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Tuned Feedback Rocks My Socks (and can have my babies)

Tuned Feedback Rocks My Socks (and can have my babies)
« on: December 01, 2021, 06:58:04 PM »
Someone on another forum mentioned "tuning" the noise generator using the feedback control, not realizing they had just reinvented Karplus Strong style physical modelling synthesis.  So I told them the name of what they had created, and decided to mess with the idea myself.

It's ridiculously expressive and fun to play, even with all the oscillators turned off.  Just send a quick burst of noise to get the feedback circuit started, then play the feedback.  It's basically an entire acoustic instrument hidden inside the Pro 3.

Here's a demo showing some of the various timbres and textures it can generate using only the performance controls.  Sometimes it sounds like an acoustic guitar.  Sometimes it sounds like a cello being bowed.  Sometimes it's a big angry growl.  Sometimes it's a searing lead.  Sometimes just a soft hum.  All from a single, surprisingly simple, patch:

https://youtu.be/faCHya1DYgE

Also a second demo, playing in a different style to show it more as an electric lead:

https://toykeeper.net/tmp/music/TK_Karpluck_String_Example_2.mp3

... and almost no other hardware synths do this.  It's a really unusual feature, and a huge part of the Pro 3's sound.  It's unfortunate that so few synths have this sort of thing.

In the next comment I'll post details about how to make this patch yourself.  You'll probably need to adjust the parameters a little though, because it seems to be pretty sensitive to differences in temperature, and may vary from one Pro 3 to another.  Mostly it can be fine-tuned with the touch slider though.

Re: Tuned Feedback Rocks My Socks (and can have my babies)
« Reply #1 on: December 01, 2021, 07:09:18 PM »
Okay, here's how to make this patch.  I recommend doing it yourself instead of loading it over midi, because it may need to be tuned for your individual instrument.  Plus it's good to know how it was made:

Create an "exciter":
  • Create an init patch (OctDown + Latch).
  • Turn off all the oscillators in the mixer.
  • Map aux 1 env to noise level.
  • A:0, D:3, S:0, Amt: 127
  • Set the filter to state-variable lowpass, cutoff ~874, no resonance

Add feedback:
  • Enable Tuned Feedback:  Amt +61, Tune 24 (Amt varies with temperature)
  • Map Slider to Feedback Amt, +4
  • Enable Slider latch, and slide it to control whether note grows or fades over time.
  • Increase the range which is in tune: Map Note Num to Feedback Tune, +2 (may require adjustment on each Pro 3)

Vibrato:
  • Map Pressure to LFO1 Amt, +1
  • LFO1 Freq 110, Amt 0, Shape triangle
  • Map Note Num to LFO1 Freq, +57

Distortion:
  • Map ModWheel to Distortion, Amt +127

Detuning:
  • Map PitchBnd to Cutoff, +58
  • Map PitchBnd to Feedback Tune, -2

Delay:
  • Enable effect 1: DelayStereo, FX Mix 40
  • Sync On, Sync Freq 8, Feedback 110, LPF 140

I think that's everything.

With this, you should have a nice, expressive Karplus Strong style instrument which can cover a ton of different sounds depending on how you play it.  Just use the touch slider, mod wheel, and pitch wheel...  then be careful to play legato (or not), and use aftertouch (or not), to add extra expression.  You can also adjust the brightness of each pluck with the filter cutoff knob, to simulate nylon or metal strings.

... and then there's also the other 95% of the Pro 3's features to explore.   ;D

Re: Tuned Feedback Rocks My Socks (and can have my babies)
« Reply #2 on: December 02, 2021, 09:54:23 AM »
I forgot one detail in the patch instructions...  also have to map LFO1 to the feedback tuning, to make vibrato work.

I'd edit the comment to add this, but I don't see a way to edit after posting.  The actions menu only shows me "quote".  For this current comment though, it also show "modify" and "remove", so perhaps there's a time limit on those functions... a really short time limit.  Apparently can't edit something from half a day ago.
« Last Edit: December 02, 2021, 09:57:36 AM by ToyKeeper »

Re: Tuned Feedback Rocks My Socks (and can have my babies)
« Reply #3 on: December 13, 2021, 01:19:14 PM »
This is awesome!

Re: Tuned Feedback Rocks My Socks (and can have my babies)
« Reply #4 on: December 20, 2021, 01:45:27 AM »
Thanks for sharing this. I have also been playing around with Karplus as it is a patch mentioned in the Pro3 manual, but didn't get the cool sounds you share. I will give it a second try for sure!

Re: Tuned Feedback Rocks My Socks (and can have my babies)
« Reply #5 on: December 20, 2021, 06:28:22 PM »
I finally backed up my patches.  Here's the patch file:

https://toykeeper.net/tmp/music/TK_Karpluck_String.midi

This is free to use... but if you use it, I'd really like to hear what you make.

The performance controls are:

  • aftertouch: vibrato
  • touch strip: feedback
  • mod wheel: distortion
  • pitch bend wheel: pitch and feedback
  • filter knob: brightness
  • legato play style: change pitch but don't pluck string

So... mess around with these to get different sounds.  Like, plucking vs bowing, etc.  I recommend turning latch on for the touch strip, and experimenting with overlapping vs non-overlapping notes to build and break resonance.  With feedback up, long notes can fade and recover by using the pitch bend wheel.

It should be in tune for at least 3 octaves, but you may need to adjust the correction factor to match your individual instrument.  That's the "Note Num to Feedback Tune" in the mod matrix.  Other settings may need to be changed too, on a per-instrument basis.  I find mine makes different sounds when it's cold than it does when it's warmed up.

If you play an octave up or down legato style, it likely won't change the sound much.  Play some intermediate notes though, and the octave change is more effective.

Anyway, this can be sent to the Pro 3 the same way as any other patch.  If I recall correctly, just navigate to the slot you want to save to, then send the patch file via midi from a computer.  It may also be necessary to save afterward, same as if you had created the patch manually.  Has been a while since I loaded an individual patch.

Re: Tuned Feedback Rocks My Socks (and can have my babies)
« Reply #6 on: December 22, 2021, 08:53:23 AM »
I finally backed up my patches.  Here's the patch file:

https://toykeeper.net/tmp/music/TK_Karpluck_String.midi


Anyway, this can be sent to the Pro 3 the same way as any other patch.  If I recall correctly, just navigate to the slot you want to save to, then send the patch file via midi from a computer.  It may also be necessary to save afterward, same as if you had created the patch manually.  Has been a while since I loaded an individual patch.

Note that the TK_Karpluck_String.midi file above is for Bank 4 Program 17, so it'll load into and overwrite that slot. I edited the SysEx file to convert it to an Edit Buffer patch. Then, it would load into memory and you would need to save it.

If you want to request that the Pro 3 send the Edit Buffer (without the Bank/Program numbers) as a SysEx file, send F0 01 31 06 F7 to it. Here's how using sendmidi:

Code: [Select]
:; sendmidi dev 'Pro 3' syx hex 01 31 06
where Pro 3 is the name of the MIDI device connected to the Pro 3 in the sendmidi list. fyi.

Fun work on the patch. Tuned feedback is one of my favorite features (as it was with the Evolver) along with the analog feedback loop when nothing is connected to the External Audio Input jack, controlled by the Ext Audio level.
Jeff Kellem—Typeface designer, Composer, Pianist, Analog synths, Dancer
https://1403.slantedhall.com/ | https://slantedhall.com/