Power . How much do we need...

[LL21]

Hi Rob,

I hear what you are saying...to be honest, i purposely did the math on my system to get close to 120db peaks on purpose...mainly to ensure i was effortless at my desired listening levels...which are far far lower. I suppose i was just stating the obvious health warning...which is that 109db over any protracted period will risk deafening any of us. so will 100db for that matter.

To be honest, i have a good friend who sells/installs Alexandrias and other high end equipment for a living. He was listening to Krell Evo Ones/Twos with Alexandrias in a small room at rock concert levels for several hours...and lost his hearing the next morning and it never came back. He now wears 2 hearing aids.

The point about effortless delivery of 110db peaks is that you are right...it is so effortless, it does not seem loud...usually when we yell 'turn it down!' it is the distortion we are actually seeking to turn down. With 110db of clean music, you [think] you can keep listening...except that it is still damaging hearing.

i suppose instantaneous peaks are another matter...like walking by a jack hammer in the street. but still, a fair health warning for those of us with systems that can do this.

 

[Ron Party]

Rob, I completely agree. The math is the math. And for some, even 110dB peaks may not be enough. Crest factors in the kinds of music one will listen to must be taken into account.

 

[DonH50]

But the relationship between the average power an amp can produce (RMS?) and the peaks it can deliver is not fixed, is it? Isn't it possible that the right design in a 50 watt amp could deliver higher peaks than some 100 watt amps? And isn't the possible length of the peaks also variable? And couldn't this be critical if your transient peaks are orchestral crescendos instead of snare drum rim shots?

Forgive me if this has been covered; I haven't read the full 11 pages.

Tim

All true Tim. The peak to average power (headroom) is generally fixed, or nearly so, by design. However, different designs can indeed exhibit much different "dynamic" headroom. A tightly-regulated amp with massive charge storage (big capacitors) etc. may have little headroom. A supply with higher power supply voltages (rails) and smaller caps with fewer output devices may have much higher headroom. If they are both rated at 50 W, the latter has much more headroom and so may "sound" louder. There are usually other trades in such designs (everything is a compromise).

The length (duration) of the peaks is the rub, natch. If the peak lasts longer than the high-headroom amp can handle it won't sound any better than the other amp; perhaps worse.

The IHF used to define the duration required for "dynamic headroom"; it was one of the questions in the tests I took to become an IHF-certified consultant many years ago. So many years that I've forgotten what the spec was...

Lots of charge storage (big capacitors) usually goes along with better, "tighter" bass and lower distortion (less modulation of the power supply rails). Smaller caps and higher rails often provides the headroom to not clip short peaks, but the amp might not sound as "powerful" on bass-heavy music and big orchestral swells. The higher-voltage devices required often have higher output impedance, meaning lower damping factor. And so forth...

 

[Robh3606]

If we had super effecient speakers we could all get along on 50 watts till the cows come home.

Hello Tom

We do, well not really, but you can find systems with sensitivity in the high 90's up to 97-100 Db using dynamic drivers as woofers and you can up from that if you horn load them. That gives you a distinct advantage power wise.

Rob

 

[DonH50]

Last time I lived at a place the cows came home, it meant it was milking time...

 

[Orb]

All true Tim. The peak to average power (headroom) is generally fixed, or nearly so, by design. However, different designs can indeed exhibit much different "dynamic" headroom. A tightly-regulated amp with massive charge storage (big capacitors) etc. may have little headroom. A supply with higher power supply voltages (rails) and smaller caps with fewer output devices may have much higher headroom. If they are both rated at 50 W, the latter has much more headroom and so may "sound" louder. There are usually other trades in such designs (everything is a compromise).

The length (duration) of the peaks is the rub, natch. If the peak lasts longer than the high-headroom amp can handle it won't sound any better than the other amp; perhaps worse.

The IHF used to define the duration required for "dynamic headroom"; it was one of the questions in the tests I took to become an IHF-certified consultant many years ago. So many years that I've forgotten what the spec was...

Lots of charge storage (big capacitors) usually goes along with better, "tighter" bass and lower distortion (less modulation of the power supply rails). Smaller caps and higher rails often provides the headroom to not clip short peaks, but the amp might not sound as "powerful" on bass-heavy music and big orchestral swells. The higher-voltage devices required often have higher output impedance, meaning lower damping factor. And so forth...

Heya Don,
from my experience (owning amps with small and large amounts of capacitance storage) it is the amps with greater storage that provide better dynamic swells (I think this can usually be associated with mid-low frequencies from brass instruments and synthesized strings waveforms and comes back IMO to impedance-frequency range-etc) and weight, this is not the same as overall loudness though.
As an example look at the capacitance storage ability of the latest Mark Levinson interleaved class D amp, this has massive power reserve-storage,and this is recognised as being an incredibly dynamic amp in loudness and also the aspect I mention above.
I appreciate though you may be talking about the size of the capacitors used, and again appreciate this is also made more complex by the voltage spec of the capacitors that is not same in every amp.

One aspect I find interesting in design-manufacturing, is that most times mono amps will have greater power reserve-capacitance than their stereo counterpart model (that is dealing with 2 channels instead of 1) from the same manufacturer, you would expect it to be the other way round.

Edit:
just to add you mention a critical point and totally agree on and that is duration of peak; to me this is compounded by dynamic swells (sorry for crud description) that have a sustained duration while usually also being lower impedance into the speaker.
Cheers
Orb

 

[Phelonious Ponk]

I feel proud to have been able to ask decent questions here. I only wish I fully understood the answers. I would have guessed what orb said above - bigger storage capacity would = better dynamics. I'll keep following this thread for an answer.

It seems that the bottom line is that our system of rating amplifier power is woefully inadequate, but that even if we upgraded it to an average power, transient peaks and peak length it still would only be marginally useful in the face of the unevenness of complex, multi-driver passive speaker systems. It all reinforces my jaundiced view of the engineerless engineering of mix and match synergy seeking and makes me happier than ever that I discovered actives, the ultimate engineer-integrated system.

So I have taken from all of this what I wanted to hear: Expectation bias at work!

Then there is the tube talk. I got a little validation for what I have long suspected: SET has a sound. It may be lovely, but it's not really hifi. On the other hand, given enough money and excellence in design, push-pull tube systems can reduce distortion to levels so close to SS that the differences are insignificant. But at that point, won't the tube "magic" be lost? Won't good tube and solid state become pretty close to indistinguishable?

Whatever the answers are, this has been one of the best WBF threads in months, and it has some decent competition. These are very rich, informative days on the board. Thanks to all of you who know so much for being here and sharing your knowledge and experiences.

Tim

 

[Orb]

Tim,
I think it is a combination of watts and also power reserve (or capacitance storage if one prefers to call it), as I mentioned awhile ago both seem to have a place in dynamics (watts also in overall loudness), but the trait or what is perceived may be subtly different between the two as I mention in earlier threads and recently touched on by a few others.
Easiest way to follow this may be look at real world and try to look at several products out there; compare the mono to stereo counterpart from same company, also look at various other amps and see what the spec is for watts and power reserve-capacitance-joules.
Cheers
Orb

 

[Phelonious Ponk]

...if they publish a spec for power reserve-capacitance-joules.

Tim

 

[Orb]

...if they publish a spec for power reserve-capacitance-joules.

Tim

Indeed, pain in the expletive to check
Cheers
Orb

 

[Phelonious Ponk]

Indeed, pain in the expletive to check
Cheers
Orb

It pains my expletive just to thing about it.

Tim

 

[DonH50]

I feel proud to have been able to ask decent questions here. I only wish I fully understood the answers. I would have guessed what orb said above - bigger storage capacity would = better dynamics. I'll keep following this thread for an answer.

Yup. Bigger capacitors holds the voltage longer before sagging, allowing maximum power to be delivered for longer time (longer peaks/swells/crescendos/whatever).

Then there is the tube talk. I got a little validation for what I have long suspected: SET has a sound. It may be lovely, but it's not really hifi. On the other hand, given enough money and excellence in design, push-pull tube systems can reduce distortion to levels so close to SS that the differences are insignificant. But at that point, won't the tube "magic" be lost? Won't good tube and solid state become pretty close to indistinguishable?

Every time a designer has designed a really clean tube amp it gets shot down because "it no longer sounds like a tube amp". 'Nuff said.

BTW, even with low distortion levels, you will have a very hard time matching the low output impedance of a SS amp, meaning a tube amp is still best with a relatively "nice" load.

Whatever the answers are, this has been one of the best WBF threads in months, and it has some decent competition. These are very rich, informative days on the board. Thanks to all of you who know so much for being here and sharing your knowledge and experiences.

Thank you for the questions and many other contributions! Nobody knows it all, despite what (insert favorite scapegoat here) says!

 

[DonH50]

Heya Don,
from my experience (owning amps with small and large amounts of capacitance storage) it is the amps with greater storage that provide better dynamic swells (I think this can usually be associated with mid-low frequencies from brass instruments and synthesized strings waveforms and comes back IMO to impedance-frequency range-etc) and weight, this is not the same as overall loudness though.

Naturally, as I'm sure you already know! The charge storage (among other things but caps probably dominate) dictates how long the power can be sustained, other design factors determine how much power that is.

As an example look at the capacitance storage ability of the latest Mark Levinson interleaved class D amp, this has massive power reserve-storage,and this is recognised as being an incredibly dynamic amp in loudness and also the aspect I mention above.

I believe ML uses a regulated output supply (true, Amir?) so is very stiff. Class D requires that more than most because PSRR is usually very poor -- you are switching to the rail and off, so any voltage modulation ends up as ditortion on the output.

One aspect I find interesting in design-manufacturing, is that most times mono amps will have greater power reserve-capacitance than their stereo counterpart model (that is dealing with 2 channels instead of 1) from the same manufacturer, you would expect it to be the other way round.

I think that is more size and component/board/design re-use. Monoblocks are often the same size as the stereo (or multichannel) versions, so it's easier to just use the same supply in the same space, meaning you now have 2x the supply capacity.

Lots of good comments/questions in this thread, I agree 100% with Tim on that! - Don

 

[microstrip]

...if they publish a spec for power reserve-capacitance-joules.

Tim

Tim,
If you are referring to tube power amplifiers, this is the correct and fair way of referring to the capacitance of the power supply, as tube amplifiers have output transformers that change the impedance of the output stage connected to the output devices.

 

[DonH50]

I have typically seen the supply storage in Joules, which can be converted to capacitance if you know the supply voltage. I suspect tube amps prefer this as the actual capcitance is actually low, but energy storage is large due to the high voltages. I am not sure there is a standard definition for power "reserve" capacity.

 

[KeithR]

this is a silly thread as all it has done is brought out a tube vs. ss argument and the OP already has a dead set opinion, so not sure why the question is even being asked. a better thread would be to debate large push/pull tube amps vs. SET, but leave that for another day.

more power is always better, all things equal. unfortunately they are not imo.

but for people to disparage others with systems they have never heard before is mind blowing to me---Mike Lavigne has had the best of high power (ML33s) and low power, has one of the best rooms in the US, and is coupled with SOTA speakers, and i must have read about him having 20+ amps in his room over the years. I am not as quick to dismiss his opinion as others are on this forum. for all those who want his written proof---why not take a trip up north and try and go hear his room (i'd love to btw), which by all accord, is amazing. why not ship your mammoth Krell or whatever and do a shootout with him---THAT would be interesting, not random speculation.

On the other side, i do think distortion comes out of low powered tubes, but I also feel what everybody leaves out is that typical SS distortion is much worse on the ears due to harmonics. i'm not sure which is more preferable. also, Mike has admitted previously that he can only listen to 60-70% of his music on 3 watts. that is a big negative imo.

people quoting systems as requiring 120db level bursts are crazy too. that is the equivalent of a jet engine on a run way. i would NEVER want to have peaks that loud in my room for my own hearing and even worse, for children. common volumes for stereo listening are what, 80dbs. i would never even tune a system for 120db peaks. if you want to get tinnitus, of which i already suffer not due to loudness, be my guest. it sucks.

just my 1.5 cents,

KeithR

 

[Orb]

Yeah with Don on that as it is a right pain and his other comments.
Just to add usually you will find the spec if given in either Joules or microfarads, if it is given.
Regarding monos double capacitance, yeah you are right that there are those using same board-design hence doubling, but the examples I am thinking of actually have had to be subtly redesigned for the capacitors on the mono and in high end this still seems reasonably common.

Cheers
Orb

 

[KeithR]

Then there is the tube talk. I got a little validation for what I have long suspected: SET has a sound. It may be lovely, but it's not really hifi. On the other hand, given enough money and excellence in design, push-pull tube systems can reduce distortion to levels so close to SS that the differences are insignificant. But at that point, won't the tube "magic" be lost? Won't good tube and solid state become pretty close to indistinguishable?

Tim

To be honest Tim---i don't think you really care about others opinion on the subject, because of what you just said. You are a tried and true ss objectivist and that's all. you don't need to pretend like you aren't.

And i don't think you accurately prove that SS is "hifi" to begin with. SS by all means has a sound, not just tubes.

 

[amirm]

but for people to disparage others with systems they have never heard before is mind blowing to me---Mike Lavigne has had the best of high power (ML33s) and low power, has one of the best rooms in the US, and is coupled with SOTA speakers, and i must have read about him having 20+ amps in his room over the years. I am not as quick to dismiss his opinion as others are on this forum. for all those who want his written proof---why not take a trip up north and try and go hear his room (i'd love to btw), which by all accord, is amazing. why not ship your mammoth Krell or whatever and do a shootout with him---THAT would be interesting, not random speculation.

Keith, I don't know what Mike has had in the past but I visited him this summer. His current speakers have a powered low-frequency driver. In that sense, he doesn't need a lot of power anymore.

I live local to him. I would be happy to accept the challenge you put forward with our Mark Levinson NO 53 amplifiers. We would bring them to his house and take them back, free of charge. The problem I have is how to do the evaluation. A sighted test won't do from my point of view. And a blind test won't from his vantage. Do you have an idea of how we would do an honest evaluation of the Mark Levinson against his current amp?

BTW, I don't know that the ML will win the race here. I am simply willing to do the experiment and gather some data if we can figure out how.

also, Mike has admitted previously that he can only listen to 60-70% of his music on 3 watts. that is a big negative imo.

Again, he has a speaker that is mostly powered by its own amplifier so the 3 watt number is not a fair number to use here .

 

[amirm]

I should add that Mike's system present a poor choice here due to the reason I mentioned: the fact that he has a powered speaker.