Hey all,
I am stumped on this one - tried searching the forum and believe it or not, could not find anything...I have been scratching my head for months...
I built a point to point GC with the 9 components per the original. Originally had the input cap removed and works perfectly with my 12B4 preamp. But once I put my passive pre in front of the amp, Oscillates like crazy. Tried my Lightspeed pre and again oscillates like crazy. Tried my Foreplay, and another tubed pre and works great.
I put in the Input caps on the amp, and it still oscillates like nuts with the passive pre, LS, but not with the tubed preamps....
I do not have bypass caps on the 2200uF caps on rails at chip. I basically have it as shown on Mick's url:
http://dogbreath.de/Chipamps/GainCardCopy/GainCardCopy.html
Identical, but with 30V rails, and a Preamp where the front end Pot is. And I do have 6800uf caps/Rail on the supply end too.
I put a voltmeter across the dummy resistors while it was oscillating and read 20VAC (no DC on outputs that I could measure) before the 2A fuse blew.
Any advice???
I am stumped on this one - tried searching the forum and believe it or not, could not find anything...I have been scratching my head for months...
I built a point to point GC with the 9 components per the original. Originally had the input cap removed and works perfectly with my 12B4 preamp. But once I put my passive pre in front of the amp, Oscillates like crazy. Tried my Lightspeed pre and again oscillates like crazy. Tried my Foreplay, and another tubed pre and works great.
I put in the Input caps on the amp, and it still oscillates like nuts with the passive pre, LS, but not with the tubed preamps....
I do not have bypass caps on the 2200uF caps on rails at chip. I basically have it as shown on Mick's url:
http://dogbreath.de/Chipamps/GainCardCopy/GainCardCopy.html
Identical, but with 30V rails, and a Preamp where the front end Pot is. And I do have 6800uf caps/Rail on the supply end too.
I put a voltmeter across the dummy resistors while it was oscillating and read 20VAC (no DC on outputs that I could measure) before the 2A fuse blew.
Any advice???