Requirement of SS amp warmup to sound their best a myth?

[3dbinCanada]

I see two fundamental flaws with SS amp warmup and the audible differences people claim they hear. 1) The warmer the transistor becomes, the more thermal or Johnson noise is generated at the junctions of the transistor. It may or may not be audible but the point is that noise generation is increased at the junctions. 2) The warm up time claimed by people is many magnitudes greater than the time required to accurately recall the sound they were hearing when the amp was first powered on. 3) People who claim to hear differences never performed the tests under controlled listening situations.

 

[JStewart]

1) The warmer the transistor becomes, the more thermal or Johnson noise is generated at the junctions of the transistor. It may or may not be audible but the point is that noise generation is increased at the junctions.

Amir on ASR does a warm up test on amps and the data supports your statement. Here’s a most recent example:

3) People who claim to hear differences never performed the tests under controlled listening situations.

Or looked at objective data?

 

[ddude003]

And some noise does sound good to some people with some equipment... Take my tube preamp for example... And then there are things like MQA...

 

[skid00]

Take my MQA...

PLEASE!

 

[highstream]

Why not ask the people who develop and make them, e.g., Paul McGowan of PS Audio, who has mentioned the matter now and then. You can email him via the sales address, the Ask Paul form or post on their forums. I’m sure developers of other brands would be glad to tell you what they’ve found as well, since they have a lot of experience listening to and testing their products, as well as technical expertise.

 

[DonH57]

IME (as a designer though not of audio amps in a while now) the biggest factor in amplifier performance changes with temperature (warm-up) are due to changes in bias levels inside the amp. That changes the gain, distortion, noise, output impedance (damping factor), and many other things. This can be exacerbated by low feedback which makes the amp more sensitive to these changes. A good amplifier should settle out within a second or two, with subsequent changes very small (note the change of the amp above is about 1 dB -- significant, but unlikely to be audible at the distortion levels shown). I have seen tube amps, which use thermionic devices and generally low feedback (SETs often use no global feedback), take many minutes (5~30 or more) to reach steady-state operating conditions.

FWIWFM, YMMV, etc. - Don

 

[3dbinCanada]

Why not ask the people who develop and make them, e.g., Paul McGowan of PS Audio, who has mentioned the matter now and then. You can email him via the sales address, the Ask Paul form or post on their forums. I’m sure developers of other brands would be glad to tell you what they’ve found as well, since they have a lot of experience listening to and testing their products, as well as technical expertise.

I won't ask Paul because he doesnt support blind listening protocol and prefers sighted tests. Thats a subjective flaw.

 

[Kal Rubinson]

I won't ask Paul because he doesnt support blind listening protocol and prefers sighted tests. Thats a subjective flaw.

I regard is as an objective flaw.

 

[highstream]

Leaving aside the general issue of blind testing, how could you conduct a blind test on the issue you’re addressing? A test should be appropriate to the specific problem posed.

 

[3dbinCanada]

I regard is as an objective flaw.

Sorry Karl. Im from the objective side of the camp and do not believe in long term hearing accuracy that some people claim to possess when Dr Toole and others have shown in their research that accurate hearing memory lasts for all but one minute tops.

Have a Merry Christmas.

 

[3dbinCanada]

Leaving aside the general issue of blind testing, how could you conduct a blind test on the issue you’re addressing? A test should be appropriate to the specific problem posed.

Two of the same amps, one left on for hours, the other turned off being fed by the same source and played through identical speakers. Turn the cold amp on, listen, turn the cold amp off and listen to the warm amp.

 

[JStewart]

Two of the same amps, one left on for hours, the other turned off being fed by the same source and played through identical speakers. Turn the cold amp on, listen, turn the cold amp off and listen to the warm amp.

Blind, of course.

 

[Ian Eales]

Like most things audio, the proof of the pudding is in the eating. Some product stabilizes in a few seconds and gets progressively worse when pushed hard. Some product takes a while to settle in and then remains unperturbed regardless of how long or how hard it is pushed. And every possibility in between.

As far as sighted vs unsighted: Some can tell all the time, some can tell none of the time and every possibility in between.

 

[3dbinCanada]

Blind, of course.

My bad.. right!!

 

[Kal Rubinson]

Sorry Karl. Im from the objective side of the camp and do not believe in long term hearing accuracy that some people claim to possess when Dr Toole and others have shown in their research that accurate hearing memory lasts for all but one minute tops.

Have a Merry Christmas.

I was commenting that purely subjective tests are objectively flawed. Hey, I am on your side.
(BTW, my name Kal.)

 

[3dbinCanada]

I was commenting that purely subjective tests are objectively flawed. Hey, I am on your side.
(BTW, my name Kal.)

My bad. Ummm too much eggnog on my part?