Rackmount Tom Oberheim SEM ?

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appliancide
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Post by appliancide » Sun Feb 13, 2011 10:30 am

Thanks for the explanation and pics James! It looks like new and old are pretty DIY friendly, with the new ones being the easiest to patch out.

M6live
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Post by M6live » Mon Feb 14, 2011 2:05 am

Redacted.
Last edited by M6live on Sat Jun 04, 2016 3:54 pm, edited 1 time in total.

skylab001
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Post by skylab001 » Fri Feb 18, 2011 5:41 pm

So can anybody tell me if it is possible to patch out (with a custom panel) a midi-cv SEM and still retain the midi-cv functions as well, so it would be similar to a SEM Pro but racked in a custom case? This is the setup I'm looking to do.

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Post by userwave » Sun May 15, 2011 4:40 pm

i'd like to rack my tomoberheim SEM midi - cv version as well,
any off the shelf solution ?

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Post by userwave » Mon May 16, 2011 9:04 am

does anyone have the manual handy ? (mine is at home, i'm at office)
(ideally for the midi - cv model)

looking for exact dimensions as i can maybe get a quote on a custom rack shelf.

thanks!

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krv
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Post by krv » Mon May 16, 2011 3:51 pm

suitandtieguy wrote:as soon as he starts shipping the panel-only SEM i'm going to make a moog-format panel for it, maybe with some infrastructure included.
Any (good) news about this project?

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Cat-A-Tonic
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Post by Cat-A-Tonic » Sun Aug 14, 2011 5:03 am

For users of the SEM Patch Panel:

I'm planning on adding some patchpoints to my MIDI SEM.

How does sending triggers to the gate inputs differ from sending triggers to the trigger inputs?
I'm wondering if I can do without the trigger inputs (as on the SEM Pro).

Do you often use CV1, CV2, & Ext. Mod. inputs simultaneously for VCO 1, VCO 2, and VCF?

It seems to me that (at least) CV2 inputs could benefit from attenuators.
Do you concur?

CV1, CV2, Gate, & Trigger all have jumpers that lock VCO1>VCO2 & Env1>Env2.
Whilst this arrangement is handy for playing via MIDI...
It seems to me that it would be handy to disable these at will with switches.
I wonder if the SEM Pro accomplished this with (normalled) switching jacks.
Anyone know?

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Cat-A-Tonic
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Post by Cat-A-Tonic » Tue Aug 16, 2011 8:56 pm

Bump for SEM love.

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Cat-A-Tonic
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Post by Cat-A-Tonic » Sun Aug 21, 2011 3:04 am

I made some progress on the layout.

I'm planning on putting the outputs on the top bit where the PRO version has jacks.
And 4 switches for the CV and Gate jumpers to the left above the MIDI section.

All the inputs and attenuators will be down in front.

If noone thinks Trigger Inputs are necessary in addition to the Gate Inputs for the Envelopes,
then there will be room enough for and additional utility section.
So I have to decide between a multiple, switch router, OR combiner, or passive slew...
I suppose a passive ring mod would be another option, but I'm leaning away from that one for this unit.

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Isaiah
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Post by Isaiah » Wed Aug 24, 2011 2:00 pm

Cat-A-Tonic wrote:I made some progress on the layout.

I'm planning on putting the outputs on the top bit where the PRO version has jacks.
And 4 switches for the CV and Gate jumpers to the left above the MIDI section.

All the inputs and attenuators will be down in front.

If noone thinks Trigger Inputs are necessary in addition to the Gate Inputs for the Envelopes,
then there will be room enough for and additional utility section.
So I have to decide between a multiple, switch router, OR combiner, or passive slew...
I suppose a passive ring mod would be another option, but I'm leaning away from that one for this unit.

The 4 switches to enable/disable the CV/Gate connections would be a wise addition, good thinking!

You could wire a 3P4T rotary switch with 4 jacks (A, B, C, D), space permitting, for the following functions:
*Switch I - A is routed to B, and C to D
*Switch II - A is routed to C, and B to D
*OR - inputs A, B, C are routed to output D
*Multiple - A, B, C, D are shorted

I don't think a passive slew would be much good for accurate pitch-tracking since the CV inputs aren't buffered. But could be useful for other things.

I'll get back to you soon regarding the Trigger functionality.

:guinness:

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Isaiah
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Post by Isaiah » Thu Aug 25, 2011 4:29 am

You could also add this circuit:
Image

I tested it, mixing different waveforms from both of SEM's VCOs and sending it to the input. I used an amp to make up for the volume loss after, but you'd be able to use the MIDI SEM's pre-amp.

Sonically, it can get pretty gnarly with the VCOs detuned. Intermodulating kind of effect, from what I remember (it's been a while since I had it on the breadboard).

I used an AC187 transistor and ~0.047uF.
You could use a passive mixer circuit with 2 or 3 resistors (I think had my all my mixer levels all the way up, so you probably wouldn't need pots).

Cheers!

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Post by roginator » Sun Nov 04, 2012 4:41 am

waiting for my MU panels for SEM

Image

will be finished in few days by http://www.bigbluewave.co.uk/custom_modular_panels.htm

also i ordered mirrored version for Upper moog cabinet .. Ill post few pictures when i get em!

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sempervirent
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Post by sempervirent » Sun Nov 04, 2012 1:10 pm

roginator that is awesome, I look forward to seeing the finished panel.

A rackmounted fully modular SEM with 1/4" jacks seems like an obvious gap in the Oberheim product lineup.

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m0rb1d
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Post by m0rb1d » Sun Nov 04, 2012 1:37 pm

hm, would making this using bananas be any more difficult?
very intriguing thread!

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MechaSeb
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Post by MechaSeb » Mon Nov 05, 2012 6:12 am

Really nice work Roginator !

I'm willing with this idea for a pretty long time now. Having a Midi SEM is quite frustrating time to time. So i planned to semi-modularize it based upon banana layouts (still working on it).

Speaking about adding functionality or not, i'd like to know if passive attenuators on CV inputs would be enough to do the trick ?!

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Post by dumbeat » Sat Jul 16, 2016 5:41 pm

Ive got 2 Vintage 70's SEM's and a 70"s sequencer module that i want to rack and have full patch points.

What are your thoughts about fabricating a custom faceplate for the modules(and save aside the originals- respect to the design),
and have holes in the custom fabricated faceplate to have the patch points right next to it's corresponding control? Like in a proper modular synth or an ARP2600, eurorack modules?

Would that work non-distructively with the wiring of the module?

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iamkory
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Post by iamkory » Sun Sep 01, 2019 5:46 pm

roginator wrote:waiting for my MU panels for SEM

Image

will be finished in few days by http://www.bigbluewave.co.uk/custom_modular_panels.htm

also i ordered mirrored version for Upper moog cabinet .. Ill post few pictures when i get em!
I know this is like 7 years old, but was wondering what became of this, if anything. Looking to do something similar. Thx!

danmccullough
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Post by danmccullough » Sun Sep 01, 2019 7:21 pm

See this topic:

viewtopic.php?t=162235&start=0&postdays ... highlight=

I had an SEM made into a 5U module by Dave Brown of Modular synthesis. He actually made two for me and one for another customer. Later I decided to make the Mini Sequencer into a 5U Module. Dave helped with the design and I did the build. These are the Crown Jewels of my 88 space system.

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r0main
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Re: Rackmount Tom Oberheim SEM ?

Post by r0main » Sat Jan 09, 2021 8:25 am

Hi @roginator, I am building my 5U panel based on the design you quoted. How do you connect PWM1 & PWM2 to each oscillator? Did you build an active mixer? A1 & E1 molex connectors are single signals.

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