Dumb Quest : Amp Clips Or Speakers Blow Up First?

Fatparrot,

Thanks - you were right to correct me. Indeed, it would be more accurate to say "deliberately compressed" than "deliberately clipped". Not so many are actually hard clipped. The majority of modern pop CD's are "soft limited", which clips the peaks in a rounded fashion (meaning that the peaks above a certain level are limited in a gentle manner in order to reduce the dynamic range).

However, excessive compression due to "soft limiting" or hard clipping will tend to sound the same anyway....harsh, loud and distorted at the end of the day excessive soft limiting becomes the shape of a squared of sine wave too.

Let me pass on an experience I had regarding McIntosh amps. I hooked up a MAC 602, which is 600wpc, to a couple of little Cambridge bookshelf speakers and cranked it up just to see if their Power Guard and Sentry Monitor technology would work... and it worked perfectly.

Thanks for all responses. Shadorne, actually what I meant by the line 'when my ears fail first' is that my ears cannot take the sound pressure anymore although I can still crank up the volume. The music is already very loud and if I turn up the volume further it's not the equipment or speakers that would blow first but my ear drums would! This is due to the fact that my listening room is quite small, and if I were to place the system in a larger room I am sure I can still turn up the volume higher with/without going into clipping.

I would agree that nearfield monitors can't play too loud as they have their limitations in their design. However, I find the PMC's are able to go louder and deeper without showing any distortion whereas the N805's seem to lose it a bit. THe PMC's can really go loud and still stay clean at complex musical passages, and although I was tempted to test it to the limits, my ears tell me to stop due to room limitations. Got to be the transmission line thing. I highly doubt it's due to 'perceptive loudness' in my case.

Shadorne, a slight correction regarding your statement

The "perceptive loudness" effect is what is often used on modern pop CD's, whereby the waveforms are deliberately clipped in the recording/mastering process in order to create a "loud" sounding CD

In fact, I believe that these CD's are compressed, so that the dynamic range may be as little as 6 dB's, so that it sounds "louder"...this is a common trick for TV commercials. Limiters would be used to actually "clip" a very dynamic waveform, but are used more for radio broadcasting than recording.

Great post, Shadorne. This issue is one reason why its hard to duplicate actual live music levels at home; it just dounds like crap and your ears beg for mercy unless as you put it, you have a rare uncompressed recording and a system that can reproduce those dynamic peaks.

Speakers blow first....but a blown speaker may in turn then damage an amplifier!

Clipping is when the amp cannot follow the proper waveform (voltage) due to exceedingly high current demands and the output will flat top. It is unlikley to damage your amplifier (at least initially) but can easily damage a speaker...usually the smallest driver, the tweeter, blows first as the coils get too hot with the distorted squared off signal.

Clippiing results in all kinds of non linear distortion that is audible but can easily be confused with or perceived as "loudness" (call this "perceptive loudness"). Your observation that "ears fail first before my equipment does" may be a sign that the music is clipping and has dramatically increased your "perceptive loudness" (since your B&W and PMC speakers are both near field monitors that are unlikley to be able to play very loud).

The "perceptive loudness" effect is what is often used on modern pop CD's, whereby the waveforms are deliberately clipped in the recording/mastering process in order to create a "loud" sounding CD; the distortion makes the "perceptive loudness" much higher (even at low actual loudness levels).

The "perceptive loudness" effect is what makes most consumers feel that there Hi-Fi system plays extremely loud when in reality it does not (it just begins distorting at some point and thereafter is perceived as extremely loud).

A really good recording (uncompressed) on an excellent system (large dynamic range without clipping = large headroom) can be played extremely loud and still sound pleasant to the ears.....you may have experienced this at a concert where live music levels are thrilling and exhilarating and you can hear such incredible detail. (even an unamplified piano has a huge dynamic range, well exceeding that of most consumer audio)

Bob Katz at digital domain has an honor roll of CD's that are not compressed and hence have a very low "perceptive loudness" and can therefore be played at extremely loud actual SPL's without sounding "perceptively loud".

"Actual Loudness" and "Perceived Loudness" and their relation to distortion/clipping is quite misunderstood even by most audiophiles.

'Clipping' describes the shortening...lowering...chopping off of the complex musical wave. This happens because some stage of the amplifier, usually the output stage, simply has no more Voltage available from the powersupply to follow the original shape being delivered to it by the prior stage. When they clip, SS amps often generate ugly-sounding high-frequency garbage that's far in excess of what's in the normal, musical waveform, and this high-frequency garbage is what kills tweeters. Tubed amps clip more 'gracelully', that is, they generate lots less garbage and sound not nearly as bad, but they, too, definitely clip the music when overdriven.

Rarely will anything bad happen to an amp upon clipping, altho the DC-rail-Voltage fuses may blow. If driven hard for medium or long periods, an amp will get very hot, and some may shut themselves off until they cool.

It's good that your ears give up before your equipment, but listeneing at such high levels really does damge, PERMANENTLY, your hearing, even if done for short periods of time. If you're tempted to listen at such high levels, I suggest you install inline fast-blow fuses that will blow before the speakers do. Only you can determine, by trying different values, the right value for your speakers. I suggest RadioShack for the fuseholders and fuses; I guess I'd start at, say, 3 amps and see what happens. BTW, adding a fuse will decrease sound quality very slightly, but it won't sound NEARLY as bad as a blown speaker driver!

The best advice anyone could give you is NOT to listen at such high levels, but it reads as if you do it often, so be smart and fuse your speakers.
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