#342

A good explanation :slight_smile:

The Doepfer PLL breaks out the phase comparator, filter and VCO as separate sections. I often substitute a different VCO for the built-in one, making it track with another signal ā€“ a neat way to get an oscillator that doesnā€™t track 1V/OCT to sync (more or less) to another one that does. It can be used with dynamic exponential FM, for instance.

PLLs tend to only be reliable over a small range of frequencies, dependent on pretty much every possible factor in the patch ā€“ but that just means theyā€™re weird little beasts full of character.

In my patch, the PLL is trying to make its internal VCO (that weā€™re not listening to) track the feedback noises made by Cold Mac. But at the same time, itā€™s also feeding its frequency adjustment signal back to Cold Mac, which serves to throw it back off again. So the result is modulation of the Cold Macā€™s frequency, but the shape and frequency of that modulation depends on all the various settings. Come to think of it, that signal might make a really interesting LFO for some other purposeā€¦

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#343

Getting off topic here, but could a Maths be used to make the PLL in this patch? Or would a synced mangrove do the same thing?

#344

Maths canā€™t do the phase comparator part, but it could act as the filter and VCO. (*)

A logical XOR gate can work as a phase comparator ā€“ and post 294 above shows how to patch an XOR gate with a Cold Mac :smiley: Even if your signals arenā€™t exactly square waves in exactly the 0V to +5V range, it may be ā€œgood enoughā€ to act as a phase comparator.

As a proof of concept, I set up two square LFOs in Stages at different rates, patched them into Cold Mac as an XOR, patched the output through Maths channel 4 to slew it, and the channel 4 output into one of the two LFO inputs. With some tweaking of the slew times, the two LFOs synchronized (a bit imperfectly, but better than I expected).

ā€¦in fact I had accidentally patched the Cold Mac-as-XOR output into the Trig input of channel 4 without even noticing, and that worked.

ā€¦in fact I just bypassed Maths entirely and used the raw XOR output and that works too. It may be a little less stable about frequency changes though.

(*) (apparently I was wrong, Maths can be patched as an XOR gate using channels 1-3, while still leaving 4 available as a slew.)

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#345

Ah, the slew/filter is necessary for it to work at audio rate without just devolving into weird FM noise.

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#346

I just discovered the upcoming SSF Zero Point Oscillator and while reading through the details about itā€™s ā€œThru-Zero FMā€ technique I was wondering, if something similar could be acheived using the Cold Mac (and possibly some other common utilities or mod sources).

The fullwave rectification can be done quite easily using CMs SLOPE circuit. However, Iā€™m not sure about the ā€œreversing the wave-formā€™s polarityā€ part.

Iā€™m actually just starting to get a bit deeper into FM synthesis techniques and Iā€™d be happy to hear your ideas about how to use the Cold Mac in this context!

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FM synthesis
#347

Iā€™ve been working on a patch with the ZPO and Cold Mac over the last week, and I must add that with all those modulation inputs on the ZPO, the two make a particularly wonderful pair. In general, I love the opportunity to use Cold Mac to focus in on just one module, it helped me get a feel for the module better than anything else.

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#348

I guess this patch is mostly a Just Friends one, but since Cold Mac is also playing an essential role:

  • Patch 4 of JFā€™s outs into CMā€™s AND/OR ins
  • Patch the AND/OR outs into some v/oct inputs
  • Use JFā€™s knobs to travel between tone (weird arpeggios) and timbre (FM territory).

In my current patch, Iā€™m using use Teletype as a S/H and quantizer for one of the CM outs; the other one goes into Three Sisterā€™s FM in.

9 Likes
#349

Is this Just Friends in sound or shape mode? Sounds like a fun patch!

2 Likes
#350

Oh right, so I used Just Friends in SHAPE/CYCLE mode, but other modes should also work.

Using SOUND/CYCLE will probably result in mostly FM sounds, although with INTONE and TIME somewhere CCW there should also be single discernable pitches.

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#351

I think you might be able to do this with the addition of some extra utilities. Might be mistaken but I think it would work like this:

Modulation Osc > CM Slope
CM Rectified Out > OR In 1 (since rectifying the wave will cut its amplitude in half, do this to boost it back up to its original total amplitude at the MAC output)
MAC Out > Mult > Carrier Osc FM In
MAC Out > Mult > Offset mixer, apply -5V offset > CM Fade (since the fade circuit requires -5V to +5V and your MAC out signal should be 0 - 10V at this point depending on the osc youā€™re working with)

Carrier Osc > CM Left In
Carrier Osc > inverter > CM Right In

CM Left Out should resemble TZFM, and I think youā€™d need to patch a dummy cable into the Right out to keep it from mixing into the MAC Out.

I only got my Cold Mac last night so Iā€™m just trying to think through how to do this at work but Iā€™m going to try it out tonight when I get home.

EDIT: actually I donā€™t think the fade circuit would be best suited for this, at least not without converting the rectified modulation osc into a square wave first. Youā€™d want an immediate swap in polarity, rather than a fading of polarity. Might still sound interesting though.

2 Likes
#352

I got weird results from the patch. Lots of pitch drift, but also some really nice tones that could be fun to mess with. Found the whole 2x gain thing to not really work well so I skipped that part, too.

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#353

Iā€™ve been interested in this module for a long time but havenā€™t taken the plunge, mostly because I already have lots of utilities in my system. Iā€™m wondering if anyone has thoughts about the benefits of using Cold Mac vs. using individual utilities.

From what I can tell, the strength of this module is being able to put multiple aspects of a patch under the control of one knob. Anything else Iā€™m missing?

#354

I find that it encourages patching I wouldnā€™t normally think of if each component was separated. Cold Mac to me is a case where the sum is greater than the parts. The individual circuits themselves as utilities are pretty multifunctional too, like Peak and Trough or Crease for example.

5 Likes
#355

you are also unlikely to get as many utilities/functions in 8hp by getting individual modules. from that perspective, application of Survey and normalizations are a bonus.

#356

Totally - it does a lot in 8hp. The thing is I already have all of those utilities and Iā€™m unlikely to sell them all and replace them with Cold Mac. However, there might be a couple which I could switch out if it seemed like Cold Mac could do some things I couldnā€™t achieve with the modules I already have.

2 Likes
#357

To be more precise - the two modules I would switch out would be the SSF/WMD Toolbox and the ADDAC Crossfader/Panner. It seems would lose some functions from the Toolbox (VC switch, comparator). Also, Iā€™m not sure how well Cold Mac works as a vc panner/crossfader compared to the ADDAC module.

That said, Cold Mac seems like it would fit my patching style; Sport Modulator is one of my favorite modules for instance.

#358

I havenā€™t used the ADDAC one, but crosspanning/crossfading is really the main thing I use Cold Mac for and it does it well.

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#359

Fellow Cold Mac-ers, has your pot/knob ever become scratchy or otherwise intermittently made unpleasant noises when moved? For example, when swapping panning on left and right ins with the fade jack i donā€™t get any nastiness, but doing this with the physical knob instead of fade i get scratches about a third of the time. Based on the faceplate design i think i have an earlier edition of the module (Got it used).

Any suggestions on a fix? If this is a spray fix, what spray would work for this kind of pot (if i remember correctly metal and plastic parts need different lubricants/deoxidizers)? If itā€™s a pot replacement, what part would i need and is it as easy as desoldering and resoldering? Thanks!

#360

my cold mac had the same issue and some deoxit d5 in the pot shaft fixed it real quick ! itā€™s expensive stuff though and one can of it will probably last me forever, so if youā€™re in the nyc area and donā€™t feel like shelling out that $15 or whatever youā€™re welcome to swing by and use mine heh

#361

Thanks @feathers

Iā€™m on the other side of the continent but i appreciate the offer! I know i have one can of deoxit at home, cross my fingers itā€™s the right flavor. Cheers

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