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CEM3394 modular schematic
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trig



Joined: Apr 27, 2008
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Location: usa

PostPosted: Sun Apr 27, 2008 5:32 pm    Post subject: CEM3394 modular schematic
Subject description: anyone have a modular adaptation for this chip?
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I have some spare cem3394s that I wanted to make into a modular synth.

Anyone have a schematic for using these with a 1volt/octave signal?

Thanks
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andrewF



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PostPosted: Sun Apr 27, 2008 7:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hello
welcome welcome welcome
I can't remember where i found this but thanks to Aaron Cram -


CEM3394_V2.pdf
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richardc64



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PostPosted: Sun Apr 27, 2008 8:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

I have the Cram and this one. I'm skeptical about both of them. I doubt either one was ever built or even breadboarded.

Tracking at 1v/oct is a simple matter or adjusting the CV scaling trimmer.


cem3394a_sd.gif
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cem3394a_sd.gif



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machine.cuisine



Joined: Jul 20, 2007
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PostPosted: Wed Apr 30, 2008 9:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

I have a couple of these ICs too. I also have a SCI MAX synth (I made a little VST editor for it) and I'll say that the 3394 sounds pretty good.

According to Crams old website he actually built it and it worked.
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Mooger5



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PostPosted: Wed Oct 07, 2009 8:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

I´m going to try this.
Found a cheap source for 100k multi-turn pots and I was wondering if I could use one instead of the fine and tune pots. Isn´t 100k too much though? Or is that what the vernier dial brake is for?
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fonik



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PostPosted: Thu Oct 08, 2009 3:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

i took a short look at both schematics. aaron cram used more active mixers.
however, where he just mixed CVs without OpAmp there i can't find the resistors to GND!? (according to the annonymous schematic you would use 390k here).

Mooger5 wrote:
Isn´t 100k too much though? Or is that what the vernier dial brake is for?

don't know about the range 100k gives. anyways, the break is for locking the dial.

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Mooger5



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PostPosted: Thu Oct 08, 2009 5:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

I don´t see any 390k in the anon circuit. Do you mean the 330k (badly written) between pins 1 & 3 of the CEM? That´s part of the chip´s supply. In the Cram schematic a 270K is used but an error in the drawing makes it look like pin 2 is shunting pin3. Is that it? Confused

I just found the same supplier also sells 20k multi-turn pots. I think these are OK Smile
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fonik



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PostPosted: Thu Oct 08, 2009 5:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

sorry for having been unclear. Embarassed

what i meant was the following (2nd try):
in the schematic richard posted we see passive mixing of the CV signals all over the place (without the course CVs, which are mixed with an inverting mixer stage). take a look at i.e. resonnance lower right corner: the CVs are summed via the 12k and a 47k to GND.
in aaron crams schematic that andi posted the resonance CVs are mixed via 100k resisots, but a resistor to GND is missing. given that the ratio of the resistors in richards schematic are fine (47k/12k) i would expect to see a 390k resistor to GND here (390k/100k).

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Mooger5



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PostPosted: Thu Oct 08, 2009 6:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ah yes, well observated Smile Something´s not quite right in one or the other. Both should follow a similar logic. According to your experience, the annonymous schematic is the functioning one, although it would benefit from adding active mixing? In the meanwhile I will have a look at the CEM datasheet and some other circuits, since I don´t intend to follow neither one "blindly" Smile
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fluxmonkey



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PostPosted: Thu Oct 08, 2009 6:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

i believe the schemo richardc64 posted is and old Electronics For Music design... in general, those designs were meant to be pretty barebones rudimentary, but were often buggy as well.
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ickystay



Joined: Nov 15, 2006
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PostPosted: Thu Oct 08, 2009 6:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

I would not use a multi-turn for "tune". With that one it's nice to just reach out and turn it for a nice bend.

As Aaron Cram's stuff seems gone from the internet, I'll just attach the other related pdfs.


PowerSupply_V1.pdf
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 Filename:  PowerSupply_V1.pdf
 Filesize:  12.17 KB
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Noise_V1.pdf
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 Filename:  Noise_V1.pdf
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Mooger5



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PostPosted: Thu Oct 08, 2009 6:54 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
i believe the schemo richardc64 posted is and old Electronics For Music design... in general, those designs were meant to be pretty barebones rudimentary, but were often buggy as well.

Thanks for the warning. Looks like I´ll have to do some exaustive breadboarding. The datasheet is not very helpful. The Sequential Six-Trak Service manual is available online, but the controls are digital...
bah, the whole thing must not be that different from a common modular filter, I suppose...

There´s a video on Youtube. The chip sounds good. Seems like a sound board from an arcade machine was used, so no reference to these schematics...
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Mooger5



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PostPosted: Thu Oct 08, 2009 7:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

ickystay wrote:
I would not use a multi-turn for "tune". With that one it's nice to just reach out and turn it for a nice bend.

As Aaron Cram's stuff seems gone from the internet, I'll just attach the other related pdfs.


yeah, I just find the vernier dials look cool Smile No idea how they´re supposed to work though. When Jarre is seen at the VCS3 I´m not even sure if it´s the dials or the joysticks that did the wide and fast sweeps.

Edit - Thank you for the schematics. The noise will be a useful add-on. For the psu I was thinking towards LM317/337...

Here´s the link to the video
http://www.youtube.com/watch?v=bJKHgz3ZP-I
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5thfloor



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PostPosted: Tue Oct 26, 2010 8:43 am    Post subject: Reply with quote  Mark this post and the followings unread

Don't know if this is still for interest here....but... BOTH schematics are CRAP!
Crams schematic is a little less crappy but I suppose that they both couldn't read a datasheet Wink
Thank you Mr.Curtis, this is my absolute favourite.

You may look at the book for the face...
PHILSYNTH - Guerilla Synthesizers

newest project: HOLGER MEINS analogue desktop semi-modular synthesizer based on CEM3394 and CEM3310.

Last edited by 5thfloor on Mon Nov 01, 2010 8:48 pm; edited 1 time in total
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phdinfunk



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PostPosted: Tue Oct 26, 2010 9:14 am    Post subject: Reply with quote  Mark this post and the followings unread

fluxmonkey wrote:
i believe the schemo richardc64 posted is and old Electronics For Music design... in general, those designs were meant to be pretty barebones rudimentary, but were often buggy as well.


I'm quite certain that is the source. I remember this one well.... always thought it looked so simple.

I would be willing to assume TomG at least breadboarded that circuit.... however, it may be written down with an error or two just for fun.
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5thfloor



Joined: Oct 26, 2010
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PostPosted: Tue Oct 26, 2010 11:49 am    Post subject: Reply with quote  Mark this post and the followings unread

...yeah, just go ahead and don't care about capacity,impedance and currents Rolling Eyes Confused
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Blue Hell
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PostPosted: Tue Oct 26, 2010 12:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

5thfloor wrote:
...yeah, just go ahead and don't care about capacity,impedance and currents Rolling Eyes Confused


Shocked Laughing

welcome 5thfloor.

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The Peasant



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PostPosted: Tue Oct 26, 2010 2:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

phdinfunk wrote:
fluxmonkey wrote:
i believe the schemo richardc64 posted is and old Electronics For Music design... in general, those designs were meant to be pretty barebones rudimentary, but were often buggy as well.


I'm quite certain that is the source. I remember this one well.... always thought it looked so simple.

I would be willing to assume TomG at least breadboarded that circuit.... however, it may be written down with an error or two just for fun.


With regards to Tom G I think that you are being too kind. I found all of his circuit designs that I worked with to be complete crap, most required a complete redesign to be functional at all. The worst part about it was that he took down his web pages with all of the technical info needed to use his pcbs, leaving everybody who sent him money in the lurch. He claimed that other prople were "stealing" his designs, even though they were all derived from other people's circuits in the first place. I will never go anwhere near any of his so called "designs" again.

So, does anyone have any suggestions for using a CEM3396 chip in a similar manner, or is this one pretty much useless without digital control?

Take care,
Doug

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richardc64



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PostPosted: Tue Oct 26, 2010 2:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

5thfloor wrote:
Don't know if this is still for interest here....but... BOTH schematics are CRAP!


I thought I said that, just not as bluntly -- which some would say is out of character for me. (I'm looking at you, RF.)

But yeah, both schemas ignore voltage input limitations stated in the datasheet. The Cram circuit is better about that in some places, the E4M is better in others. If anyone is interested, I've copypasta a schema together that at least tries to take into account the voltage restrictions.

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emdot_ambient



Joined: Nov 22, 2009
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PostPosted: Tue Oct 26, 2010 2:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

Don't know anything about that chip, but according to the datasheet:

http://www.synthtech.com/cem/c3396pdf.pdf

Quote:
The CEM 3396 is a complete system for the generation and processing of audio waveforms in electronic musical instruments. Intended to be driven from digitally generated square or pulse timing signals...
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Jojjelito



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PostPosted: Wed Oct 27, 2010 5:02 am    Post subject:   Reply with quote  Mark this post and the followings unread

emdot_ambient wrote:
Don't know anything about that chip, but according to the datasheet:

http://www.synthtech.com/cem/c3396pdf.pdf

Quote:
The CEM 3396 is a complete system for the generation and processing of audio waveforms in electronic musical instruments. Intended to be driven from digitally generated square or pulse timing signals...


Errrm, been through this already - imagine that your oh so precise timing signal derived from a crystal or MCU timer pin instead is a garden-variety square wave sitting between 0 - 5V, say from another VCO. The 3396 doesn't need to be told for sure Shocked !

As has been stated earlier on, the follow-up is to apply noise, sync and waveform select signals PLUS keeping the waveshape constant with varying frequencies. Therein lies the trick.

On with the 3394 show instead.
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soundlimit15



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PostPosted: Thu Apr 28, 2011 10:09 pm    Post subject: CEM3394 Reply with quote  Mark this post and the followings unread

Has anyone got the CEM3394 chip working successfully? Cheers,soundlimit
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5thfloor



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PostPosted: Fri Apr 29, 2011 5:21 am    Post subject: Reply with quote  Mark this post and the followings unread

yes. just read my post above

PHILSYNTH- Guerilla Synthesizers
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fonik



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PostPosted: Fri Apr 29, 2011 2:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

and akai and sequential circuits did it.

however, i would think the question in this DIY forum would be: HOW to do it without digital control. at least that was the content of this thread as i understood it. would buying one of your products help me?

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5thfloor



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PostPosted: Fri Apr 29, 2011 3:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

confutius says: he who doesn't even know the use of voltage dividers and opamps, shouldn't try to massacre good old vintage chips.
I don't know your problems with this piece of cake one. Just look into the datasheet. everything is written down and even explained in a sophisticated way.
please just sell your cem's to people who can deal with electronics instead of melting nice ICs. they are to good to be wasted.

so much for me in this forum, it is annoying...over and out
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