u-he

justin3am · Post by **justin3am** » Tue May 24, 2011 4:17 pm

I've talked about this a bit in the Bazille thread. Here is some info that explains what makes an LPG special.

http://www.ear-group.net/model_13.html
http://vimeo.com/2431125 my favorite vactrol filter

It's quite easy to replicate the sound of an LPG in Bazille or Zebra. I typically use one of the 12dB LPFs with some drive, followed by a mixer channel which I use as a VCA. However, this isn't the whole story... the way an LPG responds to control signals is very unique and is a contributing factor to the natural/organic timbre it imparts of complex signals. The vactrol in simplest terms, slews the filter's response to CVs but that slewing effect is very much dependent on incoming signal levels. Basically, because of the nature of vactrols, the LPG opens faster than it can close (I guess this is because it takes longer for the LDR to discharge than it does to charge). This along with the how feedback (resonance) is implemented in the circuit causes the filter to ring when you open the filter with a short trigger or envelope. As you increase the resonance, it dampens the decay of that ringing effect. The effect is most dramatic on harmonically rich sound sources like FM'd signals or complex wavetables.

Urs, I can try to create a video demonstrating the LPG mode of the QMMG. If there is anything specific you want to hear, let me know.

jobromedia · Post by **jobromedia** » Wed May 25, 2011 5:11 am

Why not add "random" as a modulation source in Zebra? You got this in TyrelN6 and it truly enhances the speed of generating interesting dubstep basses. And since Zebra is much more versatile when it comes to sound it also can produce phatter basses.

Howard · Post by **Howard** » Wed May 25, 2011 7:15 am

jobromedia wrote:Why not add "random" as a modulation source in Zebra? You got this in TyrelN6 and it truly enhances the speed of generating interesting dubstep basses. And since Zebra is much more versatile when it comes to sound it also can produce phatter basses.

Its already in there - see LFO waveforms.

hakey · Post by **hakey** » Wed May 25, 2011 8:09 am

jobromedia wrote:dubstep basses

A characteristic common to many dubstep basses that Zebra can't do is the routing of modwheel to affect instantaneous stepping up or down of an LFO rate from one note value to another (LFO rate changes are smooth and continuous).

Not that I've lost any sleep over it.

Urs · Post by **Urs** » Wed May 25, 2011 10:26 am

Hmmm... still don't get the Lowpass gate. So it's either a lowpass filter or a VCA...?

whyterabbyt · Post by **whyterabbyt** » Wed May 25, 2011 10:33 am

Urs wrote:Hmmm... still don't get the Lowpass gate. So it's either a lowpass filter or a VCA...?

actually 'and/or' rather than 'either/or'.

Urs · Post by **Urs** » Wed May 25, 2011 10:38 am

whyterabbyt wrote:
Urs wrote:Hmmm... still don't get the Lowpass gate. So it's either a lowpass filter or a VCA...?
actually 'and/or' rather than 'either/or'.

Yes. I still don't understand what it's actually desirable for.

whyterabbyt · Post by **whyterabbyt** » Wed May 25, 2011 11:22 am

Urs wrote:
whyterabbyt wrote:
Urs wrote:Hmmm... still don't get the Lowpass gate. So it's either a lowpass filter or a VCA...?
actually 'and/or' rather than 'either/or'.
Yes. I still don't understand what it's actually desirable for.

I think its the LPG's characteristics that are seen as desirable, rather than its functionality, much like with certain other filter architecture (eg transistor/diode ladders).

xh3rv · Post by **xh3rv** » Wed May 25, 2011 4:50 pm

hakey wrote:
jobromedia wrote:dubstep basses
A characteristic common to many dubstep basses that Zebra can't do is the routing of modwheel to affect instantaneous stepping up or down of an LFO rate from one note value to another (LFO rate changes are smooth and continuous).

Not that I've lost any sleep over it.

Could it be done with MMap somehow? Or really slow '10s' random LFOs? Or am I missing something here?

Also had a horrible contest idea - super long Dubstep basses but use every trick in the book to make them keep evolving into different sounds

News From The Sky · Post by **News From The Sky** » Wed May 25, 2011 9:04 pm

Sounds like a quantizer - does Zebra not have one of those? Seems like it could be useful for other things.

Edited to add: MMap's what I would try, if it's like the ModMap in ACE - I haven't played with it.

djsubject · Post by **djsubject** » Wed May 25, 2011 9:10 pm

xh3rv wrote: Also had a horrible contest idea - super long Dubstep basses but use every trick in the book to make them keep evolving into different sounds

now that's a contest i will enter!

hakey · Post by **hakey** » Wed May 25, 2011 9:47 pm

xh3rv wrote:
instantaneous stepping up or down of an LFO rate from one note value to another (LFO rate changes are smooth and continuous).
Could it be done with MMap somehow? Or really slow '10s' random LFOs? Or am I missing something here?

Hmm.. might have to have an experiment. There's certainly no way to directly change the note value of an LFO with modwheel, which, according to some random youtube vid I came across, is the way to get that quantized and synched rate change wobble in Massive.

Also had a horrible contest idea - super long Dubstep basses but use every trick in the book to make them keep evolving into different sounds

I'll put up a July Patch Contest thread in a week or so with that as the first suggestion.

justin3am · Post by **justin3am** » Wed May 25, 2011 10:21 pm

whyterabbyt wrote:
Urs wrote:
whyterabbyt wrote:
Urs wrote:Hmmm... still don't get the Lowpass gate. So it's either a lowpass filter or a VCA...?
actually 'and/or' rather than 'either/or'.
Yes. I still don't understand what it's actually desirable for.
I think its the LPG's characteristics that are seen as desirable, rather than its functionality, much like with certain other filter architecture (eg transistor/diode ladders).

Yeah, agreed on all counts. LPGs usually have a VCA mode, an LPF mode and a "both" mode. The "both" mode is what people are typically talking about when we say Low Pass Gate. In this mode the "Offset" controls a combination of Cutoff and Gain and feedback controls the damping.

The filter topology of LPGs can change a lot. Buchla uses a different filter circuit for the 292 vs. the Wiard Borg vs. but both can be considered Low Pass Gates.

I think you have to use these kinds of things in the context of that style of synthesis. In Buchla and Wiard synths, the filter is commonly the least important aspect of the synth. Still, while there is more emphasis on timbre shaping via the oscillators, the LPGs do play an important role. It's tough for me to say if U-He synths really need an LPG model because you *can* simulate the effect somewhat with existing filter models and envelope tweaking. That said, I'm always up for different flavors. Don't worry if you don't get teh LPG Urs, even after the first time I played with a 200e, I didn't get it either. It wasn't until I spent a decent amount of time with my QMMG (which I bought for the mixer/filter functionality) that I really understood what makes it different from other subtractive synth filter-> VCA topology.

Howard · Post by **Howard** » Fri May 27, 2011 11:21 pm

hakey wrote:Hmm.. might have to have an experiment. There's certainly no way to directly change the note value of an LFO with modwheel, which, according to some random youtube vid I came across, is the way to get that quantized and synched rate change wobble in Massive.

Yes, experiment with a ModMapper!

MitchK1989 · Post by **MitchK1989** » Sat May 28, 2011 12:46 pm

yeah, the combination of a 'both' mode for buchla style patches (it can be emulated, but requires asymmetrical slew, a filter, AND a vca...) and just having the ability to really shape timbre and volume easily in a way less destructive than one of zebra's VCF mid lane would be great (since emulating an LPG right now requires you to use the mixer channel at the bottom... Which means it has to come absolutely last in the signal chain...)

u-he

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