... in a tube preamp... So, I do it as with single supply, or do I have to trim some bias to grids? Thanks!
Well, it will be like any guitar amp preamp, but I want to build some hybrid, so, with SS output, I have dual supply, 50Vdc, and I have a couple of 6SN7 and a pair of ECC84 (yes, I know, they're not for audio purposes...) and I wanted to make them work with that supply, not just single 50V dc... would be like the old-style marshall preamp, like plexis.
6SN7 does not compute at those voltages, well maybe they do, but they don't sound good. ECC88 types would be better and could probably be run of a split rail if you like
however, since it's for a guitar amp, you might like the distortion and limited swing a 6SN7 with a low B+ will give. i'd forget about curves and such and just throw a 10k on the plate and a 1k on the cat and take it from there
i've never seen any old style amp run off anything like 50V, btw
cheers,
mb4b
however, since it's for a guitar amp, you might like the distortion and limited swing a 6SN7 with a low B+ will give. i'd forget about curves and such and just throw a 10k on the plate and a 1k on the cat and take it from there
i've never seen any old style amp run off anything like 50V, btw
cheers,
mb4b
2 posts, you still don't give us enough information. This is plain rude.
Post something sensible, like a drawing, since you obviously got no talent for explanation.
No wonder you not getting any replies.
w
Post something sensible, like a drawing, since you obviously got no talent for explanation.
No wonder you not getting any replies.
w
That was kinda rude, wakibaki, it's pretty simple!
2 or 3 triodes stage, b+ to resistor to plates, cathode to resistor to b-, and don't know what I can do with grids! 6SN7 are pretty linear, so, make them work with 100V would make them distort easily, right?
I could use some trimmer as plate resistors... maybe...
Ok, I'll post some drawing later.
2 or 3 triodes stage, b+ to resistor to plates, cathode to resistor to b-, and don't know what I can do with grids! 6SN7 are pretty linear, so, make them work with 100V would make them distort easily, right?
I could use some trimmer as plate resistors... maybe...
Ok, I'll post some drawing later.
Oh! I see. You're trying to run a tube amp off your dual 50V power supply.
Putting the two outputs in series would give you 100V to work with. I would ignore ±50 with a 0V tap and just think of it a 0V and +100V.
Can you make a tube preamp work on 100V? I'm sure the answer is yes. Someone else is probably better able to suggest designs than me.
Putting the two outputs in series would give you 100V to work with. I would ignore ±50 with a 0V tap and just think of it a 0V and +100V.
Can you make a tube preamp work on 100V? I'm sure the answer is yes. Someone else is probably better able to suggest designs than me.
I'd go for something like this:-
You can steal the tonestack values from a fender champ, the data is for 6sn7, 90V is close enough.
w
An externally hosted image should be here but it was not working when we last tested it.
You can steal the tonestack values from a fender champ, the data is for 6sn7, 90V is close enough.
An externally hosted image should be here but it was not working when we last tested it.
w
Great data! The fact is I want to use a mosfet power amp, with 50V dual suply, and that's why I wanted to use dual supply! Tubes can run with lower voltages... they just become less linear...
Thanks!
Thanks!
I don't see why you can't run the tube pre off the 100V and the MOSFET off the ±50V. You'll have to dc couple the stages with HV caps but as long as the input and output impedances of each stage are considered you'll be fine.
Obviously, ground in Waki's schematic would be the -50V rail.
Problems could start if your supply has a current limit that prevents the MOSFET power stage from powering up cleanly (inrush to on board caps) That rail fluctuation might upset the tubes - you may want individual switches to stagger the power up sequence. Any opinions?
Obviously, ground in Waki's schematic would be the -50V rail.
Problems could start if your supply has a current limit that prevents the MOSFET power stage from powering up cleanly (inrush to on board caps) That rail fluctuation might upset the tubes - you may want individual switches to stagger the power up sequence. Any opinions?
slideman82 said:
An ECC88/6DJ8 will be pretty linear with 100V to work with, no compromises there. Just make sure you AC couple the input as well (think 2 triodes in between 3 caps).
So, -50V as ground... but I still have the doubt for the grids... there's a well-known starved plate distortion for guitar that uses dual supply, and also a bias for the grids, right here
http://www.freeinfosociety.com/electronics/schematics/audio/pictures/tubedriver.gif
So, this has left me thinking...
http://www.freeinfosociety.com/electronics/schematics/audio/pictures/tubedriver.gif
So, this has left me thinking...
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