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previous: Rebel420 Ray, first off, welcome aboard. I'v... -- 4/20/2000 2:50 PM

Re: Swapping Preamp Tubes

4/20/2000 4:06 PM
Ray Ivers	Re: Swapping Preamp Tubes Thanks - and thanks also for the 'brown sound' info. So many times I'm asked to get a certain sound from an album, and don't know what to say: "I can't really do that, and here's why" gets old real quick. Sounds to me from your postings that you're no stranger to design-level stuff, either. Yeah, after I made that last posting I kind of wondered if I should have; but I'd be glad to figure out what cathode/plate resistor values I feel would be good for anyone who wants to ask me. I just got thru with my own Ampeg V-9 (SVT for guitar), redesigning the negative-headroom driver stage to obtain full output while maintaining as many original parts as possible (ended up moving only one resistor!). I really enjoy doing this, maybe more than I should. So much focus is put on preamp tubes' gain factor, when there are so many other parameters that affect tone and power output - that's why there are so many tube types, and a lot of times a 12AX7 is NOT the best choice for a given circuit, as you well know. A cool multi-purpose 12AX7 circuit, though, is the Marshall/tweed Bassman tone stack driver circuit: a 12AX7 gain stage direct-coupled to a cathode follower (the 30th Anniversary has three of these 'stagelets' in its 4-stage overdrive channel; it's why I bought the amp, and I think it sounds great) - I've got a paper by T.E. Rutt for the AES convention about this circuit... See what I mean? I have to get a life! Just kidding - I eat, sleep, and breathe this stuff, and wouldn't have it any other way. Ray

4/20/2000 4:06 PM

Ray Ivers

Re: Swapping Preamp Tubes

Thanks - and thanks also for the 'brown sound' info. So many times I'm asked to get a certain sound from an album, and don't know what to say: "I can't really do that, and here's why" gets old real quick. Sounds to me from your postings that you're no stranger to design-level stuff, either.

Yeah, after I made that last posting I kind of wondered if I should have; but I'd be glad to figure out what cathode/plate resistor values I feel would be good for anyone who wants to ask me. I just got thru with my own Ampeg V-9 (SVT for guitar), redesigning the negative-headroom driver stage to obtain full output while maintaining as many original parts as possible (ended up moving only one resistor!). I really enjoy doing this, maybe more than I should.

So much focus is put on preamp tubes' gain factor, when there are so many other parameters that affect tone and power output - that's why there are so many tube types, and a lot of times a 12AX7 is NOT the best choice for a given circuit, as you well know. A cool multi-purpose 12AX7 circuit, though, is the Marshall/tweed Bassman tone stack driver circuit: a 12AX7 gain stage direct-coupled to a cathode follower (the 30th Anniversary has three of these 'stagelets' in its 4-stage overdrive channel; it's why I bought the amp, and I think it sounds great) - I've got a paper by T.E. Rutt for the AES convention about this circuit...

See what I mean? I have to get a life! Just kidding - I eat, sleep, and breathe this stuff, and wouldn't have it any other way.

Ray

Replies:

Rebel420 Wellth brown sound info was truely ... -- 4/20/2000 4:56 PM