Fine Tune Filter

Hi, I connect the synth to an amp, when I’m go to tune the filter as show the instruction:

“Oscillator 1 shape: none
Oscillator 2 shape: none
Filter cutoff: 64
Filter resonance: 63 (maximum value)
Filter envelope and LFO modulations: 0
Play on the keyboard. You should hear a pure tone (sine wave)…”

I don’t hear a pure tone, I have to turn it up to the end of amp volume and I hear it is a “percussive sound” when I play a note with the keyboard.

Could you help me please?

Did you use the INIT patch? From the manual - While the browse page is displayed, hold S6 and press S1 to revert the current patch to init.

Does the resonance work? Maybe there’s a pole of your filter that doesn’t work, could you post photos of your filter board?

I think I had the same problem: http://www.mutable-instruments.net/forum/discussion/3961/strange-self-oscillation-on-shruthi-smr-4-mkii#Item_3

These are photos

Looks good. Is the resonance working? Can you feel that, for example when playback a sawtooth wave, increasing resonance to the maximum value almost brings the filter to the self-oscillation point?

ohhh my god, I reassemble, and now no sound

the only thing I did was clean the filter board with ethyl alcohol.

That’ll be the board connectors, make sure they’re making good contact and the solder joints haven’t been damaged.

the board connectors and the solder joints are ok

Don’t panic! Trace the sound on the filter board as explained at the end of the filter board assembly instructions.

I do it without connecting the control board?

You will have to do it with the control board… You’ll need it to make sound. So play some midi notes to it or have the test note running.

I connect the filter to the power supply?

yes

Ok, I trace the sound on the filter board as explained in the instructions… sounds only in point one, the others does not sound.

what should I do?

Check voltages - do you still have -5V ?

Right now I have no way to measure the voltage, so I did the test with an audio jack.

You need to use the multimeter to check the power supply voltages or CV ; and the audio probe to test the audio path. Both methods have their uses…