should i parallel this AX7?

[iknowjohnny]

I made major changes to my amp recently and i was going to leave it as is, but B4 i do i'm wondering if i should make this one last change. After removing the cathode follower stage in favor of a plate driven stack, i now have 1/2 of the 12ax7 that drives the tone stack left unused. I've paralleled ax7's before and it seems to sound fuller. So today i thought why not do this? But i really would like to hear opinions from those who have done this a lot as to what stage to parallel. I have the two V1 stages and the one V2 stage that drives the stack. So i have 3 stages any of which i could parallel. Should i, and if so which stage? here is the schematic....

http://i24.photobucket.com/albums/c39/d ... 1273124181

[selloutrr]

if i was going to i would try your V2 only because you have a volume control over how much you drive the tube. V1 and V3 look like a set it and forget it. possibly V3 i'd have to hear the effect in that circuit.

[tubeswell]

You could lower the noise floor in V1 with the plate resistor and cathode resistor values halved.

Or wire it as a switchable parallel first stage for an optional boost.

Or wire it as an alternate first stage with different r-k combinations (like a marshall/fender option), which you could then parallel.

Or here's a dumb idea I had a month or so back that I haven't tried yet - maybe you could try it for me? (ha ha)

(I think - although I haven't tested it yet) with the switch one way, you either have V1a on its own as a marshallesque channel, and the other input is V1b in parallel with V1a. And with the switch the other way, V1 b is a fenderesque channel, and the other input is V1a cascaded into V1b (which to my way of thinking is the 'right' way around, freq-roll-off-wise so to speak, if you are going about cascading the two stages. Um...)

[Andy Le Blanc]

Try the one driving the tone stack.

[iknowjohnny]

I don't want any switchable things or extra inputs. (not that i'd have room anyways)

Andy, that would be the simplest place since thats the tube with 1/2 not being used, but any reason you chose that?

[Andy Le Blanc]

When you parallel you affect voltage, capacitance, current.... and impedance.
You driving a tone stack with a high impedance stage, try it there first.

[iknowjohnny]

Ok, then in the schematic below is there anything i should do different, and second, should i change the plate and cathode values?

http://i24.photobucket.com/albums/c39/d ... 1273241003

by the way, thats a old schematic so much of it is totally different than it is now, and ignore the cathode bypass cap on the 820

[Andy Le Blanc]

try it simply with the existing values and see what happens first.
Then something from a 33k to a 56k on the plate, around a 470r cathode.

Scab in temporarily a 100k pot. in the plate, and 1k pot. for the cathode
dial your way around the idea, listen as you go.

[iknowjohnny]

will do, thanks. I'll let u know what i find. I just hate to waste a stage if it can be put to good use.

[iknowjohnny]

Well, no go senior. It does make for a fatter sound but fatter in this case does not=better. The tone of this thing is so harmonically complex that it's just erotic, and that fatter tone somehow seems to lose some of that. I could try V1, but i think this tells me don't mess with a good thing. So back to the way it was, but at least now i know i'm not missing anything by not using that 1/2 tube. Thanks all.

[Andy Le Blanc]

Good.... you end up in just the right spot, but its also important to keep exploring.

[iknowjohnny]

You know me...thats all i do !! Ad nausium as i'm sure those who know me here will surely say. But this time it's in the combo cab to stay. I've had it good to great. but this time it went up another whole rung on the tone ladded and i have never heard another amp sound like this one does no. It's so harmonically rich it sounds like i'm running a chorus or phaser. The attack has that gritty grindy squawky thing going on to the nth degree. This is exactly what i have been after for 2 friggin' years ! The low end is not quite as tight as i'd like it, so it's not perfect. But it's good enough, and in all other respects it is. It's the tone i have heard in my head since i was a kid. Similar to those old ZZ top records but accomplished with preamp distortion, a feat i didn't think i'd ever be able to do. Dynamics are very clean to all out screaming with your hands and guitar pot. And it all came together when i dumped the cathode follower ! Granted, once i did that i have to do several other tweaks to compensate for the change, but i could tell right away there was big potential when i sheet-canned the CF. It was like i found the reason i could never be totally satisfied with the amp. No more CF amps for me !

So it's "put a fork in it" time because this mutha is done ! I just hope i don't get that burning desire to "explore" again down the road. But if i do i gotta keep my grimy hands off the preamp section cuz i just don't think a better hi gain pre can be had as far as my likes go