#238

Is this correct for a ring modulator?

OSCc --------> [L IN] ----> [L OUT] -->
            \–(-)-> [R IN]
OSCm ------> [FADE]

I don’t have a ring modulator in my rack to compare.

edit: cleaned up diagram.

2 Likes
#239

Hi guys, recently I got a Coldmac as my Christmas gift and really enjoy it a lot!

However I noticed a phenomenon of signal bleeding in the MAC output while the survey knob turned all the way down (CCW) if using coldmac as VCA mixer. Same phenomenon is also seen in the crossfading circuit too. There seems some replies mentioned this before.

I really curious if this kind of VCA circuits that controlled by bipolar signal cannot be fully closed and this is its nature. Because this phenomenon can also been seen in Xaoc Praga mixer module. (Although this is not as significant as Coldmac because it appears only when the gain at my external mixer is opened to almost maximum.)

1
Figure1: from the manual of Xaoc Praga mixer module. When attenuator knob is all the way down, the gain always still has -55dB if it’s in bipolar mode and accepting -5V control voltage to close the VCA circuit.

2
Figure2: if it’s in unipolar mode (accepting 0 to +10V) and attenuator knob all the way down, the gain is approaching negative infinity, even if 10V CV is applied.

#240

I think during the Coldmac lecture at Control, we tested that if you put some voltage into the OFFSET, you can push it beyond the +5 and -5 range on SURVEY. That might help close it all the way. Not by my system, but give it a shot. I think we had to push +10 or -10 through 2nd channel on MATHS.

#241

20 characters of that should work!

1 Like
#242

On my particular Cold Mac, I get no bleed at all on MAC: turning Survey fully CCW fully shuts it off, even if I load up the inputs with signal.

However, my crossfader bleeds quite badly on the left channel for me (fails to fully attenuate the RIGHT input with SURVEY fully CW). My right channel seems well behaved. Dunno if this is a calibration thing, a tolerances thing, or a spiritual matter. Additional offset voltage through SURVEY or FADE from outside doesn’t seem to have any affect in this situation for me.

1 Like
#243

Cold Mac Idea for 2019: explain the origin of the name “Cold Mac.”

4 Likes
#244

Tangent here: ADDAC has just released their model 306, which presents a comparatively straightforward and focused take on the “patch surveillance” concept. In comparison to Cold Mac, you get to directly dial in the voltage ranges that surveillance traverses. The 306 would complement Cold Mac for some, although the ADDAC is unipolar only, posing an integration inconvenience. The 306 appears to have jumpers to individually configure the voltage ranges of the five channels between 0-5v and 0-10v.

http://www.addacsystem.com/news/introducing-addac306-vc-transitions

7 Likes
#245

just got a cold mac! can anyone verofy the proper way to connect the PSU? my build is the one with the cabin on top of the tower on the back. there’s no red line and both -12 and +12 are on the same side of the image

1 Like
#246

Hullo! The cable should be prevented from being attached the wrong way because of the notch. But mine’s like this:

image
183A6569-25DB-4872-BA3A-773FD66EDB59.jpeg3024×4032 2.87 MB

1 Like
#247

The header is shrouded, so there shouldn’t be any ambiguity, but I suppose you can’t completely trust that. Actually, if you look really closely, a tiny black “-12v” should be visible on the dark green side of the house. Red stripe to left.

1 Like
#248

thank you my friends :)))

#249

I’ve yet to take a deep dive and read this whole thread (I’m really looking forward to it) but let me take the opportunity to wax lyrically about the packaging of the Cold Mac. It’s just so lovely. I had to send one back with a fault so I got to open the module twice. The colourful box combined with the reversed module’s artwork sitting tightly in its cardboard surround is an absolute joy.

1 Like
#250

I would recommend against blindly trusting shrouded headers & cables. I’ve received cables in used module exchanges where the key on the cable was on the wrong side :confused:

Always looks both ways even when crossing a one way street.

(Not directed specifically at you of course)

5 Likes
#251

Here’s another Cold Mac idea for your entertainment:

Sine --> Offset
CV --> Survey
Falling out --> Crease In
Mac --> Slope
Rectifier out --> Left
Crease out --> Right & output

As survey changes, notice different harmonics and subharmonics of the input.

54 Likes
#253

I love this. The use of MAC, here, is particularly eye-opening to me.

2 Likes
#254

Great! And I really like this format, with you following along to the patch notes. Nice and clear. Thanks for posting!

1 Like
#255

geez i really love this module. as someone new to eurorack (but not to synthesis as such) it feels inspiring, educational, and of course a bit mysterious :slight_smile:

@mdoudoroff thanks so much for your videos, they’re superb- you definitely have a knack for modular pedagogy!

#256

Dawned on me that you could probably make a pretty workable Bernoulli gate with the crossfade section, or perhaps the and/or section using survey and the rectifier. Anyone tried this?

#257

That’s crazy! I love patches that explore this kind of weird feedback behaviour! Thanks for posting.

1 Like
#258

Love it! You just turned a DPO into a Mangrove!

9 Likes