Saturday, January 4, 2014

a burst of vocoder progress

I have checked the V/UV and the synth / noise inputs and all is working


I had a bit of a scare when testing this module. Voiced was locking on and it seemed that something was wrong. Luckily I tracked the issue pretty quickly - the 330k in one of the filters was 330r. I looked in my 330k bag and it was full of 330r resistors. I then checked to see how many resistors I'd have to replace on the board and luckily there was only one - phew! Large projects and systematic errors are not good - lucky break.

So after this fix it appears to be working. Unvoiced vocal sounds triggers the unvoiced channel. The user 'sound' on e-m has recommend different filters for the unvoiced but I kept it at Jurgen's design since it is based on a ems vocoder. I made no other component modifications the only mod is that I am using a pot for v/uv threshold as i think this is a neat feature to have on the panel. 

I might even take the v/uv triggers out to the panel like on the doepfer v/uv module. 

The only part that i'm curious about is that the voiced channel is always on even when there is no input. Hopefully someone can give me feedback on that.

Happy with this for now - I'll re-review it once I have some channels working

Synth Input

Synth Input is working fine. I had to replace a dead bf245 but otherwise no issues. 'Sound' on e-m recommend changing some resistors in this section which I followed but I had to revert the 1k8 / 10k which controls the noise amplitude back to 18k and 100k to ensure it was around +4dbu.

I am going to have the synLevel as a pot on the panel as the level should be the same as the noise input and the input may be an iPod, a module signal or a synth so it needs to be controlled by the user.

so where to now...

I am going to skip the slew and silence bridging modules for now. Time to get some channels working. Once that is done I can test the output and hear it for the first time. I will also be able to hear how the v/uv sounds as well as check the slew / silence bridging.

Once everything is tested I can finalise my panel design and send it off for fabrication. I am 99% sure on my current design but since it will be an expensive panel I'd like to verify my choices are all going to work and I'm not missing anything.

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