'Headroom' is a measure of the badness of an amplifier. The bigger the number, the worse the amplifier.

[IPunchCholla]

An amplifier with a stiff power supply, when compared with an otherwise identical amplifier with a soft power supply will always measure better and possibly sound better.

Under what conditions? Listening at 70dB SPL at 2 meters?

 

[JustJones]

Not enough headroom

 

[Multicore]

I think this entire thread boils down to the fact that Zaphod thinks the "C" amplifier above is the best of those three, and that makes the others 'bad', especially B, which is obviously a Gatsby-esqe pretender that wants to walk in the rarified air of real 150wpc amplifiers but doesn't deserve to be there.

Nicely put.

 

[voodooless]

Under what conditions?

“Always” implies under all conditions, doesn’t it?

 

[Zaphod]

Under what conditions? Listening at 70dB SPL at 2 meters?

That would depend entirely on the impedance and efficiency of the speakers.

Please note that I used the term: "POSSIBLY" to describe the impact on sound quality.

Measurements will show differences that listening may not.

 

[Blumlein 88]

Well this discussion had gone around and around in just the circle I would have predicted with no real benefit to anyone that I can see. Might even get to 200 posts. Click bait title and all.

 

[antcollinet]

An amplifier with a stiff power supply, when compared with an otherwise identical amplifier with a soft power supply will always measure better and possibly sound better.

I thought we were talking about headroom (whatever you mean by that), not stiff or soft power supplies. It's right there in the thread title.

 

[Zaphod]

I thought we were talking about headroom (whatever you mean by that), not stiff or soft power supplies.

It is the power supply that, overwhelmingly, dictates how much long term, vs. short term power can be delivered by an amplifier. There are other factors as well, but the power supply is pivotal.

 

[IPunchCholla]

That would depend entirely on the impedance and efficiency of the speakers.

Please note that I used the term: "POSSIBLY" to describe the impact on sound quality.

Measurements will show differences that listening may not.

My speakers are about 91dB at 1w @1 meter
They are 8 ohm and never drop below 3.5 ohm. What measured difference do you think there would be for two identical 150 watt into 8 ohm amplifiers playing a 20 hZ tone at 78 dB? Let’s assume that 20 hZ is 3.5 ohm, that the power supplies are identical except one is 5 amps and the other is 10.

My point is, under those conditions rms vs peak isn’t going to come into play at all.

 

[Zaphod]

My speakers are about 91dB at 1w @1 meter
They are 8 ohm and never drop below 3.5 ohm. What measured difference do you think there would be for two identical 150 watt into 8 ohm amplifiers playing a 20 hZ tone at 78 dB? Let’s assume that 20 hZ is 3.5 ohm, that the power supplies are identical except one is 5 amps and the other is 10.

My point is, under those conditions rms vs peak isn’t going to come into play at all.

Very probably correct.

Also, irrelevant to my original point.

 

[antcollinet]

It is the power supply that, overwhelmingly, dictates how much long term, vs. short term power can be delivered by an amplifier. There are other factors as well, but the power supply is pivotal.

But there are also many amps that thermally limit output power. Either by direct measurement of device temperature, or by modelling it, and limiting output current accordingly.

This can result in a significant headroom spec (if we are calling headroom "short term power capability over continuous power rating"

Are such amps similarly universally "bad" when providing headroom specs?


And, again - you've not specified "bad compared to what" Or even what you mean by bad. As I stated above:

You need to:

1 - Define what you mean by headroom.
2 - Define your definition of "better" as has been pointed out above.
3 - As part of 2, define "than what": What are you comparing with?
4 - Describe why you seem to think headroom is only related to power supply "stiffness" - a term you've also not defined, but your posts suggest you think it is one or both of output impedance or current rating.

 

[MAB]

I used to sell an NAD amplifier (the NAD 2200) which possessed ENORMOUS headroom. Around 6dB. That was great, until I began receiving speakers from owners that were VERY badly damaged. I popped the amp on my bench and began measuring. Sure enough: The 100 Watts rated NAD could deliver around 400 Watts for short periods. However, when the amp had exhausted it's headroom, the clipping became utterly horrendous. It soon became obvious what was happening. I ceased selling that model and any other that used such a silly system.

Seems you confirmed what NAD said their amp would do. Then you seem to evoke an age-old myth about what really blows speakers as evidence for your OP, and it isn't clipping. (I say seem because you are very imprecise in your language, and very spare with actual info in your posts, others have commented, it's as if you want the mystery to carry the day rather than a clear discussion). It seems to enable to speculate dramatically that the NADs clipped and that the clipping was what caused the speaker failure, thus headroom is bad... You keep appealing to reason, but a bit of math and physics would cause you to reconsider, for instance:.

Speaker Failure Analysis

ESP - The Audio Pages. An analysis of speaker driver failure with particular reference to high powered audio systems as seen in the worlds of Sound Reinforcement and Disco

sound-au.com

People thinking high-frequency components of a clipped amp is the destructive force aren't doing the calculation. How many 400 watt amps were you selling back then? I sold that NAD 2200 as well so I know the answer is likely none, and certainly not significant volume. Big amps destroy speakers. NAD was one of the biggest back then, not because of any of the things you are referencing here though.

This is one of the many arguments you put forth, that illustrates an incorrect observation and an oversimplified model.

 

[Cbdb2]

With out peak duration and recovery time peak power means nothing, so mostly a useless term. And with the over compression/limiting of so much music even less.

 

[daftcombo]

Does "bad" in the title refer to bad sound or bad engineering?

 

[Galliardist]

Does "bad" in the title refer to bad sound or bad engineering?

It looks like this has been qualifiied: bad engineering, possibly leading to worse sound when the "bad" amps run out of power. I don't believe anyone is arguing that the amps will sound bad when run well within their capabilities.

 

[rdenney]

It's easy to get a bit confused by the arguments in this thread. Lemmy try to confirm something. Let's say (using Amir's protocol for testing peak power)

• amp A can deliver 100 W continuous and 100 W peak
• B can deliver 100 W continuous and 150 W peak
• C can deliver 150 W continuous and 150 W peak

Can I then claim that

• B has headroom while amps A and C do not
• B can deliver more power for some signals than A
• C can deliver more power for all signals than A
• C can deliver more power for some signals than B

If I understood that correctly, I don't see how headroom is a measure of badness.

The extent to which headroom is any use (value) depends on the signals you send to the amp and what you think is important.

There's tuba fan on ASR, I forget his handle, but he or she insists that reproducing unattenuated down to the fundamental is important and is willing to pay for it in sound reproduction equipment. Idk what music this tuba fan listens to but let's imagine there are tuba ensembles doing avant garde stuff with sustained loud low notes. This, I imagine, demands lots of continuous power.

For many of the rest of us, a compromise that takes a statistical view of the power needs of our music might make sense. The 16 to 32 Hz octave isn't significant in most of my collection. Similarly, maximum loudness is not something I can put up with for no more than a couple of seconds.

So I don't think headroom is bad. It's just that it's not quite as clear how useful it is since relating continuous and peak power specs to the real world involves assumptions that can be debatable. If this is what Zaphod means then I think that poster could find better words to state that case.

I think I'm the only tuba player on ASR, at least that admits to it

But I don't think I've said what you said. I've said that tuba notes are routinely recorded down to frequencies in the 20's, even though tubas themselves don't produce a lot of fundamental at those frequencies (the sound is dominated by higher harmonics). I've also said that I don't want harmonic distortion at those frequencies, because it makes tubas sound like euphoniums (which are pitched an octave higher). I've also said that the bass Moog licks on Rick Wakeman's King Arthur and the Knights of the Round Table are a better test of bass response in my systems than any of my (many) tuba recordings. That Moog can deliver sine waves down in the 20-40 Hz range with a great deal more power than can a tuba. But it still has to have enough harmonic distortion to sound clear, which a 30 Hz sine wave by itself will not.

Yes, my current main-system amp is capable of delivering over 300wpc continuous, and I do appreciate how well it delivers that bass end of the Moog.

I suspect my amp uses that power much more fulsomely delivering percussive transients than any sustained bass note. At least, that's what the clipping indicators tell me.

Even so, I think it's reasonable to ignore claims of momentary headroom and purchase amps based on continuous output. That should be easy to do, given how much power is available for a reasonable cost these days. My amp that gives me that 300wpc continuous cost about $700.

Rick "16 Hz is a double-pedal C on a tuba, created by most performers using flutter tongue, and required in only one work" Denney

 

[MAB]

Rick "16 Hz is a double-pedal C on a tuba, created by most performers using flutter tongue, and required in only one work" Denney

Which work? I am intrigued!

 

[Multicore]

I think I'm the only tuba player on ASR, at least that admits to it

But I don't think I've said what you said. I've said that tuba notes are routinely recorded down to frequencies in the 20's, even though tubas themselves don't produce a lot of fundamental at those frequencies (the sound is dominated by higher harmonics). I've also said that I don't want harmonic distortion at those frequencies, because it makes tubas sound like euphoniums (which are pitched an octave higher). I've also said that the bass Moog licks on Rick Wakeman's King Arthur and the Knights of the Round Table are a better test of bass response in my systems than any of my (many) tuba recordings. That Moog can deliver sine waves down in the 20-40 Hz range with a great deal more power than can a tuba. But it still has to have enough harmonic distortion to sound clear, which a 30 Hz sine wave by itself will not.

Yes, my current main-system amp is capable of delivering over 300wpc continuous, and I do appreciate how well it delivers that bass end of the Moog.

I suspect my amp uses that power much more fulsomely delivering percussive transients than any sustained bass note. At least, that's what the clipping indicators tell me.

Even so, I think it's reasonable to ignore claims of momentary headroom and purchase amps based on continuous output. That should be easy to do, given how much power is available for a reasonable cost these days. My amp that gives me that 300wpc continuous cost about $700.

Rick "16 Hz is a double-pedal C on a tuba, created by most performers using flutter tongue, and required in only one work" Denney

Well, apologies, I was going from memory. At least I remembered right that your commitment to the cause is an inspiration. But isn't it swell that it turns out it doesn't really matter? The point is that some of us think 300 W continuous is the best and having headroom above and beyond that is a measure of badness. Indeed, according to Amir's measurements, my power amp has small but negative headroom and that makes it even better than good.

Sorry if I sound flip about this but the basic premise of this thread depends on the assignment of morality to the measurements of consumer electronics. I find that very amusing.

 

[Vladimir Filevski]

I think this entire thread boils down to the fact that Zaphod thinks the "C" amplifier above is the best of those three, and that makes the others 'bad', especially B, which is obviously a Gatsby-esqe pretender that wants to walk in the rarified air of real 150wpc amplifiers but doesn't deserve to be there.

But you are comparing apples to oranges orcas! Only meaningful comparison is amplifier "A" (100W cont., 50W headroom) to amplifier "B" (100W cont., Zero W headroom) - they differ only in their headroom! And Zaphod clearly prefers amplifier "A" with higher headroom:

Amplifier A MIGHT sound better than amplifier B.

But that contradicts his original premise:

Therefore, all other things being equal, an amplifier with a higher headroom figure will always sound worse than one with a lower headroom figure.

After this, I really don't think there is any logical sense to discuss with Zaphod any longer.

 

[EJ3]

Which work? I am intrigued!

Exactly! I want to know, just to try it when I get my system hooked back up in a couple of weeks.