- Joined
- Mar 11, 2014
- Messages
- 228
Hello, I hope that someone can help understand the theory behind this.
Some years ago I experimented with increasing the cathode capacitor, C9, in an M49 circuit. When I reached 100uF the microphone started to oscillate in the low end. I just lowered it and everything was fine.
Yesterday I finished two almost identical M49c clones. The only difference is that one has a Moby BV11 10:1 and the other one has a AMI BV11 Classic 10:1. Both have 47uF between cathode and ground. When I connect the high pass filter with R2, C2 and C3 the microphone with the AMI transformer starts to oscillate in the low end but the one with the Moby transformer works fine. If I lower the cathode capacitor, C9, to 22uF in the microphone with AMI transformer the oscillation disappears.
Can anyone explain this?
Best Regards
Tomas
Some years ago I experimented with increasing the cathode capacitor, C9, in an M49 circuit. When I reached 100uF the microphone started to oscillate in the low end. I just lowered it and everything was fine.
Yesterday I finished two almost identical M49c clones. The only difference is that one has a Moby BV11 10:1 and the other one has a AMI BV11 Classic 10:1. Both have 47uF between cathode and ground. When I connect the high pass filter with R2, C2 and C3 the microphone with the AMI transformer starts to oscillate in the low end but the one with the Moby transformer works fine. If I lower the cathode capacitor, C9, to 22uF in the microphone with AMI transformer the oscillation disappears.
Can anyone explain this?
Best Regards
Tomas