uScale II unpleasant glitching sound

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analogue01
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uScale II unpleasant glitching sound

Post by analogue01 » Wed Nov 27, 2013 8:18 pm

So, I get a spontaneous glitching sound form time to time when using my uScale II. I can't seem to reproduce it on purpose, but it happens often enough to be annoying. Anyone else get this? Is it a matter of calibrating the module? Is it something uScale users have to live with? Or is my unit faulty?

Love my uScale and wouldn't want to ever live with out it, but sometimes weird nasty sounds surprise me when I don't want them. :sadbanana:
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Post by shady smiles » Wed Nov 27, 2013 8:30 pm

What are you putting through the uScale? I noticed mine was really touchy with the outs from my Pressure Points but I was able to live with it. That said, hpsounds did some deep research into a related issue with the quantimator. Pop over to this thread for some good science.

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Post by analogue01 » Wed Nov 27, 2013 8:43 pm

Thanks. I'll read through that thread. Already I think I'm hearing what Dcramer describes in the second post.

I'm mostly running s/h stepped voltages into the uScale. I've used a quantimator before and never got the same glitchy sound I hear with the uScale.

Also, the glitch lasts long enough that dialing back the attack on the envelope can't hide it.
shady smiles wrote:What are you putting through the uScale? I noticed mine was really touchy with the outs from my Pressure Points but I was able to live with it. That said, hpsounds did some deep research into a related issue with the quantimator. Pop over to this thread for some good science.
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Post by Abraxis » Wed Nov 27, 2013 11:03 pm

Do you have anything plugged into the shift input?

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analogue01
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Post by analogue01 » Wed Nov 27, 2013 11:08 pm

Abraxis wrote:Do you have anything plugged into the shift input?
Sometimes yes, sometimes no. I'll do some tests tomorrow, see if it effects the noise.
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Post by Dcramer » Thu Nov 28, 2013 12:12 am

Yes I sometimes get a weird buzzy tone as if the cv output is modulating quickly between to side by side notes, unable to pick which to stay on. I think it may only crop up between close notes like tones or semitones but will have to check more to see.

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Post by spritepixie » Thu Nov 28, 2013 12:37 am

Dcramer wrote:Yes I sometimes get a weird buzzy tone as if the cv output is modulating quickly between to side by side notes, unable to pick which to stay on. I think it may only crop up between close notes like tones or semitones but will have to check more to see.
I get this often with my uScale when I use the QCV from Rene. Now I just use the CV out, which still happens but not as often.

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Re: uScale II unpleasant glitching sound

Post by intellijel » Thu Nov 28, 2013 1:06 am

analogue01 wrote:So, I get a spontaneous glitching sound form time to time when using my uScale II. I can't seem to reproduce it on purpose, but it happens often enough to be annoying. Anyone else get this? Is it a matter of calibrating the module? Is it something uScale users have to live with? Or is my unit faulty?

Love my uScale and wouldn't want to ever live with out it, but sometimes weird nasty sounds surprise me when I don't want them. :sadbanana:
Shouldn't do this.

Make sure you are not feeding in voltages greater than about 9V to the 1V/Oct input. Anything greater will cause a lot of noise on the ADC input.

Also make sure you have a clean PSU and a clean signal being fed. Glitchy signal (i.e. rapid changes) will possibly result in unexpected glitchy responses.

There is oversampling and low pass filtering in code and hardware that should be helping counteract this.

If you want me to check out your module I am happy to put it through some tests.

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Re: uScale II unpleasant glitching sound

Post by analogue01 » Thu Nov 28, 2013 2:25 pm

Thanks Danjel!

I did a bunch of tests this morning. It seems to only happen with stepped voltages and s/h type patches. I can feed it a sine wave LFO and it goes without glitches for hours. As soon as I give it a stepped voltage the glitches start to happen.

Whether or not I'm using the shift input doesn't matter. And it's definitely not a problem of with the signal exceeding 9v, since I always attenuate on the way in.

Anyway, I'll pull it out and make sure the PSU is clean before resorting to sending it in for testing.

Here's a crappy phone video of the problem. It's a sine wave LFO into a s/h clocked at a slow-ish speed, attenuated and fed into the uScale.

View My Video
intellijel wrote:
analogue01 wrote:So, I get a spontaneous glitching sound form time to time when using my uScale II. I can't seem to reproduce it on purpose, but it happens often enough to be annoying. Anyone else get this? Is it a matter of calibrating the module? Is it something uScale users have to live with? Or is my unit faulty?

Love my uScale and wouldn't want to ever live with out it, but sometimes weird nasty sounds surprise me when I don't want them. :sadbanana:
Shouldn't do this.

Make sure you are not feeding in voltages greater than about 9V to the 1V/Oct input. Anything greater will cause a lot of noise on the ADC input.

Also make sure you have a clean PSU and a clean signal being fed. Glitchy signal (i.e. rapid changes) will possibly result in unexpected glitchy responses.

There is oversampling and low pass filtering in code and hardware that should be helping counteract this.

If you want me to check out your module I am happy to put it through some tests.
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Rob Ae wrote:plugging CV gate cables in my mouth, to taste the voltages, turned out to enhance my skills.

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Post by wbuttler » Thu Nov 28, 2013 5:15 pm

I have a similar issue, mainly when feeding CVs from a Turing Machine, and generally fairly high notes. Might be the TM is generating voltages that are too high? Anyway, the comments above are useful, and give me a place to start looking for a solution. Up to now, I have just accepted it as an occasional glitch, but it would be nice to eliminate them.

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Post by intellijel » Thu Nov 28, 2013 9:00 pm

If you are using a stepped voltage source then there are some potential issues to be aware of.

I took a look at the stepped output from the Wogglebug as an example.

The CV steps are derived from an LF398 sample and hold IC connected to a noise source. This IC requires an extremely short pulse (in the order of nS) to sample because while the sample pulse is high, the source signal is passed to the output. This means that if the sample pulse is even slightly too long then you will get small bursts of noise in between in each step.

When this is presented to the input of a Quantizer it is going to cause it to glitch out. I can change the code to spend a longer time filtering the inputs to average out noise burst but then you will have significantly more latency and slew.

My main priority with the uScale design was to make it work well with sequencers (smooth DC source) and smooth LFO sources.

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Post by analogue01 » Thu Nov 28, 2013 10:32 pm

Okay, that makes sense. I've owned a wogglebug and got the same sound form its stepped voltages as I'm getting now. So I'm sure that's what I'm hearing.

Not sure I would want more latency, I like how it sounds on smooth sources too.

I'll just live with it and experiment with slewing my s/h.

Just curious: is there more latency on the first version than on the II?

Thanks again!
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Post by wbuttler » Fri Nov 29, 2013 12:04 am

Is there value in smoothing a stepped voltage slightly with a slew limiter?

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Post by analogue01 » Fri Nov 29, 2013 9:38 am

wbuttler wrote:Is there value in smoothing a stepped voltage slightly with a slew limiter?
Yes. This seems to help quite a bit, although it changes the effect slightly. I also found it happens less with certain clock sources. Clocking the s/h with a Dixie produced less noise bursts than clocking with a Maths end of cycle or a Zorlon Canon.

Nothing I've done has entirely removed the problem, but I've reduced it enough to be happy. And mostly it's good to know that my uScale is preforming as it should.
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Post by Dcramer » Fri Nov 29, 2013 10:03 am

Interesting, this probably explains what I noticed as well. I've thrown tons of crazy stuff into my uScale 2 to experiment, things like dual cyclotron, S&H, and weird stuff like 6 unsynced Lfo square waves attenuated and mixed together. It makes sense that some of my crazy cv sources are glitchy to begin with. I have sometimes used a slew on the output, which helps, but I will try it on the input as well. Actually my VC slew on the input does great things for adding variable scale runs between large leaps in self generative patches. I'm certain that my uScale is running up to spec as Danjel was kind enough to tweak mine right after purchase (at robot speed I might add!). I love the design of the uScale and can't imagine using a quantizer with the scale buttons.

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analogue01
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Post by analogue01 » Fri Nov 29, 2013 4:46 pm

I wonder, would a digital s/h have the same problem?
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Post by StoneLaw » Fri Nov 29, 2013 11:46 pm

I dont think a digital samp,e and hold might flip between two notes fast but it could round improperly and turn an in key sequence to an out of key sequence

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Post by analogue01 » Wed Feb 26, 2014 10:06 am

Just got a Modcan Quad LFO and would like to report that I still get glitching sounds when using it's stepped random output into the uScale.
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Post by jc3music » Wed Feb 26, 2014 12:57 pm

I love my uScale, but I haven't had the chance to throw anything too weird into. I normally just feed my z8000 into it.
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Post by Dcramer » Fri Mar 07, 2014 7:09 pm

I just recently had Danjel do some work on mine and am happy to say that so far it seems way better. He had indicated in another thread that he had a fix for it. I will keep playing and let you know.
And of course once again he sped through the fix at a speed suggesting the use of heart adorned androids from space! :tu:

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Post by matttech » Wed Apr 02, 2014 4:32 am

do you know where the fix was explained, and whether it will be applied to new uScales? am thinking of getting one

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Post by analogue01 » Wed Apr 02, 2014 6:39 am

Email Danjel. If you order direct from Intellijel I'm sure he can send you one with updated firmware. Otherwise uScales for sale in the wild probably still glitch with stepped voltages.
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Post by matttech » Wed Apr 02, 2014 6:55 am

ah, ok....not super keen on ordering from outside the EU any more, due to complexities in returning things (more expensive postage, import duty/ vat potentially being added on way back from repairs)

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Post by exper » Wed Apr 02, 2014 7:05 am

UK Customs won't honor packages clearly marked 'for repair'? That stinks. I've never had a problem sending a couple of packages back to Danjel for mods back and forth to the US.

Anyway, the firmware update is perfect. Haven't had a single glitch since I had it done. Technically, it wasn't a problem, it's just that it was almost too sensitive, and fluctuating or slightly unsteady CVs going in would cause it to follow those rapid tiny flutters occasionally.
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Post by oootini » Wed Apr 02, 2014 7:24 am

hmm. i presume this firmware update could be done by a reasonably technically proficient person with a AVR ISP programmer.

it is an avr in there IIRC...

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