Intellijel Designs Dr. Octature någon?

[steffensen]

Inväntar denna best för tillfället, och nyfiken om någon mer kör den? (Hej SnareTheMind och stabilt :) )
La en order på en Unity mixer också, i hopp om att kunna patcha utgångarna för att skapa lite andra modeller, som BP/HP osv.. Kanske är helt ute & cyklar där dock. :)

[m]

Jag har en, och har väl mest kört den som oscillator/lfo än, men filtret är bra det också, just nu är min inte i något rack, men kanske borde koppla in den.

[steffensen]

Känner mig inte helt haj på hur man ska koppla utgångarna för att bilda olika filter-modeller, vore kul med lite djupgrävning inom det området. :)

Hoppas det räcker med Unity Mixern för att kunna skapa lite standard modeller iaf, sparar de mer exotiska till senare.

Alla demos låter helt kanon dock!

Som VCO har jag läst att folk kopplat en output till en input FM, och på så vis skapat en Saw eller liknande. Ser fram emot att testa det. Påminner om hur jag använt FM synthar, genom att köra en Sine i overdrive för att få fram Saw..

[stabilt]

Bra fråga, jag vill också veta. :)

[steffensen]

Denna infon har jag funnit på muffwiggler, men vad hjälper det. :">
Hajjar ju så mycket som att en ställbar mixer krävs för att nå alla dessa varianter, men om en Unity Mixer räcker för det jag vill åt, är just frågan. Hoppas och tror det dock!


If you mix one part of the input, 8 parts the inverted 1-pole, 24 parts the 2-pole, 32 parts the inverted 3-pole, and 16 parts the 4-pole, you get 4-pole allpass (perfectly flat response, and no change with resonance, even if the filter is nearly oscillating).

If you mix 1 part of the input, 4 parts the inverted 1-pole, 12 parts the 2-pole, 16 parts the inverted 3-pole, and 8 parts the 4-pole, you get a frequency response with two deep notches (zeros on the imaginary axis), at +/-0.38 log units from the cutoff frequency. Remove the 1 part of the input, the notch moves to the cutoff frequency, and you get unity-gain peaks at +/-0.38 log units away. Sweep back and forth between 0 and 1 part of the input, and the two waveforms morph back and forth with the offset notches becoming peaks, and the centre peak becoming a notch. Sweep the frequency and resonance at the same time, and who knows what the hell might happen! (Actually, I do, but I'm not tellin'.)

And, of course, different stuff happens with all of these synthetic modes with increasing resonance depending on whether you've got the switch set to Mono or Quad.

This is just SOME of the fun you'll be able to have with the Doc Oc expander (coming soon).


The filter has eight lowpass outputs: -6dB, -12dB, -18dB, and -24dB, and their inversions. When self-oscillating, each output will give a sine wave 45 degrees phase-shifted from the last. So:

-6dB = 45 degrees
-12dB = 90 degrees
-18dB = 135 degrees
-24dB = 180 degrees
-6dB (inverted) = 225 degrees
-12dB (inverted) = 270 degrees
-18dB (inverted) = 315 degrees
-24dB (inverted) = 360 degrees (in phase with the filter input signal)

The different cutoff slopes give different degrees of filtering which result in a cleaner, more refined filter sweep as the slope increases.

There's a switch to select between "Quad" and "Mono" resonance gain configurations. "Mono" is the classic COTA-filter configuration, with a single resonance amp sending the inverted -24dB output back to the input. This will give the classic 4P sound associated with the Jupiter, etc, and will also give the expected filter mode responses with increasing resonance when using the expander. "Quad" is my own innovation, and activates four separate resonance amps, one for each stage. This gives a richer sound (IMHO) because the signal does not get swamped by resonance (as tends to happen in the classic configuration). It also ensures that the octature sine waves all have the same amplitude during self-oscillation.

The phase-shifted sine waves may be used as CV sources for various processes to achieve "circular" effects. For example, if two adjacent sine waves are used to control two VCOs, then one will "follow" the other's pitch at a distance. If four sine waves (at 90 degrees offset) are used to control four VCAs, then you can mimic quadraphonic movement. There are many more uses -- I'm sure the Muffmunity will have lots of suggestions.

And, perhaps the coolest thing about this type of filter is that you can take four of the outputs and feed them to a multimode matrix filter expander in various gain ratios to achieve virtually any sort of filter mode you can imagine. This is what the expander will do. So far, we have identified 4 lowpasses (the raw outputs of the filter), 4 highpasses, 6 bandpasses, 4 allpasses, and about 12 distinct types of notches (including the "double notch") with various LP and HP slopes. There are many more filter types to be made, and again we will be relying on the Muffocracy to give us suggestions as to what types they might like to have available. The expander we are designing will be capable of programming any gain combination of Doc Oc outputs, but only select combination are really useful. The expander will also allow smooth morphing from one mode to another, and this morphing will be achieved in such a way that the output will not undergo severe changes of amplitude inbetween types. You will also have the ability to assign up to 8 different modes (out of a much larger number) to panel buttons to be selected at will, or morphed in series, or morphed by voltage-control. At least, that is the plan at present. As Danjel has said, this design is still a little bit in flux. The core circuit is figured out, but we're still thinking through some of the panel controls. No matter what, it's going to be awesome and user-friendly.

[steffensen]

Nu har jag minsann luskat ut ett flertal BP, HP+LP, Notch+LP modeller. Riktigt kul o bra låter det. :)
Föredrar oftast Mono läget istället för Quad också, mer vintage och inte så "fylligt perfekt" som Quad annars kan låta. Vilket har sina fördelar också såklart, ti's all good.

HP kanske inte är möjligt med bara en A-138 mixer, får se..

[eXode]

Nu har jag minsann luskat ut ett flertal BP, HP+LP, Notch+LP modeller. Riktigt kul o bra låter det. :)
Föredrar oftast Mono läget istället för Quad också, mer vintage och inte så "fylligt perfekt" som Quad annars kan låta. Vilket har sina fördelar också såklart, ti's all good.

HP kanske inte är möjligt med bara en A-138 mixer, får se..

Om du blandar en inventerad ofiltrerad signal med den filtrerade signalen bör du få HP.

[steffensen]

Anade det.. Behöver en multiplier för det. Undra om nån vill byta en Unity mixer mot en multi kanske..

[jgb]

Hoppas det kommer en expander till den här snart!

[altemark]

Det blev aldrig någon expander va? Har någon jury-riggat något smart alternativ?