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3 posts since 18 Feb, 2006

Postby airbag76; Tue Mar 13, 2018 8:39 am ROLAND SYSTEM 100M OSCILLATORS

Hi everyone

I had the idea of taking some readings of my synth oscillators and I m not satisfied especially on the lower scales. Saw, triangle and square appear in my oscilloscope totally out of shape.
the triangle very curvy instead of straight and saw - square out of recognition. As i turn the range knob to higher scales things get better yet little bit distorted.

Any suggestions? Do I have to open and tune the module from the inside?

I m posting some of my oscilloscope readings for better understanding

thanks in advance
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Distorted Horizon
975 posts since 17 Jan, 2017

Postby Distorted Horizon; Tue Mar 13, 2018 10:26 am Re: ROLAND SYSTEM 100M OSCILLATORS

Just in case that you're serious, those are basic analog waveforms. They really look like that.

Someone can give a more scientific explanation but still, there's nothing wrong with your 100M.
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1209 posts since 12 May, 2004, from Oxford, UK

Postby ChamomileShark; Tue Mar 13, 2018 11:02 am Re: ROLAND SYSTEM 100M OSCILLATORS

Generally analogue hardware VCO waveforms are a disgrace. The square waves in particular are appalling - they generally sag at the top. However as long as the rise and fall are straight they will sound like a pulse/ square wave.

Probably if you zoom in you will see a ragged area where the slope changes.

If they sound like the respective waveforms are supposed to sound then they are probably ok. If they've not been serviced for a while then get a competent tech to do so.
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16760 posts since 6 Jan, 2009, from Croatia

Postby EvilDragon; Tue Mar 13, 2018 11:12 am Re: ROLAND SYSTEM 100M OSCILLATORS

Don't forget that those waveforms are most definitely going through a DC blocker or two before the output (basically highpass filters), so this is what skewes their shapes.
18 posts since 15 Mar, 2018

Postby Shockwave77598; Wed Mar 21, 2018 6:32 am Re: ROLAND SYSTEM 100M OSCILLATORS

Especially at the lower registers eh?

I'll bet you'll find that you have not one, but two DC blocking caps in the circuit. One is on the output of the synth. The other is the input of your sound card. Both are pretty big and usually set to block DC -20Hz signals.

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