Clicks/Pops with LFO - AMP

The Sequential Prophet-6 Analogue Synthesizer

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Clicks/Pops with LFO - AMP

Post by gridpower » Fri Oct 16, 2015 8:17 pm

First of all...let me just say that I am so impressed with this Prophet-6. My spine tingles with some of the sounds that I am making with this beast.
Bravo Dave and Co.....!

I am having some trouble with making smooth AMP transitions using the LFO in SQUARE Wave mode. Especially with LOWER Frequency sounds.
I am trying to design a sound that pulses the soundwave in and out DIRECTLY...Full on, full out in a clean way.

The Prophet 6 does this effectively with LFO SQUARE Wave modulating AMP, but does so with some clicks and pops during the transitions.

I can get by to a point with LFO REV SAW modulating AMP or SQUARE WAVE Modulating LF and it is very nice and musical. Just not FULL on/FULL off

If this is inherent in the design of the PROF-6 or current OS and could possibly be upgraded to be a bit more smooth and musical in a future OS I would love to add that to the list of upcoming updates. However, I would assume making such a change would effect previous user's existing presets quite a bit.

Any other insights into this issue..I would appreciate hearing your thoughts

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Re: Clicks/Pops with LFO - AMP

Post by drxcm » Sat Oct 17, 2015 10:51 am

This is a problem with just about any analog system.

If the VCA opens instantly (e.g. with a square wave or reverse sawtooth wave) anywhere on the waveform but on a zero crossing you will get a click / pop.
Not obvious with high frequency sounds, but very obvious with low frequency sounds.

If you were to slew the LFO, it wouldn't generate the pops but you wouldn't have a square wave anymore.

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Re: Clicks/Pops with LFO - AMP

Post by maNŒuvre » Thu Jun 02, 2016 1:13 am

See lower down in this article where it talks of this annoying occurrence. Hoping for a solution. :?

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Re: Clicks/Pops with LFO - AMP

Post by Ambient Architect » Fri Jun 10, 2016 8:24 am


I'm also getting this too on a lot of patches. Can anyone try out the patch 'Fluttering JH' from the OMOM sound set and tell me what they find? It's terribly clicky on my P6 in a very non-analog kind of way! The Amplifier attack on this particular patch is quite high(29) so I'm guessing it's more of an LFO thing here?


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Re: Clicks/Pops with LFO - AMP

Post by maNŒuvre » Fri Jun 10, 2016 12:19 pm

I was wondering if my Prophet 6 was faulty! After sending patches and audio files to DSi; this was the explanation I received. For me, as said before, it is peculiar that these pops and clicks sound anything but analog!

DSi response:
Please Regarding the clicking that you're experiencing and have outlined in your audio example, I encounter the same thing when I load the patch you attached on the P6 at my desk.

The oscillators in the Prophet 6 are free running. As such, when you play a note, the oscillator's waveform could be at any phase of it's cycle. This fact combined with fast attack/release times in the filter and VCA envelope sections can lead to discontinuities arising from the waveform being at a non zero crossing when the envelopes are triggered on. This is the clicking you are experiencing.

One thing to point out with the "Patch 6" that you sent is that the Key Mode for this patch is set to "LAr", which stands for Last Note Retrigger. With this Key mode, every time you play a new note in your Unison patch, the envelopes are retriggered, which is exacerbating the clicking. I suggest changing the Key Mode to "LAS", and turning up the Sustain portion of the Amp Envelope. This way, you still get last note priority, but the envelopes are retriggered only when you strike a key with no other keys depressed. I think you will find that, especially with fast playing, the sound of the patch is more or less identical, but with virtually no clicking.'

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