Not so many responses, hmm. Perhaps people are on vacation. Or maybe I should be more clear.
If one wants a 2-band tone control that can enhance treble and bass response on some recordings - what type of circuit is generally thought of as best, i.e. creating minimal distorsion or other problems in a tube context? I have found two basic solutions from the tube era, but until I build them I an unsure what works best.
Most TC circuits I have studied are meant for guitar amps, where coloration and distortion is something wished. Purist high end preamps seem to be made without tone controls, which I am recently starting to find a bit silly - however pure the signal path is, the esoteric builder is still voicing the amp by choosing component brands and operating points of the tubes so why not give more control to the listener. (PIO vs. teflon caps anyone?) So that is why I want to learn about tone controls.
Baxandall works in the feedback loop, and the earlier E. J. James version although similar looking is inserted as a passive circuit between two stages.. Both use up some of the gain. There is also the question of which circuit is easiest to bypass with a simple switch. I am thinking that a Baxandall can be replaced by a resistor of equal value to the TC network, to maintain the feedback and signal level on the output. Or does anyone have a better idea?
A simple loudness switch would also be interesting, something that can boost the top and bottom a bit. I know it is not the purist approach, but, hey, its meant to be a fun hobby
Link to James's 1949 paper:
http://www.thermionic.info/james/Jam...oneControl.pdf
Martin