Author Topic: Vintage Mistress ticking  (Read 3201 times)

yeeshkul

Re: Vintage Mistress ticking
« Reply #40 on: March 16, 2018, 05:21:55 PM »
Yes, i did the star grounding. I may try two decoupled power sources :), however the pedal is quiet now, so nothing really pushes me in that direction.
« Last Edit: March 16, 2018, 05:24:41 PM by yeeshkul »
I don't believe anything i haven't measured with my RoHS friendly Chinese multimeter.

yeeshkul

Re: Vintage Mistress ticking
« Reply #41 on: March 20, 2018, 07:32:38 AM »
I see it now in the photo.  A big fat wire going to the light blue section. Seems the light blue and dark blue sections are directly connected after all.
That means that although you have a star ground, you don't in fact have separate decoupled supplies for the audio and LFO/VCO sections.  You really have a single supply node and a single ground node, with a lot of capacitance between those two nodes.
It just happens to be distributed over the board.

Actually not. Look at the schematics image above the pictures - it is done just how you suggest it. On the image, i have shorts instead of 10R filtering resistors as i wasn't sure what value would be the best.
One of the filters is "sideways", because i am filtering noise *from* VCO that can get to signal part via the DC  path.
« Last Edit: March 20, 2018, 07:35:28 AM by yeeshkul »
I don't believe anything i haven't measured with my RoHS friendly Chinese multimeter.

DrAlx

Re: Vintage Mistress ticking
« Reply #42 on: March 22, 2018, 03:38:30 PM »
Separating VCO supply from audio supply in the hope of stopping VCO (clock) noise from affecting the audio is pointless, since the VCO signal is actually operating on and affecting the audio ***within*** the BBD itself.  E.g.  if you amplitude modulated the clock pulses, that would carry across into the output from the BBD, and no amount of supply separation would fix it.  I wonder if anyone has deliberately amplitude modulated the clock pulses to produce an effect :icon_idea:

LFO tick noise is another story. You can give the LFO its own filtered supply, but to be honest I have found what helps the most is to keep the wires to the rate pot (which are often directly on the square wave output of the LFO) as short as possible and as far away from the audio part of the board.