Since I never said that, I have no idea what you’re talking about. It never sounded bright to me, but it was horribly unstable design, so I didn’t live with it long term.
So using the 55 year old Tiger’s distortion vs frequency, are you ready to go to demonstrate your assertions? Name the cut and I’ll publicly post the files.
In that case I'm putting the Tiger comment up to a communication error. As
I recall it was a painful amp.
cut 1: Algunas Bestias
cut 2: Sandino
Or we could use your claimed "bright" GFA-565, which has the turnover at about 14kHz, putting the harmonics well above the human range.
View attachment 397673
Reference:
https://www.stereophile.com/content/adcom-gfa-565-monoblock-power-amplifier-measurements
Its been my theory that above 10KHz a distortion rise with frequency won't be heard for obvious reasons. So this has my interest piqued.
They do the exact opposite (when no to little feedback is used).
Funnily enough people find less dynamic music often more dynamic because you can hear smaller signals more clearly.
Could be by association, could be rolled-off response, could be a higher output impedance in combination with a varying (lower impedance) headphone.
Citation needed; this appears a highly speculative and a rather subjective observation. FWIW, SET users (Single Ended Triode amps typically are zero feedback) commonly describe SETs are being
more dynamic rather than less. Its my contention this is caused by how the amplifier distorts and how that in turn skews the ear's mechanism for sensing sound pressure (IOW, its an illusion). Actual,
real dynamic qualities reside in the recording and are not actually a function of amplifiers whether tube or solid state.
'Rolled off response' makes no sense as many tube amps have wide bandwidth; that was a big deal with Stu Hegeman, the designer of early HK tube equipment including the Citation series. The Citation 2 of this thread has bandwidth that often goes higher than the published specifications, which can be regarded as nominal (I just put my Citation 2 on the bench and it easily made full power to 70KHz). The Citation 2 BTW employs enough feedback that it is able to act as a Voltage source as long as the load impedance does not get too low so FR variation is not a variable. Tube headphone amps tend to have much wider response and headphones tend to be a very easy load.
I commented earlier on the subjective quality of 'dynamics'.
Sound tube what is that?
A simple way to answer than of course is to obtain a good tube amplifier and find out. IME a side by side demo easily shows the difference to anyone in the room as its usually not subtle. The speakers used for such a demo should be of the kind that both the control amplifier and the tube amp both find to be an easy load so FR variation can be ruled out.
IME, these are the differences, which are easily measured:
1) more prodigious 2nd and 3rd harmonic than seen in most solid state amps; which the ear interprets as 'warmth'. I know some people think this is because of a hump in the bass or some such but if you put such amps on the bench you see there isn't anything like that unless the amp lacks feedback.
If it lacks feedback the amp is meant to be used on
a speaker that is designed with that in mind to prevent coloration.
2) A 'smoother more relaxed sound'; my theory being that the 2nd and 3rd harmonics are masking higher orders in the same way as seen in loudspeakers.
3) The reduced generation of higher orders at clipping, which allows for a graceful overload characteristic. Quite often people are overloading their tube amps and don't even know it. Guitar players in the past are well-known for using tube amplifiers for exactly the purpose of overdrive; that is how Marshall, Fender, Ampeg and so on made their names.
Once you really understand these facts it allows an access for designing and building a solid state amp that does the same thing should that be desired. You can even get the 3rd aspect of soft clipping if SITs are used in the output section. Its highly likely that a multi-ordered feedback loop will be needed and care in the circuit design should be taken to minimize distorting the feedback signal at the feedback node.
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