6581 Sammich Stuck Notes

[schmidtc]

Hi All,

Forgive me if this problem is covered elsewhere. I'm getting so stuck notes with my 6581 Sammich, where there is indefinite and audible tones pitched to the last midi note played. It seems better / worse on certain patches. Any ideas what to check?

Many thanks!

[Wilba]

This could just be the 6581 SID... the oscillators don't fully "gate off" properly, a known problem with this type of SID.

Check that this effect is happening regardless of whether the note played is via external MIDI or by pressing the Play button (F1).

Perhaps you can record what you hear and share it, then I could give a better opinion.

[antman49443]

Another possibility is "wimpy" midi output on your keyboard. For some reason, my M-Audio 49e keyboard does the same thing. try changing the 1200 ohm pullup resistor on the 6N138 output to something like 390 ohms. You can try tack soldering in a parallel resistor on top of the 1200 ohm unit to see if that helps before removing and replacing a resistor. On second thought, if it happens to solve the problem, just leave the parallel resistor.

[Wilba]

If "wimpy MIDI output" is the problem, then it would be the same for note on and note off events, so I don't think that's the problem here.

[antman49443]

If "wimpy MIDI output" is the problem, then it would be the same for note on and note off events, so I don't think that's the problem here.

Good point, Wilba! Yes, besides stuck notes I would have note on issues too on my keyboard.

[schmidtc]

Yep, the notes stick on both speakers, both via with external MIDI and via Play button (F1). Looks like I'm on the hunt for a pair of 6582 or 8580? Do most 6581s have this issue with gates not closing all the way? Thanks!

[Wilba]

I'm not an expert with 6581, but from those I've sampled, they all make some sound when the gate is off, but some are louder than others.