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stupid waveform city vco->vca patching issue
MUFF WIGGLER Forum Index -> Wiard  
Author stupid waveform city vco->vca patching issue

flts

i'm trying to get a simple plain analog VCO->VCA patch done with the waveform city. my intuition was that it would be done just by patching one of the analogue waveform outputs to the VCA in and taking the audio from VCA out as usual. the AR generator is normalled to the VCA control anyway, and i thought that inserting a cable to the VCA input would break the VCDO out -> VCA in normalization.

now, instead of getting the plain analogue waveform thru the VCA, that way i get something resembling a (VCDO generated?) square wave no matter which of the waveform outputs i patch to the VCA in. i think it is not the same as what VCDO is outputting either, but just a static square wave with no wavetable modulation to be heard. is this normal / intended behaviour or am i doing something completely wrong?

this is a bantam jack equipped model if that makes any difference (probably not) and everything seems to work logically as it should otherwise.


flts

To clarify further, the direct sin / tri / saw outputs are working fine - I get the right waveform when I patch directly from those. When I connect one of them to VCA in I just don't get the correct waveform modulated by the VCA at VCA out.


laserpalace

Hmmm. Bantam shouldn't change anything. It sounds like your patch is right too. SIN > VCA IN2 should give you an attenuated output. I would say make sure you are patching into the VCA2 to break the normalization, are you possibly patching through the WAVE IN?

Edit - If this is a newer WFC with the latest legend then disregard the "VCA2". Another thing you might want to check is that you aren't patching into the VCA's VC control. The labels were a little confusing to me at first.


chamomileshark

odd. I seemed right to me and I've just checked it out.

Just patched sine, tri or saw into VCA < monitored via VCA > and I'm getting the different waveforms.


chamomileshark

sorry, just had one thought, turn the volume down - it's probably not the case but it it's cranked up you may be causing distortion somewhere else in your audio path.


flts

okay, did some more experiments with the audio path, there's definitely something wrong or something i don't understand with the VCA. when i first plugged the module in i thought the VCDO sounded quite grungy and hardcore (which was a nice thing even though i thought it would've been different), but now that i took output directly from the WS OUT it the same banks sound nice and mellow (like i imagined they would). take output from the VCA and it sounds like same thing clipped to practically a square.

i confirmed my suspicions by plugging in an euro VCO to the waveform city VCA. same thing - direct out from euro VCO was a fine triangle, whereas output from the VCA (even at volume set really low) was basically a square wave at the same frequency. or at least something with MUCH more harmonic content.

so it seems like the VCA is clipping its input for some reason. any ideas why this would happen, what am i doing wrong? i've emailed wiard / cary (with a link to this thread) but if anyone sees something obviously wrong here, feel free to chime in.

using the manual volume knob (which gets really LOUD really fast) i've set the output volume to a level that shouldn't clip the following stages (they don't clip with the direct waveform outputs at same volume) so that's ruled out i guess. the voltage level is set at +-5 and the fact that the unit sounds normal otherwise should probably rule out me having plugged the power cable the wrong way.


laserpalace

Are you monitoring your output through anything that would be causing the distortion? I'm sure that's obvious but in my experience the VCA never distorts or clips even when it's full clockwise.

Sounds to me like the VCA might be defective. I would probably just email Cary and see if she can identify the issue. She and Grant have both been extremely helpful when I was troubleshooting issues.


flts

laserpalace wrote:
Are you monitoring your output through anything that would be causing the distortion? I'm sure that's obvious but in my experience the VCA never distorts or clips even when it's full clockwise.


i've tried controlling that error by making sure that the audio level at the next stages (test chain is always chosen wiard output -> euro mixer / attenuator -> rme audio interface input) stays consistent between "hey, this output sounds like it should" and "hey, this one is distorting", and checking that the audio level indicators don't indicate clipping either. so i'm pretty sure it is the vca somehow, and i thought it probably isn't operating normally.

Quote:
Sounds to me like the VCA might be defective. I would probably just email Cary and see if she can identify the issue. She and Grant have both been extremely helpful when I was troubleshooting issues.


yeah, i just emailed cary 15 minutes ago, hope she'll be able to tell what is wrong.

thanks!


slow_riot

if you have the volume on the VCA at max, and something is triggering the gate, the AR envelope normalised to the VCA control will push the amplitude into distortion.


flts

slow_riot wrote:
if you have the volume on the VCA at max, and something is triggering the gate, the AR envelope normalised to the VCA control will push the amplitude into distortion.


yeah, that sounds understandable. what i tried in the end was just turning the volume something like two millimeters up from minimum point (already as loud as needed) and not connecting anything to gate... still the same result. i don't think i've so far tried anything seriously with VCA at max, on my unit it seems after like 1/3 of the turn it is already at a point where everything is clipping and not getting any louder after that. at that point it may very well be that the next stage in the chain would be clipping...


carygrace

flts:

I just emailed you. Sorry for the delay, somehow I missed your message when it came in.


flts

No problem, situation in control! Guinness ftw!


flts

just had to update on this - the module had indeed broken (perhaps during its trip across the atlantic) and it was repaired by wiard.
w00t


jamb

flts wrote:
just had to update on this - the module had indeed broken (perhaps during its trip across the atlantic) and it was repaired by wiard.
w00t


No way! I packed that sucker like a newborn! I never tested it for that specific issue you've been having- could've been like that the entire time......


carygrace

jamb wrote:
I never tested it for that specific issue you've been having- could've been like that the entire time......


It would have been obvious. Everything coming out was a square wave!

I am sure your packing was fine, but it did travel across the pond twice, so there is every possibility the module was intercepted by Daleks and implanted with an alien consciousness or two before being returned to our timestream. :-)

No worries though - the fault was repaired under warranty for the new owner, and as far as I know all is well.


jamb

Aha, yes I was certainly getting more than square.

Glad it's back in tip-top shape. Those DALEKS must've moved quick, or else the employees at the customs office in Finland are covert Daleks!


carygrace

jamb wrote:
or else the employees at the customs office in Finland are covert Daleks!


You may be on to something there. If I had to guess at likely places for Daleks to hide out unnoticed, customs offices would make a whole lot of sense...


flts

hmm, no wonder the local customs office doesn't have a visiting address downtown anymore, i've had to handle all my business with them online now. makes sense...

just to make it perfectly clear: i don't think the issue was anyone's fault and no bad feelings whatsoever - the module was packed super safely and after i noticed the issue it was repaired super quickly. these things may happen during transit / handling no matter what. according to graham it was a cracked resistor somewhere inside the unit.

now to spend some more quality time with the wfc and save up for more hihi

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