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ChewPick
August 28th 03, 09:45 PM
I apologize if this is not the correct NG to post this in.

I just finished sending my Infinity Alpha 40's out for warranty work.
Somehow in the last two months I blew one of my tweeters. I couldn't
actually tell by listening that a tweeter was blown (I am green to
home audio). I decided to check out the tweeters on the speakers
after trolling different audio newsgroups and somebody had posted
describing recurring problems with the tweeters in this model speaker.

I think because I am so new to audio I may be turning these things up
way too loud. Is there a way I can tell how loud I can turn these
speakers up without risk of damage?

There is also a chance that the tweeter was blown before I bought them
because they were floor model speakers.

FYI: My receiver is a Yamaha 5650 and my speaker wire is 16 Gauge
Monster cable...and yes I know I got ripped off with the monster cable
:)

Rudi Fischer
August 29th 03, 06:42 PM
Hi

"Mr 645" wrote

> it's probably not volume that will blow speakers, but distortion will.

NAK.
It's too much volume resulting in compression.

> If your
> pushing the amplifiers to the limits they will start to deliver a 'clipped'
> signal to the speakers. In this case the amp cannot deliver the peaks that
> the volume and music require for proper listening at the volume you want.

ACK

> It is much easier to damage speakers with too little power then it is with too
> much. Lets say you use a 60 watt per channel amp to push the speakers to a
> certain high level, you may start to overheat the speakers and blow them. But
> using a 200 watt amp will let you push to higher sound levels before a
> dangerous, clipped signal is delivered by the amps.

Oh, no, not again!;-)

BTW: A little logic will tell you that you're totally wrong here.

Please have a look at
www.rane.com/pdf/note128.pdf

Rudi Fischer
--
...and may good music always be with you

ChewPick
August 30th 03, 02:09 AM
> This looks like a fairly average 80 wpc multichannel receiver. If you
> completed your multichannel system with a center channel, surround and
> subwoofer, it would take some stress off of your main speakers

I do plan on adding these other components in due time, however I will
be mainly listening to music. When I am listening to music doesn't it
send most of the signal to the main speakers even when I have a center
and rears? Would it be advisable to upgrade to a low end Harman
Kardon receiver? I believe the store I originally purchased this
receiver from will let me do this.


"Arny Krueger" > wrote in message news:<BxM3b.299902$uu5.64834@sccrnsc04>...
> "ChewPick" > wrote in message
>
>
> > I apologize if this is not the correct NG to post this in.
>
> > I just finished sending my Infinity Alpha 40's out for warranty work.
> > Somehow in the last two months I blew one of my tweeters. I couldn't
> > actually tell by listening that a tweeter was blown (I am green to
> > home audio). I decided to check out the tweeters on the speakers
> > after trolling different audio newsgroups and somebody had posted
> > describing recurring problems with the tweeters in this model speaker.
>
> I hvae to admit that when I first saw these speakers I was impressed with
> how much cone area was devoted to bass and midrange and how little that
> tweeter looks perched up near the top.
>
> > I think because I am so new to audio I may be turning these things up
> > way too loud. Is there a way I can tell how loud I can turn these
> > speakers up without risk of damage?
>
> One rule of thumb is to avoid audible distortion.
>
> > There is also a chance that the tweeter was blown before I bought them
> > because they were floor model speakers.
>
> Indeed.
>
> > FYI: My receiver is a Yamaha 5650 and my speaker wire is 16 Gauge
> > Monster cable...and yes I know I got ripped off with the monster cable
> > :)
>

Mr 645
August 30th 03, 06:47 PM
(Mr 645) wrote:

>it's probably not volume that will blow speakers, but distortion will. If
>your
>pushing the amplifiers to the limits they will start to deliver a 'clipped'
>signal to the speakers. In this case the amp cannot deliver the peaks that
>the volume and music require for proper listening at the volume you want.
>
>It is much easier to damage speakers with too little power then it is with
>too
>much. Lets say you use a 60 watt per channel amp to push the speakers to a
>certain high level, you may start to overheat the speakers and blow them.
>But
>using a 200 watt amp will let you push to higher sound levels before a
>dangerous, clipped signal is delivered by the amps.
>
>Jon
><A
HREF="http://www.jonlayephotography.com">http://www.jonlayephotography.com</A>

If this were true than I should be able to destroy speakers with more and more
serious underpowering. I've been trying to blow up a tweeter with the output
from my Walkman (really tiny amp) yet have been unable to do so.

OTOH my 5000 watt amplifier will turn practically any tweeter into a fuse in
quick time.

What blows out any speaker is delivering too much power to them. This is easier
to do with more powerful amplification.

IOW the way to save your tweeters is to keep from delivering more power than
they can handle. because typical tweeters often can only handle 10 watts or so
its possible to destroy them with relatively small amplifiers.

The most effective way to do this at the consumer level is to turn the volume
control down.

Some points are correct. It is most likely impossible to blow a B&W 801 with a
walkman. It simply cannot generate enough voltage to do any damage. But you
certainly could with a basic Sony receiver cranked well into audible
distortion, pushing the 40 or 60 watt amps to the max. Now replace that Sony
box with a nice CD player and Pass 1000 watt amps and see how much volume those
same speakers can take without complaint. I have found that good quality
speakers can easily handle more power then they are rated for provided that the
power is clean and distortion free. I have also seen various speakers
destroyed by low powered amps pushed beyond their limits. My brother was
always taking out the tweeters on my Boston speakers with an old 20 watt
receiver. Upgrading to a much more powerful model stopped the speaker damage.

Using a 5000watt amp to power a small tweeter will most likely fry it quick,
but I can't imagine any reason or any person that would do that. But lets say
that a speaker is rated to handle 200 watts. You will have a much easier time
damaging it with a 30 watt receiver then with a pair of 400 watt high quality
amps.
http://www.jonlayephotography.com

Arny Krueger
August 30th 03, 06:51 PM
"ChewPick" > wrote in message


>> This looks like a fairly average 80 wpc multichannel receiver. If
>> you completed your multichannel system with a center channel,
>> surround and subwoofer, it would take some stress off of your main
>> speakers

> I do plan on adding these other components in due time, however I will
> be mainly listening to music. When I am listening to music doesn't it
> send most of the signal to the main speakers even when I have a center
> and rears?

Whether your center channel speaker would help with dynamic range while
playing 2-channel recordings would depend on what settings you use on your
receiver.

You'd still get a dynamic range boost with use of a good subwoofer, but it
probably wouldn't help take much load off your tweeters.

>Would it be advisable to upgrade to a low end Harman
> Kardon receiver? I believe the store I originally purchased this
> receiver from will let me do this.

I can't recommend doing that because I think that Harman's claims for
superior sound from their receivers are mostly based on hype and bad
science.

Nousaine
August 30th 03, 11:33 PM
(Mr 645) wrote:

(Mr 645) wrote:
>
>>it's probably not volume that will blow speakers, but distortion will. If
>>your
>>pushing the amplifiers to the limits they will start to deliver a 'clipped'
>>signal to the speakers. In this case the amp cannot deliver the peaks that
>>the volume and music require for proper listening at the volume you want.
>>
>>It is much easier to damage speakers with too little power then it is with
>>too
>>much.

Again this is an old wives tale. I began audiolife with a 33-watt per channel
Heathkit in 1968 and NEVER once damaged a speaker tweeter or otherwise.

Occasional tweeter failure began occuring when I started using a 200-watt
amplifier and was typically a function of an accident such as hitting the on
switch with interstation radio noise 'tuned' in or a dropped stylus.

It is true that you "can" destroy tweeters with a 50-100 watt receiver but
that's because tweeters often can only handle 10-watts.

Lets say you use a 60 watt per channel amp to push the speakers to a
>>certain high level, you may start to overheat the speakers and blow them.
>>But
>>using a 200 watt amp will let you push to higher sound levels before a
>>dangerous, clipped signal is delivered by the amps.
>>
>>Jon
>>http://www.jonlayephotography.com

"Clipping" doesn't deliver that much more high frequency energy all by itself
in terms of spectrum. But it is true that an amplifier run 10 dB into clipping
will usually be capable of more than rated power output.

nousaine wrote: >
>If this were true than I should be able to destroy speakers with more and
>more
>serious underpowering. I've been trying to blow up a tweeter with the output
>from my Walkman (really tiny amp) yet have been unable to do so.
>
>OTOH my 5000 watt amplifier will turn practically any tweeter into a fuse in
>quick time.
>
>What blows out any speaker is delivering too much power to them. This is
>easier
>to do with more powerful amplification.
>
>IOW the way to save your tweeters is to keep from delivering more power than
>they can handle. because typical tweeters often can only handle 10 watts or
>so
>its possible to destroy them with relatively small amplifiers.
>
>The most effective way to do this at the consumer level is to turn the volume
>control down.
>
>Some points are correct. It is most likely impossible to blow a B&W 801 with
>a
>walkman. It simply cannot generate enough voltage to do any damage.

So it isn't "underpowering" that causes the problem. I agree.

But you
>certainly could with a basic Sony receiver cranked well into audible
>distortion, pushing the 40 or 60 watt amps to the max.

Sure you can burn out a 10-watt tweeter with a 50-watt amplifier. That much is
obvious; but you can do the same thing more effectively with a 1000-watt
amplifier.

Now replace that Sony
>box with a nice CD player and Pass 1000 watt amps and see how much volume
>those
>same speakers can take without complaint.

Exactly the same at higher frequencies. It's a Urban Legend that 1000-watts
'clean' power is somehow less dangerous than 50-watts clipped. Sure a given
full range speaker will play louder with a 1000-watt amplifier but the tweeter
still has exactly the same power handling capacity.

I have found that good quality
>speakers can easily handle more power then they are rated for provided that
>the
>power is clean and distortion free. I have also seen various speakers
>destroyed by low powered amps pushed beyond their limits. My brother was
>always taking out the tweeters on my Boston speakers with an old 20 watt
>receiver. Upgrading to a much more powerful model stopped the speaker
>damage.

I've heard these stories too. But generally if you dig down into the details of
the situation you'll find that often the extent and precise circumstance of
tweeter damage is not accurately represented or remembered.

The typical tweeter burn-out story often includes someone trying to get a
speaker to play more loudly at middle and low frequencies than it can with
given power. So the volume control is run full throttle and eventually the
10-watt tweeter gets fried.

But there is often other circumstance that gets overlooked. Manufacturers may
make running changes in replecement speakers that does improve power handling
and simultaneous electronic upgrades get credit for tweeter shield they did not
provide.

I have never seen any credible evidence that smaller amplifiers represent less
danger to tweeters than larger amplifiers. Too much power is too much power.

>Using a 5000watt amp to power a small tweeter will most likely fry it quick,
>but I can't imagine any reason or any person that would do that.

I use occasionally use a 5000 watt amplifier to test car speakers. I also have
50, 100 and 250 watt ampliifers. The tweeters are far safer with the smaller
units although any of them will take out a 10-watt tweeter with an accidental
burst of MLS noise.

But lets
>say
>that a speaker is rated to handle 200 watts. You will have a much easier
>time
>damaging it with a 30 watt receiver then with a pair of 400 watt high quality
>amps.
>http://www.jonlayephotography.com

This is simply not the case. It is true that a 30-watt receiver can take out a
10-watt tweeter included with a 250-watt rated loudspeaker system but so can
any amplifier with higher power capability.

Nousaine
August 30th 03, 11:47 PM
(Mr 645) wrote:

...large snips.....

> I have also seen various speakers
>destroyed by low powered amps pushed beyond their limits.

Do you have some example to share? I've been an audio enthusiast for 35 years
and have not seen a single example of this. I've blown up countless woofers,
midranges and tweeters and in every case it required an amplifier with enough
power to destroy the device and amplifiers with a surplus of power do the job
more quickly and more capably.

There are many friends who have damaged speakers but I've not seen any damage
actually caused by using 'too small' an amplifier.

The most common form of damage is an open or rubbing tweeter voice coil which
can happen with nearly any amplification on the market because most tweeters
can only handle 10-15 watts.

My brother was
>always taking out the tweeters on my Boston speakers with an old 20 watt
>receiver. Upgrading to a much more powerful model stopped the speaker
>damage.

Here's a wonderful anecdote from a audio store speaker technician. He was
giving a talk to the PSACS Audio Club about speaker damage and repair. He
reconed a woofer for us and he had damaged speakers and parts on hand to
demonstrate how things get busted.

Someone asked if 'underpowering' a speakers could cause damage. He ackowledged
that this was true and dragged out a burned looking voice coill from a small
woofer as an example.

Because it didn't look much different from other damaged coils he showed I
asked how he knew this particular damage was caused by underpowering?

His reply was "I know the guy who owns this speaker and I watched him 'abuse'
this speaker for YEARS with that LITTLE AMP." When asked how many times the
speaker had been repaired he said "once."

So the Legend overrode the evidence in this case. The owner eventually burned
out this speaker by playing it flat out for "years" but the blame was put on
"underpowering." I submit that a larger amplifier would have damaged that
woofer more quickly.

The Urban Legend aside we should all take the obvious message here. The tweeter
is the most fragile part of any loudspeaker system with a power handlling
capability much lower tnan the power rating of the speaker total system.

Thus they are more easily damaged and can be damaged by even fairly small
amplifiers.

René
September 1st 03, 06:51 AM
On 28 Aug 2003 20:45:38 GMT, (ChewPick)
wrote:

>I apologize if this is not the correct NG to post this in.
>
>I just finished sending my Infinity Alpha 40's out for warranty work.=20
>Somehow in the last two months I blew one of my tweeters. I couldn't
>actually tell by listening that a tweeter was blown (I am green to
>home audio). I decided to check out the tweeters on the speakers
>after trolling different audio newsgroups and somebody had posted
>describing recurring problems with the tweeters in this model speaker.
>
>I think because I am so new to audio I may be turning these things up
>way too loud. Is there a way I can tell how loud I can turn these
>speakers up without risk of damage?
>
>There is also a chance that the tweeter was blown before I bought them
>because they were floor model speakers.
>
>FYI: My receiver is a Yamaha 5650 and my speaker wire is 16 Gauge
>Monster cable...and yes I know I got ripped off with the monster cable
>:)

I once have seen tweeters utterly obliterated (as in melted cone
plastics, plastic threads hanging down dripping towards the bottom),
by an amp that was never used above normal "livingroom" volume.

After investigation, it appeared that the amp sometimes went in
spontaneous +100 KHz of oscillation, delivering near full power to the
tweeter.

The amp in question was a Yamaha. (too long ago to remember type no,
it had a Class "A" / "B" setting).

Solution was (second strange coincidence coming up):
Adding a series network of 10 Ohm and 100 nF in series. (see other
related subject in this group)

In the PA shop I was working that was standing practice when std amps
were used in backround music applications and the wires got somewhat
long. (but long enough to warrant a more expensive and less
qualitative mono 70 / 100V system)

...All this happened > 20 years ago - YMMV

--=20
- Ren=E9

Rudi Fischer
September 1st 03, 05:02 PM
Hi

"René" wrote

[HF oscillating amps]
> Solution was (second strange coincidence coming up):
> Adding a series network of 10 Ohm and 100 nF in series. (see other
> related subject in this group)

You're right, in series to speakers you'll never blow them
- but you won't hear much;-)

So putting this 'network' _parallel_ to speakers might do it,
NOT in series!

Rudi Fischer
--
...and may good music always be with you

Nousaine
September 2nd 03, 05:19 PM
Terry Zagar wrote:

>Nousaine wrote:
>>
>> The Urban Legend aside we should all take the obvious message here. The
>tweeter
>> is the most fragile part of any loudspeaker system with a power handlling
>> capability much lower tnan the power rating of the speaker total system.
>>
>> Thus they are more easily damaged and can be damaged by even fairly small
>> amplifiers.
>
>Doesn't that depend on the tweeter model being used and the specifics
>of the loudspeaker 'system'?

Of course; and your anecdote that follows demonstrates this.

>
>My old IM Fried Model M2's had Dynaudio tweeters (6.5 Ohms nominal
>impedance) with specs that claimed they could handle up to 500 Watt
>pulses.

The system or the tweeters? :)

As I recall, the 'system' spec called for an amp in the range
>of 25-100 Watts. The only time I got a chance to see if that might be
>true was when I once turned on my system with the preamp volume
>control set to its max position (rather than the min position I
>normally set on shut-down). With a source playing through my 180
>Watts RMS per channel amp, which has around 360 Watts peak power per
>channel into 8 Ohms and 600 Watts peak into 4 Ohms, the sound emitted
>by the Fried's was not pretty (the preamp outputs up to 25 Volts and
>the amp needs only 1.65 Volts for full output - obviously a case of
>severe amp overload :( ).

You're now describing a typical type of tweeter/system damage scenario.

Once I ran across the room and turned
>down the volume, I found that one loudspeaker had blown its in-line
>protective fuse, the other had not. Both tweeters, however, survived,
>apparently unscathed. In this case, the one fuse was the 'most
>fragile' part of the system, not the tweeters. :)

Ain't that the moral to this story. It's interesting that for some time 'fuses'
were considered sound quality degraders by the high-end.

If one of the fuses survived this incident I would be considering going to a
smaller value.

Some newer models use 'solid state' protection devices for the tweeter. These
devices seem to work pretty sell. I test several dozen speaker systems every
year and haven't seen a tweeter fuse in the past couple years.

Nousaine
September 2nd 03, 05:56 PM
"normanstrong" wrote:

>Let's suppose your speaker is rated up to 100 watts, and it crosses
>over from woofer to tweeter at 2000Hz. Since music contains very
>little content above 1000Hz it is unlikely that a 100W signal will
>contain enough power above 2000Hz to damage your tweeter, which might
>very well be limited to about 10 watts.
>
>Now imagine a change: a 1000Hz note is played at full output. That
>will be 100W, most all of it going into the woofer. Now we continue
>increasing the input so that what comes out of the amplifier consists
>of a 1000Hz square wave having the same peak value as the original
>100W output. The amplifier is now outputting a 200W signal, half of
>which is the original 1000Hz sine wave, and the rest consisting of all
>the odd harmonics (3000, 5000, 7000, etc.) What you have here is 100
>watts worth of signal being fed directly to the tweeter. Since the
>tweeter itself cannot handle anything like 100 Watts, it burns out.
>
>Any questions?
>
>Norm Strong

This scenario contains some interesting assumptions doesn't it? First it
assumes the power supply of the 100 watt amplifier can deliver 200 watts simply
by driving it into clipping? And it assumes that the harmonic structure of
clipping distributes equal energy above the fundamental.

John Atkinson
September 4th 03, 04:44 AM
(Nousaine) wrote in message
>...
> "normanstrong" wrote:
> >Let's suppose your speaker is rated up to 100 watts, and it crosses
> >over from woofer to tweeter at 2000Hz. Since music contains very
> >little content above 1000Hz it is unlikely that a 100W signal will
> >contain enough power above 2000Hz to damage your tweeter, which might
> >very well be limited to about 10 watts.
> >
> >Now imagine a change: a 1000Hz note is played at full output. That
> >will be 100W, most all of it going into the woofer. Now we continue
> >increasing the input so that what comes out of the amplifier consists
> >of a 1000Hz square wave having the same peak value as the original
> >100W output. The amplifier is now outputting a 200W signal, half of
> >which is the original 1000Hz sine wave, and the rest consisting of all
> >the odd harmonics (3000, 5000, 7000, etc.) What you have here is 100
> >watts worth of signal being fed directly to the tweeter. Since the
> >tweeter itself cannot handle anything like 100 Watts, it burns out.
>
> This scenario contains some interesting assumptions doesn't it? First
> it assumes the power supply of the 100 watt amplifier can deliver 200
> watts simply by driving it into clipping?

Only if the sinewave is so overdriven that a completely square waveform
results. This may be unlikely but it is not impossible. And for the same
output voltage the squarewave does indeed offer twice the power. In
reality, the clipped amplifier will be giving out more power for the same
output voltage, the amount of which depends on the degree of clipping.

> And it assumes that the harmonic structure of clipping distributes
> equal energy above the fundamental.

For a fully squared waveform, I believe this is the case. For a clipped
but not fully squared signal, all that can be said is that the extra power
represented by the harmonics in the scenario that Norm was referring to
is indeed fed to the tweeter, which might not be able to handle it.

Having seen speakers with tweeters blown by relatively low-powered
amplifiers driven continuously into clipping (the so-called "Party Test"),
I think it not improbable.

John Atkinson
Editor, Stereophile

Nousaine
September 4th 03, 04:44 PM
(John Atkinson) wrote:

(Nousaine) wrote in message
>...
>> "normanstrong" wrote:
>> >Let's suppose your speaker is rated up to 100 watts, and it crosses
>> >over from woofer to tweeter at 2000Hz. Since music contains very
>> >little content above 1000Hz it is unlikely that a 100W signal will
>> >contain enough power above 2000Hz to damage your tweeter, which might
>> >very well be limited to about 10 watts.
>> >
>> >Now imagine a change: a 1000Hz note is played at full output. That
>> >will be 100W, most all of it going into the woofer. Now we continue
>> >increasing the input so that what comes out of the amplifier consists
>> >of a 1000Hz square wave having the same peak value as the original
>> >100W output. The amplifier is now outputting a 200W signal, half of
>> >which is the original 1000Hz sine wave, and the rest consisting of all
>> >the odd harmonics (3000, 5000, 7000, etc.) What you have here is 100
>> >watts worth of signal being fed directly to the tweeter. Since the
>> >tweeter itself cannot handle anything like 100 Watts, it burns out.
>>
>> This scenario contains some interesting assumptions doesn't it? First
>> it assumes the power supply of the 100 watt amplifier can deliver 200
>> watts simply by driving it into clipping?
>
>Only if the sinewave is so overdriven that a completely square waveform
>results.

So exactly how does being driven into clipping make the output devices and
power supply capable of delivering power that is un-tappable under other
operating conditions?

This may be unlikely but it is not impossible. And for the same
>output voltage the squarewave does indeed offer twice the power.

In
>reality, the clipped amplifier will be giving out more power for the same
>output voltage, the amount of which depends on the degree of clipping.

But you're assuming it ALL goes to tweeter frequencies. What are the
frequencies at which amplifiers are driven into clipping?

>> And it assumes that the harmonic structure of clipping distributes
>> equal energy above the fundamental.
>
>For a fully squared waveform, I believe this is the case. For a clipped
>but not fully squared signal, all that can be said is that the extra power
>represented by the harmonics in the scenario that Norm was referring to
>is indeed fed to the tweeter,

Maybe.

which might not be able to handle it.

That's the prime issue here. Tweeters are cooked by too much power over a given
period. What clipping, as you call the party effect, does is raise the average
power level over time. It doesn't, by itself, represent a danger to tweeters.

>Having seen speakers with tweeters blown by relatively low-powered
>amplifiers driven continuously into clipping (the so-called "Party Test"),
>I think it not improbable.
>
>John Atkinson
>Editor, Stereophile

Drive the speaker to the same SPL level with a larger amplifier and you'll fuse
that tweeter in exactly the same time.

Nousaine
September 8th 03, 04:52 PM
(John Atkinson) wrote:



(Tom Nousaine) wrote in message
>...
>> (John Atkinson) wrote:
(Nousaine) wrote in message
>...
>>>>"normanstrong" wrote:
>>>>>Let's suppose your speaker is rated up to 100 watts, and it crosses
>>>>>over from woofer to tweeter at 2000Hz. Since music contains very
>>>>>little content above 1000Hz it is unlikely that a 100W signal will
>>>>>contain enough power above 2000Hz to damage your tweeter, which might
>>>>>very well be limited to about 10 watts.
>>>>>
>>>>>Now imagine a change: a 1000Hz note is played at full output. That
>>>>>will be 100W, most all of it going into the woofer. Now we continue
>>>>>increasing the input so that what comes out of the amplifier consists
>>>>>of a 1000Hz square wave having the same peak value as the original
>>>>>100W output. The amplifier is now outputting a 200W signal, half of
>>>>>which is the original 1000Hz sine wave, and the rest consisting of all
>>>>>the odd harmonics (3000, 5000, 7000, etc.) What you have here is 100
>>>>>watts worth of signal being fed directly to the tweeter. Since the
>>>>>tweeter itself cannot handle anything like 100 Watts, it burns out.
>>>>
>>>>This scenario contains some interesting assumptions doesn't it? First
>>>>it assumes the power supply of the 100 watt amplifier can deliver 200
>>>>watts simply by driving it into clipping?
>>>
>>> Only if the sinewave is so overdriven that a completely square
>>> waveform results.
>>
>> So exactly how does being driven into clipping make the output devices
>> and power supply capable of delivering power that is un-tappable under
>> other operating conditions?
>
>Not sure I follow you Tom. The peak voltage remains remains the same but
>squaring the waveform increases the RMS voltage hence the power delivered
>into the load. In a real-world amplifier, the increased current demand
>will cause the supply rails to droop a little so you won't get exactly
>twice the power, but the difference doesn't change Norm's argument: that
>in the case he describes fully clipping a 100W amplifier results in more
>power being fed to the tweeter in the frm of odd-order harmonics..
>
>> But you're assuming it ALL goes to tweeter frequencies. What are the
>> frequencies at which amplifiers are driven into clipping?
>
>I was specifically addressing Norm's scenario, where the test frequency
>is below the crossover frequency and its third harmonic and higher are
>above. Clip a 100Hz tone int the same speaker and the first 4 odd
>harmonics will now be within the woofer's passband, resulting in less
>stress on the tweeter.
>
>>> And it assumes that the harmonic structure of clipping distributes
>>> equal energy above the fundamental.
>>
>>> For a clipped but not fully squared signal, all that can be said is
>>> that the extra power represented by the harmonics in the scenario that
>>> Norm was referring to is indeed fed to the tweeter, which might not be
>>> able to handle it.
>>
>> That's the prime issue here. Tweeters are cooked by too much power
>> over a given period. What clipping, as you call the party effect, does
>> is raise the average power level over time. It doesn't, by itself,
>> represent a danger to tweeters.
>
>It does in the scenario described by Norm. The relatively "pink" energy
>distribution of normal music allows a speaker designer to get away with
>using a tweeter with less long-term power handling capability than the
>woofer. But "whiten" the musical spectrum by, say, driving the amplifier
>into clipping, and the tweeter can be overloaded in a relatively short
>period of time.
>
>> Drive the speaker to the same SPL level with a larger amplifier and
>> you'll fuse that tweeter in exactly the same time.
>
>You are overlooking the fact that the clipping changes the crest factor
>of the music Tom. A fully clipped 100W amplifier frys the tweeter in
>Norm's speaker whereas a 200W amplifier driven to its maximum output
>voltage into the same speaker without clipping will not destroy the
>tweeter because the short-term transients will not exceed the unit's
>short-term thermal capability.
>
>You need to describe at the music's spectral content, its crest factor
>(peak:mean ratio), and the time it takes for the tweeter to thermally
>overload (as well as the time cnstant of your SPL meter) before you can
>say something like "Drive the speaker to the same SPL level with a larger
>amplifier and you'll fuse that tweeter in exactly the same time."
>
>All I am saying is that my experience aligns with Norm's hypothesis:
>clipped amplifiers tend to destroy tweeters; unclipped, high-power
>amplifiers tend not to.
>
>John Atkinson
>Editor, Stereophile

My experience does not. The most likely scenario for frying a tweeter is an
accidental high power high frequency signal (MLS mostly with an untended gain
setting and an accidental input switch) delivered to the speaker system.
Otherwise small amplifiers never seem to endanger tweeters even with a 50-watt
Bryston or Stewart driven into heavy clipping at 10-100 Hz.

Using a larger amplifiers (larger Bryston or Crown Macro-Tech for example)
endangers tweeters in a much more imposing manner.

Back in the 70s I had a pair of Dahlquist DQ-10s with a tweeter fuse. 10 watt
amplifiers amost never took out a tweeter fuse while my 250-watt Heathkit
AA-1640 seemed to think that tweeter fuses were clay pigeons.

For those who weren't familiar with those speakers they had severe dynamic and
extension limitations at low frequencies and users often cranked the hell out
of them trying to get some bass out of them. But as you turned the gain up the
upward spectral shift turned them into screamers.

For me, this pointed out to me the real need for a subwoofer (which the
companion Dahlquist product was NOT.) But even after adding a subwoofer and a
larger amplifier the most easily damaged part of the system was the tweeter
fuse. And open fuses became more common with a bigger ampliifer.

This, by the way, is one of the endearing characteristics of active speakers
.... precice amplifier sizing for any given piece of the system. IME Active
systems are among the most reliable of speaker systems (although well designed
speakers in general are incredibly reliable as a class.)

What I mean is that during any gathering I can hand the remote to anybody and
leave the room without worry that drivers will be fried while I'm gone.

But I don't see any 300-watt tweeter amplifiers used to "protect" the driver.
That's more easily accomplished with a properly sized amplifier and good
engineering.