How much amplifier power do you really need?

[Pim]

10 pages of technical blah blah and I still get better sound out of my more powerful amp than my less powerful amp...

[RebelMan]

I'm sorry but it is a complicated question. You assume that "people" believe more power will sound better so they're asking how much power they need to make things sound the best that they can sound but if people simply believed that more power sounded better everyone would be buying D1000s and no one would be buying D140s. While you may argue that the depth of our wallets is a limiting factor that too isn't universally the case. Lots of people buy smaller amps than they could afford to buy. You've got a straw man argument going on.

It's only complicated for people working with unknowns.   When you have the answers to the unknowns the question (How much power do I need?) becomes quite clear.  So what's the problem?  Where people are getting their answers from... the sales guy (and misinformed users).

I have the funds to purchase the D1000 but I don't need it, unlike the O d'A, which I also do not need, but find so beautifully irresistible.  In fact, I replaced a whole mountain of gear that totaled more than $25K USD with a diminutive D120 (D140) which produced 400 watts less so I am living proof that less is more.

The problem is people believe more power will sound better because some joker says it will and they have no reason to question that.  After all, they are in the "business" or they are the listening "experts", so they take their advice on face value, aka faith.  And for the record, I am not assuming anything.  Look around here and you'll see plenty of comments supporting the "belief".

The reason the question is going on is because of the factors involved, factors such as preferred listening and peak listening levels, speaker sensitivity, listening distance, room size and setup of the speakers and listening position in the room, room construction and furnishings, openings to other spaces and the characteristics of the other spaces. All of those things affect the level of sound we hear in the room for a given amount of power and none of them have anything to do with a belief that more power sounds better.

Totally agree.  I never once said that people don't need more power.  I have only said that more power does not imply better sound quality.  If it is determined that someone needs a D1000 because a D140 distorts or goes into clipping or the protection circuits trigger frequently then by all means use the bigger amp.  On the other hand, if a D140 can satisfy every criteria the listener needs using a D1000 in place of that WILL NOT make the system sound better.  That's the point.

In an earlier post above you said  "…more power does not sound better than less power all else being equal."  I agree, all else being equal an amp with more power will not sound better than an amp with less power when both are producing the same SPL at the listening position but how often is all else equal? If you have a situation where an amp with more power sounds better than an amp with less power when both are producing the same SPL at the listening position then obviously all else is not equal. If you want to claim that an amp with more power can't sound better than a smaller amp which is also capable of producing the same level then you need to show that all else is equal and you haven't attempted to do that. I would respectfully suggest to you that when you compare amps with different power outputs, even amps from within the same range such as the 140/220/250 you will find differences apart from the power output so all else is not equal. That being the case I have to say that, at the very least, a difference in sound quality is possible.

What do I mean by all else being equal?... well... by all else being equal!  Joking aside, lets assume the only two differences in a given room and system were the D140 and the D1000.  If the D140 was pushed beyond it's capabilities, lets say to an SPL of about 102dB (my setup) then the extra headroom (8.54dB) provided by the D1000 could make it sound better than the D140 but only because the D140 is underperforming, not because the D1000 is not underperforming.

Power, in and of itself, does not determine sound quality.  It's the engineering that goes into making power that determines sound quality.  Architecturally speaking, the Expert Pros are identical and so they should sound the same for a given SPL that does not breach the capabilities the weakest amplifier, the D140 in this case.  I say "should sound" because people have varying opinions about what they hear.  But what they hear has no baring on what is, the Expert Pros are in fact the same.

Any differences that exists between the models (besides the additional power) has to do with how efficient each model tackles the additonal heat that is generated.  The D1000 can produce more heat than the others and therefore steps were taken to make it dissipate heat better allowing it to be a true dual-mono design.  The other models like the 440 and 210 are "dual-mono" in nomenclature only and are not true dual-mono capable.  If they were then the power output of each would QUADRUPLE, not be limited to double more power you get with the D440 and only one and a half times more power you get with the D210. But let me be clear, the D440 and the D210 are true dual-mono designs but Devialet limits their capability because of the additional costs it would incur to deal with the additional heat.  This in turn helps lower per unit costs making it possible for Devialet to sell to a larger audience.  Remember, this is a business... first, and power is expensive but sound quality needn't be.  Want proof?  The DAC shootout I briefly mentioned in another post was very telling.  The cheapest DAC won!

[thumb5]

...
Architecturally speaking, the Expert Pros are identical and so they should sound the same for a given SPL that does not breach the capabilities the weakest amplifier, the D140 in this case.  I say "should sound" because people have varying opinions about what they hear.  But what they hear has no baring on what is, the Expert Pros are in fact the same.

You can argue until you're blue in the face that two different amplifiers should sound the same because they have the same specifications, design, etc., but what people actually hear is what matters.  This is not an academic exercise to "spot the difference" between amplifiers, it's about a subjective experience.

Speaking as someone who has heard pretty much the whole of the Devialet Expert/Pro range, in my own room with no pressure or advice from people you dismiss as "jokers", I've chosen the one that gives me the best sound quality.  I feel no urge to talk condescendingly about your choice so perhaps you'd show me (and others) the same courtesy.

Enough said, from my point of view.

[Pim]

The problem is people believe more power will sound better because some joker says it will and they have no reason to question that. 

That joker would be my ears. And that difference is most noticeable at lower volumes.

I can try to explain (to myself as well as anyone else here) why there is a difference but I'm not sure how accurate that would be. Let's just give it a try:
Say you want to travel on the freeway at 100 kilometres per hour. You probably only 'need' 50 horse power in your car to achieve that. But if you had a nice 6 litre V8 you're going to be doing that 100 kilometres per hour a lot more quietly than with the little 50 horse power car. A more powerful amp might sound more 'relaxed' at any give volume.

Below is a link to a video John Darko made at HEDD Speakers> Klaus Heinz explains how he can't technically measure dynamic capabilities of a speaker @ 22 minutes in. It might be the answer to the question.

https://www.youtube.com/watch?v=SPJu7OUS...-184647161

[David A]

… If it is determined that someone needs a D1000 because a D140 distorts or goes into clipping or the protection circuits trigger frequently then by all means use the bigger amp.  On the other hand, if a D140 can satisfy every criteria the listener needs using a D1000 in place of that WILL NOT make the system sound better.  That's the point.

2 amps can satisfy the same criterion but one can exceed the other in the extent to which it satisfies that criterion. The fact that both satisfy the criterion doesn't mean that they will perform equally well in satisfying it. Lets say you only need 100 watts/channel into 4 ohms. An amp specified to deliver 140 watts and one that specified to deliver 200 watts both satisfy the criteria but measurement procedures for testing specifications are standardised and a standard test load will be used to confirm the specification. Speakers aren't standard test loads and one amp may be capable of handling the load a given speaker presents better than the other. The amp that handles the given speaker better may be the smaller amp or it may be the larger but whichever one handles the load better will perform better with that speaker. The fact that both meet the specification doesn't mean that both will perform indistinguishably with the same speaker.

What do I mean by all else being equal?... well... by all else being equal!  Joking aside, lets assume the only two differences in a given room and system were the D140 and the D1000.  If the D140 was pushed beyond it's capabilities, lets say to an SPL of about 102dB (my setup) then the extra headroom (8.54dB) provided by the D1000 could make it sound better than the D140 but only because the D140 is underperforming, not because the D1000 is not underperforming.

Power, in and of itself, does not determine sound quality.  It's the engineering that goes into making power that determines sound quality.  Architecturally speaking, the Expert Pros are identical and so they should sound the same for a given SPL that does not breach the capabilities the weakest amplifier, the D140 in this case.  I say "should sound" because people have varying opinions about what they hear.  But what they hear has no baring on what is, the Expert Pros are in fact the same.

Any differences that exists between the models (besides the additional power) has to do with how efficient each model tackles the additonal heat that is generated.  The D1000 can produce more heat than the others and therefore steps were taken to make it dissipate heat better allowing it to be a true dual-mono design.  The other models like the 440 and 210 are "dual-mono" in nomenclature only and are not true dual-mono capable.  If they were then the power output of each would QUADRUPLE, not be limited to double more power you get with the D440 and only one and a half times more power you get with the D210. But let me be clear, the D440 and the D210 are true dual-mono designs but Devialet limits their capability because of the additional costs it would incur to deal with the additional heat.  This in turn helps lower per unit costs making it possible for Devialet to sell to a larger audience.  Remember, this is a business... first, and power is expensive but sound quality needn't be.  Want proof?  The DAC shootout I briefly mentioned in another post was very telling.  The cheapest DAC won!

I remember seeing somewhere the specs for the power supplies of the different models and there are differences in the size of the power supplies. My understanding is that the 140 can only deliver 50% more power in a dual amp setup because it is current limited, and the 220 only delivers twice the power in a dual setup because it is limited by it's ability to dissipate heat. The 250 can deliver 4 times the power in a dual setup because it suffers from neither of those limitations. The architecture of the power supply in each case may be identical, the capacity of the power supply in each amp is not identical. It is not the case that the 3 amps are identical in every performance respect apart from power output.

As I said, the specifications tell you about what was measured and not everything relevant to the amp's performance gets measured or included in the specification sheet. The specifications tell you nothing about performance parameters that were neither specified or measured. No manufacturer provides specifications for how well an amplifier deals with the non-standard load presented by every speaker, they provide a specification based on a standard load and the only way to find out how it will work with your speakers is to hook them up and listen.

The day when we can dispense with the need to listen and know everything about how a speaker will perform with a given speaker under real life conditions are still a long way away. Until that day people will be reporting differences in sound quality between amps which are capable of delivering enough power for their needs and there are reasons for the differences they hear which have nothing to do with one amp having more or less power output than the other. If there is a difference in power output then there will almost certainly be other differences as well. All other things besides power output are never equal in real life, even with amps in the same range such as the Expert Pro models.

[Confused]

Just as a point of note, there are a number of known differences between the Pro models. As mentioned earlier in this thread the class D board varies between models, the power supplies have firmware differences, and the hardware for the ADH boards vary between models. On top of this we have the more obvious stuff like the 250/1000 case and copper bottom. There may of course be some other details that we are not aware of.

In terms of "dual mono", this obviously provides more power, but in addition the dual mono configuration offers lower distortion in comparison to the equivalent "stereo" model.

Some details (and nice pictures) here:

https://devialetchat.com/Thread-D220-Pro...the-inside

[ogs]

Let's not forget that dual mono Devialet amplifiers are bridged (balanced) devices where both the positive and negative output is driven by an amplifier stage (much of the lower distortion in mono blocks comes from this). The stereo models are single ended with the negative speaker terminals common - and tied to ground.

[Jean-Marie]

Just a reminder that with SAM activated, the peak power delivered can be much much higher than the peak power of a traditional amplifier on the same program.

So even if I was listening to my former D120 at -6dB and I’m now listening to my D220 at -8dB (this is when listening to classical programs with a very high dynamic) both amplifier do not behave the same way because of SAM. If SAM were off, given my speakers are 8 ohms, the peak power would be around 45W for both amps, but because of SAM the D120 was peaking at 180W and the D220 is peaking at 330W, which makes a lot of difference in the low bass compartment. (I’m listening to a lot of pipe organ, so there are really low basses when you listen to a 32’ pedal)

Jean-Marie

[thumb5]

Here's an interesting blog post I stumbled across while looking for something else: https://www.kvalsvoll.com/blog/2018/12/0...do-i-need/.  This is written by someone who sets up sound systems professionally for homes, media/music rooms, and small cinemas.  It covers much of the same ground as this thread (albeit in a more compact form...) but this section stood out particularly:

Amplifier power must be dimensioned for the peaks. The rms power will be much lower, but we need to be able to reproduce all peaks with no clipping and compression.

If the music has a crest factor of 20dB – normal for good quality recordings – then the actual power to the speaker will be 1/100 of the peak power, so that a 200W amplifier operating at its limits actually delivers only 2W power that goes into heat. Even with very loud and compressed recordings, with crest around 10dB, rms power will be only 20W. Amplifiers are usually dimensioned with this in mind, so they will actually overheat if you try to draw max power continuously over some time.

It is the most dynamic recordings, often with acoustic instruments, that will test the limits of your power amplifiers. Nublado by Sera Una Noche is never too loud, even though the peaks will use up all available headroom.

Much of that is not new for anyone who's made it this far, but the comments about 20 dB crest factor being "normal for good quality recordings" and acoustic instruments being particularly demanding caught my eye.  (Sadly the Sera Una Noche album is currently £133 on Amazon so not something I'm planning to try out in the near future...)

[Greg]

(Sadly the Sera Una Noche album is currently £133 on Amazon so not something I'm planning to try out in the near future...)

You might find this more affordable.

https://www.ebay.co.uk/itm/SERA-UNA-NOCH...SwkZxdAoQL