Frac envelope generators

[Tubeampguy]

Hi, I have 2 FRAC MOTM Looping Envelope Generator PCB's stuffed but no front panels and no Pots. Could someone take pictures of the rear of their 1800 and if possible note the values of the pots. The schematics are unavailable from Paul (HD crash).

Thanks in advance.
dave

I have (over many years) found several MOTM-1800 ADSR's
My first one had been modified with banana jacks. I still haven't figured out how I'm going to fix that one. Here are some of the pictures I have on my computer. The pictures show the lower circuit board for the jacks and the ribbon cable jumper to the main circuit board. Sorry no pot pictures. Hope it helps you?

Thanks, these are helpful, but unfortunately do not answer the Pot question.

There were only a small amount sold unfortunately.
I will likely have to make an educated guess then observe the results then fine tune.
dave

Dave, Working around my work schedule and the bad weather, I can take more pictures and get you the values on the pots. Also some views from the main circuit board & panel details. The 1800's are the best around, They are comparable mostly to the Bananalogue VCS But those are really rare too.
dave

[werock]

I wonder how similar circuit wise this was to the MOTM-800 ADSR.

That used 1M log pots for the A, D & R pots and 10k lin for the sustain pot. Might be a good starting point?

[Synthnerd]

I have a MOTM1800. All 4 pots appear to be the same, stamped "DI YA 05 43". I'm frustrated that I can't find my multimeter at the moment to measure values, but I'll take the module into work tomorrow, as we have one there. I read elsewhere that Doepfer and Carvin Amps use DIYA pots and they are usually custom made in large order quantities. Here's a picture:
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[diophantine]

A multimeter may not tell you the answer, if there is any sort of resistance in the circuit that is in parallel with the two ends of the pot.

A lot of times pots only have the value written on the front, in which case you'd have to pop off the knobs & remove the nuts...

If I had one I'd be happy to do that, but I don't...

[Synthnerd]

Thanks for passing on the knowledge. It was easy to take the front panel off. The pots are marked B50K. I think this means 50K ohms, linear taper. Here's another picture to show how the pots are mounted:

[davedatt]

Thanks for passing on the knowledge. It was easy to take the front panel off. The pots are marked B50K. I think this means 50K ohms, linear taper. Here's another picture to show how the pots are mounted:

Thank you guys! 50K Linear!

I will assemble will let you know!

dave

[chachi]

bought that MOTM 1800 that was hanging around reverb and then did a bunch of reading waiting for it to arrive and then wished maybe i’d just bought another EG1.

[Tajnost]

Btw... something like DUSG or Maths in frac format would b amazing.

[Cat-A-Tonic]

Btw... something like DUSG or Maths in frac format would b amazing.

There used to be Bananalogue VCS in Frac.

Some folks have DIY slopes from CGS.

While the Blacet EG1 doesn't have the amplitude following aspect,
it is has plenty of features to make up for it.
I reckon the same is true with TEM (perhaps more so), but I haven't tried it.

What functionality from "DUSG" are you missing?

[chachi]

bought that MOTM 1800 that was hanging around reverb and then did a bunch of reading waiting for it to arrive and then wished maybe i’d just bought another EG1.

yeah, sorry paul, the EG1 is king.

maybe what the poster above would like with a Maths/DUSG is the dual nature, some of the portamento patches require the two maths channels. a dual EG1 in a 2U frac would be quite amazing towards this end.

just daydreaming!

[Tajnost]

What functionality from "DUSG" are you missing?

I never played with maths or dusg, so all my experience based on reviews and demos, anyways, what I find really impressive is of course their dual nature, ability to apply slew, depth control incl. going to negative, option to integrate, mix and process ext. voltages, clever control and patch points for almost everything.

With maths it’s easy to achieve very interesting and rhythmically complex modulations with external gates and cv, I find it quite useful in music.

I guess there are still many other options to discover, at least I can’t think of anything similar in my BugBrand system.