Two examples from my personal testing:
- I am lucky enough to have a Matchless Thunderchief 200, which is as clean and powerful as you can get for a 4xKT88 amp, but it doesn't even come close to my Trace Elliot VR350 6xKT88 amp in terms of clean headroom and loudness. And it's not just the amount the tech specs would say.
I imagine that what the "tech specs say" is merely a figure of output power produced to X -ohm load at Y % of THD. ...Which in terms of perceived loudness is practically a worthless spec. You can have two amps where those two specs are identical and they still end up having different perceived loudness in practical applications. Even with same speaker system.
I imagine that the "tech specs" also say nothing about some VERY important characteristics like frequency response, signal compression and its effects to overall average signal magnitude / crest factor, characteristics of the ovedrive and how tolerable it is to listen, dynamic characteristics (like whether the output power rating was continuous or "burst"), etc. These can all have far more important effect to perceived loudness than mere output power, which - due to logarithmic ratio - requires substantial changes to warrant effects one can distict by ear.
The spec really just gives a crude indication of how much power is fed to the speaker system. It's almost worthless for anything else. Very often you also need to dial in specific settings to actually meet the quoted specs. For example, Ampeg SVT-3PRO is quoted to produce about 300 watts of output power but the specification ignores to state that if "plate voltage" control is dialled down the output power will drop to about 60 watts due to intentionally decreased headroom of the power amp's input stage. It is also common that the spec covers power amp section only, and when preamp (and especially its built-in effects like compression or distortion) becomes part of the signal chain the rated figures can change substantially.
So if you just randomly compare two amps you practically ensure that your test results mean virtually nothing. Did you actually measure that both amps produce the same amount of output power to the load? Uniformingly, throughout their entire bandwidth? At same % of THD in each case?
No you didn't. Because your test would have showed the amps perform identically in such case.
Your test merely showed that two amps with same output power spec can still be very different in practice, especially what comes to perceived loudness, because there are other specs of higher importance in that regard than output power rating. And that we knew already.
-I used to have a Traynor YBA200 and I put in low-gain, high-current tubes in the preamp, and it was not even as close to loud and clean as the YBA300 I have now.
Which gives...? Some other dude, dialling in different settings, preferring different tone than you, might end up to entirely different results. Try other amps, change dial settings and tone, and the test results might again be all over the place.
Of course we all have different needs, so there's no absolute, but the point of this thread was to wonder about the curiosity that 300W is always "way too much" and 200W is often "not quite enough" for some.
All in all, this just reminds me of the popular "My 1000W amp isn't 1000W loud" -threads. But in slightly different package. As if we had a standard of how loud this and that amount of watts is. Overall, what's being discussed is still the same thing: Output power spec is almost worthless spec what comes to perceived loudness. IF everything else is identical (which it never is when it comes to practical musical instrument amps) 300W warrants just -slight- volume increase in comparison to 200W. Keword: Slight. Most likely other amp characteristics explain why difference in perceived volume is actually bigger in a practical applications where we are not comparing watts to watts.
