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DRM1X DIY Expander Info
MUFF WIGGLER Forum Index -> BugBrand Devices  
Author DRM1X DIY Expander Info
BugBrand
Given that the DRM1/DRM1X have been out of stock for some time and some people have asked for details about expansion, I thought I'd write up something about the workings / options for expansion.

**Hopefully Batchas can join in as he did a DIY expander - though I can't now find details about it..**

****************************************
Passive parts:

Exp-Filt switch - 3pin header.
There is a jumper setting on the DRM1 to select either HP or LP filter response - a simple SPDT toggle switch can replace this jumper.
Pin 1 HP Pin 2 Return Pin 3 LP

Exp-Misc - 4 pin header
Pin 1 - Filter Input [expects typical +/-5V input]
Pin 2 - Osc Triangle Out [+/-5V output]
Pin 3 - Osc Square Out [+/-5V output]
Pin 4 - White Noise out [+/-5V output]

Exp-Envs - 4 pin header
Pin 1 - Env Filter Amp
Pin 2 - Env Filter Bend
Pin 3 - Env Osc Bend
Pin 4 - Env Osc Amp

**
Active parts on DRM1X

Exp-OFCV - 2 pin - extra 1V/Oct inputs for Osc Freq and Filter Cutoff
Exp-AMPS - 2 pin - extra CV input Osc-side VCA and Filter-side VCA

Those two headers expect standard 1V/Oct CV inputs to the VCO, VCF, VCA. I put some active electronics to feed them - for summing and for polarizing.

The Osc and Filter have simple 'attenuverter' circuits - the Osc side can also have its input switched between banana (ext) and a 0.5V source (so that the depth dial becomes a fine-tune control)

The Amp sides have 'Initial' controls (DC generators) and polarizing CV modulation inputs.

***
Sync - 3 pin header. [pin1 return, pin2 send, pin3 no connection]
This replaces a DRM1 option header which syncs the VCO with each trigger.
The switch selects 'self-sync' (ie. from the master trigger) or from Sync socket on DRM1X - that passes through a standard comparator pulse conditioner.

***
Exp-FTrg - 3 pin header [pin1 external trigger, pin2/pin3 connect for triggering from Master trigger of DRM1]
The DRM1X allows you to 'disconnect' the master trigger from the filter side and then adds the extra controls so you can trigger it independently.
Pin1 is where we feed the extra trigger - there's circuitry to combine a manual button trigger with an external trig input - passes through standard comparator conditioning.
Pins 2 & 3 simply connect to an SPDT - join the contacts to select 'master' triggering.

****

Hope that helps // hope that is relatively clear?!
GryphonP3
w00t

You rock Tom we're not worthy we're not worthy we're not worthy
bakedcircuit
nanners applause applause applause It's peanut butter jelly time!

YEEESSSS!
rowsbywoof
Add me to the pool of people who want one (and have bugged you over email about it), and would love a DYI solution if someone comes up with a module or kit. smile
Tajnost
rowsbywoof wrote:
Add me to the pool of people who want one (and have bugged you over email about it), and would love a DYI solution if someone comes up with a module or kit. smile


+1
pustule
Yes!! I've also bugged BugBrand over e-mail about adding an expander onto my "normal" DRM1s. I'd love a DIY solution! Thanks for sharing this info -- If anyone makes any panels, i'd buy two, and a BOM for any parts needed would be great

Batchas, can you offer any tips or photos of your build?
batchas
pustule wrote:
Batchas, can you offer any tips or photos of your build?

Sorry I missed this post.
I made the panel at Whitewall and I don’t like it at all. Of course it’s handy cause now I have the module running, but I don’t like the finish (like paper matt) and I don’t like this dibond either (cannot make clean holes etc etc).

Of course it’s be possible to go the pcb screenprint way like the original, but it’s much more work to get all in the software for the manufacture. Pers. I don’t have time for this I’m afraid.

For Whitewall I made all in illustrator, exported as tiff, finished. And I’m fast in a software I used many years professionally, while making the Orgone Accumulator panel for instance was as first try a pita work. Believe me. The prob being the formats needed for the pcb print which I never worked with before and the sftware needed for thihs (pcb circuit tools).

I can't tell much more than what states in the op about the circuit. There are pins behind the DRM1 which connect most directly to whichever in/out you'll need.

For the -/+ pots I used atternuvators chicklets I had in stock from fonik (if I remember well). Very handy to make quick atternuvators with any pot.
Now I have only "atternuvator" in the mind as word and when I make a search here it's not found. I don't remember how these are called atm...
Anyway, I mean you'll need a circuit if you don't have these to make the -/+ FM and AM. You could decide to go only positive too. Why not. This is what I'd do.


Here is the layout I did. It’s different from Tom’s original creation. I had what I needed in mind and did it according to this.
I don’t remember why I had to give Whitewall a file bigger than the panel itself (looks strange) but I have no tool here at hand to manipulate and crop the file (crashes non-stop on this new mac). Anyway. It’s easy if you have the tool.
The photo in the system is not actual cause I didn’t have back then the right knob colours nor the right bananas… But you get the picture.
batchas
Hmmm... The 2nd file won't work as attachment.. So here in a separate post as image:

batchas
And here's the original illustrator file I made if you need to make it fit your needs. See attachement.
For Whitewall I had to put the colour for the background so they print this colour. Was not easy to match the exact pcb red colour! And it turned matt anyway.
Actually I'd choose today the metalphoto on alu from Whitewall for this panel. Cause they put a plastic film on it. I ordered 1 of these for my buchla later. It looks horrible on my buchla (never used it because of this), but might look quite good on the bugbrand (glossy). Except the red... You'd have to find the right tint and change it in my .AI original file.
Remember if you go this way that you'll have to make all holes by yourself.
I went Whitewall as a test. Ordering 1 x pcb was not possible, expensive and I did not know how to do these GERBER files back then.
Whitewall was as I mentionned much more easy to do cause I could send a TIFF. And very cheap.

Sorry I cannot offer any pcb panel, much too busy atm. I don't have the tools needed on this computer etc etc.

Oh and remember that my panel is a bit different than Tom's original one.
batchas
And the switch on my panel named FM+ is a bad idea. I would not do this if you decide to use my layout file.
It was an internal wiring. But the result is not controllable. Not a good idea smile
Instead you could add the manual switch/push button for trigger like Tom's did on his panel.

So. Need to go now!
pustule
Batchas, thanks a bunch for the detailed info! Much appreciated.
Not sure if this is a DIY project I can take on myself, but happy the info is out there! w00t
orz
Great write up, thanks!

BugBrand wrote:
Exp-OFCV - 2 pin - extra CV input for Osc side (1V/Oct)
Exp-AMPS - 2 pin - extra CV input for Filter side (1V/Oct)

Those two headers expect standard 1V/Oct CV inputs to the VCO, VCF, VCA. I put some active electronics to feed them - for summing and for polarizing


Any pointers for how to do this? Would love some chromatic FM boings from the DRM1.
BugBrand
Oops, I maybe have that written wrongly - should be::

Exp-OFCV - 2 pin - extra 1V/Oct inputs for Osc Freq and Filter Cutoff
Exp-AMPS - 2 pin - extra CV input Osc-side VCA and Filter-side VCA

I'll edit the orig. post now.

Regarding the circuitry:

For the Exp-OFCV - simple 1-opamp attenuverter circuit for each

For the Exp-Amps - slightly more complex 2-opamp per side because you also have to sum in the Initial Amp controls (and keep polarity right)
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