Again, do a spreadsheet assuming the same frequency components instead all constructively add -- your woofer amp then needs 22x as much power as in your analyis, but not the tweeter amp.
There's nothing magic about a square wave's phasing, other than it being easy to draw and talk about. Phases can come in any arrangement. A square wave is an amplitude limited waveform, certainly not the only way all those frequencies can be timed! You picked the best case for the "equal amp" argument, and ignored the other possibilities (if we're going to play the "any possible signal" game!).
For that matter, why not talk about a linear sweep (surely that's possible, too)? Then the same power would be required for all the amplifiers, at least until I start moving phase components around on you again!
There's nothing magic about a square wave's phasing, other than it being easy to draw and talk about. Phases can come in any arrangement. A square wave is an amplitude limited waveform, certainly not the only way all those frequencies can be timed! You picked the best case for the "equal amp" argument, and ignored the other possibilities (if we're going to play the "any possible signal" game!).
For that matter, why not talk about a linear sweep (surely that's possible, too)? Then the same power would be required for all the amplifiers, at least until I start moving phase components around on you again!
Please measure your tone of voice in your writing on a logarithmic scale proportional to the number of people you tell off on the forum.
There, now I said measure to something, so please, obey your measure god. Because clearly every time someone tries to persuade a subjective action as measuring, it should be only quantified as such; and elevated to pure objectivity since it supersedes all social bounds now that it's a measure.
The aggressive binary flavour around here gets really old. You probably think I'm anti-measurement but I'm not at all. The difference is I keep a curious mind, and respect other people's choices. I'm not the guy who believes someone selling something without measurements is a crook stealing anyone's money because it fits my agenda - regardless to the fact no one forcibly made anyone purchase anything.
Because amplifier power and heatsinks don't tend to be free.
Agreed, though, that singling out a square wave as actually representing anything relevant seems kind of silly. Especially since storage oscilloscopes are so commonly available that real answers can be obtained.
(The mentioned spreadsheet is attached here, btw)
edit, found an error...... fixing it
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Destroyer, not all of us have your magical imagination when hearing things, either.
Binary flavour get's old, no? Why contribute to it?
Bill--when observed from speaker sensitivity perspective, we really only need gigawatts (outside of prosound) in the subs. Class D is cheap and cheerful down there. So, at least to me, that seems to mitigate a lot of the issues with PSU/heatsink.
Binary flavour get's old, no? Why contribute to it?
Bill--when observed from speaker sensitivity perspective, we really only need gigawatts (outside of prosound) in the subs. Class D is cheap and cheerful down there. So, at least to me, that seems to mitigate a lot of the issues with PSU/heatsink.
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Right, but that's the LF amp, no is arguing that doesn't need to be large. The discussion is about tweeter amps (that some don't think class D does well.... though I'm ok with it)
OK, I screwed up, picked the wrong line in the spreadsheet for the HF/LF break. So, in my phase alignment of the square wave's terms, the woofer amp needs only to be 10.8x the power (3.299x the peak amplitude of the square wave), and the tweeter needs to be 3.64x the power (1.9071x the square wave peak amplitude). Sorry about that 
.
A lot of difference, but still same argument applies, the woofer amp for those frequency components (if we don't force them to line up as a square wave) would need to be 3x the tweeter amp. Still, I can't fathom a reason why a square wave (or it's frequency components) are in any way relevant. One can make up any waveform, doesn't mean a music system needs to be able to produce it (H-Bomb, anyone?)
. A lot of difference, but still same argument applies, the woofer amp for those frequency components (if we don't force them to line up as a square wave) would need to be 3x the tweeter amp. Still, I can't fathom a reason why a square wave (or it's frequency components) are in any way relevant. One can make up any waveform, doesn't mean a music system needs to be able to produce it (H-Bomb, anyone?)
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I use equal power amps for all frequency sections, it's simpler, but technically it's not needed, period.
How am I contributing? Because I don't allow myself to believe there's a fence? And please enlighten me about my magical imagination.
There are reasonable changes in one's gear, but there was a certain discussion about changing rectifiers making *huge* changes that makes it pretty much impossible for me to take your listening impressions seriously. This is the one that comes most immediately to mind, but I remember other head scratching moments with pretty well zero plausibility.
So if we want no fences, perhaps we should contain our enthusiasm to something reasonable? Open minded is good until your brains leak out.
So if we want no fences, perhaps we should contain our enthusiasm to something reasonable? Open minded is good until your brains leak out.
On the subject of power or current requirements, I think there's a thread here (or maybe it's at AVS forums?) about what kind of PEAK amplifier power we actually use. Using the fact that a DAC can't produce more than its FS peak value, and using the volume settings people use to listen with, and a voltage measurement of a FS sinewave with that volume setting, the resulting value determined by all who tested was rather amazingly low.
Related, a couple of years back I made a very fast clipping detector circuit and mounted it my power amplifier, along with a 2 second pulse stretcher so I ccould know when the amplifier clipped, at all. 100W ampllifier (at 8 ohms), 4 ohm speaker, about 86dB SPL/1W/1m. I found that it never clipped at any level I listened at. I blasted it with some R&R at high level to make sure that detector hadn't broken -- the sound when if finally tripped was very much louder than anyone in my house (and probably my neighbors) would tolerate.
The speaker was a mag planar (not ribbon) type above 350Hz, (dynamic below that), and the impedance didn't dip below 3 ohms, though, so there are sure to be speakers and carefully selected program materials that could make it clip at muck lower volumes. But still, I was amazed (and stopped worrying about whether my amps had enough power or could deliver the needed current to keep the feedback loop tracking).
Related, a couple of years back I made a very fast clipping detector circuit and mounted it my power amplifier, along with a 2 second pulse stretcher so I ccould know when the amplifier clipped, at all. 100W ampllifier (at 8 ohms), 4 ohm speaker, about 86dB SPL/1W/1m. I found that it never clipped at any level I listened at. I blasted it with some R&R at high level to make sure that detector hadn't broken -- the sound when if finally tripped was very much louder than anyone in my house (and probably my neighbors) would tolerate.
The speaker was a mag planar (not ribbon) type above 350Hz, (dynamic below that), and the impedance didn't dip below 3 ohms, though, so there are sure to be speakers and carefully selected program materials that could make it clip at muck lower volumes. But still, I was amazed (and stopped worrying about whether my amps had enough power or could deliver the needed current to keep the feedback loop tracking).
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As far as I am aware, the answer to the question how much current will we need has no definite answer. For one thing, it will depend on how much power are we demanding into a load with unknown electrical properties, not least of which will be its actual measureable impedance. Just compare a pure impedance value with say Nelson Pass' test load and watch your current requirements sky rocket.
The other thing is that not too many specs make much sense. Some wild specs, such as those from say Electrocompaniet, will be defined at the end somewhere, using an unbelievabley small print font, as 1 mS. Despite all my efforts, I never did find the duration of Harman Kardon's short time burst capability, so what seem to me to be kinda wild specs could be related to ridiculously short durations, such as 1 mS. Impulse current bursts of 100A for a nominally 170W/8 Ohm power amp using 4 pairs of 150W devices, each frated at 15/30 A continuous/impulse power rating canot last very long (model PA 2400).
In my view, the old guys did it beter. For example, IEC standards define short term power bursts as 20 mS, and in fact some memorable amps from yesteryear, such ad the German made LAS Mega 1, nominally 100/150W into 8/4 Ohms, used a gentle action protection delay of 200 mS for 4 pairs of BD 249C/250C power devices, each rated at 15/40A continuous/impulse devices (50A if made by SGS-Thomson).
What would help matters is sticking to say IEC ratings for all, so more models could be made more comparable. To be frank, using even less potent amps with my fairly efficient and clean speakers (92 dB/2.83V/1m, nominal impedance 8 Ohms, minimum impedance 6.5 Ohms, worst case phase shift just -25 degrees), I was literally never left with a feeling of a lack of power as long as I didn't start asking for trouble by overdriving an amp (by asking for voltage peaks which exceed the amp's nominal rating).
And anyway, what's the point of the actual discussion? We've had every now and then many times before, and achieved exactly nothing except to confirm that everybody's sex machine was the biggest and best. And that it was all John's fault because:
1. His opinion differed from would-be those of the masters of the Universe,
2. He dared to claim that his approach worked best for him (the gall of him!),
3. He offered his numerous award winning designs 50 years down the road as proof that he seems to be doing something right, even when (gasp!) he's peeking.
This time, it'll all turn out the same and we'll be repating this again in a few moths, and since poor students of history are doomed to repeat it, with the same zilch results as we have so far.
The other thing is that not too many specs make much sense. Some wild specs, such as those from say Electrocompaniet, will be defined at the end somewhere, using an unbelievabley small print font, as 1 mS. Despite all my efforts, I never did find the duration of Harman Kardon's short time burst capability, so what seem to me to be kinda wild specs could be related to ridiculously short durations, such as 1 mS. Impulse current bursts of 100A for a nominally 170W/8 Ohm power amp using 4 pairs of 150W devices, each frated at 15/30 A continuous/impulse power rating canot last very long (model PA 2400).
In my view, the old guys did it beter. For example, IEC standards define short term power bursts as 20 mS, and in fact some memorable amps from yesteryear, such ad the German made LAS Mega 1, nominally 100/150W into 8/4 Ohms, used a gentle action protection delay of 200 mS for 4 pairs of BD 249C/250C power devices, each rated at 15/40A continuous/impulse devices (50A if made by SGS-Thomson).
What would help matters is sticking to say IEC ratings for all, so more models could be made more comparable. To be frank, using even less potent amps with my fairly efficient and clean speakers (92 dB/2.83V/1m, nominal impedance 8 Ohms, minimum impedance 6.5 Ohms, worst case phase shift just -25 degrees), I was literally never left with a feeling of a lack of power as long as I didn't start asking for trouble by overdriving an amp (by asking for voltage peaks which exceed the amp's nominal rating).
And anyway, what's the point of the actual discussion? We've had every now and then many times before, and achieved exactly nothing except to confirm that everybody's sex machine was the biggest and best. And that it was all John's fault because:
1. His opinion differed from would-be those of the masters of the Universe,
2. He dared to claim that his approach worked best for him (the gall of him!),
3. He offered his numerous award winning designs 50 years down the road as proof that he seems to be doing something right, even when (gasp!) he's peeking.
This time, it'll all turn out the same and we'll be repating this again in a few moths, and since poor students of history are doomed to repeat it, with the same zilch results as we have so far.
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When I was developing some 100W into 4 stereo switchmode amps, I had some bookshelf speakers on loan that ought to have been reasonably well-behaved loads. I found that I could clip pretty easily (as monitored on an oscilloscope) with highly-asymmetrical program material, with minimally-processed brass instruments very effective in this regard. This was at listening levels over what I might have customarily, but not ridiculous. I regret I have forgotten what the speakers were.
EDIT: they were CDs mastered from backup tapes from Sheffield D-to-D recordings of Harry James' Band. I observed the remarkable asymmetries on the scope as well.
EDIT: they were CDs mastered from backup tapes from Sheffield D-to-D recordings of Harry James' Band. I observed the remarkable asymmetries on the scope as well.
Interesting. It would be interesting to know some numbers (peak current levels, for instance). Why do you think it was because of asymmetric signal (maybe making you turn the volume up higher for subjective signal level?)
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