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M-Audio's response to 48v phantom power bug

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Anonymous
September 28, 2005 10:56:13 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Here's a copy of an email I sent to M-Audio. Please send email to
sales@m-audio.com and/or info@m-audio.com if you are also concerned
about this problem.

<<

A rep from your company recently addressed the list of bugs associated
with the Microtrack 2496. Among them, was the underperforming phantom
power supply. Here is a copy of the reply as posted to rec.audio.pro and
rec.arts.movies.production.sound

"BUG:
- 30v max on Phantom on stead of advertised 48v

ANSWER:

I believe our marketing mentions "Phantom Power", but never states
48v. We took a prototype down to an equipment rental store, and they
let us go through their mic closet. The MicroTrack provided enough
power for everything we tried, from the U87 to Sennheiser shotgun mics
and some esoterics. So, is this a complaint that a mic didn't work,
or is it a complaint that the Volt-Ohm meter needle didn't go where
they wanted?"



In fact, your marketting DOES specifically state 48v phantom power as is
apparent from page 6 of your own 2005 Product Guide.

http://www.m-audio.com/images/global/media/M-Audio2005C...

Likewise, every retailer and M-Audio dealer's website had advertised 48v
phantom power before the MT's release (while they were still taking
pre-orders) and most still advertise it even though it has been found
that the unit may only deliver 30v of phantom power (according to Len
Moskowitz of core-sound.com and others, see taperssection.com archives).

http://www.bhphotovideo.com/bnh/controller/home?O=NavBa...
http://66.102.7.104/search?q=cache:aKjfIljToEUJ:www.aud...
http://66.102.7.104/search?q=cache:YUjbMmFMSFgJ:www.swe...
http://66.102.7.104/search?q=cache:EbZh4NftKBYJ:www.min...
http://72.14.207.104/search?q=cache:gqAJ7pUb-X4J:www.ba...
http://72.14.207.104/search?q=cache:4SWOO0xgbGgJ:www.to...

Even such major retailers as Sweetwater, BH Photo Video and
AudioMidi.com are advertising 48v Phantom Power.

As such, I believe this is a product defect that should be fixed and
addressed in later revisions. Despite what your own testing indicates,
it is true that many mics will not function properly with highly
underrated phantom power supplies. Schoeps has confirmed that it's
12-48v phantom mics will only operate properly when powered by 12v OR
48v, not 12 TO 48v..

I'd like to thank you for making such a great product. I'm sure if you
can work out most of the firmware bugs, and bring the phantom power
supply up to it's rated voltage, it will be a VERY succesful machine.
Please let me know how, or if you plan to address this issue. Thankyou!

--

Jonny Durango

www.jdurango.com

"If the key of C is the people's key, what is the key of the bourgeoisie?"

>>

Will post more when/if I get a response.

Jonny Durango
Anonymous
September 29, 2005 12:50:32 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Jonny Durango wrote:

> "BUG:
> - 30v max on Phantom on stead of advertised 48v
>
> ANSWER:
>
> I believe our marketing mentions "Phantom Power", but never states
> 48v. We took a prototype down to an equipment rental store, and they
> let us go through their mic closet. The MicroTrack provided enough
> power for everything we tried, from the U87 to Sennheiser shotgun mics
> and some esoterics. So, is this a complaint that a mic didn't work,
> or is it a complaint that the Volt-Ohm meter needle didn't go where
> they wanted?"

There are in fact mics that seriously underperform
without the correct voltage. AKG C452 and the 'P48'
version of the C414. There most likely are others.
That a mic 'works' and works properly to spec are
different animals.

rd
Anonymous
September 29, 2005 1:44:20 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

RD Jones wrote:
> Jonny Durango wrote:
>
>
>>"BUG:
>>- 30v max on Phantom on stead of advertised 48v
>>
>>ANSWER:
>>
>>I believe our marketing mentions "Phantom Power", but never states
>>48v. We took a prototype down to an equipment rental store, and they
>>let us go through their mic closet. The MicroTrack provided enough
>>power for everything we tried, from the U87 to Sennheiser shotgun mics
>>and some esoterics. So, is this a complaint that a mic didn't work,
>>or is it a complaint that the Volt-Ohm meter needle didn't go where
>>they wanted?"
>
>
> There are in fact mics that seriously underperform
> without the correct voltage. AKG C452 and the 'P48'
> version of the C414. There most likely are others.
> That a mic 'works' and works properly to spec are
> different animals.
>
> rd
>

Very good point...I really hope M-Audio doesn't try to play this off as
"well the mic makes sound, so there's no problem." Unless we raise a
fuss about it though, I'm afraid they will.

Something is happenin here, and I don't know what it is. Do you, Mr. Jones?

heh, sorry I couldn't resist! Thanks again!

--

Jonny Durango

"If the key of C is the people's key, what is the key of the bourgeoisie?"
Related resources
Anonymous
September 29, 2005 8:45:43 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Pooh Bear wrote:
> The info on their advertising quite definitely says *48* V.

Jonny seemed to find plenty of evidence about that, but the question of
phantom power came up on the Ampex list and nobody was able to find the
stated voltage in the available literature. This is confusing. But it's
not the first product that M-Audio has built with less than 48V phantom
powering. I believe it was the Audio Buddy (one of the early
inexpensive outboard mic preamps) that provided 30 volts or so.

Still, and while I can't condone or excuse this, terms that have a
proper scientific definition tend to become corrupted as the technology
trickles down to users with a non-technical background. And while
design engineers and even marketing copy writers may know the classical
definitions, the marketeers have to write to the level of their
expected customers. In this case, I suspect that "Phantom powering"
means "48 V. Phantom Powering", and which one sounds better to the
uneducated potential customer? The one with the 48V or without?

Are battery manufacturers lying when they say it's a 1.5V battery? It's
just a matter of tolerance. If you're willing to accept a 50%
tolerance, 30V qualifies as a 48V power supply. Not unreasonable in a
world where we're supposed to be impressed with "Frequency respons 22Hz
- 22kHz" which is not at all an unusual statement for low-budget
microphones.

Not that I'm defending M-Audio here, and I'm glad that the word is out
on the street for those who care. But I suspect that it isn't going to
get changed as a result of a letter-writing campaign, or even in a
magazine-published review. When I had a TASCAM US-122 in for review, I
managed to blow out an input by plugging in a mic with phantom power
(48V, really) turned on, and suspected the same failure mode that Phil
described (and the lack of the standard protection diodes that Graham
mentioned). I mentioned this in my review, and as far as I know there
was never a change.

Products like this are like that. It means that sometimes we just have
to exercise our common sense and NOT buy something that we would
otherwise like to have - not out of protest (that does no good) but
because we know it isn't going to work some times, and we can't afford
that in a professional working environment. Or we decide to buy it
anyway, learn its limitations, and only use it where it will work.
Anonymous
September 29, 2005 9:22:05 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

In rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech, On
Wed, 28 Sep 2005 18:56:13 -0700, Jonny Durango
<jonnydurango1BUSH_FROM_OFFICE@comcast.net> wrote:

>Here's a copy of an email I sent to M-Audio. Please send email to
>sales@m-audio.com and/or info@m-audio.com if you are also concerned
>about this problem.

I guess I'm "concerned" ... I wonder if the FTC is concerned.

>"BUG:
>- 30v max on Phantom on stead of advertised 48v
>
>ANSWER:
>
>I believe our marketing mentions "Phantom Power", but never states
>48v. We took a prototype down to an equipment rental store, and they
>let us go through their mic closet. The MicroTrack provided enough
>power for everything we tried, from the U87 to Sennheiser shotgun mics
>and some esoterics. So, is this a complaint that a mic didn't work,
>or is it a complaint that the Volt-Ohm meter needle didn't go where
>they wanted?"

So what they "mean" by 48V Phantom Power is it "will power mics
that claim to run on 48V Phantom Power."

I'm starting to catch on to this marketing/advertising stuff. I
could end up being very rich, or very dangerous, or both.
Anonymous
September 29, 2005 10:42:14 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

"Mike Rivers" wrote ...
> Not that I'm defending M-Audio here, and I'm glad that
> the word is out on the street for those who care. But I
> suspect that it isn't going to get changed as a result of a
> letter-writing campaign, or even in a magazine-published
> review.

Indeed. It seems highly unlikely that they just picked 30v
out of the air if they were capable of doing 48v. With the
battery life already questionable, using that much more
power for the phantom supply would just exacerbate the
problem.
Anonymous
September 29, 2005 12:12:58 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Mike, "phantom powering" is defined by the international standard IEC
1938 for 12-Volt, 24-Volt and 48-Volt implementations. In Europe, it's
EN 61938.

The 24-Volt implementation has never been widely adopted by equipment
manufacturers due to a chicken and egg problem (why build consoles and
preamps to work with microphones that don't exist, and vice versa?),
leaving just the 12 and 48 Volt versions ("P12" and "P48") in practice.

The standard has a long history and is well established. But exactly
the same can also be said for pig-headedness, no?

By the way, PreSonus went through a similar fiasco with their original
"Blue Tube" preamp. Its front panel switch was even labeled "48 V," but
it put out only thirty-something (open circuit). The company revised
the preamp after receiving complaints and didn't even go through a
public denial phase about it first, which I thought was very mature of
them.

--best regards
Anonymous
September 29, 2005 1:42:06 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Chel van Gennip wrote:

> With current technology I don't see any reason for such a high phantom
> voltage or power.

Are you suggesting that we should be prepared to buy new microphones to
go with our new low-powered recorders? And if so, that's likely to
limit our choices. We may not like what's available.

> Besides that many (most?) microphones are designed to
> work well with a wide range of voltages e.g. 9-52V.

Some, yes. I'm not convinced by your statement that many or most are. I
know that I have at least three here that won't work at 30V, at least
not to their full level of performance.

> In this world it is
> not strange to use a design that will work and has benefits.

It's unfortunately becoming stranger to provide backward compatability,
and that's what this is about. No problem for people with plenty of
money to spend, and no problem for those with no previous investment.
But there are others to consider.

> BTW, the IEC
> standard will cost about 1W power, that is quite a lot for a small battery
> driven recorder.

Correct, for a pair of worst case mics, and that's indeed a concern.
It's been suggested that one could use an external phantom power supply
to accommodate mics that the Micro Trak won't power. This partially
defeats the advantage of self-containd mic power since it's another
box, another set of batteries, and another pair of cables and
connectors for the signal to go through. If I had to use external power
I'd rather have a box (or belt) with D-cells to get enough current to
power the mics and recorder, and make sure it will keep running for the
whole gig. A Nagra uses a bundle of D-cells, but it will run all day on
them. And while it won't fit in a jacket pocket, it won't easily get
yanked by a cable and fall off the table.
Anonymous
September 29, 2005 2:08:47 PM

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

On Wed, 28 Sep 2005 18:56:13 -0700, Jonny Durango
<jonnydurango1BUSH_FROM_OFFICE@comcast.net> wrote:

>Here's a copy of an email I sent to M-Audio. Please send email to
>sales@m-audio.com and/or info@m-audio.com if you are also concerned
>about this problem.
>
><<
>
>A rep from your company recently addressed the list of bugs associated
>with the Microtrack 2496. Among them, was the underperforming phantom
>power supply. Here is a copy of the reply as posted to rec.audio.pro and
>rec.arts.movies.production.sound
>
>"BUG:
>- 30v max on Phantom on stead of advertised 48v

--- I'm following this thread with interest. Now I am thinking about
this issue and my opinion is that microphones should be able to work
OK at 30 V if designed properly and, will the Microtrack 24/96 be
able, without major design changes, to supply full 48 V to 2
microphones given its batteries? -- I mean 48 V is here a maximum
which can't be reached easily given the dimensions of Microtrack or?

Edi Zubovic, Crikvenica, Croatia
Anonymous
September 29, 2005 2:24:25 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Richard Crowley <rcrowley@xpr7t.net> wrote:
>"Mike Rivers" wrote ...
>> Not that I'm defending M-Audio here, and I'm glad that
>> the word is out on the street for those who care. But I
>> suspect that it isn't going to get changed as a result of a
>> letter-writing campaign, or even in a magazine-published
>> review.
>
>Indeed. It seems highly unlikely that they just picked 30v
>out of the air if they were capable of doing 48v. With the
>battery life already questionable, using that much more
>power for the phantom supply would just exacerbate the
>problem.

Maybe they made use of +/-15V supply rails with a funny ground reference?
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
September 29, 2005 2:52:23 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Jonny Durango wrote:

> Here's a copy of an email I sent to M-Audio. Please send email to
> sales@m-audio.com and/or info@m-audio.com if you are also concerned
> about this problem.
>
> <<
>
> A rep from your company recently addressed the list of bugs associated
> with the Microtrack 2496. Among them, was the underperforming phantom
> power supply. Here is a copy of the reply as posted to rec.audio.pro and
> rec.arts.movies.production.sound
>
> "BUG:
> - 30v max on Phantom on stead of advertised 48v
>
> ANSWER:
>
> I believe our marketing mentions "Phantom Power", but never states
> 48v. We took a prototype down to an equipment rental store, and they
> let us go through their mic closet. The MicroTrack provided enough
> power for everything we tried, from the U87 to Sennheiser shotgun mics
> and some esoterics. So, is this a complaint that a mic didn't work,
> or is it a complaint that the Volt-Ohm meter needle didn't go where
> they wanted?"
>
> In fact, your marketting DOES specifically state 48v phantom power as is
> apparent from page 6 of your own 2005 Product Guide.
>
> http://www.m-audio.com/images/global/media/M-Audio2005C...
>
> Likewise, every retailer and M-Audio dealer's website had advertised 48v
> phantom power before the MT's release (while they were still taking
> pre-orders) and most still advertise it even though it has been found
> that the unit may only deliver 30v of phantom power (according to Len
> Moskowitz of core-sound.com and others, see taperssection.com archives).
>
> http://www.bhphotovideo.com/bnh/controller/home?O=NavBa...
> http://66.102.7.104/search?q=cache:aKjfIljToEUJ:www.aud...
> http://66.102.7.104/search?q=cache:YUjbMmFMSFgJ:www.swe...
> http://66.102.7.104/search?q=cache:EbZh4NftKBYJ:www.min...
> http://72.14.207.104/search?q=cache:gqAJ7pUb-X4J:www.ba...
> http://72.14.207.104/search?q=cache:4SWOO0xgbGgJ:www.to...
>
> Even such major retailers as Sweetwater, BH Photo Video and
> AudioMidi.com are advertising 48v Phantom Power.
>
> As such, I believe this is a product defect that should be fixed and
> addressed in later revisions. Despite what your own testing indicates,
> it is true that many mics will not function properly with highly
> underrated phantom power supplies. Schoeps has confirmed that it's
> 12-48v phantom mics will only operate properly when powered by 12v OR
> 48v, not 12 TO 48v..
>
> I'd like to thank you for making such a great product. I'm sure if you
> can work out most of the firmware bugs, and bring the phantom power
> supply up to it's rated voltage, it will be a VERY succesful machine.
> Please let me know how, or if you plan to address this issue. Thankyou!
>
> --

The info on their advertising quite definitely says *48* V.

They need to make their product work properly or withdraw the 48V claim.

Whilst they're at it they can add some input protection too.

This is what happen when computer geeks start thinking they can be audio pros. Big learning curve before they can get it right.

Graham
Anonymous
September 29, 2005 4:31:10 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Jonny Durango wrote:

> "BUG:
> - 30v max on Phantom on stead of advertised 48v

Has anyone checked the phantom resistors? If they were less
than the usual 6.8K then for the higher current mics you
could end up with as much or more voltage after the drop
across them.

48 V/10 mA/6.8K leaves 14 V at pins 2 and 3. 4250 Ohm
resistors would yield the same voltage at 30 V/10 mA.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein
Anonymous
September 29, 2005 4:38:27 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

"Jonny Durango"

** This was posted on sci.electronics design a few days ago:


-----------------------------------------------------------------------------

Actually a repair problem for a low noise microphone pre-amp but seems to be
a general design flaw.
Pre-amp uses a Burr Brown INA103 very low noise instrumentation op-amp.
In this M-Audio Omni i/o preamp and an outline design application in the
Burr Brown book show much the same circuitry.
The 48Volt phantom supply to the mike is protected by 6.8K limiter
resistors.
But to block the 48V DC to the op-amp there is a 10uF/100V electrolytic in
each line directly to the inv & non-inv i/p of the op-amp .

If , as seems in this case, a balanced line microphone with a short to
ground is connected to such a system
then the +48V / 0V across the elecrolytic will instantneously go to 0V
/ -48V with -48V
directly connected to the op-amp i/p powered from +-15V rails and according
to the databook
can be taken to only +-12V.

Blown input to this op-amp due to just the owner connecting a microphone.
Anyone familiar with this, adding limiting diode pair at each input ?
I see no point in replacing this 15 GBP/ 25 USD IC until this design flaw
is attended to or it will happen again should a fault to ground develop in a
mike or lead while the 48V power is on.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs
http://home.graffiti.net/diverse:graffiti.net/

--------------------------------------------------------------------------------


** Looks like the wankers at M-Audio need to go figure how phantom powering
is actually done in the real world.




.......... Phil
Anonymous
September 29, 2005 4:38:28 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Phil Allison wrote:
> "Jonny Durango"
>
> ** This was posted on sci.electronics design a few days ago:
>
>
> -----------------------------------------------------------------------------
>
> Actually a repair problem for a low noise microphone pre-amp but seems to be
> a general design flaw.
> Pre-amp uses a Burr Brown INA103 very low noise instrumentation op-amp.
> In this M-Audio Omni i/o preamp and an outline design application in the
> Burr Brown book show much the same circuitry.
> The 48Volt phantom supply to the mike is protected by 6.8K limiter
> resistors.
> But to block the 48V DC to the op-amp there is a 10uF/100V electrolytic in
> each line directly to the inv & non-inv i/p of the op-amp .
>
> If , as seems in this case, a balanced line microphone with a short to
> ground is connected to such a system
> then the +48V / 0V across the elecrolytic will instantneously go to 0V
> / -48V with -48V
> directly connected to the op-amp i/p powered from +-15V rails and according
> to the databook
> can be taken to only +-12V.
>
> Blown input to this op-amp due to just the owner connecting a microphone.
> Anyone familiar with this, adding limiting diode pair at each input ?
> I see no point in replacing this 15 GBP/ 25 USD IC until this design flaw
> is attended to or it will happen again should a fault to ground develop in a
> mike or lead while the 48V power is on.
>
> --
> Diverse Devices, Southampton, England
> electronic hints and repair briefs
> http://home.graffiti.net/diverse:graffiti.net/
>
> --------------------------------------------------------------------------------
>
>
> ** Looks like the wankers at M-Audio need to go figure how phantom powering
> is actually done in the real world.
>
>
>
>
> ......... Phil
>
>
>
>

Wow! Well hopefully the MT isn't designed with the same op-amp as the
Omni interface. Regardless, has anybody contacted M-Audio about this flaw?

--

Jonny Durango

www.jdurango.com

"If the key of C is the people's key, what is the key of the bourgeoisie?"
Anonymous
September 29, 2005 4:38:29 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Jonny Durango wrote:

> Phil Allison wrote:
> > "Jonny Durango"
> >
> > ** This was posted on sci.electronics design a few days ago:
> >
> >
> > -----------------------------------------------------------------------------
> >
> > Actually a repair problem for a low noise microphone pre-amp but seems to be
> > a general design flaw.
> > Pre-amp uses a Burr Brown INA103 very low noise instrumentation op-amp.
> > In this M-Audio Omni i/o preamp and an outline design application in the
> > Burr Brown book show much the same circuitry.
> > The 48Volt phantom supply to the mike is protected by 6.8K limiter
> > resistors.
> > But to block the 48V DC to the op-amp there is a 10uF/100V electrolytic in
> > each line directly to the inv & non-inv i/p of the op-amp .
> >
> > If , as seems in this case, a balanced line microphone with a short to
> > ground is connected to such a system
> > then the +48V / 0V across the elecrolytic will instantneously go to 0V
> > / -48V with -48V
> > directly connected to the op-amp i/p powered from +-15V rails and according
> > to the databook
> > can be taken to only +-12V.
> >
> > Blown input to this op-amp due to just the owner connecting a microphone.
> > Anyone familiar with this, adding limiting diode pair at each input ?
> > I see no point in replacing this 15 GBP/ 25 USD IC until this design flaw
> > is attended to or it will happen again should a fault to ground develop in a
> > mike or lead while the 48V power is on.
> >
> > --
> > Diverse Devices, Southampton, England
> > electronic hints and repair briefs
> > http://home.graffiti.net/diverse:graffiti.net/
> >
> > --------------------------------------------------------------------------------
> >
> >
> > ** Looks like the wankers at M-Audio need to go figure how phantom powering
> > is actually done in the real world.
> >
> >
> >
> >
> > ......... Phil
> >
> >
> >
> >
>
> Wow! Well hopefully the MT isn't designed with the same op-amp as the
> Omni interface. Regardless, has anybody contacted M-Audio about this flaw?

It's not the *IC* that's the problem. It's the poor implementation of the circuitry
around it.

Decent console makers have incorporated proper protection for ages. It costs about 10
cents in parts.

Graham
September 29, 2005 5:16:54 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

digidesign owns m-audio now. or does it?
Anonymous
September 29, 2005 5:17:03 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Chel van Gennip wrote:

> What I ment is that if you design a microphone circuit now, you could
> well do with 10V 2mA and create a perfect circuit.

Maybe. You certainly could if you used an electret element, but an
electrically polarized element still needs 50 to 80 volts in order to
work, and that means a DC-DC converter in the mic. Remember that you're
not just powering an impedance converter.

While you need essentially no current to polarize the capsule element,
you need a certain amount of current to polarize the converter. If you
wanted to use a lower polarizing voltage, you'd have to move the
diaphragm closer to the back plate or put it at higher tension. Both
probably have more things going against them than for them when it
comes to capsule design. Not to say that someone couldn't come up with
a radically different capsule design, in over 50 years, we still think
that Mr. Neumann got it right.

> This situation is
> different from e.g. 1966 when the DIN 45596 standard was made.

The only thing different is that there are lower power components
available today than there were then, but there are certain design
elements that you can't get rid of. This isn't consumer electronics.

> If you look at currently available microphones, most are designed to work
> with little power.

Have YOU looked at them? Got a list of mics that will run at 12-24V
with current requirements of 2 mA or so? Show me my choices and I'll
tell you what I might want to buy to freshen up my mic closet.

> There are some microphones in the "vintage area" that won't work with low
> phantom power (and did not work with standard phantom power at the time
> they were designed: some Neumans, the Schoeps CMC ("Colette") series,
> some Shure KSM-series microphones etc.).

The Shure KSM is "vintage" already? My, how time flies! We didn't have
phantom powering until the KM80 series Neumanns from 1966. Were you
born then? If not, that might explain your perspective on this.

> For me it is important to have a small light device capable of making
> high quality recordings. For backwards compatibility with vintage
> microphones you could use external phantom power, or use a different
> device, e.g. the 722.

I'll put up with a little extra weight in exchange for less haywire and
the ability to use the mics that I want to use, not the subset of mics
that work at low power. And I'd like it to be less expensive than the
Sound Devices 722. A unit of that cost will never pay for itself around
here, and I don't have that kind of money to throw at a device that
I'll only use for my own amusement.
Anonymous
September 29, 2005 7:02:15 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

"Jonny Durango"
> Phil Allison wrote:
>> "Jonny Durango"
>>
>> ** This was posted on sci.electronics design a few days ago:
>>
>>
>> -----------------------------------------------------------------------------
>>
>> Actually a repair problem for a low noise microphone pre-amp but seems to
>> be
>> a general design flaw.
>> Pre-amp uses a Burr Brown INA103 very low noise instrumentation op-amp.
>> In this M-Audio Omni i/o preamp and an outline design application in the
>> Burr Brown book show much the same circuitry.
>> The 48Volt phantom supply to the mike is protected by 6.8K limiter
>> resistors.
>> But to block the 48V DC to the op-amp there is a 10uF/100V electrolytic
>> in
>> each line directly to the inv & non-inv i/p of the op-amp .
>>
>> If , as seems in this case, a balanced line microphone with a short to
>> ground is connected to such a system
>> then the +48V / 0V across the elecrolytic will instantneously go to 0V
>> / -48V with -48V
>> directly connected to the op-amp i/p powered from +-15V rails and
>> according
>> to the databook
>> can be taken to only +-12V.
>>
>> Blown input to this op-amp due to just the owner connecting a microphone.
>> Anyone familiar with this, adding limiting diode pair at each input ?
>> I see no point in replacing this 15 GBP/ 25 USD IC until this design flaw
>> is attended to or it will happen again should a fault to ground develop
>> in a
>> mike or lead while the 48V power is on.
>>
>> --
>> Diverse Devices, Southampton, England
>> electronic hints and repair briefs
>> http://home.graffiti.net/diverse:graffiti.net/
>>
>> --------------------------------------------------------------------------------
>>
>>
>> ** Looks like the wankers at M-Audio need to go figure how phantom
>> powering is actually done in the real world.
>>
>
> Wow! Well hopefully the MT isn't designed with the same op-amp as the Omni
> interface. Regardless, has anybody contacted M-Audio about this flaw?
>


** Wanna guess what their reply would be ?

Allege user error ?

Point out no claim is make re input IC protection ??

Blah, blah ........


............ Phil
Anonymous
September 29, 2005 7:07:09 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Chel van Gennip wrote:
> On Thu, 29 Sep 2005 22:17:03 +0200, Mike Rivers wrote:

> I have bought a device that fullfills my requirements, you will have to
> wait a little longer.

Yes, sigh, again.
Anonymous
September 29, 2005 7:33:23 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

vin wrote:
> digidesign owns m-audio now. or does it?
>

I believe Avid (famous for video editing software) acquired Digidesign
and M-Audio. And when they did so, it appears as though they cleaned
house of all their Digidesign product engineers/testers.

--

Jonny Durango

www.jdurango.com

"If the key of C is the people's key, what is the key of the bourgeoisie?"
Anonymous
September 29, 2005 7:34:12 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

It's the old horses for courses argument.

In my opinion, there is absolutely no excuse for M-Audio claiming 48v
if it is not true, or even that it reduces battery time so much that it
is not worth it.

I will buy one, because my mixer supllies all the 48v I need. It may be
handy to run the unit on it's own, but I will work within the
limitations of the gadget. I also have a denecke 48v power supply lying
around somewhere - and I would rather change the batteries on that
occasionally, than relying on the recorders powering.

It was cool how all the techno wizards came out on this topic, though.
Anonymous
September 29, 2005 7:39:46 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Jonny Durango wrote:
> it appears as though they cleaned
> house of all their Digidesign product engineers/testers.
>

Oops, typo, should be "cleared house of a lot of their GOOD Digidesign
product engineers/tester." I really don't think they axed the entire
Digi production staff.

--

Jonny Durango

www.jdurango.com

"If the key of C is the people's key, what is the key of the bourgeoisie?"
Anonymous
September 29, 2005 7:50:01 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

On Thu, 29 Sep 2005 13:45:43 +0200, Mike Rivers wrote:

> Still, and while I can't condone or excuse this, terms that have a
> proper scientific definition tend to become corrupted as the technology
> trickles down to users with a non-technical background. And while design
> engineers and even marketing copy writers may know the classical
> definitions, the marketeers have to write to the level of their expected
> customers.

Technology is not fixed. You are right there is a standard for phantom
power. The 1966 DIN 45596 standard well defined phantom power as: 48V, 6k8
resistors and a maximum current of 2mA. That worked well, until some
manufacurers, like Schoeps, started to build microphones that needed
tripple that current or more. There came a new standard: IEC 61938.

With current technology I don't see any reason for such a high phantom
voltage or power. Besides that many (most?) microphones are designed to
work well with a wide range of voltages e.g. 9-52V. In this world it is
not strange to use a design that will work and has benefits. BTW, the IEC
standard will cost about 1W power, that is quite a lot for a small battery
driven recorder. I understand the M-Audio choices. I also understand some
people would have made other choices. These people can choose to provide
the 0.5W per microphone IEC standard phantom power externaly or use other
devices.

--
Chel van Gennip
Visit Serg van Gennip's site http://www.serg.vangennip.com
Anonymous
September 29, 2005 7:50:02 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Chel van Gennip <chel@vangennip.nl> wrote:
>
>With current technology I don't see any reason for such a high phantom
>voltage or power. Besides that many (most?) microphones are designed to
>work well with a wide range of voltages e.g. 9-52V. In this world it is
>not strange to use a design that will work and has benefits. BTW, the IEC
>standard will cost about 1W power, that is quite a lot for a small battery
>driven recorder. I understand the M-Audio choices. I also understand some
>people would have made other choices. These people can choose to provide
>the 0.5W per microphone IEC standard phantom power externaly or use other
>devices.

If anything, I want MORE power available! More power means more electronics
at the microphone are possible, electronics that otherwise might need to run
in class AB can run in class A, and output impedances can be lower! Give me
more current and higher voltages! I want to run incandescent tally lights
off the mike! I want to run submini tubes! I want more!
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
September 29, 2005 8:20:37 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

On Thu, 29 Sep 2005 15:58:55 +0200, wildt®ax wrote:

> See here:
>
> http://groups.google.com/group/rec.arts.movies.producti...
>
> He states that a CMC6 will not work at full specs ... He also says that
> he doesn´t understand why an audio device with 30V is released because
> it is beyond all phantom standards.

Well, when the Schoeps introduced the CMC ("Colette") series microphones,
they used about tripple the current specified in the phantom standard
then. But, "it worked with most pre-amps". That is not so differet from
the M-Audio concept, they supply less power to stretch battery life, but
it works with many (most?) microphones.

--
Chel van Gennip
Visit Serg van Gennip's site http://www.serg.vangennip.com
Anonymous
September 29, 2005 9:08:08 PM

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

"Edi Zubovic" wrote ...
> --- I'm following this thread with interest. Now I am thinking about
> this issue and my opinion is that microphones should be able to work
> OK at 30 V if designed properly

Maybe you're thinking only of electret-capsule microphones,
not externally-polarized ones?

> and, will the Microtrack 24/96 be
> able, without major design changes, to supply full 48 V to 2
> microphones given its batteries? --

Seems dubious. If I had the choice, I'd rather have longer battery
life and 30v of phantom. If I want to use the good mics that require
48v, I'll likely use something a bit more substantial to record on.

Seems to me the objections here are mainly over the "false-
advertising" where M-Audio apparently thought that "48v"
was just a *name* rather than the spec for phantom power.
It does show some bone-headedness on their part (and their
goofy "where the needle lands" response just made it worse.)

If they had just correctly called it 30v phantom power, we
would be back concentrating on the real issues. But this is
Usenet where we will flog any topic long past its due.
Anonymous
September 29, 2005 9:22:45 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

SoundSpeed wrote:
> It's the old horses for courses argument.
>
> In my opinion, there is absolutely no excuse for M-Audio claiming 48v
> if it is not true, or even that it reduces battery time so much that it
> is not worth it.
>
> I will buy one, because my mixer supllies all the 48v I need. It may be
> handy to run the unit on it's own, but I will work within the
> limitations of the gadget. I also have a denecke 48v power supply lying
> around somewhere - and I would rather change the batteries on that
> occasionally, than relying on the recorders powering.
>
> It was cool how all the techno wizards came out on this topic, though.

to those people that have an MT and are using with their mixers, how
have you intergrated the MT into the bag cable wise?
i've been advised not to use 3 pole input jacks (1/4") and that 2 pole
jacks will be best if i'm using the unbalanced mixout from my sd302,
i'm trying to patch a power supply from the np1into the usb and would
also like to make a monitor return. been thinking about putting all 3
on a breakaway as i want to keep the jacks into and out of the MT under
somekind of protective pouch. i read someone was using an "L" shaped
bracket to fix an MD to his mixer bag. unless something is designed to
be used in a bag with other things it is always a problem to have good
ergonomics.
any thoughts?

dan.
Anonymous
September 29, 2005 9:30:55 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Jonny Durango wrote:
> Phil Allison wrote:
>
>> "Jonny Durango"
>>
>> posted on sci.electronics design a few days ago:
>>
>>
>>> Actually a repair problem for a low noise microphone pre-amp but
>>> seems to be a general design flaw. Pre-amp uses a Burr Brown
>>> INA103 very low noise instrumentation op-amp. In this M-Audio
>>> Omni i/o preamp and an outline design application in the Burr
>>> Brown book show much the same circuitry. The 48Volt phantom
>>> supply to the mike is protected by 6.8K limiter resistors. But to
>>> block the 48V DC to the op-amp there is a 10uF/100V electrolytic
>>> in each line directly to the inv & non-inv i/p of the op-amp .
>>
>>
>> Looks like the wankers at M-Audio need to go figure how phantom
>> powering is actually done in the real world.
>
>
>
> Wow! Well hopefully the MT isn't designed with the same op-amp as the
> Omni interface.


Highly unlikely, given the INA103's optimum rail voltages and power
consumption.
Anonymous
September 29, 2005 9:38:38 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Chel van Gennip wrote:
>
> Technology is not fixed. You are right there is a standard for phantom
> power. The 1966 DIN 45596 standard well defined phantom power as: 48V, 6k8
> resistors and a maximum current of 2mA. That worked well, until some
> manufacurers, like Schoeps, started to build microphones that needed
> tripple that current or more. There came a new standard: IEC 61938.
>
> With current technology I don't see any reason for such a high phantom
> voltage or power.

Wait -- many of us (and quite a few higher end mic designers) want MORE
power available and are pushing for the P48H standard to be ratified
(48V through 2k1 resistors.)

Also note that P12 provides higher current thanks to its 680 Ohm
resistors (though still not as much juice as T-power offers.)
Anonymous
September 29, 2005 9:59:28 PM

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

Jonny Durango wrote:

> My feelings exactly.....great product with great potential, but I get
> the feeling it was pushed out the door too early. I also wouldn't be
> surprised if M-Audio lost a lot of good engineers when it was acquired
> by Avid, although I couldn't confirm this.

Typical product research and development has gone
through it's cycle before release. So any significant
changes will likely be applied to a product revision
that also might get a facelift, for example, and a price
increase. This is especially true when R&D is half way
round the globe from manufacturing. Small, repair or
mod resistant design is another stumbling block to
such changes.

Anybody willing to wait for a SuperMT or the MT Ultra ?

The mics I used as examples that wouldn't work well
(or at all) with the 30v are old out-of-production
models and it's reasonable to assume that very few
might actually be used with the MT. But that's not a
justification to mislabel (or de-spec) the phantom
supply voltage.

rd
Anonymous
September 29, 2005 10:01:44 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

SoundSpeed wrote:
> It's the old horses for courses argument.
>
> In my opinion, there is absolutely no excuse for M-Audio claiming 48v
> if it is not true, or even that it reduces battery time so much that it
> is not worth it.
>
> I will buy one, because my mixer supllies all the 48v I need. It may be
> handy to run the unit on it's own, but I will work within the
> limitations of the gadget. I also have a denecke 48v power supply lying
> around somewhere - and I would rather change the batteries on that
> occasionally, than relying on the recorders powering.
>
> It was cool how all the techno wizards came out on this topic, though.

to those people that have an MT and are using with their mixers, how
have you intergrated the MT into the bag cable wise?
i've been advised not to use 3 pole input jacks (1/4") and that 2 pole
jacks will be best if i'm using the unbalanced mixout from my sd302,
i'm trying to patch a power supply from the np1into the usb and would
also like to make a monitor return. been thinking about putting all 3
on a breakaway as i want to keep the jacks into and out of the MT under
somekind of protective pouch.
any thoughts?

dan.
Anonymous
September 29, 2005 10:34:27 PM

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

Edi Zubovic wrote:
> --- I'm following this thread with interest. Now I am thinking about
> this issue and my opinion is that microphones should be able to work
> OK at 30 V if designed properly

But the fact is that some of the best mics won't work properly at 30 V.
For example, my Neumanns specify 48 V +/- 4 V. That's nowhere near to 30.
Anonymous
September 29, 2005 10:45:13 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

"Jonny Durango" <jonnydurango1BUSH_FROM_OFFICE@comcast.net> wrote:
>
> I really hope M-Audio doesn't try to play this off as "well the mic
> makes sound, so there's no problem."
> Unless we raise a fuss about it though, I'm afraid they will.




So, vote with your wallet. Don't buy it.

Just say No to bad gear.

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

(Remove spamblock to reply)
Anonymous
September 29, 2005 11:14:24 PM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

On Thu, 29 Sep 2005 18:42:06 +0200, Mike Rivers wrote:

> Chel van Gennip wrote:
>
>> With current technology I don't see any reason for such a high phantom
>> voltage or power.
>
> Are you suggesting that we should be prepared to buy new microphones to
> go with our new low-powered recorders? And if so, that's likely to limit
> our choices. We may not like what's available.

What I ment is that if you design a microphone circuit now, you could
well do with 10V 2mA and create a perfect circuit. This situation is
different from e.g. 1966 when the DIN 45596 standard was made.

If you look at currently available microphones, most are designed to work
with little power.

There are some microphones in the "vintage area" that won't work with low
phantom power (and did not work with standard phantom power at the time
they were designed: some Neumans, the Schoeps CMC ("Colette") series,
some Shure KSM-series microphones etc.).

For me it is important to have a small light device capable of making
high quality recordings. For backwards compatibility with vintage
microphones you could use external phantom power, or use a different
device, e.g. the 722.

--
Chel van Gennip
Visit Serg van Gennip's site http://www.serg.vangennip.com
Anonymous
September 30, 2005 12:23:04 AM

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

"Edi Zubovic" <edi.zubovic[rem this]@ri.t-com.hr> wrote in message
news:en7nj19eleka0pld9qnouu2uilcmop2obm@4ax.com...

> --- I'm following this thread with interest. Now I am thinking about
> this issue and my opinion is that microphones should be able to work
> OK at 30 V if designed properly and, will the Microtrack 24/96 be
> able, without major design changes, to supply full 48 V to 2
> microphones given its batteries? -- I mean 48 V is here a maximum
> which can't be reached easily given the dimensions of Microtrack or?

What the product should do is specify the voltage and current it can supply
to microphones. And what the microphone manufacturers should do is specify
the voltage and current required by their microphones to achieve the
specified performance.

That is, manufacturers should provide accurate and informative product
specs.

Whether a phantom power supply should deliver 10 milliamps per microphone at
48V can then be left to the marketplace to decide - together with whether
it's OK for a microphone's performance to be worse if supplied with 30V
phantom power at 5 milliamps or whatever.

Obviously it's easiest in some ways if products all complied with an
international standard; however, if complying with the standards results in
some disadvantage for the user (eg cost, weight) then it's reasonable for
manufacturers to offer products which do not conform. There's no need for
all products to meet the same specs; however, the buyer needs to know what
specs the product *does* meet.

Tim
Anonymous
September 30, 2005 2:30:36 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

On 29 Sep 2005 13:16:54 -0700, schreef:

>digidesign owns m-audio now. or does it?

It does. But i'm not sure if that is positive, or negative.

R
Anonymous
September 30, 2005 2:46:01 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

On Thu, 29 Sep 2005 22:17:03 +0200, Mike Rivers wrote:


> Chel van Gennip wrote:
>
>> What I ment is that if you design a microphone circuit now, you could
>> well do with 10V 2mA and create a perfect circuit.
>
> Maybe. You certainly could if you used an electret element, but an
> electrically polarized element still needs 50 to 80 volts in order to
> work, and that means a DC-DC converter in the mic. Remember that you're
> not just powering an impedance converter.

I've discussed the AKG microphone circuit with the DC-DC converter on the
stabalised low voltage for the 62V polarising voltage in r.a.p before.

> We didn't have phantom powering until the KM80 series Neumanns from
> 1966. Were you born then? If not, that might explain your perspective on
> this.

I started hobying in electronics round 1960. I noticed a lot of things
changed in these 45 years, e.g. low power DC-DC converters.

>> For me it is important to have a small light device capable of making
>> high quality recordings.
>
> I'll put up with a little extra weight in exchange for less haywire and
> the ability to use the mics that I want to use, not the subset of mics
> that work at low power. And I'd like it to be less expensive than the
> Sound Devices 722.

I have bought a device that fullfills my requirements, you will have to
wait a little longer.

--
Chel van Gennip
Visit Serg van Gennip's site http://www.serg.vangennip.com
Anonymous
September 30, 2005 3:07:03 AM

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

On Thu, 29 Sep 2005 20:23:04 GMT, in rec.audio.pro "Tim Martin"
<tim2718281@ntlworld.com> wrote:

>
>"Edi Zubovic" <edi.zubovic[rem this]@ri.t-com.hr> wrote in message
>news:en7nj19eleka0pld9qnouu2uilcmop2obm@4ax.com...
>
snip
>That is, manufacturers should provide accurate and informative product
>specs.
snip
> however, the buyer needs to know what
>specs the product *does* meet.
>
>Tim
>
>
>
I've just got this feeling that the MT was pushed out of the door by
the marketing department before it was ready for release. M-Audio do
know how to design audio. The techs working on the MT would have
known exactly what was wrong with the MT, they probably lurk here, and
on RAMPS.

I think its a shame that something with the potential of the MT has
had such a bad professional launch. A dilbert problem


martin
Anonymous
September 30, 2005 3:07:04 AM

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

martin griffith wrote:
> On Thu, 29 Sep 2005 20:23:04 GMT, in rec.audio.pro "Tim Martin"
> <tim2718281@ntlworld.com> wrote:
>
>
>>"Edi Zubovic" <edi.zubovic[rem this]@ri.t-com.hr> wrote in message
>>news:en7nj19eleka0pld9qnouu2uilcmop2obm@4ax.com...
>>
>
> snip
>
>>That is, manufacturers should provide accurate and informative product
>>specs.
>
> snip
>
>>however, the buyer needs to know what
>>specs the product *does* meet.
>>
>>Tim
>>
>>
>>
>
> I've just got this feeling that the MT was pushed out of the door by
> the marketing department before it was ready for release. M-Audio do
> know how to design audio. The techs working on the MT would have
> known exactly what was wrong with the MT, they probably lurk here, and
> on RAMPS.
>
> I think its a shame that something with the potential of the MT has
> had such a bad professional launch. A dilbert problem
>
>
> martin

My feelings exactly.....great product with great potential, but I get
the feeling it was pushed out the door too early. I also wouldn't be
surprised if M-Audio lost a lot of good engineers when it was acquired
by Avid, although I couldn't confirm this.

--

Jonny Durango

www.jdurango.com

"If the key of C is the people's key, what is the key of the bourgeoisie?"
Anonymous
September 30, 2005 4:19:31 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

"Chel van Gennip"

> BTW, the IEC
> standard will cost about 1W power,


** How so ?

Even 4 mA at 48 volts is under 200mW.



............ Phil
Anonymous
September 30, 2005 4:19:32 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

On Thu, 29 Sep 2005 16:19:31 +0200, Phil Allison wrote:


> "Chel van Gennip"
>
>> BTW, the IEC
>> standard will cost about 1W power,
>
>
> ** How so ?
>
> Even 4 mA at 48 volts is under 200mW.

2 microphones at (IEC) 10mA at 48V is 960mW or ~ 1W

--
Chel van Gennip
Visit Serg van Gennip's site http://www.serg.vangennip.com
Anonymous
September 30, 2005 4:19:33 AM

Archived from groups: rec.audio.pro,rec.arts.movies.production.sound,rec.audio.tech (More info?)

Chel van Gennip wrote:
> On Thu, 29 Sep 2005 16:19:31 +0200, Phil Allison wrote:
>
>>"Chel van Gennip"
>>
>>
>>> BTW, the IEC standard will cost about 1W power,
>>
>>
>> How so ?
>> Even 4 mA at 48 volts is under 200mW.
>
>
> 2 microphones at (IEC) 10mA at 48V is 960mW or ~ 1W


Did you forget the 6k8 resistors? Maximum power transfer does not occur
at 48V...
!