Dear Gregadd and friends: ****" Raul this is from an earlier post by you. The audioholics does not agree with your conclusion that a tube amp is an ucorrectable equalizer. "*****
They don't disagree too, right?. But this is not the point, the point is that till today does not exist any tube amplifier with very low output impedance. That's why a tube amplifier change the frecuency response with the changes that has the speaker. Now, in and SS amplifier that changes can be of a very low order: 0.1 db to 0.3 db, but in a tube amplifier that changes are really high ones deviations from the original: 0.5 to 10db or more. This is a heavy degradation. Take the TWL amplifier that has an output impedance of 1.8 Ohms, this one will had a deviation between 1.0 to 2.5 db: unacceptable by any standard.
TWL post this: ****" To me, the key here is not whether there may be some slight affects to the amplifer based on speaker reactances, but whether these small effects could even be actually audible, given wider range tolerances in many other parts of the sytem context. "****
Dear TWL, first there are not " slight effects " ( ****" , As amplifier output impedance rises, these differences in frequency response are exaggerated. The changing speaker impedance actually pushes the output voltage of the amplifier around thereby changing the acoustic output of the speaker. The amplifier cannot control its own output. "**** This comes from the Gregadd link. ), in the case of tube electronics it is a heavy effects ( degradation and always audible by anyone, but a deaf. ) ), second: what are you telling us? that because there are other wider range effects in other parts of the audio system, these ones does not matters?. Example: assume that the discrete frecuency response at 100 Hz of a speaker has a deviation of -10 db and that the effect of the tube amplifier is -3 db at that discrete frecuency: TWL, till today 10+3 sum: 13 ( I know that the sum of db it will be a logarithymic sum ) and you try to telling that it does not matters?, come on TWL.
Now, the tube amplifier degradation to the signal is worst than what Stereophile shows in the diagrams, why?, because Norton/Atkinson use a constant resistance at the amplifier outputs, normally a 8, 4 and 2 Ohms resistors. This is very gentle for the tube amplifier and far from reallity, because the impedance of the speaker is not constant it has heavy variations with the frecuency response in all the frecuency spectrum, and you can check this too through the Stereophile tests on speakers,: can you imagine other worst degradation on the signal reproduction in a high end audio system and that that degradation can hear it?
This is one of the reasons why I always speak of " equalizers " in reference to tube electronics. The real name has to be: UNCONTROLLABLE EQUALIZERS.
It is already clear that the tube electronics goes against the music reproduction, and till now anyone can do nothing for to change it. This is the point: AGAINST THE MUSIC REPRODUCTION.
All these statements are for the people that really cares about. Ask you what are you hearing from a tube electronics in front of live music.
In this analog forum all of us are trying to obtain the best from our analog system: phono preamp, phono cartridge, tonearm, turntable, phono cables, etc.... Here we are talking to do the very best for our analog system: VTA, VTF, Azymuth, cartridge load impedance, resonnce frecuency on the cartridge/tonearm combo, metal platter or acrylic one, MC or MM cartridges, pivot or linear traking tonearms, air bearings, mass, etc..... We do all this job ( time, money, know-how,..) trying to obtain the best analog music reproduction, and for what if in the next audio system link: UNCONTROLLABLE EQUALIZERS ( tube electronics ), all our efforts goes dead-down.
That's why I always speak to be sure that exist the LESS degraded effects at any link in the whole audio system, and why any one that has these UE does not knows the real performance of his audio system.
Regards and always enjoy the music.
Raul.
