SynthVoice Oscillator bizarre waveforms

[sekim]

They don't resemble a physical ARP 2600 nor resemble the CA2600 waveforms. I've never seen anything quite like them. Anyone know what's up with this?

[sekim]

triangle.JPG (49.11 KiB) Viewed 7495 times

[UrbanCyborg]

That is interesting. The sine and triangle look like they're getting asymmetric fold-over. The others look like they're skewing.

Reid

[Steve W]

Does attenuating the raw signal help? Maybe with some DC Bias to center it if needed?

I answered this myself: No.

By the way, early on, I checked a number of oscillator waveforms and found all sorts of "variations" when looking at them in the oscilloscope. Not sure if I ever posted them. I recall just deciding which one(s) sounded good to me and used them as needed.

[sekim]

I don't know what to make of them, they don't appear to be modelled on anything. As someone who does analog circuit design I don't even know how to build a physical circuit that would output the pulse and saw forms this thing is generating. And though I could build circuits to output the sine and triangle with the partial rectification, it would beg the question "but why?"... I've seen the sine and triangle of a real ARP 2600 on a real oscilloscope and they're basically clean. If someone from Cherry could comment, that would be great. Maybe I'm just missing something and they have a reason.

[seal58]

Perhaps silly question: Does the oscilloscope eventually clip signal to match selected range?

[Steve W]

Perhaps silly question: Does the oscilloscope eventually clip signal to match selected range?

Yesterday, I switch to 2V and on the sine wave, yes, both top (+) and bottom (-) peaks visually clipped at 2V. As I turned the attenuverter down from full, the top stayed clipped at 2V for a while but the bottom started to show the inverted lower peak. As the signal going into the 'scope was attenuated further, the top of the sine returned normally and the bottom retained the inverted tip.

I just added an attenuated triangle wave. It does the same thing as the sine (clipped at the top, inverted at the bottom).

Maybe I will try with an absolute value conversion in there.

[Steve W]

Here's the CA-MRB Oscilloscope set to 1V:

[Steve W]

With Absolute Value Conversion of both SIne and Triangle (pre-attenuation and post-attenuation).

[sekim]

I also checked it using Lightbridge's excellent Signalizer plugin that includes a good oscilloscope. Same waveforms there....