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Audio amp 40 watts, loudspeaker 19 watts; How to adapt?

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June 22, 2004 5:54:11 PM

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

Hello,
I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
to plug to one channel a small speaker 19 watts (8 ohm).

4 questions:
1- What circuit should I build to adapt?

2- How can I know how much ampere the amp is using to drive one
loudspeaker?

3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?

Thank you.
June 22, 2004 9:32:48 PM

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

"Jean" <Robijean@hotmail.com> wrote in message
news:2306b1e3.0406221254.7a64dd91@posting.google.com...
> Hello,
> I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
> to plug to one channel a small speaker 19 watts (8 ohm).
>
> 4 questions:
> 1- What circuit should I build to adapt?

none. just connect it. The power in your program signal is NOT the full
power of the amplifier.

And after that, if it sounds bad, turn it down.

Unless you plan to pound the amp at clipping levels constantly (i.e., use it
as a guitar amp), there is very little danger of hurting the speaker with
too much power (you're probably more likely to hurt it with too LITTLE
power). If you plan to abuse the volume control (play loud without regard
to how much it is disorting), though, then you may need to watch out.

>
> 2- How can I know how much ampere the amp is using to drive one
> loudspeaker?

It varies constantly with the program (music, voice, whatever).

>
> 3- A better suitable newsgroup to post this question?
>
> Search on the internet:
> 4- What words should I use to find some appropriate technical texts?
>
> Thank you.
June 23, 2004 9:55:19 AM

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

In article <40d8a580$1@news.xetron.com>,
"Billw" <notarealemail@nowhere.com> wrote:

> (you're probably more likely to hurt it with too LITTLE
> power).

How does that happen?

--
cyrus

*coughcasaucedoprodigynetcough*
Related resources
June 23, 2004 12:16:33 PM

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

"Billw" <notarealemail@nowhere.com> wrote in message news:<40d8a580$1@news.xetron.com>...
> "Jean" <Robijean@hotmail.com> wrote in message
> news:2306b1e3.0406221254.7a64dd91@posting.google.com...
> > Hello,
> > I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
> > to plug to one channel a small speaker 19 watts (8 ohm).
> >
> > 4 questions:
> > 1- What circuit should I build to adapt?
>
> none. just connect it. The power in your program signal is NOT the full
> power of the amplifier.
>
> And after that, if it sounds bad, turn it down.
>
> Unless you plan to pound the amp at clipping levels constantly (i.e., use it
> as a guitar amp), there is very little danger of hurting the speaker with
> too much power (you're probably more likely to hurt it with too LITTLE
> power). If you plan to abuse the volume control (play loud without regard
> to how much it is disorting), though, then you may need to watch out.

Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
with enough power to be driven by the amp? ( I use my amp only for
music)

3- A better suitable newsgroup to post this question?

Search on the internet:
4- What words should I use to find some appropriate technical texts?
Anonymous
June 23, 2004 2:30:15 PM

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

>> (you're probably more likely to hurt it with too LITTLE
>> power).
>
>How does that happen?

If you're in a position to turn the input (or maybe preamp stage) too
far up in a vain quest for extra volume, it may start clipping, giving
the power amplifier a nasty square-edged waveform to amplify.
Tweeters can succumb to these waveforms rather easily.
Anonymous
June 23, 2004 3:43:00 PM

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

cyrus <invalid@i.like.spam> writes:

> In article <40d8a580$1@news.xetron.com>,
> "Billw" <notarealemail@nowhere.com> wrote:
>
> > (you're probably more likely to hurt it with too LITTLE
> > power).
>
> How does that happen?

The typical scenario to destroy speaker high frequency
driver in a hifi speaker is to have too low power
amplifier and running it to severe distortion.
The disortion causes lots of high frequency components
to be generated by the distortion, and those high
frequency components can overload the high freuqncy driver
even through the total power to the speaker is much less
than the speaker power rating. The reason for this is
that the high freuqncy driver has typically much lower
power rating then the other drivers on the speaker, because
normal sounds do not have much high frequency signals.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/
Anonymous
June 23, 2004 8:56:51 PM

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

> If you're in a position to turn the input (or maybe preamp stage) too
> far up in a vain quest for extra volume, it may start clipping, giving
> the power amplifier a nasty square-edged waveform to amplify.
> Tweeters can succumb to these waveforms rather easily.

It's not the waveform in and of itself that tweeters are sensitive to. It's
simply the increased high frequency power content. The distinction is
important.
Anonymous
June 23, 2004 9:40:35 PM

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

Jean <Robijean@hotmail.com> wrote:

> Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
> with enough power to be driven by the amp? ( I use my amp only for
> music)

The key is to understand what the ratings mean.

The speaker is able to withstand 19W of clean signal before it fries.
The amplifier is capable of putting out 40W of power before it blows
up or distorts the signal excessively.

An amplifier that only puts out 10W cleanly will be distorting heavily
at 15W. This is VERY likely to blow up the tweeter in your speakers.
An amp that can put out more than 19W cleanly (in this case, 40W) is
probably NOT going to blow up your speakers at 15W output.

Consider it this way: Your speakers will blow up at 19W with a clean
signal, or sooner with a bad signal.

Something else to consider is that for an average home, 10W continuous
into typical speakers is almost enough to make your ears bleed! In my
(small and hard-surfaced) living room, the loudest I can stand listening
to my stereo leads to peaks of about 2W on the VU meters--continuous is
less than 1W.

So hook 'em up, and don't worry about it.
Anonymous
June 24, 2004 12:14:27 AM

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

"Tomi Holger Engdahl" <then@solarflare.cs.hut.fi> wrote

> The typical scenario to destroy speaker high frequency
> driver in a hifi speaker is to have too low power
> amplifier and running it to severe distortion.
> The disortion causes lots of high frequency components
> to be generated by the distortion,

No. That's an UL.
http://www.rane.com/note128.html

Rudi Fischer
--
....and may good music always be with you
Anonymous
June 24, 2004 12:14:28 AM

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

> > The typical scenario to destroy speaker high frequency
> > driver in a hifi speaker is to have too low power
> > amplifier and running it to severe distortion.
> > The disortion causes lots of high frequency components
> > to be generated by the distortion,
>
> No. That's an UL.
> http://www.rane.com/note128.html

That Rane note says exactly the same thing. Only they refer to the
introduction of additional high frequency components as dynamic compression.
Anonymous
June 24, 2004 4:48:24 AM

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

On Wed, 23 Jun 2004 16:56:51 -0400, "MZ"
<zarellam@twcnyremove.rr.comspam> wrote:

>> If you're in a position to turn the input (or maybe preamp stage) too
>> far up in a vain quest for extra volume, it may start clipping, giving
>> the power amplifier a nasty square-edged waveform to amplify.
>> Tweeters can succumb to these waveforms rather easily.
>
>It's not the waveform in and of itself that tweeters are sensitive to. It's
>simply the increased high frequency power content. The distinction is
>important.

A squared-off waveform has added hf. Why is one way of describing it
better?
Anonymous
June 24, 2004 4:48:25 AM

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

> >> If you're in a position to turn the input (or maybe preamp stage) too
> >> far up in a vain quest for extra volume, it may start clipping, giving
> >> the power amplifier a nasty square-edged waveform to amplify.
> >> Tweeters can succumb to these waveforms rather easily.
> >
> >It's not the waveform in and of itself that tweeters are sensitive to.
It's
> >simply the increased high frequency power content. The distinction is
> >important.
>
> A squared-off waveform has added hf. Why is one way of describing it
> better?

Because it's important to emphasize that it's not the shape of the waveform
that's the killer, but rather the amount of power being delivered to the
driver. When you just say that square waves blow tweeters, then this
implies that this is true independent of the amount of power being
delivered. This is what feeds the myth that "distortion blows speakers."
Many people, if not most, believe in this myth - that is, a "distorted"
waveform, even when absent a sufficient amount of power, can blow a speaker.
This idea is simply untrue.
Anonymous
June 24, 2004 6:24:55 AM

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

Jean wrote:
>
> "Billw" <notarealemail@nowhere.com> wrote in message news:<40d8a580$1@news.xetron.com>...
> > "Jean" <Robijean@hotmail.com> wrote in message
> > news:2306b1e3.0406221254.7a64dd91@posting.google.com...
> > > Hello,
> > > I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
> > > to plug to one channel a small speaker 19 watts (8 ohm).
> > >
> > > 4 questions:
> > > 1- What circuit should I build to adapt?
> >
> > none. just connect it. The power in your program signal is NOT the full
> > power of the amplifier.
> >
> > And after that, if it sounds bad, turn it down.
> >
> > Unless you plan to pound the amp at clipping levels constantly (i.e., use it
> > as a guitar amp), there is very little danger of hurting the speaker with
> > too much power (you're probably more likely to hurt it with too LITTLE
> > power). If you plan to abuse the volume control (play loud without regard
> > to how much it is disorting), though, then you may need to watch out.


I agree with all of the above. In fact, it can be advantageous to
have an amp that is rated higher in power than the rating on the
speakers. I've seen a 40 watt amp fry a pair of speakers rated at
100 watts each due to significant abuse of the system (they were
trying to use it in a hall much larger than they should have).


> Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
> with enough power to be driven by the amp? ( I use my amp only for
> music)


That really is kinda reversed. You want an amp that can produce
clean undistorted power over the range that the speakers are
rated for. It's only a rough reference and does not mean as much
as some sales people would have you think. All things being even,
a 40 watt speaker can be driven to a louder level than a 20 watt
one before it begins to distort (i.e., is being driven beyond its
physical capabilities).

The problem is that things are almost NEVER all even! For
example, if the 40 watt speakers were 3dB less sensitive than the
20 watt ones, driving them at 40 watts would produce the SAME
loudness as driving the 20 watt ones at 20 watts. If you had 100
watt rated headphones and fed 100 watts of audio power into them,
you still couldn't fill a dance hall with music. You could though
with some very efficient speakers such as a horn type design, etc.

Frequently, in order to get extremly "clean" sound from a
speaker, exotic designs are used that can be very inefficient and
have strange reactive characteristics. This has the interesting
effect that on a lower power or moderate quality amplifier, the
exotic (and usually pricey) speaker can sound much worst that
some other bargin bin speaker. It won't start to really sing
until it is coupled with a high quality, highly resolving
amplifier, etc.

The really important thing is, can you get the maximum volume
that you want to listen to out of the speakers with it sounding
clean and without distortion? If you can, then you need an amp
with a higher power rating than the speakers, that will help to
ensure that you will always be sending clean audio to the
speakers. If the amp is MASSIVELY powered compared to the
speakers it just means you might only use a tiny part of your
volume control before things get too loud and start to distort
(or if you have children in the house, the possibility of blowing
the speakers are greater when someone leaves the volume dial at
100% :-).

You pick your speakers for the volume level and distortion free
sound that you want, then make sure your amp can provide
distortion free audio at that level and somewhat above. Your
system should be fine and you need no "adapter" of any sort. In
fact, you don't want anything between the two components that
would affect the sound.


> 3- A better suitable newsgroup to post this question?
>


This is not a "Pro" audio group, its a "Recreation-Audio" group
so my opinion is that this one is fine (although it HAS been a
while since I read the charter :-) However, there are also folks
here with very advanced understanding (or some that just THINK
they do :-) so some basic questions can spin off some more
complicated threads. I appreciated the reference to the RANE
article that was mention earlier by someone in this thread. I was
not aware of some of the issues that it addressed.


> Search on the internet:
> 4- What words should I use to find some appropriate technical texts?


Not sure here. You are looking at many different issues when you
start dealing with loudspeakers. E.g., did you know that the 8
ohm rating is only nominal? that actual impeadance can vary from
as low as 4 ohms and go as high as 15,000 ohms depending on the
frequency that the impeadance is being measured at. Some basic
introductory texts on speaker theory might work for you.

Hope this helps some.

- Jeff
Anonymous
June 24, 2004 6:24:56 AM

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

> I agree with all of the above. In fact, it can be advantageous to
> have an amp that is rated higher in power than the rating on the
> speakers. I've seen a 40 watt amp fry a pair of speakers rated at
> 100 watts each due to significant abuse of the system (they were
> trying to use it in a hall much larger than they should have).

That's what you get when you assume power ratings to accurately reflect true
power handling capabilities. :) 
Anonymous
June 24, 2004 7:26:42 AM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote in
news:p oidnbTGJ42IhEfdRVn-jA@giganews.com:

>> >> If you're in a position to turn the input (or maybe preamp stage)
>> >> too far up in a vain quest for extra volume, it may start clipping,
>> >> giving the power amplifier a nasty square-edged waveform to amplify.
>> >> Tweeters can succumb to these waveforms rather easily.
>> >
>> >It's not the waveform in and of itself that tweeters are sensitive to.
> It's
>> >simply the increased high frequency power content. The distinction is
>> >important.
>>
>> A squared-off waveform has added hf. Why is one way of describing it
>> better?
>
> Because it's important to emphasize that it's not the shape of the
> waveform that's the killer, but rather the amount of power being
> delivered to the driver. When you just say that square waves blow
> tweeters, then this implies that this is true independent of the amount
> of power being delivered. This is what feeds the myth that "distortion
> blows speakers." Many people, if not most, believe in this myth - that
> is, a "distorted" waveform, even when absent a sufficient amount of
> power, can blow a speaker. This idea is simply untrue.
>
>
>

I don't recall seeing a spectrum analyzer display of a square wave on the
web so I posted one. I think the point about clipping and tweeter damage
is made quite clear if you look at the jpeg I posted to
alt.binaries.schematics.electronic. The subject is 400hz square wave.
The poor tweeter is expected to reproduce all of those frequencies all at
once with harmonics well beyond it's range. That is just one frequency. I
hate to imagine if one had many frequencies clipping.

r

--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
Anonymous
June 24, 2004 7:08:01 PM

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

"MZ" zarellam@twcnyremove.rr.comspam
wrote:


>
>> I agree with all of the above. In fact, it can be advantageous to
>> have an amp that is rated higher in power than the rating on the
>> speakers. I've seen a 40 watt amp fry a pair of speakers rated at
>> 100 watts each due to significant abuse of the system (they were
>> trying to use it in a hall much larger than they should have).
>
>That's what you get when you assume power ratings to accurately reflect true
>power handling capabilities. :) 

This is true. Tweeters generally have a modest power handling capability. But
the Urban Legend about small amplifiers being dangerous to speakers is chronic
and widespread.

A few years ago at a PSACS meeting a speaker technician from an Illinois
retailer gave a talk about speaker damage and repair. When asked if small
amplifiers were dangerous to tweeters he emphatically said "oh yes" and
produced a discolored voice coil (from a small woofer) and declared that this
damage came from using a small amplifier.

Because the coil looked like several others he had shown earlier I asked how he
knew that that had been the case. He said that he knew the owner of that
speaker and had watched him "abuse that speaker with that little amp ... for
years" completely ignoring the possibility that the guy might have blown up
that speaker in much less time with a bigger amplifier.

I'm of the thought that the urban legend of small amplifiers and tweeter damage
is simply a retail technqiue to sell amplifiers when some one brings in a
damaged speaker. Because the most likely speaker damage is a blown tweeter the
Legend gets to be used most often for that situation.

I sometimes challange the Legend with what I call the "Underpowering Contra
Argument". If "underpowering" with a small amplifier were the true cause of
speaker damage then driving one with the output from your preamplifier or from
the headphone jack on a walkman should be avoided at all cost.
Anonymous
June 24, 2004 7:52:10 PM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote in message
news:6a-dnTc9BvjJc0TdRVn-vA@giganews.com...
> > > The typical scenario to destroy speaker high frequency
> > > driver in a hifi speaker is to have too low power
> > > amplifier and running it to severe distortion.
> > > The disortion causes lots of high frequency components
> > > to be generated by the distortion,
> >
> > No. That's an UL.
> > http://www.rane.com/note128.html
>
> That Rane note says exactly the same thing. Only they refer to the
> introduction of additional high frequency components as dynamic
compression.

Not exactly, they say it's NOT due to the "introduction of additional HF
components" but due to dynamic spectral compression when driven well beyond
the point of clipping. The solution is simple, turn it down when it's
distorting. If the amplifier is small enough, and the tweeter large enough
however, then clipping will NOT blow up the tweeter. OTOH a big amp will
always require some attention to it's power output.

TonyP.
Anonymous
June 24, 2004 7:52:11 PM

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

> > That Rane note says exactly the same thing. Only they refer to the
> > introduction of additional high frequency components as dynamic
> compression.
>
> Not exactly, they say it's NOT due to the "introduction of additional HF
> components" but due to dynamic spectral compression when driven well
beyond
> the point of clipping.

They can call it whatever they want, but it's the same exact thing! Looking
at their proposition in Fourier space is identical to the notion of a mere
increase in high frequency content.
Anonymous
June 24, 2004 8:04:18 PM

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

"Rich.Andrews" <spmaway@ylhoo.com> wrote in message
news:Xns9511E452D8420mc2500183316chgoill@10.232.1.1...
> "MZ" <zarellam@twcnyremove.rr.comspam> wrote in
> news:p oidnbTGJ42IhEfdRVn-jA@giganews.com:
> > Because it's important to emphasize that it's not the shape of the
> > waveform that's the killer, but rather the amount of power being
> > delivered to the driver. When you just say that square waves blow
> > tweeters, then this implies that this is true independent of the amount
> > of power being delivered. This is what feeds the myth that "distortion
> > blows speakers." Many people, if not most, believe in this myth - that
> > is, a "distorted" waveform, even when absent a sufficient amount of
> > power, can blow a speaker. This idea is simply untrue.
> >

> I don't recall seeing a spectrum analyzer display of a square wave on the
> web so I posted one. I think the point about clipping and tweeter damage
> is made quite clear if you look at the jpeg I posted to
> alt.binaries.schematics.electronic. The subject is 400hz square wave.
> The poor tweeter is expected to reproduce all of those frequencies all at
> once with harmonics well beyond it's range. That is just one frequency. I
> hate to imagine if one had many frequencies clipping.

Which is exactly the point. *ANY* speaker can accommodate a 400 Hz Square
wave, or any other arbitrary waveform, *IF* the power delivered to the
drivers is less than it is designed to handle.
For tweeters that is usually in the range of 1 watt RMS continuous, to over
50 watts in the case of some horn drivers. It's simply the fact that most
tweeters fall near the lower end of the range despite claiming "system music
power" ratings of up to 100 times more, that is the cause of tweeter
failure.

TonyP.
Anonymous
June 24, 2004 8:08:17 PM

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

"Colin B." <cbigam@somewhereelse.nucleus.com> wrote in message
news:40d9bf1c_2@news....
> In my
> (small and hard-surfaced) living room, the loudest I can stand listening
> to my stereo leads to peaks of about 2W on the VU meters--continuous is
> less than 1W.

Yeah, pop music is getting pretty bad with peak to average ratio's of only 6
dB or so!
For real music you will find the peaks much higher, and the average maybe
even lower.

TonyP.
Anonymous
June 24, 2004 8:30:35 PM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote
> "TonyP" wrote
> > "MZ" <zarellam@twcnyremove.rr.comspam> wrote

> > > That Rane note says exactly the same thing. Only they refer to
> > > the introduction of additional high frequency components as
> > > dynamic compression.
> > Not exactly, they say it's NOT due to the "introduction of
> > additional HF components" but due to dynamic spectral
> > compression when driven well beyond the point of clipping.

He's got it:) 

> They can call it whatever they want, but it's the same exact thing!

Not so.

> Looking
> at their proposition in Fourier space is identical to the notion of a
> mere increase in high frequency content.

This is (you might say trivially) correct for clipped sine-waves
but not for clipped /music/. Try it...

Rudi Fischer
--
....and may good music always be with you
Anonymous
June 24, 2004 8:30:36 PM

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

> > They can call it whatever they want, but it's the same exact thing!
>
> Not so.

Care to elaborate?

>
> > Looking
> > at their proposition in Fourier space is identical to the notion of a
> > mere increase in high frequency content.
>
> This is (you might say trivially) correct for clipped sine-waves
> but not for clipped /music/. Try it...

What's the difference between sine waves and music (or any signal for that
matter)? Nothing! Music is, of course, composed of sine waves.

Look, they claim that tweeters blow because high frequency content
increases. That's what we've been saying all along. So how on earth are
the two notions different aside from the fact that they've tagged along a
nifty phrase for it?
Anonymous
June 24, 2004 10:16:29 PM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote

> > > They can call it whatever they want, but it's the same exact
> > > thing!
> > Not so.
> Care to elaborate?
> > > Looking
> > > at their proposition in Fourier space is identical to the notion
> > > of a
> > > mere increase in high frequency content.
> > This is (you might say trivially) correct for clipped sine-waves
> > but not for clipped /music/. Try it...
> What's the difference between sine waves and music (or any signal for
> that
> matter)? Nothing! Music is, of course, composed of sine waves.

Oh well...

> Look, they claim that tweeters blow because high frequency content
> increases.

How much does the h_f_c increase if you clip music
(say +1dB, 10W Amp) relative to the unclipped signal?
Is this relative amount enough to instantly grill a tweeter?
Not so.

BTW: About 20% of modern CDs are _very_badly_ clipped.
Does that kill more tweeters?

> That's what we've been saying all along.

Seems to me it will stay that way...

> So how on earth are
> the two notions different aside from the fact that they've tagged
> along a nifty phrase for it?

And why on earth don't you try an FFT on clipped music
relative to unclipped first and than tell us the outcome?

It's simply too much power and (thermal) compression that
kills speakers, with or without signal distortion. So *big*
amps will be doing this job way *better*.

Rudi Fischer
--
....and may good music always be with you
Anonymous
June 24, 2004 10:16:30 PM

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

> > Look, they claim that tweeters blow because high frequency content
> > increases.
>
> How much does the h_f_c increase if you clip music
> (say +1dB, 10W Amp) relative to the unclipped signal?

It depends on the frequency content of the original signal and on what you
define as "high frequency". It can, of course, be calculated when you
provide those parameters.

> Is this relative amount enough to instantly grill a tweeter?
> Not so.

Depends on the tweeter and the high frequency content. After all, power is
the only thing that can blow a tweeter.

Anyway, I'm not sure where you're going with this line of questioning.

> BTW: About 20% of modern CDs are _very_badly_ clipped.
> Does that kill more tweeters?

I think you're taking a basic concept of compression in modern day CDs and
distorting the facts. But your underlying point is not one that I disagreed
with. So how does this address whether or not the Ranenote is saying the
same as what the other poster said?


> > So how on earth are
> > the two notions different aside from the fact that they've tagged
> > along a nifty phrase for it?
>
> And why on earth don't you try an FFT on clipped music
> relative to unclipped first and than tell us the outcome?

I've done in many many times. What are you getting at? Yes, the high
frequency content increases! That's my entire point. And what Rane is
saying is the same thing.

> It's simply too much power and (thermal) compression that
> kills speakers, with or without signal distortion.

Yes, too much power will blow speakers. Who argued otherwise? Certainly
not me. I don't know what "thermal compression" is. Power compression
perhaps? That won't blow speakers. In fact, it acts in the opposite
manner.
Anonymous
June 25, 2004 1:19:20 AM

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

Nousaine wrote:
<<stuff deleted>>
> I sometimes challange the Legend with what I call the "Underpowering Contra
> Argument". If "underpowering" with a small amplifier were the true cause of
> speaker damage then driving one with the output from your preamplifier or from
> the headphone jack on a walkman should be avoided at all cost.


An interesting response but perhaps a little anticdotal. The
shortest job that I ever had was once I was hired to be a
bricklayer's helper. I was healthy, but not a really strong guy.
I was strong enough to lift buckets of morter and concrete but
after a short while I would get a little shakey. I spilled some
concrete once or twice on a wall because of my lack of strength.
If they had hired a stronger guy, it wouldn't have happened. If
they had hired a 3 year old kid, it ALSO wouldn't have happened
since the kid wouldn't have had the strength to even lift the
bucket in the first place. To say that the damage I caused was
not due to my lack of strength/control and say the proof is that
someone with even less strengh wouldn't cause any damage seems to
ignores some key elements of logic somewhere :-)

The problem is where there is enough power to get things going
but not enough to control things well. If my boss missed the
issue and somehow thought I could do twice as much work, he might
of made me carry two buckets at a time (like the other "Charles
Atlas" helper he had). Since I COULD lift two buckets, you might
say I could do it, but I suspect that there would have been twice
as much damage.

The issue with the speaker ratings is that they never tell you
how the rated power can be safely distributed across the spectrum
of the speaker or how they even arrived at the rating in the
first place. A "50 watt" speaker may only be rated for 1/4 watt
across the 5KHz to 20KHz band. As has been pointed out before, a
speaker rating is not linear across its entire bandwidth.

There may be some standards for speaker power rating but I don't
think that I've ever come across one.

- Jeff
Anonymous
June 25, 2004 1:19:21 AM

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

>Nousaine wrote:
><<stuff deleted>>
>> I sometimes challange the Legend with what I call the "Underpowering Contra
>> Argument". If "underpowering" with a small amplifier were the true cause of
>> speaker damage then driving one with the output from your preamplifier or from
>> the headphone jack on a walkman should be avoided at all cost.

Okay, let's look at this problem slightly differently and see if it makes more
sense.

When a small amp goes into heavy clipping it produces a signal that looks pretty
much like a square wave. Forget about the harmonic train for a moment and just
look at (or consider) the shape of the signal: a sudden rise to the top, it
stays there for a while, then a sudden drop to the bottom, where it stays for a
while, and then it repeats all over again.

There's another way to describe that kind of signal: pulsating DC. For a
speaker, it's a hard signal to handle. The speaker moves out and simply sits
there, then it moves in, and sits there. While it's just sitting there, being
held out (or in) by the voltage, the temperature in the voice coil is rising,
since there's no way to dissipate the heat from the "DC" that's holding the
speaker still. Do that long enough (even at lower than maximum speaker ratings)
and the coil will eventually burn up.

Is that easier to grasp?
Harvey Gerst
Indian Trail Recording Studio
http://www.ITRstudio.com/
Anonymous
June 25, 2004 1:19:22 AM

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

> Okay, let's look at this problem slightly differently and see if it makes
more
> sense.
>
> When a small amp goes into heavy clipping it produces a signal that looks
pretty
> much like a square wave. Forget about the harmonic train for a moment and
just
> look at (or consider) the shape of the signal: a sudden rise to the top,
it
> stays there for a while, then a sudden drop to the bottom, where it stays
for a
> while, and then it repeats all over again.
>
> There's another way to describe that kind of signal: pulsating DC. For a
> speaker, it's a hard signal to handle. The speaker moves out and simply
sits
> there, then it moves in, and sits there. While it's just sitting there,
being
> held out (or in) by the voltage, the temperature in the voice coil is
rising,
> since there's no way to dissipate the heat from the "DC" that's holding
the
> speaker still. Do that long enough (even at lower than maximum speaker
ratings)
> and the coil will eventually burn up.
>
> Is that easier to grasp?

Unfortunately, it doesn't really clarify anything. In fact, it muddies
things up even more. First of all, there's not really such a thing as
"pulsating DC". That's an oxymoron. If it's "pulsating", it's by
definition an AC signal.

The rest of what you say would be true only if the fundamental was on the
order of fractions of a Hz. It's a nice idea, but it's simply not the way
it works. The voice coil doesn't care a whole lot about the motion
waveform - it just cares that motion is occurring. Whether it's a square
wave or a sine wave, it makes no difference. Also, due to the inductance of
the voice coil and the limitations of the amplifier, most speakers will
generally not move in a square wave fashion anyway, even when the amplifier
is severely clipped.
Anonymous
June 25, 2004 11:58:37 AM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote in message
news:LJudnZVPQulh6EbdRVn-sw@giganews.com
>> Okay, let's look at this problem slightly differently and see if it
>> makes more sense.
>>
>> When a small amp goes into heavy clipping it produces a signal that
>> looks pretty much like a square wave. Forget about the harmonic
>> train for a moment and just look at (or consider) the shape of the
>> signal: a sudden rise to the top, it
>> stays there for a while, then a sudden drop to the bottom, where it
>> stays for a while, and then it repeats all over again.

>> There's another way to describe that kind of signal: pulsating DC.
>> For a speaker, it's a hard signal to handle. The speaker moves out
>> and simply sits there, then it moves in, and sits there. While it's
>> just sitting there, being held out (or in) by the voltage, the
>> temperature in the voice coil is rising, since there's no way to
>> dissipate the heat from the "DC" that's holding the
>> speaker still. Do that long enough (even at lower than maximum
>> speaker ratings) and the coil will eventually burn up.
>>
>> Is that easier to grasp?

> Unfortunately, it doesn't really clarify anything. In fact, it
> muddies things up even more. First of all, there's not really such a
> thing as "pulsating DC". That's an oxymoron. If it's "pulsating",
> it's by definition an AC signal.

Your skepticism is IMO well-founded.

When you cleanly clip a music waveform, it doesn't just look like a square
wave, it is a variable-frequency square wave. However, there's no guarantee
that a true POS power amp will clip cleanly. What this comes down to is that
a POS is a POS, and using a POS power amp can be dangerous to your system,
no matter what its power rating is.

If we drop the POS power amps from the discussion, we're left with what
happens with a competent low power amp as opposed to what happens to a
competent high powered amp.

To understand this better, you have to consider how speakers fail. IME the
most common form of driver failure is caused by overheating of the voice
coil. Second is fracturing of the voice coil wiring due to excess flexing. A
third failure mode relates to over-travel of the cone. These three most
common loudspeaker driver failure modes have a common cause - too much
power.

Much has been written about spectral shifting due to clipping, and this can
clearly stimulate the first and second modes of failure by causing more
power to be routed to high frequency drivers.

However, there's a lot of music around whose high frequency spectral
content actually decreases when it is cleanly clipped, and even more where
there are no appreciable changes.

Classical music is one genre where upward spectral shifting can still be
dominant, but even there it's not a sure thing. During crescendos crashing
cymbals and blaring horns can build up a lot of power at high frequencies.

The bottom line is that most of the failure modes of drivers come from the
driver receiving too much power, too long. The easiest way to get more power
to a speaker is to have a more powerful amplifier. These days, 100 wpc power
amps are unbelievably inexpensive. 100 wpc is a lot of power for most
consumer speakers to handle, long term.

Intensely powerful *accidents* are more likely with more powerful
amplifiers.

More powerful amplifiers also provide a psychoacoustic cause for speaker
damage. Undistorted music often sounds less loud than distorted music with
equal power. Therefore, a listener is more likely to apply more power to his
speakers with a more powerful amplifier. In the absence of clipping, the
music will not sound as loud as it will if it is clipped.

That all said, I have just a few kilowatts of power amps around the house,
and most of them are hooked to speakers. The good news for my speakers is
that I have a lot of fairly robust speakers, and I try to be careful.

I don't think there is any doubt that over the past 30 years loudspeakers
have become as a rule, more robust.
Anonymous
June 25, 2004 3:27:43 PM

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

> More powerful amplifiers also provide a psychoacoustic cause for speaker
> damage. Undistorted music often sounds less loud than distorted music
with
> equal power. Therefore, a listener is more likely to apply more power to
his
> speakers with a more powerful amplifier. In the absence of clipping, the
> music will not sound as loud as it will if it is clipped.

This is an excellent point, and one that I had overlooked in the context of
this discussion.
June 25, 2004 3:46:04 PM

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

Jeff Wiseman <wisemanja@earthlink.net> wrote in message news:<40DA3B37.E4484CBD@earthlink.net>...
> Jean wrote:
> >
> > "Billw" <notarealemail@nowhere.com> wrote in message news:<40d8a580$1@news.xetron.com>...
> > > "Jean" <Robijean@hotmail.com> wrote in message
> > > news:2306b1e3.0406221254.7a64dd91@posting.google.com...
> > > > Hello,
> > > > I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
> > > > to plug to one channel a small speaker 19 watts (8 ohm).
> > > >
> > > > 4 questions:
> > > > 1- What circuit should I build to adapt?
> > >
> > > none. just connect it. The power in your program signal is NOT the full
> > > power of the amplifier.
> > >
> > > And after that, if it sounds bad, turn it down.
> > >
> > > Unless you plan to pound the amp at clipping levels constantly (i.e., use it
> > > as a guitar amp), there is very little danger of hurting the speaker with
> > > too much power (you're probably more likely to hurt it with too LITTLE
> > > power). If you plan to abuse the volume control (play loud without regard
> > > to how much it is disorting), though, then you may need to watch out.
>
>
> I agree with all of the above. In fact, it can be advantageous to
> have an amp that is rated higher in power than the rating on the
> speakers. I've seen a 40 watt amp fry a pair of speakers rated at
> 100 watts each due to significant abuse of the system (they were
> trying to use it in a hall much larger than they should have).
>
>
> > Then, what is the purpose to have a loudspeaker (on a HI-FI audio amp)
> > with enough power to be driven by the amp? ( I use my amp only for
> > music)
>
>
> That really is kinda reversed. You want an amp that can produce
> clean undistorted power over the range that the speakers are
> rated for.
> ...
> The really important thing is, can you get the maximum volume
> that you want to listen to out of the speakers with it sounding
> clean and without distortion?
> - Jeff

My situation: I already have a Hi-Fi amp 40 watts. I have extra
loudspeakers 19 watts. I do not want to damage my 19 watts. I am not
concerned about distortion because my guess ( before plugging my 19
watts) is if I put the volume 40 watts at 10/10, I will damage my 19
watts, tweeters probably first than woofers as I understand from the
postings...
The really important thing is getting max volume 10/10 from a kid not
without distortion, but without damaging my 19 watts loudspeakers.
I could try this: plug the 19 watts, take up the volume to 5/10
(20watts?), 6/10 (24 watts?)... 10/10 (40 watts) and see at what level
I blow up the 19 watts speakers?
I wanted to adapt the power so that if a kid turn the volume 10/10,
yes, the 19 watts speakers are still reproducing the sound.
Then I will think about distortion: If I hear distortion, it is
because the loudspeaker is not able to reproduce the music, then
because there is too much power sent to the speaker: therefore, turn
dowm the volume!
A 1 watt speaker is able to reproduce a 1000 watt amp if you do not
turn the volume at 10/10! You have to adapt in some ways ( which is
the first question ) to keep alive the 1 watt speaker. Then I will
think about a clean reproduction of the music...
Anonymous
June 25, 2004 4:56:18 PM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote in message
news:YIWdnVVsXuXz2UHdRVn-jg@giganews.com
>> More powerful amplifiers also provide a psychoacoustic cause for
>> speaker damage. Undistorted music often sounds less loud than
>> distorted music with equal power. Therefore, a listener is more
>> likely to apply more power to his speakers with a more powerful
>> amplifier. In the absence of clipping, the music will not sound as
>> loud as it will if it is clipped.
>
> This is an excellent point, and one that I had overlooked in the
> context of this discussion.

While were're on a psychological, social, and behavioral mood, let's
consider the effect of blood alcohol on driver connectivity. Alcohol is a
general nervous system depressant, and the ears are hooked to the brain via
the nervous system...
Anonymous
June 25, 2004 5:05:12 PM

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

> > This is an excellent point, and one that I had overlooked in the
> > context of this discussion.
>
> While were're on a psychological, social, and behavioral mood, let's
> consider the effect of blood alcohol on driver connectivity. Alcohol is a
> general nervous system depressant, and the ears are hooked to the brain
via
> the nervous system...

I don't know of any evidence that suggests that alcohol would have an
influence on loudness perception, though it almost certainly would
contribute to the stupidity factor - that is, turning it up beyond reason.
Anonymous
June 25, 2004 6:34:39 PM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote in message
news:XaydnUZJ37vVxkHdRVn-sA@giganews.com
>>> This is an excellent point, and one that I had overlooked in the
>>> context of this discussion.
>>
>> While were're on a psychological, social, and behavioral mood, let's
>> consider the effect of blood alcohol on driver connectivity. Alcohol
>> is a general nervous system depressant, and the ears are hooked to
>> the brain via the nervous system...
>
> I don't know of any evidence that suggests that alcohol would have an
> influence on loudness perception, though it almost certainly would
> contribute to the stupidity factor - that is, turning it up beyond
> reason.


http://alcoholism.about.com/cs/brain/a/blacer040314.htm

http://hearingloss.upmc.com/Treatment.htm
Anonymous
June 26, 2004 12:01:41 AM

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

Jean wrote:
> My situation: I already have a Hi-Fi amp 40 watts. I have extra
> loudspeakers 19 watts. I do not want to damage my 19 watts. I am not
> concerned about distortion because my guess ( before plugging my 19
> watts) is if I put the volume 40 watts at 10/10, I will damage my 19
> watts, tweeters probably first than woofers as I understand from the
> postings...

In general, putting the setting at 10/10 will cause damage on
most systems anyway if left running long enough.


> The really important thing is getting max volume 10/10 from a kid not
> without distortion, but without damaging my 19 watts loudspeakers.
> I could try this: plug the 19 watts, take up the volume to 5/10
> (20watts?), 6/10 (24 watts?)... 10/10 (40 watts) and see at what level
> I blow up the 19 watts speakers?
> I wanted to adapt the power so that if a kid turn the volume 10/10,
> yes, the 19 watts speakers are still reproducing the sound.


Ahh! NOW we're getting to the crux of the matter :-) Cranking the
volume up to 100% on most systems will usually result in a
failure given long enough to heat things up. That's why most
people don't do it :-) I once had a 125watt receiver that my 2
year old daughter cranked up all the way when it was off. She
then made the mistake of pushing the power button! I was in the
house as was able to turn it off before any real damage occurred
but I suspect it was close :-) Suggestions for this at the end of
this note:


> Then I will think about distortion: If I hear distortion, it is
> because the loudspeaker is not able to reproduce the music, then
> because there is too much power sent to the speaker: therefore, turn
> dowm the volume!


Exactly. If your amp is rated higher than the speakers, in
general when you start to hear distortion, is because the
speakers are being pushed to hard.


> A 1 watt speaker is able to reproduce a 1000 watt amp if you do not
> turn the volume at 10/10! You have to adapt in some ways ( which is
> the first question ) to keep alive the 1 watt speaker. Then I will
> think about a clean reproduction of the music...


OK, here's a way to deal with it but it assumes that you can get
to the signal between your preamp and your main amp. The issue is
that you don't want the signal entering the amp to be high enough
to create a damaging level of signal to the speakers. I solved my
problem as followes:

Although I had a receiver at the time, the preamp and power amp
sections were separated by a pair of jumpers on the back. I
removed the jumpers and put a "T-pad" resistor in using a value
so that when my volume level was up all the way, the total volume
in the room was only slightly louder than I normally listened to.
By putting the resistance between the preamp and the main amp, it
prevented the amp itself from being overdriven into distortion
even when the preamp's volume was up all the way. In other words,
even though the main amp was rated for 125 watts, I was
preventing it from getting enough signal to ever reach that level.

I used a pair of T-pads but I also could have just used a stereo
potentiometer (about a 50Kohm unit wired across the output of the
preamp with the common and tap going to the main amp) adjusted to
limit the maximum volume in the room when the preamp's volume was
set to 100%. I had to make them myself as I couldn't find
something off the self. I'm not sure where you might find
something like this pre-built but anyone handly with a soldering
iron could put something like that together real cheap.

- Jeff
Anonymous
June 26, 2004 6:40:45 AM

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

just put a 1 or 2 ampere fuse in the speaker line and forget about it.

On 22 Jun 2004 13:54:11 -0700, Robijean@hotmail.com (Jean) wrote:

>Hello,
>I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
>to plug to one channel a small speaker 19 watts (8 ohm).
>
>4 questions:
>1- What circuit should I build to adapt?
>
>2- How can I know how much ampere the amp is using to drive one
>loudspeaker?
>
>3- A better suitable newsgroup to post this question?
>
>Search on the internet:
>4- What words should I use to find some appropriate technical texts?
>
>Thank you.
Anonymous
June 26, 2004 8:53:27 AM

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

"Stu-R" <stu-r@sbcglobal.net> wrote in message
news:mfopd058hce4asma4tiho4lt4908dtvkbv@4ax.com...
> just put a 1 or 2 ampere fuse in the speaker line and forget about it.
>
> On 22 Jun 2004 13:54:11 -0700, Robijean@hotmail.com (Jean) wrote:
>
> >Hello,
> >I have an audio amp, 40 watts RMS per channel (8 ohm) and I would like
> >to plug to one channel a small speaker 19 watts (8 ohm).
> >
> >4 questions:
> >1- What circuit should I build to adapt?
> >
> >2- How can I know how much ampere the amp is using to drive one
> >loudspeaker?
> >
> >3- A better suitable newsgroup to post this question?
> >
> >Search on the internet:
> >4- What words should I use to find some appropriate technical texts?
> >
> >Thank you.
>

I agree. Fuse the speaker and forget it. P = (I^2) * R. Solving for I, the
maximum current at 19 watts would be 1.5 amps. I'd use a 1.0 amp fast-blow
fuse to be safe.

To put things in perspective, the difference between 40 watts and 19 watts
just a little over 3 dB. In other words, you could make the 40 watt
amplifier "safe" for the 19 watt speaker by turning down the volume by 3dB,
a barely audible difference.
Anonymous
June 26, 2004 8:53:28 AM

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

> I agree. Fuse the speaker and forget it. P = (I^2) * R. Solving for I,
the
> maximum current at 19 watts would be 1.5 amps. I'd use a 1.0 amp fast-blow
> fuse to be safe.
>
> To put things in perspective, the difference between 40 watts and 19 watts
> just a little over 3 dB. In other words, you could make the 40 watt
> amplifier "safe" for the 19 watt speaker by turning down the volume by
3dB,
> a barely audible difference.

3dB is most certainly audible. Especially across the entire spectrum.
Anonymous
June 26, 2004 11:33:08 AM

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

On Sat, 26 Jun 2004 02:10:33 -0400, "MZ"
<zarellam@twcnyremove.rr.comspam> wrote:

>> I agree. Fuse the speaker and forget it. P = (I^2) * R. Solving for I,
>the
>> maximum current at 19 watts would be 1.5 amps. I'd use a 1.0 amp fast-blow
>> fuse to be safe.
>>
>> To put things in perspective, the difference between 40 watts and 19 watts
>> just a little over 3 dB. In other words, you could make the 40 watt
>> amplifier "safe" for the 19 watt speaker by turning down the volume by
>3dB,
>> a barely audible difference.
>
>3dB is most certainly audible. Especially across the entire spectrum.
>

A 3dB change in sound level is, as you say, very audible. But to
substitute an amplifier, a job which would take several minutes, with
another of 3dB lower power - and then tell which was which - would not
be easy. Judging the difference in loudness at which clipping starts
isn't easy at all.

d
Pearce Consulting
http://www.pearce.uk.com
Anonymous
June 26, 2004 11:40:54 AM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote in message
news:6MadnTnO6t_FjkDdRVn-uw@giganews.com...
> > I agree. Fuse the speaker and forget it. P = (I^2) * R. Solving for I,
> the
> > maximum current at 19 watts would be 1.5 amps. I'd use a 1.0 amp
fast-blow
> > fuse to be safe.
> >
> > To put things in perspective, the difference between 40 watts and 19
watts
> > just a little over 3 dB. In other words, you could make the 40 watt
> > amplifier "safe" for the 19 watt speaker by turning down the volume by
> 3dB,
> > a barely audible difference.
>
> 3dB is most certainly audible. Especially across the entire spectrum.
>
>
I didn't say it wasn't audible. I just said it was barely audible. If I
thought I was going to have to footnote my post, I would have said it
wouldn't be noticed by the average person, listening casually to normal
programming (not tones or other highly correlated or highly uniform
signals). Sheesh.
Anonymous
June 26, 2004 3:46:54 PM

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

> >3dB is most certainly audible. Especially across the entire spectrum.
> >
>
> A 3dB change in sound level is, as you say, very audible. But to
> substitute an amplifier, a job which would take several minutes, with
> another of 3dB lower power - and then tell which was which - would not
> be easy. Judging the difference in loudness at which clipping starts
> isn't easy at all.

I don't understand what you're getting at. Why would you need to substitute
an amplifier? And how does that change the fact that 3dB is very audible.
Anonymous
June 26, 2004 3:48:15 PM

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

> I didn't say it wasn't audible. I just said it was barely audible. If I
> thought I was going to have to footnote my post, I would have said it
> wouldn't be noticed by the average person, listening casually to normal
> programming (not tones or other highly correlated or highly uniform
> signals). Sheesh.

I disagree. 3dB is usually easily noticeable.
Anonymous
June 26, 2004 9:31:29 PM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote in message
news:lqydnRHU64cun0bd4p2dnA@giganews.com...
> I've done in many many times. What are you getting at? Yes, the high
> frequency content increases! That's my entire point. And what Rane is
> saying is the same thing.

No they are not. The whole article is to contradict your notions, but it
seems you still don't get it.

> > It's simply too much power and (thermal) compression that
> > kills speakers, with or without signal distortion.

Exactly.

> Yes, too much power will blow speakers. Who argued otherwise? Certainly
> not me.

Why all the nonsense about "clipping increasing HF components" being the
problem then? And the assertion that bigger amps are safer.

>I don't know what "thermal compression" is. Power compression
> perhaps? That won't blow speakers. In fact, it acts in the opposite
> manner.

Not at all, since the average power increases and it is the average power
that will kill tweeters, regardless of spectral content (assuming a proper
Xover)

TonyP.
Anonymous
June 26, 2004 9:31:30 PM

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

> > I've done in many many times. What are you getting at? Yes, the high
> > frequency content increases! That's my entire point. And what Rane is
> > saying is the same thing.
>
> No they are not. The whole article is to contradict your notions, but it
> seems you still don't get it.

You're correct. I just reread it (I hadn't read it for well over a year).
I was thinking of another article. My apologies.

However, while I agree with the concepts put forth in the article, I do not
agree with the notion that the harmonics produced by clipping are not
harmful to high frequency drivers. The author claims that the magnitude of
the harmonics are too small to cause an effect. I'd say that this may be
true a great deal of the time, but program material that de-emphasizes high
frequency content is not nearly as uncommon as the author would like you to
believe. It's not uncommon for the magnitude of the signal within the ~1kHz
region to be 3x (or more) that of the magnitude at, say, 3kHz or so.
Driving the amplifier pretty severely into clipping will therefore produce
3rd order harmonics that rival the power content of the amplified original
signal at that frequency spectrum. So I think it's folly to dismiss this
effect.

> > Yes, too much power will blow speakers. Who argued otherwise?
Certainly
> > not me.
>
> Why all the nonsense about "clipping increasing HF components" being the
> problem then? And the assertion that bigger amps are safer.

1) I never made the assertion that bigger amps are safer. Ever. Google my
posts - I've discussed this topic at great length for literally years in
other newsgroups.

2) Why are you implying that the increase of HF components and an increase
in total power content are mutually exclusive? That notion defies all
logic. The increase in power content is a RESULT of the increase in HF
components. Let me make it simple for you: you have a 1v 40Hz wave. Now
you have a 1v 40 Hz wave together with a 0.3v 120Hz wave. Which waveform
has greater power content?


>
> >I don't know what "thermal compression" is. Power compression
> > perhaps? That won't blow speakers. In fact, it acts in the opposite
> > manner.
>
> Not at all, since the average power increases and it is the average power
> that will kill tweeters, regardless of spectral content (assuming a proper
> Xover)

Huh? When power compression occurs, the average power dissipated by the
speaker DECREASES relative to what it would be if power compression had not
set in.
Anonymous
June 26, 2004 9:42:28 PM

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

"Jean" <Robijean@hotmail.com> wrote in message
news:2306b1e3.0406251046.28cdd132@posting.google.com...
> I wanted to adapt the power so that if a kid turn the volume 10/10,
> yes, the 19 watts speakers are still reproducing the sound.
> Then I will think about distortion: If I hear distortion, it is
> because the loudspeaker is not able to reproduce the music, then
> because there is too much power sent to the speaker: therefore, turn
> dowm the volume!
> A 1 watt speaker is able to reproduce a 1000 watt amp if you do not
> turn the volume at 10/10! You have to adapt in some ways ( which is
> the first question ) to keep alive the 1 watt speaker. Then I will
> think about a clean reproduction of the music...

The simplest solution is speaker fuses. Much cheaper to replace than
speakers.

TonyP.
Anonymous
June 26, 2004 9:42:29 PM

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

"TonyP" <TonyP@optus.net.com.au> wrote in message
news:40dd28ef$0$18668$afc38c87@news.optusnet.com.au

> "Jean" <Robijean@hotmail.com> wrote in message
> news:2306b1e3.0406251046.28cdd132@posting.google.com...

>> A 1 watt speaker is able to reproduce a 1000 watt amp if you do not
>> turn the volume at 10/10! You have to adapt in some ways ( which is
>> the first question ) to keep alive the 1 watt speaker. Then I will
>> think about a clean reproduction of the music...

> The simplest solution is speaker fuses. Much cheaper to replace than
> speakers.

Absolutely! Especially true for systems that get a lot of casual use.
Example: teenagers.
Anonymous
June 26, 2004 9:42:29 PM

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

TonyP wrote:
>
> "Jean" <Robijean@hotmail.com> wrote in message
> news:2306b1e3.0406251046.28cdd132@posting.google.com...
> > I wanted to adapt the power so that if a kid turn the volume 10/10,
> > yes, the 19 watts speakers are still reproducing the sound.
> > Then I will think about distortion: If I hear distortion, it is
> > because the loudspeaker is not able to reproduce the music, then
> > because there is too much power sent to the speaker: therefore, turn
> > dowm the volume!
> > A 1 watt speaker is able to reproduce a 1000 watt amp if you do not
> > turn the volume at 10/10! You have to adapt in some ways ( which is
> > the first question ) to keep alive the 1 watt speaker. Then I will
> > think about a clean reproduction of the music...
>
> The simplest solution is speaker fuses. Much cheaper to replace than
> speakers.
>
> TonyP.


But fuses are current triggered. The problem is that the
bass/midrange drivers typcially carry MUCH more current than the
delicate tweeters. Since a fuse is not frequency dependent, using
a fuse that is a small enough rating to protect the tweeter would
never allow the bass/midrange volume to go anywhere (i.e., it
would always pop before the higher current bass/midrange could
get going) You'd have to use your speakers as headphones!

It seems to me that fuses would only work if they are installed
between the crossover and the drivers and they would have to of
be different values for the different drivers. I don't know if
the OP wants to tear their speakers apart to do such a modification.

If the sound to the speakers is not distorted/compressed or of
unusual equalizing (i.e., has a normal power distribution
spectrum), then all that is really necessary is limiting the
volume sent to the speakers such that the speakers are not driven
into distortion. This can be done with some resistive arrangement
in the cables between the preamp and amp (my preference) or even
with a physical block on the volume control knob. I've even seen
this done by epoxying a small stick onto the top of the volume
control knob and sticking a small adhesive rubber foot onto the
front of the preamp next to the volume knob so as to stop the
knob's movement beyond a certain point. (get another cheap knob
for this and save the original until the kids grow up, then peel
off the rubber foot and replace the original knob)

- Jeff
Anonymous
June 26, 2004 9:42:30 PM

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

> But fuses are current triggered. The problem is that the
> bass/midrange drivers typcially carry MUCH more current than the
> delicate tweeters. Since a fuse is not frequency dependent, using
> a fuse that is a small enough rating to protect the tweeter would
> never allow the bass/midrange volume to go anywhere (i.e., it
> would always pop before the higher current bass/midrange could
> get going) You'd have to use your speakers as headphones!
>
> It seems to me that fuses would only work if they are installed
> between the crossover and the drivers and they would have to of
> be different values for the different drivers. I don't know if
> the OP wants to tear their speakers apart to do such a modification.

It's not difficult or uncommon. And you probably only need one for the
tweeter.

>
> If the sound to the speakers is not distorted/compressed or of
> unusual equalizing (i.e., has a normal power distribution
> spectrum), then all that is really necessary is limiting the
> volume sent to the speakers such that the speakers are not driven
> into distortion. This can be done with some resistive arrangement
> in the cables between the preamp and amp (my preference) or even
> with a physical block on the volume control knob.

This isn't a very good idea. "Quieter" recordings would of course suffer
because you wouldn't be able to attain the maximum volume level for these
recordings if you limited the volume based on 0dB recordings.
Anonymous
June 26, 2004 9:42:30 PM

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

On Sat, 26 Jun 2004 17:23:44 GMT, Jeff Wiseman <wisemanja@earthlink.net> wrote:


>TonyP wrote:
>> The simplest solution is speaker fuses. Much cheaper to replace than
>> speakers.
>>
>> TonyP.


>But fuses are current triggered. The problem is that the
>bass/midrange drivers typcially carry MUCH more current than the
>delicate tweeters. Since a fuse is not frequency dependent, using
>a fuse that is a small enough rating to protect the tweeter would
>never allow the bass/midrange volume to go anywhere (i.e., it
>would always pop before the higher current bass/midrange could
>get going) You'd have to use your speakers as headphones!

Fuses work well to protect an amp, not the speaker. They protect well
against things like shorted wiring.

The way to protect the speakers is to have a functioning brain. When
it starts to sound bad, TURN IT DOWN!

If turning up the volume makes the sound "sound fuller" not "sound louder",
you're driving the speaker into distortion.
Anonymous
June 26, 2004 9:42:31 PM

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

> Fuses work well to protect an amp, not the speaker. They protect well
> against things like shorted wiring.

Conceivably, they protect both.

>
> The way to protect the speakers is to have a functioning brain. When
> it starts to sound bad, TURN IT DOWN!

This is generally good advice. However, distortion isn't always audible.
Sometimes the speakers blow without distorting at all. Other times, the
volume level itself could mask the distortion. And sometimes you actually
smell the problem before you hear it!

> If turning up the volume makes the sound "sound fuller" not "sound
louder",
> you're driving the speaker into distortion.

Most of the time, driving the amp into clipping will make it sound louder.
!