Cold Mac Ideas


Can anyone help me understand the following passage from the doudoroff:

Intrinsic to the function of the design (see Panning/Crossfading section below), LEFT is normalized to -5v and RIGHT is normalized to +5v.

In the diagram above this passage. “Into LEFT and out of LEFT(OUT)” appears to be a full-width LFO with survey CCW and a constant +5v when Survey is fully CW.

So if, when no attenuation is applied and LEFT to LEFT(OUT) is at full whack via cranked SURVEY, why does it appear to output +5v? I would assume by “normalled to -5v” that without any attenuation, LEFT(OUT) would simply produce a constant -5v?


the idea is that left is “in phase” with Survey input (so if you put +5v into Survey, or put it full whack, you should see +5v), while right is “fully out of phase” or the inversion of the Survey input.


But if LEFT is simply saying “If Survey is CCW I’ll apply -5v to whatever you give me,” then why does the LFO appear as a full bandwidth bipolar (-5v to +5v range)? Assuming -5v has been applied to LEFT, I’m assuming the LFO would be squashed down below the 0v line to begin, then rise above the line as you get closer to CW with Survey…


Putting something into the LEFT or RIGHT inputs breaks the normalization of the voltage.

I believe the diagram is showing a crossfade between the input to LEFT (a sinewave LFO) and the +5 volts of the RIGHT, which is normalled (no input).

This part from Martin’s Patching Cold Mac explains it a little more:

In both scenarios above, the outputs at RIGHT(OUT) and LEFT(OUT) are affected by the default -5v and +5v signals normaled to LEFT and RIGHT, respectively. If you insert a dummy cable in either LEFT or RIGHT, that will break the normalization and constrain voltage range of the output at RIGHT(OUT) and LEFT(OUT) accordingly. Moreover, you can insert your own signals at LEFT and RIGHT to modulate the voltage range at RIGHT(OUT) and LEFT(OUT).


Ahhhh okay. I get it, I’m confusing normalization with “additional offset” or some other thing.

So if nothing is patched to LEFT, LEFT(OUT) emits +5v. Inputting the full width LFO into LEFT (as shown in the diagram) breaks the normalization, which allows a progressive voltage to be added via SURVEY to LEFT(OUT) which, at full CW, is a constant +5v.

Like that… -ish?


I think you have the right idea – LEFT OUT always outputs +5v at full CW unless you plug something into the RIGHT IN. There’s a relationship between LEFT and RIGHT and their normalizations.


Ah! The offset finally makes sense! I just kept thinking of left and right for audio cross fading OR as inverse voltage sources with nothing plugged in. Never crossed my mind to use offset input to offset an lfo with a constant voltage!


To fully understand the normalizations/ offset on CM, one of my approach was in use of bipolar voltage indicator like this:

Get three maybe four of this, plug them to the outputs of CM, you would clearly see what goes on and learn much easier.


Those are handy. I use the scope on my ER-301, you could also use mordax data or dave jones o’tool.


x-post to another thread where someone was talking about “whale call” sounds…

Had a good one last night where Survey simultaneously surveilled Maths Ch.1 Rise/Fall combo, Black Hole DSP reverb wet/filter, and Mangrove Barrel.

At full Survey left the Mangrove is completely underwater, all parameters at their longest, slowest, wettest or most, uh, utonal. Turning Survey to the right causes the Mangrove to slowly float to the surface and get shorter attack/decay, less watery reverb, and a more distinct, less barrelly Mangrove tone. Over a 4/4 kick drum you can bring it slowly up, then take it slowly down. One knob, instant Warp records.

Not a pro strat I guess, but it’s a testament to the fact you can do “music” with Cold Mac too, not just invert your ands with your laggy slope. :kissing_heart:


It would be great to hear a recording of this :slight_smile:


I was gonna complain that that’s the whole idea behind inverting my ANDs and lagging my slopes,

…and then I realized that translating those kinds of abstract procedures into something that can have a more tangible effect is basically what I study (math), so I guess I’ll just cheer that you did that hard work and found a use case that sounds really sweet!


When I saw Cold Mac I was like “holy shit, a big dumb DJ fader” so I’ve depended on the intellect and savvy of folks here to get me there (I didn’t finish high school
math and also it is the case that I got a D in Logic).


hahaha I love “a big dumb DJ fader”! it’s too bad they would never put that in their official documentation.


They don’t need to. The idea of “patch surveillance” as a sort of Foucauldian DJ guard tower for your poor little proletarian modules is just too good. “Lol Plaits, through the economic adaptability of your many modes you’ve just inculcated the conditions of your own subjectivity.”

Also, hobbies with steep learning curves are the only way to live. Peace!


I recently had to sell my MN Maths and been wondering how I could reproduce the Cycle input for my MN Function using the Cold Mac. To be more specific, I wanted to trigger the Function via the Metropolis’ Gate out and also use my ls1LightStrip to activate cycle mode.
Here’s how I solved that using the Cold Mac:

  • Function’s EOC into CM AND 1
  • ls1Lightstrip Gate out into CM AND 2
  • CM AND Out into OR 1
  • Metropolis Gate Out into OR 2
  • CM OR Out into Function Trigger input

Its simple solution but it works great. It should also work with any envelopes that have EOC outputs.


brilliant solution! you got your Cold Mac to say “okay, if Metropolis triggered me, definitely trigger Function. otherwise (or “also”), if both Function’s EOC and the Lightstrip say so, let’s also trigger Function”.


Exactly :slight_smile: It should reproduce the behaviour of the Math’s cycle / trigger inputs quite well. Not a super fun use of the CM but definitely useful.


Hey sorry for what is no doubt obvious. But to understand the Cold Mac please can you tell me what the horizontal line on the symbol is on the outs? is it 0 Volts?


Yes, i believe it is.

check the doudoroff link for visual representation