Problems with envelope 1. Please help

Hello everyone.

I just build myself a struthi-1 and I have some strange problem that I think is related to env1 somehow.
Here is a link to a short demo of what it’s doing.

http://soundcloud.com/filter303/p39-bad-taste-evn2-rel-0

I am using the preset 39 badtaste with a change that env 2 release is 0.
Can someone help me out with this one? I am desperate.

I am playing a c note on 3 different octaves. When I release the note it’s still playing sound even when it shouldn’t and there is some weird modulation going on also.

I forgot to mention that I am using the SRM-4 board

I can’t tell for the “weird modulation going on” - not sure what you mean - but as for the “sound still playing” there’s an explanation:

  • the VCA on the SMR-4 board (I assume that’s the one you’re using) is bleeding a bit even when the envelope has reached a null value. This is due to the fact that the VCA CV output by the digital board is a slightly bit above zero (and not exactly equal to 0) when the envelope has reached a null value.
  • the oscillators continue running as long as one of the envelopes hasn’t reached zero. After that, the oscillators go silent, ensuring absolute “digital” silence.

This doesn’t look like a problem with your build - just design choices.

There are two ways of avoiding this:

  • hardware modification: add a small negative voltage to the VCA CV. Look how this is done on the SSM2044 filter board, which has a trimpot (GATE) to compensate for this. The CEM3379 board doesn’t need this since the CEM3379 include some kind of “noise gate” (knee in the VCA response curve).
  • patch programming: if you set a zero release time on the VCA envelope, it means that you want your sound to instantly go silent once you release the key - so there’s no need setting the other envelope to a long release time anyway, since you won’t be able to hear its release.

But to be on the safe side, I’ll try to do a software hack to output “digital silence” when the VCA signal is set to 0. I suspect this will introduce clicks so I’d rather not bet on this.

On a related note, please post links to .wav files instead of soundcloud hosted mp3s - soundcloud applies mp3 compression which might remove some of the glitches you mention, and it doesn’t allow me to download the file to inspect it into an analysis program.

Thank you very much for your quick answer. Here is a new link to a .wav file:

http://soundcloud.com/filter303/p39-env2-rel-0

I really appreciate all the help I can get because I really love my struthi but this release bug is a bit annoying.

Posting a .wav file to soundcloud doesn’t solve the problem: soundcloud still converts it to mp3, and I still can’t download it. Please send me directly the .wav file by email or post it on a file hosting website.

I will send it to you. Can you give me your email address?

thanks.

mutable.instruments at gmail dot com

The file is in your email. Let me know if there is anything else I can do.

File received. I confirm there’s not any other problem than the VCA “bleeding” thing described above. I’ll keep you updated if the software way of solving this really works. Otherwise I fear you’ll have to live with it.

If I can simplify the design of the SMR-4 board a bit to gain some PCB real estate, I’ll add the trimmer the same way I did on the SSM2044 board.