Ralph (Atmasphere) posted:
If you add a resistor to the output of a solid state amp it will indeed simulate some sort of tube amp that uses feedback. Most transformer coupled tube amps with 15dB of feedback will act as a pretty good voltage source. You might have to play with the taps on the output transformer. Between Voltage source and Current source there is Power Source, which is how a tube amp will behave if it has no feedback or if it has voltage and current feedback of equal amounts.
I think Ralph is right on. My ARC Ref 80S is a transformer coupled tube amp that uses 14db of negative feedback. And I do **play** with the taps to get the best sound. At this point, I have settled on the 8 ohm taps, which I believe have an output impedance of approximately 1 ohm. The DF is 8 if the amp is coupled to an 8 ohm speaker off the 8 ohm taps.
As to comments made by others, I believe that it is correct to say that matching my amp (or one like it) to a speaker that was designed and voiced to be driven by a constant voltage source amp is a bit of a tone control. To some extent the amp's voltage output will vary to some degree as a function of speaker impedance, which in turn, will vary with frequency.
All that said, I like the sound of my amp/speaker combo, ... tone control and all. Ironically, I surmise that between room affects which probably boost the bass a bit and and the tone control affects of the amp which soften the tweeter/high frequencies, the overall frequency response and sound is musical and pleasant. Just my opinion.
BIF
