Why do some High Efficiency Speakers Sound Better with Lower-Powered Amplifiers than with Higher Ones?

caesar

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May 30, 2010
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I am not talking about preference, but the system sounding right. For example, a 2A3 amp and its flea watts can sound right on a high-efficiency speaker (97+), while a 30 or 60 watt tube amp on the same speaker sounds "broken" or "way-off" from any semblance of realism?

Does anyone have any thoughts and theories on why this is the case? Appreciate the replies
 

Beachman

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Mar 20, 2020
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Hi Caesar,

This is my opinion and largely unsubstantiated; nevertheless, it is logarithmically harder to produce good sounding, high powered amps. In other words, twice the power will be four times more difficult to produce, four times the power, sixteen times harder, and so on. First, the signal has to run through a lot more "stuff" before it reaches the speaker and second, often with higher power comes output devices parallel and they must be matched/QC. That's the problem with good sounding, inefficient speakers: you've got to find a good sounding, high powered amp which is extremely rare and very expensive.

Also, amps typically have a linear range so to speak. At idle and full power, amps are not so good. With a flea watt amp, you're quickly off idle and into the low distortion linear range. With high powered amps, they may have to make several watts to be in their linear range (including an ideal temperature).

For your 97 dB/W/m example, if your are listening at an average of 85 dB, your amp need to supply 0.063W! If your cranking along at 95 dB, you'd need 0.630W. Thus the "first watt" school of thought/

Qualifier: my expertise is loudspeaker and thier motors: I am not electronics engineer. But, I am eager to learn should someone post a correction to my unproven theories.
 

Beachman

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Mar 20, 2020
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Hi Caesar part 2:

I've given your question further thought. With more power, a proportionately larger power supply is requred. I would speculate that the noise level is proportional to the size of the power supply; this would include the mechanical noise from the power supply's transformer. Twice the size, twice the noise?

I was hoping to learn from others on this thread. With the lack of contribution, maybe this should be moved to the "Power Amplifiers and Preampifiers Forum" and we could get some experts to lend some insight.
 

Legolas

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Well it could be that most of the lower powered amps are SET, and have a pure magical and realistic tone to them. Most higher powered tube amps tend to be PP so not have (generally) as much of the SET magic. Then SS amps are built for more power delivery, as part of the design considerations, not sound 'amazing' on 1W output. I have owned some SS power amps that didn't 'get going' till they were played pretty loud.

Again, generally, I would suggest low powered SS amps, full class A will sound closer to my own ideal sound, and more like a tube amp.
IMO and YMMV. There are exceptions of course, and there are ,any great SS amps, and many bad tube amps. I am saying what I have heard personally.
 

andromedaaudio

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Its because of the music which is played i think .
Sometimes a little underpowered sounds nice / gentler with certain music .
Dont put on rock or a full ochestra though
 

Legolas

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Don't agree, as if you have 105dB speakers and a 25W Aries Cerat, game over.
And as the previous poster said, first watt is the most important.
 

analogsa

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Apr 15, 2017
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For example, a 2A3 amp and its flea watts can sound right on a high-efficiency speaker (97+), while a 30 or 60 watt tube amp on the same speaker sounds "broken" or "way-off" from any semblance of realism?

The question is not properly formulated. Are you comparing amps of a similar topology? Of a similar damping factor?

Power alone has little to do with it, at best its effect is coincidental.

The subject is better defined if you are indeed comparing similar amps, based per example on single ended DHTs.

1. There are remarkable sounding low power valves such as 45, AD1 and a few others that just have no high power sonic equivalents.

2. Paralleling low power valves always diminishes some of the magic.

3. Higher power / higher voltage power supplies often sound worse. Many of the best capacitors are only available with up to 500v ratings, rectifier valves have current limitations, etc

4. Output transformers also sound better when designed for lower currents and power.

5. Same goes for resistors: the best sounding types are of low power and cannot work reliably at high voltages.
 
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caesar

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May 30, 2010
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The question is not properly formulated. Are you comparing amps of a similar topology? Of a similar damping factor?

Power alone has little to do with it, at best its effect is coincidental.

The subject is better defined if you are indeed comparing similar amps, based per example on single ended DHTs.

1. There are remarkable sounding low power valves such as 45, AD1 and a few others that just have no high power sonic equivalents.

2. Paralleling low power valves always diminishes some of the magic.

3. Higher power / higher voltage power supplies often sound worse. Many of the best capacitors are only available with up to 500v ratings, rectifier valves have current limitations, etc

4. Output transformers also sound better when designed for lower currents and power.

5. Same goes for resistors: the best sounding types are of low power and cannot work reliably at high voltages.

Thanks for sharing your ideas. Makes sense. I think you are hitting right on.

The interesting thing I have experienced is a lower powered amp sounding significantly better (by "fusing" with the speaker into 1) than the same high-efficiency speaker with a much higher powered tube amps - SET vs PP.

In vast majority of cases with popular, inefficient box speakers today, it's the opposite - they all need major juice to come alive, so more power is better.
 

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