Just realised, no hollow square wave

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HaveIt
Posts: 64
Joined: 04:09, 6 March 2014

Just realised, no hollow square wave

Post by HaveIt »

Comparing the waves with some other gear, I just realised there is no true square wave in either the digital or analog parts. There's a certain characteristic hollowness to the square wave at exactly 50% that just is not there on the JD-XA with both engines. Even the digital waves, every square isn't quite right.

Weird.
prophonic
Posts: 12
Joined: 17:43, 12 September 2016

Re: Just realised, no hollow square wave

Post by prophonic »

did you turn "drive" all the way down ?
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richardbates1
Posts: 389
Joined: 19:58, 19 July 2013

Re: Just realised, no hollow square wave

Post by richardbates1 »

There is no question that the square wave in the analog section does sound unique, it doesn't sound like a typical hollow square wave, not sure why but it is different. If you want a close typical hollow square wave try just using one oscillator with a square wave selected bring the volume down to zero on the 2nd osc. and zero in the aux and zero with the drive. Also bring the low pass filter at least down to 50% or around that range, see if that helps?
HaveIt
Posts: 64
Joined: 04:09, 6 March 2014

Re: Just realised, no hollow square wave

Post by HaveIt »

Yeah, I have tried a few settings. Just 1 analog osc at half volume, wide open filter, no effects, no drive. Yet the analog sounds the same as the digital, its just not an equal 50% pulse. How can they both be wrong?
HaveIt
Posts: 64
Joined: 04:09, 6 March 2014

Re: Just realised, no hollow square wave

Post by HaveIt »

Actually SQR-B in the digital parts is a true hollow square, you can compare the analog sqr with this digital wave to hear how wrong the analog one is. And strangely the digital SQR-A is extremely similar to the analog SQR.

Weird.
OneOfManyPauls
Posts: 93
Joined: 11:41, 3 May 2016

Re: Just realised, no hollow square wave

Post by OneOfManyPauls »

supposedly pure synth waveforms have always varied.

I don't think it's fair to say it's "wrong" just because it doesn't sound the way you wanted - those differences help go towards the character of a synth.
HaveIt
Posts: 64
Joined: 04:09, 6 March 2014

Re: Just realised, no hollow square wave

Post by HaveIt »

A square wave is a square wave, it takes on a hollow eerie sound at exactly 50% pulse width. The JD-XA is a pulse wave and indeed so the the TB-303 because it is close but not 50%. What is strange is the Pulse width slider has the exact same pulse sound at 0 as the square wave and the digital part does as well. This seems to be intentional. But its not a square wave. The Triangle which you could call a low pass square, well I can't tell what it sounds like because it is a very low level. I don't think I can find a use for it because its so quiet. The Sine is a good though.
OneOfManyPauls
Posts: 93
Joined: 11:41, 3 May 2016

Re: Just realised, no hollow square wave

Post by OneOfManyPauls »

Not in a position to check with the physical jd-xa itself right now, but I did sample the analog square with the filter bypassed and it has a buzziness to it due to additional higher frequencies, which you can see in the attached waveform at the corners - it's also worth noting that it's not really square either, the ratio is actually 1:1.4.

This may well be deliberate to make it more interesting from a subtractive synthesis POV - pure square waves sound very digital.
jdxa_square.jpg
jdxa_square.jpg (33.58 KiB) Viewed 1089 times
HaveIt
Posts: 64
Joined: 04:09, 6 March 2014

Re: Just realised, no hollow square wave

Post by HaveIt »

Thanks for the oscilloscope. Its ringing prior to the downstep. What would explain that? Wouldn't the ringing occur after an edge change?
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