I believe him. Of course,
that does not mean that there are no differences. Nousaine is careful, after
all, not to leave all the controls "flat," because this might let out all
sorts of differences in frequency response. He makes sure that the gains of
both amplifiers are matched within 0.1 dB at 0.1, 1, and 10 kHz. If one did
not do that, one might hear a difference."

I've personally watched a number of capacitor-paralleling advocates struggle
with these kinds of listening tests. Their circuit, their equipment, thie
room, their music, their ears, their leisure. The results are consistent -
the listeners fail to perform as they claimed based on sighted testing. And,
if you look at before and after technical tests with basic psychoacoustic
knowledge in mind, you see why: Mission Impossible.
Anonymous
July 25, 2004 7:51:11 PM

Archived from groups: rec.audio.pro (More info?)

On Sun, 25 Jul 2004 05:01:28 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>> OTOH this model is speculative at best and wasn't presented
>> in an audio context. It's certainly an interesting starting
>> point though.
>
>Actually, it is described in exactly an audio context in
>http://www.elecdesign.com/Articles/ArticleID/6096/6096....
>
>"Tom Nousaine (who did ABX testing on speaker cables) says the golden-ears
>cannot hear a difference, in truly blind tests. I believe him. Of course,
>that does not mean that there are no differences. Nousaine is careful, after
>all, not to leave all the controls "flat," because this might let out all
>sorts of differences in frequency response. He makes sure that the gains of
>both amplifiers are matched within 0.1 dB at 0.1, 1, and 10 kHz. If one did
>not do that, one might hear a difference."

If I understand this test correctly, no attempt was made to test
the validity of the proposed model. OTOH, the description is scetchy.


>I've personally watched a number of capacitor-paralleling advocates struggle
>with these kinds of listening tests. Their circuit, their equipment, thie
>room, their music, their ears, their leisure. The results are consistent -
>the listeners fail to perform as they claimed based on sighted testing. And,
>if you look at before and after technical tests with basic psychoacoustic
>knowledge in mind, you see why: Mission Impossible.

Which proves that subtle differences couldn't be heard in the test
conditions; nothing more; nothing less.

Specifically, to conclude that the tested subtle differences *cannot*
be heard is quite incorrect.

I would suggest to those who enjoy constructing these tests to tackle
the problem of insensitivity. If their test results run frequently
counter to the long term observations of many good ears, then
they still have some work to do.

That's a good thing.

Chris Hornbeck
"Vote or Die" - P. Diddy
Anonymous
July 25, 2004 7:51:12 PM

Archived from groups: rec.audio.pro (More info?)

"Chris Hornbeck" <chrishornbeckremovethis@att.net> wrote in message
news:5lk7g0pgjoi3j0bgtpvq2bs7kbu1hlneen@4ax.com
> On Sun, 25 Jul 2004 05:01:28 -0400, "Arny Krueger" <arnyk@hotpop.com>
> wrote:
>
>>> OTOH this model is speculative at best and wasn't presented
>>> in an audio context. It's certainly an interesting starting
>>> point though.
>>
>> Actually, it is described in exactly an audio context in
>> http://www.elecdesign.com/Articles/ArticleID/6096/6096....
>>
>> "Tom Nousaine (who did ABX testing on speaker cables) says the
>> golden-ears cannot hear a difference, in truly blind tests. I
>> believe him. Of course, that does not mean that there are no
>> differences. Nousaine is careful, after all, not to leave all the
>> controls "flat," because this might let out all sorts of differences
>> in frequency response. He makes sure that the gains of both
>> amplifiers are matched within 0.1 dB at 0.1, 1, and 10 kHz. If one
>> did not do that, one might hear a difference."
>
> If I understand this test correctly, no attempt was made to test
> the validity of the proposed model. OTOH, the description is scetchy.
>
>
>> I've personally watched a number of capacitor-paralleling advocates
>> struggle with these kinds of listening tests. Their circuit, their
>> equipment, thie room, their music, their ears, their leisure. The
>> results are consistent - the listeners fail to perform as they
>> claimed based on sighted testing. And, if you look at before and
>> after technical tests with basic psychoacoustic knowledge in mind,
>> you see why: Mission Impossible.

> Which proves that subtle differences couldn't be heard in the test
> conditions; nothing more; nothing less.

Plase find the conditions where they are reliably audible and post them at
your first opportunity. Just make it a reasonable application of the
concept.

> Specifically, to conclude that the tested subtle differences *cannot*
> be heard is quite incorrect.

Its only incorrect if someone provides reliable counter-evidence. Until
then, we're dealing in dueling speculations.

> I would suggest to those who enjoy constructing these tests to tackle
> the problem of insensitivity.

That there is a problem of insensitivity would be yet another speculation,
that I've thrown plenty of effort into over the years.

>If their test results run frequently
> counter to the long term observations of many good ears, then
> they still have some work to do.

Still don't believe in the power of favorable expecations?

> That's a good thing.

All the people who thought they could hear these effects, thought they had
good ears. They thought they had done appropriate long term observations.

The parallels of this situation with the Bush administration's long-term
observations of WMD in Iraq, make me smile.
Anonymous
July 25, 2004 8:05:03 PM

Archived from groups: rec.audio.pro (More info?)

"Ben Bradley"
Phil Allison
"Arny Krueger"

> >> >> No, I conclude that electrolytics first and foremost disappoint
> >> >> because they are steadily loosing their capacitance, whether slow or
> >> >> fast. No small shunt capacitor or other trick helps with that basic
> >> >> problem.
> >>
> >> > ** That just aint true. Electros hold their original capacitance
> >> > value over their whole life.
> >>
> >> Doesn't explain the distribution of capacitance values I've seen in
failed
> >> parts.
> >
> >
> >** When electro caps fail, for whatever reason, they have certainly
reached
> >the end of their life.
>
> Is that how the manufacturers define it?


** End of life is normally defined as when the ESR figure goes out of spec.
How long this takes to happen depends on the conditions of usage -
something outside the cap maker's control.


> So infant mortality means "We waranty our parts for life, but these have
obviously reached the
> END of their lives, so they're not covered under warranty." Sounds
> circular to me.
>

** The circularity was invented by YOU.


> Trollin, trollin, trollin...
>

** That sounds just like the Rawhide theme ...




.............. Phil
Anonymous
July 25, 2004 8:05:04 PM

Archived from groups: rec.audio.pro (More info?)

Phil Allison <philallison@tpg.com.au> wrote:
>"Ben Bradley"
>
>> So infant mortality means "We waranty our parts for life, but these have
>obviously reached the
>> END of their lives, so they're not covered under warranty." Sounds
>> circular to me.
>
>** The circularity was invented by YOU.

Actually, I think this ploy was invented by General Motors. If they didn't
invent it, they certainly popularized it.
--scott

"May cause hood fly-up."

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
July 25, 2004 9:44:14 PM

Archived from groups: rec.audio.pro (More info?)

On Sun, 25 Jul 2004 12:59:49 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>> Specifically, to conclude that the tested subtle differences *cannot*
>> be heard is quite incorrect.
>
>Its only incorrect if someone provides reliable counter-evidence. Until
>then, we're dealing in dueling speculations.

Let me say it a different way: *to draw the conclusion* is incorrect.
The only possible valid conclusion is that no differences were
heard under the test conditions.

But no counter-evidence is needed to criticize a test procedure. We
are indeed still dealing in dueling speculations.


>> I would suggest to those who enjoy constructing these tests to tackle
>> the problem of insensitivity.
>
>That there is a problem of insensitivity would be yet another speculation,
>that I've thrown plenty of effort into over the years.

I would not want to imply any minimization of your work, which I
admire greatly. Instead, I would suggest that there is still work to
be done. Not too earthshaking an idea, I'll admit.


>All the people who thought they could hear these effects, thought they had
>good ears. They thought they had done appropriate long term observations.

Another way of asking the question is: which is *really* the
evidence of their senses? Does the testing vibe adequately duplicate
music listening? This is still unexplored.


>The parallels of this situation with the Bush administration's long-term
>observations of WMD in Iraq, make me smile.

It's a wonderful analogy, but I'm sworn off political posts!

Thanks for your comments,

Chris Hornbeck
"Vote or Die" - P. Diddy
!