KB - Keyboard Slider / VCF

[fulvia]

Just wanted to check this is an intended characteristic. With the KB slider set highish, play a chord fairly high on the keyboard, hold down; then play a bass note, and hear how the filter kicks in for all notes the equivalent of the bass note timbre/vcf amount, thus making the high chord change its vcf/timbre. Is this correct?

[Steve W]

Sounds to me like the bass note triggers an envelope. I haven't looked into this instrument. Not sure if this is how the original version functions.

I got rid of the VCF retriggering by getting rid of the VCF ENV where it was in the Master Gain section. Another option, turn the VCF ENV pot all the way down.

Cool! When the VCF ENV is on in the Master Gain Section and the pot is up, the Filter Envelope applies a control voltage from the envelope to the gain. Now that I understand a little about the polymode, it makes sense.

[fulvia]

At first glance, yes, it seems like it does, but, even with the VCF envelope amount set to zero, it still does it, so, I don't think it's that; instead, what happens is the lower note sets the VCF position for the whole of the keyboard, basically retriggering the filter but in relation to the lower tonal amount that comes from the lower note (as you will know, the keyboard slider opens the filter out for the higher notes on the keyboard and closes it for lower notes). I've not noticed this on all my other synths before.

As an aside, this is a great synth. I'm into late 70s Genesis/Tony Banks, so, it's right up my street along with the Quadra!

[utdgrant]

Polymode is a 'paraphonic' instrument, like the original Polymoog 203a. There is only one VCF / VCF Envelope which covers every note on the instrument. So, when you hold down keys and play a new one, the single envelope generator gets retriggered, and all the held notes go through the filter's envelope cycle again. If the most recent key happens to be a large distance from the already held notes, the filter will open / close according to the setting of the "KB" slider. If "KB" is set to 0%, there shouldn't be any dramatic change in cutoff frequency. However, you will always experience a retrigger of the envelope cycle.

I'm a huge fan of '70s-era paraphonic instruments like string machines, etc. And Polymode is the king of them all! (Yes, even better than the Quadra).

[Steve W]

I got rid of the VCF retriggering by getting rid of the VCF ENV where it was in the Master Gain section.

At first glance, yes, it seems like it does, but, even with the VCF envelope amount set to zero . . . .

Another option, turn the VCF ENV pot all the way down.

I stand corrected: the other option only works on some presets.

There is only one VCF / VCF Envelope which covers every note on the instrument. . . . . If "KB" is set to 0%, there shouldn't be any dramatic change in cutoff frequency. However, you will always experience a retrigger of the envelope cycle.

Makes sense to me. For some presets, specifically where the VCF is not used, retriggering the VCF doesn't produce the unwanted effect. Isn't that what I said in the first place?

I got rid of the VCF retriggering by getting rid of the VCF ENV where it was in the Master Gain section.

Lesson learned: Once an issue has been resolved, don't suggest other options!

[utdgrant]

This is a great video for explaining the signal flow inside Polymode:

https://www.youtube.com/watch?v=xrQBbN_Yoyc

[fulvia]

Utdgrant - I had a good look at the YouTube video and it really helped understand the architecture of the synth and I now realise that the VCF will re-trigger in this way which is totally authentic to the original Polymoog. Just loving the software anyway, along with the Quadra, CA2600, Mercury 4, and Stardust 201.

[utdgrant]

Utdgrant - I had a good look at the YouTube video and it really helped understand the architecture of the synth and I now realise that the VCF will re-trigger in this way which is totally authentic to the original Polymoog. Just loving the software anyway, along with the Quadra, CA2600, Mercury 4, and Stardust 201.

That's great to know! Funnily enough, I was just re-reading this thread about 2 days ago and was wondering how you were getting on with wrapping your head around it.

Polymode is still my fave CA stand-alone instrument.