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additional gain stage
Posted: Mon Sep 14, 2009 2:22 am
by Ivabiggun
Hi, can someone send me a few links on adding another gain stage to the MV amp. It's actually going into a JCM800 50 watt circuit. I have my basic design down but I would like to get a little more info on incorporating it as the first stage with the others to follow. I want to make sure I don't design to much gain into it as I know the perils of adding a lot of gain in one stage. As always, thanks to everyone here for all the help over the last few years.
Iva
Re: additional gain stage
Posted: Mon Sep 14, 2009 12:00 pm
by gutpile
I added quite a bit of gain by changing the 10K on the left hand side of the board to a 2.7K which in turn made me had to change the NFB from a 100K to 27K... I also changed the bright cap to a 500K... I have noticably more gain that was relatively painless
... Good Luck!
Mike
Re: additional gain stage
Posted: Tue Nov 17, 2009 10:13 pm
by LP Freak
I tried this. It has a bit more gain, but the bottom end seemed to get really floppy. Any idea hoy to tighten it up without loosing the low end?
Re: additional gain stage
Posted: Sat Feb 19, 2011 1:25 pm
by erigm
If you're going for tighter bass try swapping the 2k7 (the one that replaced the 10k) with a 4k7 bypassed with .1uf or .2uf. That should give you about the same amount of distortion but with a tighter percussive sound.
Some people like swapping the first stages cathode cap of .68uf with .47uf, so you might try that as well.
Re: additional gain stage
Posted: Sat Jul 09, 2011 9:09 am
by vlad
Do you want to add another tube? Or convert the CF to a gain stage?