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Post by tarcreeper on Mar 25, 2021 22:11:14 GMT
I just received the qvca and it’s behaving very differently than expected. Firstly the audio and cv inputs are switched. That’s not really a big deal but when plugging an LFO into what seems to be the actual cv input to create a tremolo, the bottom 4 outputs seem to be a mix of normal and inverted signals with audio rising and falling twice per cycle of the LFO. I can only get it to act like a normal vca when using an envelope. In addition to that, the top outputs don’t do anything. According to the 5th volt’s tutorial these should be inverted outputs. They just run the audio signal straight through completely unaffected. Did I get a faulty module or am I just doing something wrong? Any help would be appreciated.
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namke
wonkystuff
electronics and sound, what's not to like?!
Posts: 654
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Post by namke on Mar 25, 2021 22:30:23 GMT
Oh, well that sounds very wrong — apologies. All are tested and calibrated before they go out of the door, so I don’t really have a clue what the issue is. There would be odd behaviour if the power connector is not plugged in correctly, but I have never seen what you described! I can’t actually think of what is actually going on here as there aren’t really that many variables  |
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Post by tarcreeper on Mar 25, 2021 22:33:48 GMT
Update. I just shut down my system and turned it back on. The inputs are no longer switched and the LFO is now working as expected. The inverted outputs are no longer just passing the signal straight through but now they’re not outputting anything at all. This is all very strange.
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namke
wonkystuff
electronics and sound, what's not to like?!
Posts: 654
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Post by namke on Mar 25, 2021 22:40:56 GMT
That’s very weird; there’s nothing in the module that needs ‘rebooting’, so I can’t explain that. Is there anything special about your system (running off a battery etc.?)
The only thing I can do remotely is offer a replacement, but I’d like to be able to analyse the fault in case there’s something that might need addressing because of a component tolerance or something.
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Post by tarcreeper on Mar 25, 2021 22:54:53 GMT
No I’m just plugged straight in. It is running through an extension cable so maybe that has something to do with it? I never had issues with any other modules though. Now the only thing that isn’t working is the inverted outputs. I’d feel bad making you send a replacement just for that. I’ve built a few DIY modules and did the mod on the rbss so if you have any ideas on a potential fix I could probably solder it up myself.
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namke
wonkystuff
electronics and sound, what's not to like?!
Posts: 654
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Post by namke on Mar 25, 2021 23:07:44 GMT
Ok, thanks — I know that some people run off of batteries and occasionally there are problems with voltages being a little ‘on the edge’.
I’m intrigued by the failure though, since if the VCAs are working, then the inverted outputs should also — they are physically in the same chips. Very odd.
I don’t know what test equipment you have, but maybe it’s worth taking this to email and then seeing if I can guide you to make some measurements?
Obviously I’d rather have happy customers, if you want me to send you a a replacement I will do so, no problem…
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Post by tarcreeper on Mar 25, 2021 23:18:41 GMT
Update. I’m a dullard and wasn’t patching it correctly to get the inverted output working. Everything seems to be in working order now. That hiccup at the start seems to have been an anomaly. Perhaps there was a power surge? It is storming here at the moment so that could have had something to do with it. Thanks for your timely help though!
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namke
wonkystuff
electronics and sound, what's not to like?!
Posts: 654
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Post by namke on Mar 25, 2021 23:44:36 GMT
Oh! Marvellous — that’s great news  I will dig through some data sheets at the weekend to see if there are any particular edge-cases where power fluctuations might cause issues with the chips getting into a strange state. Of course, if anything seems weird going forward then just let me know (either here or on email) and we’ll do the best that we can to help you out. |
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