I now have another Universal Slope module, the NANO Modules ARC.

I updated the Universal Slope Love post to add ARC to all the comparisons. Here are the most notable findings.

ARC Trigger Quirks

The ARC trigger input seems to be a relatively low impedance, since it loads and misshapes the incoming signal. The trigger signal must have a sharp rising edge, unless Sustain switch is on.

There is a design flaw in the ARC trigger circuit. With Sustain off, if the trigger drops prior to the output reaching its maximum level, the output reverses direction immediately and starts to fall. Very short triggers will not work with ARC for envelopes. I tested Contour 1, Function, and Tilt, and they do not exhibit this problem. The expected behavior is to ignore the falling edge of the trigger, unless Sustain is on. So this is a bug.

UPDATE: Trigger bug fixed

I reported this problem to NANO Modules. They gave this fix, which worked.

OK, we have found that some ARCs unexpectedly have one problem in the trigger input (as you suggested), but the fix is very easy and you can try it by yourself if you feel confident. It is because some boards left with some DNP (Do not place) components mounted, that was our mistake.

The problem is solved by removing 4 components on the circuit board.

In order to find these components, just dismount the component PCB from the panel PCB with your hands, it is not glued so it will be easy for you. Find attached an image pointing to the 4 components, R4 and C4 for the X function, R89 and C27 for the Y function. 

ARC SPECIAL NOTES

Offset Pot

The offset voltage is mixed with the internal output prior to the output attenuverter and CV input. So it remains proportional to the output amplitude. This is a nice feature the differs from what external gain/offset utility modules usually do. With the main attenuverter at max gain (CW or CCW), turning the Offset pot full CCW (to the left) will make the output bipolar, which can be useful for audio rates.

ARC works very nicely as an Envelope/VCA. Set the main attenuverter to the middle position (no output). Send the audio to the ATT VER CV input. The envelope will control the gain! This results in 2X gain over the input, so it is advisable to use an external attenuator on the incoming audio.