Noise section trimmer voltage?

It works

And it fixed my clap

I'll dig some more into the tr808 service manual.

Thank you so much !

pato wrote: There was a modification on the original TR-808 which has not been respected in the Yocto. Have you tried it? It worked for me.

Hi pato,

did you try some of the other improvements from the service manual? I know some people had problems with a loud HC, maybe their solution is in there too. And there's some other interesting things on that page as well.

Sorry for getting off topic!

I know some people had problems with a loud HC, maybe their solution is in there too.

My first thought is that this is caused by the BA6110 used in the Handclap instead of the BA662.
On the x0xb0xforum it's been discussed a lot.

Maybe open a new topic for this problem?

Replace R129 (330k) by a jumper (0) and replace R311 (330k) by a 100k. Also replace R127 (47k) by a 10u capacitor.

Don't forget to add a 22pF (C202) capacitor parallel with R130.

I'm getting only 13mV RMS measured with an oscilloscope with a 4K7 resistor on R127, any ideas? Perhaps I will try the revised schematic...

Never mind, I was a retard, measured the wrong point, haha. Everything is okay now, had to change R127 to 150K, but I don't mind if it sounds right.

Yes i too ran into issues when trying to calibrate the noise to 130mV with the trimpot. After implementing the changes in the service manual it was possible to get 130mV at the test point.
RMS shows differently (about 40mV difference) on my multimeter and oscilloscope (bitscope micro) but i think it's close enough.

Is it possible to trim this by ear? Doesn't this trimpot control the amount of white noise going in to the "snappy" of the snare drum?

I think you can do it by ear (haven't tried).
I think it controls the feedback in the noise circuit so i expect it to influence level and sound character, someone correct me if i'm wrong.

I actually had to lower my resistor value down to 1.5K (I didn't have a spare 1K) which gave me a max value of 120mV. It sounds ok to me, but I guess I'll replace it with a 1K so I can get up to 130mV.