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Help! Self-oscillating Bassdrum

Posted: Apr 12th, '18, 09:58
by cmroosen
Hi all,
I have a strange issue with my Bassdrum.
I seem to have the sequencer and the triggers working, I hear every second a 'bip' sound with the decay of the bassdrum closed. But when I open the decay a continuous tone is sounding, and the tone quickly changes to a low buzz when the decay is more open.

What's also strange, is that even when it is switched off, I hear a hum sound when I connect my bassdrum output to my speakers.

Does anybody have clue how to tackle this problem? Thank you in advance!

Re: Help! Self-oscillating Bassdrum

Posted: Apr 12th, '18, 16:09
by cmroosen
I have found a wrong resistor: R170 was 470 Ohm instead of 470K.

Now the strange beeps are gone, but the 50 Hz hum is still there quite loud. I hear a faint click of the kickdrum but the whole thing is very sensitive when I touch earth, like the metal parts of the pot meters! Anybody have a clue?
I'll try and see if there are more parts wrong. I HAVE TO FIND THE FAULT :twisted: :lol:

Re: Help! Self-oscillating Bassdrum

Posted: Apr 14th, '18, 09:25
by Marti
Hello,

I think I had the same issue with the hum sound of the bassdrum. As you said it was generally by touching the potentiometer. Have you soldered all the metal parts of the potentiometer that serve as support to the ground? I think I solves the hum by doing that.

Re: Help! Self-oscillating Bassdrum

Posted: May 3rd, '18, 23:18
by cmroosen
Hi,
Thank you for your help!

I solved the decay problem, it was a wrong resistor after I searched and searched.

Now it is working fine except for the ground loop hum. I also completed the snare and both the snare and bass drum have quite low volume. I will try and measure where could be a ground loop and also try to measure the signal path why the volume is so low.

But still I already reaaaaally enjoy the sounds!! :lol: Thank you!