You raise some good points. I've got a bunch of client stuff over the next few days so it will take me some time to get my thoughts together for a more complete answer.
In the mean time a quick response. I am fairly fanatical about flat frequency response and correct phase/impulse response. I own Dunlavy SC-V's and use wall treatment and a Sigtech Digital DSP to get very flat reponse.
The Speaker/room combo is usually never anywhere close to flat. Almost every amp is virtually ruler flat compared to that or to a cartridge. If you care about accurate frequency and phase reponse the speaker/room combo is where to start.
As far as measurements on electronics, it gets interesting when the steady state sine wave measurements are replaced with impulse measurements.
In theory a simple triode amp in a well designed circuit should be linear over its designed operating range. In practice it never is.
For example, the instantaneous whap of a bass drum may drop the voltage on the B+ rails that powers the tube so severely that for the instant the amp is operating nowhere near in spec. This can be detected with a 'scope and heard as a congested sound.
Some tubes are very microphonic, that is they vibrate when disturbed. In a guitar amp, this creates a desired sound that isn't "accurate". Loud music may cause vibrations in the audio amp coloring the sound.
These are just two of the dozens of these readily known departures from a completely "accurate" amp. All real world amps have these faults to some degree. This doesn't even count all of the depatures from linearity that happen through the electrical interaction of the speakers, crossovers and the amplifier playing real music.
Some faults, like even order harmonics in a SET, can be perceived as euphonic. There is no accurate mapping from the engineering circuitry to auditorily perceived accuracy. Our ears are non linear transducers. Evolution has tuned then to be amazingly sensitive to some signals and insensitive to others.
The reason "Reference" models cost so much is that every component and build decision is (should be) made around minimizing every possible fault with the hope that then the amp will be perceived as accurate. (Plus they are usually hand built in single digit qualtities).
At what point you find the sound acceptable becomes a matter of taste. Hence my comments on NOS. Your ears will detect sonic signatures from virually any piece of tube equipment. A designer who listens only to small jazz ensembles is of no use to be personally because I listen to large scale orchestral music.
More later
In the mean time a quick response. I am fairly fanatical about flat frequency response and correct phase/impulse response. I own Dunlavy SC-V's and use wall treatment and a Sigtech Digital DSP to get very flat reponse.
The Speaker/room combo is usually never anywhere close to flat. Almost every amp is virtually ruler flat compared to that or to a cartridge. If you care about accurate frequency and phase reponse the speaker/room combo is where to start.
As far as measurements on electronics, it gets interesting when the steady state sine wave measurements are replaced with impulse measurements.
In theory a simple triode amp in a well designed circuit should be linear over its designed operating range. In practice it never is.
For example, the instantaneous whap of a bass drum may drop the voltage on the B+ rails that powers the tube so severely that for the instant the amp is operating nowhere near in spec. This can be detected with a 'scope and heard as a congested sound.
Some tubes are very microphonic, that is they vibrate when disturbed. In a guitar amp, this creates a desired sound that isn't "accurate". Loud music may cause vibrations in the audio amp coloring the sound.
These are just two of the dozens of these readily known departures from a completely "accurate" amp. All real world amps have these faults to some degree. This doesn't even count all of the depatures from linearity that happen through the electrical interaction of the speakers, crossovers and the amplifier playing real music.
Some faults, like even order harmonics in a SET, can be perceived as euphonic. There is no accurate mapping from the engineering circuitry to auditorily perceived accuracy. Our ears are non linear transducers. Evolution has tuned then to be amazingly sensitive to some signals and insensitive to others.
The reason "Reference" models cost so much is that every component and build decision is (should be) made around minimizing every possible fault with the hope that then the amp will be perceived as accurate. (Plus they are usually hand built in single digit qualtities).
At what point you find the sound acceptable becomes a matter of taste. Hence my comments on NOS. Your ears will detect sonic signatures from virually any piece of tube equipment. A designer who listens only to small jazz ensembles is of no use to be personally because I listen to large scale orchestral music.
More later