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Bipolar attenuverter uses
MUFF WIGGLER Forum Index -> Modular Synth General Discussion  
Author Bipolar attenuverter uses
hw408
I got a Triatt and was really just looking for the no-input = 5 volts output behavior. But now looking at the other modes, one of them is bipolar attenuverter where middle is zero, right is regular and left is negative/inverse polarity.

I was using an lfo with sync using the gates on my riff notes from bsp, and running that lfo into a pitch, catching the rising edge of the sine on each hit. Then using the negative of that (thru triatt), I could invert the lfo and get a falling slope instead.

Just curious what are some other uses for this flipped polarity mode?
moremagic
one of my more complicated patches involved sending two pressure points CVs to maths, passing one thru triatt, so i could use the polarity switch to change which CV came out the Or output

its also fun to send envelopes through to a vcf which lacks its own attenuvertor, and adjust it manually during a sequence or whatever
Dave Peck
Lots of uses for inverting an audio signal in a patch:

- when you are combining the outputs of two filters, inverting one drastically changes the sound

- Inverting the output of a phaser before you mix it with the dry signal gives a different sound

- same with inverting a flanger / delay before mixing it with the dry

- inverting a feedback loop within a patch can change the sound in many ways depending on the patch

And lots of uses for inverting a control signal within a patch:

- inverting an envelope before it goes to the filter cutoff, so the EG lowers the cutoff instead of raising it

- As you mentioned, changing an up slope to a down slope or vice versa

- mult-ing and inverting any control signal and sending the un-inverted and inverted signals to different CV inputs so the same CV causes one thing to increase while causing another to simultaneously decrease.
cptnal
An extension of the above: crossfading/panning.
hw408
Dave Peck wrote:
Lots of uses for inverting an audio signal in a patch:

- when you are combining the outputs of two filters, inverting one drastically changes the sound

- Inverting the output of a phaser before you mix it with the dry signal gives a different sound

- same with inverting a flanger / delay before mixing it with the dry

- inverting a feedback loop within a patch can change the sound in many ways depending on the patch

And lots of uses for inverting a control signal within a patch:

- inverting an envelope before it goes to the filter cutoff, so the EG lowers the cutoff instead of raising it

- As you mentioned, changing an up slope to a down slope or vice versa

- mult-ing and inverting any control signal and sending the un-inverted and inverted signals to different CV inputs so the same CV causes one thing to increase while causing another to simultaneously decrease.


Thank you for the ideas!

I tried audio through the Triatt and it just sounded the same regardless. Seemed to act as a volume knob.

I like this one:

>>- mult-ing and inverting any control signal and sending the un-inverted and inverted signals to different CV inputs so the same CV causes one thing to increase while causing another to simultaneously decrease.

I can try that I think.

Wish my rig was sophisticated enough for a feedback loop but i dont think it is.
braids loquelic dixie
env vcas filters
mult triatt ad/lfo and a NOT
sequencer things
Dave Peck
hw408 wrote:


Thank you for the ideas!

I tried Udio through the Triatt and it just sounded the same regardless. Seemed to act as a volume knob.



I figured out what a "triatt" is (triple attenuverter from Intelligel) but I have no idea what a "Udio" module is. If you're just getting a volume control behavior from passing a signal through an attenuverter in one of the examples I gave, something isn't right. More info ?
hw408
Dave Peck wrote:

I figured out what a "triatt" is (triple attenuverter from Intelligel) but I have no idea what a "Udio" module is. If you're just getting a volume control behavior from passing a signal through an attenuverter in one of the examples I gave, something isn't right. More info ?


Sorry i typo’d “audio” there, didnt mean Udio.

I meant that instead of a cv, i ran an osc voice audio signal out through Triatt, into a vca, and didnt notice any difference when i turned the Triatt knob in bipolar mode, from 0 (center) to full CW vs full CCW (negative).

So i figured this module might just be used for cv purposes. Or maybe it sounds the same and youd need a scope to see the effect.

That wasnt part of a test of any of your examples, that was part of my examination.
nigel
hw408 wrote:
I meant that instead of a cv, i ran an osc voice audio signal out through Triatt, into a vca, and didnt notice any difference when i turned the Triatt knob in bipolar mode, from 0 (center) to full CW vs full CCW (negative).

As Dave Peck said, to hear a significant difference, mix it with the same audio sent through a separate effect, such as a filter, or as part of a feedback loop. You can't really hear any difference between a signal and its inverted version on its own.
Dave Peck
"Udio" - Aaaah, of course! I should have figured that out. Yes, you need to try the patch ideas described above, so you are combining (MIXING) one signal with another version of that signal (like sending an osc through two different filters with different settings, or one signal through a phaser/flanger/distortion/wavefolder and the other does NOT go through the phaser/flanger/distortion/wavefolder). THEN try inverting just ONE of these two signals just before they get combined in the mixer module. Inverting / not inverting will create lots of different effects.
PhineasFreak
i use 4 of em, combined with doepfer quad envelope follower to feed the vcas of my performance mixer allowing me to patch up compressor expanders...
hw408
Following up with Triatt experiment, to move copies of a cv in opposite directions:

Dixie sine LFO -> Veils1
Triatt1 no input, cv out into Veils2)
Veils2 out (mix of ins 1&2 - this seems to keep the lfo from going below 0)
into Mult.

Mult1 out into Loquelic pitch
Mult2 out into Triatt2 in invert mode, out into Braids pitch
Braids and Loquelic each out into separate filters.

So the voices are pitching in opposite directions. This is fun! and if i flip the Triatt mode they join up instead (not as fun)

At lowest lfo speed I can hear hear the two voices passing through clean octaves as they move in different directions. we're not worthy otherwise, very nice mental results
Dave Peck
You're getting it!

If I could make a suggestion for future posts - keep in mind there are a bazillion different modules out there and everyone here has a different system. So when communicating here about patch ideas, it helps to describe modules by their function, rather than the manufacturer's name. For example, I have a MU system so I had no idea what a 'Triatt' or a 'Veils' or a 'Loquelic' was. Use terms like attenuverter, VCA, VCF, mixer, etc. so people will understand what you are describing even if their modules are different from yours. thumbs up
medium Rob
All hail the scrunchie!! These handy little inventions were created sometime during the 1980’s, and if you were a young man during that decade, you had a scrunchie to match every shirt you owned. Most guys during this time wore their scrunched ponytails high atop their head, the higher, the better.

There was an incredible amount of flossing, and Aqua Net involved as well. You may remember these cute ponytails on shows like Who's the Boss? where Tonelle Dansa rocked the side high scrunchie pony.
OIP
i use them with a clock divider or other timed gate (eg from function generator) to make melodic sequences

gate output > attenuverter > pitch CV
pugix
We've seen examples of inversion and examples of attenuation. You don't need an attenuverter to do either of these. An attenuverter typically allows the user to attenuate when the knob is right of center and invert AND attenuate when the knob is left of center. Most attenuverters make it difficult to null out the signal at the center position. It seems to me that the attenuverter is a design compromise to eliminate the need for a switch or for patching a separate attenuator to an inverter. Most of the time I'm annoyed by attenuverters, because I can't zero the signal.

So, the special advantage of an attenuverter is when the user wants to make a manual transition between normal and inversion with a single sweep of the knob, across the center. I'm interested in how people use that technique. What sorts of parameters it's good for, etc.
cptnal
A couple of modules I have get around the zero problem in different ways:

Klavis Mixwitch - Each knob travels from zero to full or, with the press of a button, from zero to minus full. They actually mention this in the manual as a method of getting around the zero problem.

XAOC Samara - There are normal and inverting inputs for each channel.

I have these along with a 4MS SISM and a Mutable Blinds, so I use whatever one seems best for any given use case.

Doesn't answer your question, but since you brought up the zero thing... thumbs up
Zentek
cptnal wrote:
A couple of modules I have get around the zero problem in different ways:

Klavis Mixwitch - Each knob travels from zero to full or, with the press of a button, from zero to minus full. They actually mention this in the manual as a method of getting around the zero problem.

The Mixwitch design came from a request to solve that "fuzzy" zero point problem at the middle of a pot when using attenuverters.
On the other hand, the trouble with a mechanical switch to invert the polarity is a risk of audible click. This is why we implemented the inversion with a toggling push-button that controls analog switches to ensure a noiseless transition.

Eric
Keltie
Is there any technical reason not to use a centre detented knob to also make setting zero easier?
Zentek
Keltie wrote:
Is there any technical reason not to use a centre detented knob to also make setting zero easier?

Yes. By design an attenuverter circuit is very sensitive to compounded errors of components tolerance (allowed error). Every channel in every copy ends up having its zero in a slightly different place. (thus not matching the detent!) d'oh!
Real world validation has shown that even adding a trim does not ensure long term stability of the zero point. cry
Having to trim the zeroes regularly is more annoyance than the benefit of being sometimes OK confused
pichenettes
Keltie wrote:
Is there any technical reason not to use a centre detented knob to also make setting zero easier?


Also: (mechanical) backlash. The detent will not lock the pot at the same position if go from fully CCW to 12 o'clock or from CW to 12 o'clock.
MvK
the vermona quadropol has a center dead zone to circumvent that problem. it works very well
jorg
hw408 wrote:
I was using an lfo with sync using the gates on my riff notes from bsp, and running that lfo into a pitch, catching the rising edge of the sine on each hit. Then using the negative of that (thru triatt), I could invert the lfo and get a falling slope instead.

Just curious what are some other uses for this flipped polarity mode?


Just a slight expansion on what you're doing: Modulate pitch on two VCOs with opposite polarities from your sine LFO. Mixed together, the result will resemble a classic chorus sound such as the Boss DC-2.
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