Zap sound on power down

This aint a big problem but when I power off my ambika I get a zip/zap sound. I built two ambika’s one 6 voice and that one doesn’t do it. The two voice I built does. Any ideas? Is it simply to do with only having two cards installed? If there is a problem it certainly has to be the voice cards.

Cheers

( I tried searching but power off and sound are pretty common terms)

My 4-PM Shruthi does that too sometimes. Never really thought it could be a problem…

Cheers. I guess it’s nothing to worry about.

Apart from the occasional SD card read error (not sure why, connection looks good) seems the build went well.

Yes, this is common behavior, and from what I understand, not a symptom of a problem that must be fixed.

Yes, quite common. If your Mirage gets stuck in the limbo land of looping all of the samples on it after being on too long, when you turn it off it sounds like it is screaming in agony because all of the oscillators keep playing as the power drains. I need to remember this the next time this charming glitch happens and record it.

What’s happening:

As you remove the main power, the synth is still temporarily powered by all the reservoir and bypass caps. As they rapidly discharge, circuits start operating outside normal conditions. This can cause all kind of weird stuff, but primarily, the downward going curve of the supply voltage “leaks” onto the output. It’s the kind of “sagging” effect of guitar pedals with dying batteries, accelerated over the fraction of a second.

Why you don’t get it on the 6-voice unit?

There’s more circuitry in there so it takes shorter to discharge all the caps. You get a higher-pitched/shorter zap which might not be as noticeable.

Also, the sound depends on where you are in the mains 50Hz/60Hz cycle when you unplug. Because there won’t be the same amount of energy in the reservoir caps.

Power amp/mixer off first :slight_smile:

Thank you peeps. Especially for such a detailed response. I’m glad it was normal behaviour. Also glad I learnt a little bit more about electronics. It’s nice doing paint by numbers but it’s even better actually learning something. I especially enjoyed building the motherboard for that reason. Instructions that explained what parts did (if a little over my head) was very interesting.