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Model 15 Feedback Patches
I find that if I want a sound, I can mess about and (generally) eventually find it. But I'm having trouble finding a way to route the signal output back into the filter input, a la an MS-20 or MiniMoog.
If you use the mixer, you get kind of a high-pitched whine at high gain -- not what I'm after. I thought it might be possible via the Audio Bridge module but so far no luck. Has anyone figured this out? Or is it just not possible?
If you're unsure of what I mean, go into iMS-20 and patch the headphone out to the input of the External Signal Processor (bottom row of the patch panel), then patch the ESP Out to Ext. Signal In at the top of the patch panel. Dial in some midrange resonance on the high and low pass filters, hold a note, and adjust the Signal Level knob. Yow. I feel like this should be possible given the various mixers, attenuators, and multiples on board the Model 15. Moog popularized the trick with the Model D and hard wired it into the Sub37, but I can't for the life of me make it work in the app.
Comments
Maybe include the multiples underneath that reversible attenuator in your patch? I can get some feedback type effect in my patches...
interesting observation. The problem is, audio feedback is a bit difficult in the digital world. For example, filter emulations are one of the most difficult tasks as a programmer - and do it all in real-time with no noticeable latency. Filter resonance feeds the output back into the filter input, which can be done in analogue circuitry, but not really in software. One has to estimate the outcome/feedback by computation (high CPU) in many varieties to create the illusion of real feedback.
And it's interesting to see how certain softsynths behave similarly to the real world and some the same thing with less accuracy.
patch m15 to use the audiobridge input, probably by patching it into the mixer. prepare for high volumes!
ivcs3 is an absolute powerhouse of feedback synthesis btw
I'm not a programmer but I can appreciate the complexity involved. It's one thing to program an oscillator or envelope generator, or a delay-based effect. I can imagine how to tell a computer to do that. But filters and overdrives boggle my mind.
I didn't even really think about this sort of patch until I started messing around with Filtatron, which has a really rather lovely feedback "circuit," and started to wonder.
Brilliant! Looks like I'll finally have to splash out for AUM. And maybe iVCS3...
Thanks!
general recipe for adding feedback to a patch in m15:
1 find the module which outputs to the trunk line module, most likely a VCA
2 split the output from that module and send it into the mixer module (or the filter cv), possibly via the FFB or other processing
control the feedback with the relative mixer levels and possibly the FFB and LPF. super fun!
This was what I tried initially and I was unhappy with the results. You get a sort of clean, unmodulated howl at high filter resonance / mixer feedback, nothing like the tortured agony that Filtatron and iMS-20 offer. But on your suggestion, I spent some time refining the chain and found excellent results with the following:
Osc - Mixer - VCF - Amplifier - VCA - Trunk
Send the VCA's second output to: High Pass - Low Pass - Mixer
Set VCF range to 2 or 3 and send Pitch CV to the control input.
The amplifier lets you dirty up the filter's self-resonance (if you push it that far). Set VCF res, amp, and mixer levels to taste and play around with the envelopes and static filters. You could also use the filter bank. Good fun indeed!
I've been messing around with this further and found that the secret is to reverse polarity on the way back to the mixer. By reversing the polarity, you can mitigate "howling" and really drive the hell out of the thing
Basically just run three oscillator inputs to the mixer (I use both the square and the saw from Osc 2). Then run one VCA Out to the Trunk and run the second through an amplifier, your selection of filters, and the reversible attenuator. Set up key control on the VCF, too. This lets you "harness" the patch by INCREASING resonance rather than DECREASING gain. And just like the MS-20, work with the static HPF and LPF to centre in on something crazy.
Good point. And old Moog also dealt with the tuning errors in the analogue filter by designing it for overdrive, hence the fat and full sound. The outcome of using digital zero feedback delay approach to mimic analogue four 1 pole serial filters with feedback, is perhaps one of the most debated issue regarding new vs old synthesis methods.
I wanted to check back in on this thread.
I can't even use MODEL 15 on AIR2 in AB2 without some issues today.
Maybe it is the AB2 or something else.
I beta for them so maybe something is janky and confused.
ON AIR2 with AUDIOBUS2, is anyone having issues with MODEL 15?