MMM going DIY

Dedicated forum for the MMM synth modules, both production and DIY units.

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wetterberg
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Post by wetterberg » Sat Jan 02, 2010 5:15 am

Hi George; quick DIY question:

On the wonderful little VC mixer, is it possible/difficult to get the individual VCA outputs before they're mixed? If so then this little 80 dollar package is a really neat way to get 4 vcas and a mixer.

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Post by mmm » Sat Jan 02, 2010 11:30 am

wetterberg wrote:Hi George; quick DIY question:

On the wonderful little VC mixer, is it possible/difficult to get the individual VCA outputs before they're mixed? If so then this little 80 dollar package is a really neat way to get 4 vcas and a mixer.
Not easily with this board. All of the gain cells are tied together before the final output buffers. One buffer for the inverted out and one for the non-inverted out.

But, I do have a "dual VCA" on the drawing board. It's dual just because I run out of holes in my standard panel and would have no room for mod inputs but, now that you brought it up, I could add some DIY capabilities on my future designs knowing that some won't be constrained by a 3.5"^2 4x4 hole panel :)

Thanks for pulling that stopper out of my head wetterberg! Mmm- this will be fun :banana:

<edit> added:
I should also mention that the VC mixer IS 4 VCA's and a mixer. If no control inputs are used, it's a mixer. The 5V for the gain cells are cascaded through the jacks so, you can plug some other control CV into the later channels and control those and subsequent channels while the upper (lessor-least numbered?)channels are still a mixer. It works for CV processing too. The only caveats are: There is no additional modulation input per channel (wasn't room) and, there are only two outputs: inverted and non-inverted. But, the attenuators work nicely for setting max limits on CV's. It's really a handy little module.

Also, I calibrate the outputs to equal the inputs at full 5V CV. But, there's a trim pot for each channel to set the gain that can drive it well into full blown-square-wave clipping per channel. So, for those of you that like to uber-mangle waveforms...you just need a screwdriver 8_)

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Post by Morley » Sat Jan 02, 2010 1:37 pm

Sounds good!!

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Post by redmartian » Sat Jan 02, 2010 4:02 pm

johnnymad wrote:i still think it's a great idea even if it isn't "true" diy. you've got to start somewhere.
Yep, "true" diy would be designing your own shit, right? This is merely a
cheap avenue to a great sounding synthesizer.

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Post by mmm » Tue Jan 05, 2010 11:59 pm

Finally, the WIKI is pretty much structured and everything that's important is available in the cart.

Thanks to all of you who have been emailing me. This should make it easier. :banana:

http://mmm.sevcom.com/wiki/index.php/DI ... DIYcisions

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Post by fluxmonkey » Wed Jan 06, 2010 10:00 am

really looking great, thanks for all the hard work!

if anyone else is considering doing frontpanels in any of the standard formats, you might consider the ModularSynthPanels yahoo group... a great resource for sharing front panel designs. originally this was set up by MOTM customers doing panels in Front Panel Designer, but it since diversified & includes other formats. would be cool to wind up w/ something like Oakely, with customizable FPD files to go with the different modules.
www.fluxmonkey.com

BUILDER FOR HIRE - kits or custom, email me with your needs

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Post by mmm » Wed Jan 06, 2010 10:49 am

Two things that wear me out trying to source so I can give references to the group are custom panels at a reasonable cost, and trying to track down 90 degree angle brackets that are about 1/4" wide and around 1/2" to 3/4" per leg with a 4-40 threaded hole. Actually, the thread really isn't an issue.

I know they exist but, I sure can't locate them.

The brackets I used for the edge mount pix I picked up at Ace hardware. They're a bit big and care must be used to make sure they don't connect up a bunch of traces that shouldn't be connected.

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Post by qu.one » Wed Jan 06, 2010 11:02 am

mmm wrote: All of them hover right around $75.00
That is a great price point. Can't wait to have a row of custom MMM acrylic modules.
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Post by BananaPlug » Wed Jan 06, 2010 11:17 am

mmm wrote:Two things that wear me out trying to source so I can give references to the group are custom panels at a reasonable cost, and trying to track down 90 degree angle brackets that are about 1/4" wide and around 1/2" to 3/4" per leg with a 4-40 threaded hole. Actually, the thread really isn't an issue.

I know they exist but, I sure can't locate them.

The brackets I used for the edge mount pix I picked up at Ace hardware. They're a bit big and care must be used to make sure they don't connect up a bunch of traces that shouldn't be connected.
These are tiny about 5/16 or 3/8 on each side.
Mouser part# 534-612 (one hole threaded) or 534-621 (both threaded, 4/40).

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Post by mmm » Wed Jan 06, 2010 12:02 pm

BananaPlug wrote:
These are tiny about 5/16 or 3/8 on each side.
Mouser part# 534-612 (one hole threaded) or 534-621 (both threaded, 4/40).
Beautiful !!!

Thanks BananaPlug :nana:

I knew I could count on this group. I'll have to order some on my next order and check them out. If they work, I'll toss them into the "Convenience Accessories" page.


The orders are coming in. Mostly from overseas. Cool. And a big THANK YOU to all of those guys.

My existing cart (which is currently being replaced) only generates a US shipping fee.

If you're not a domestic customer, please email me first until we get a cart operational that actually covers the details.

Thanks

G

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Post by Scottzilla » Thu Jan 07, 2010 3:20 am

There's an international shipping option that you can add to the cart that fixes non-US shipping prices.

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Post by pugix » Fri Jan 08, 2010 9:52 pm

I'm wondering how to wire up to the headers (excluding the power connector, which I understand). What is included in these wiring kits?

http://mmm.sevcom.com/wiki/index.php/Wire_and_Cable

What are the part numbers for the mating connectors?

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Post by pugix » Fri Jan 08, 2010 10:09 pm

Never mind. I missed this page:

http://mmm.sevcom.com/wiki/index.php/DI ... onventions

The headers are all 3-pin 0.1" MTA connectors. Now I'm wondering if I want a tool to press the wire into the connector or to just solder these. Sure sounds like I'm interested in these, doesn't it.
:hyper:
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Post by mmm » Fri Jan 08, 2010 10:24 pm

Phew, glad you found that, I was just going to try to explain it.

The wire kits just have the 3-pin MTA 0.100 socket connector already connected to the 2 or 3 wires necessary to hook up the wire 'cable' to the module (just plug it on the correct on-board header spot-they're labelled)
The 2C or two wire cables are a connector and 8" length of a red wire in pin 1 and a black wire in pin 3. The 3C or, 3 wire cables are the same only, there's a 8" length of white wire connected to pin 2. All of the wires in each cable are twisted together.

The other ends of the wires are just blunt cut. I figured that the customer can determine how long it should be for they're panel arrangement, cut, trim, tin the ends and solder them to their panel components.

Each module page in the WIKI specifies the wire kit necessary to connect the module to the "standard" panel components. It also lists the wires in the wire kit, where the connector attaches to the module board and what component the other end attaches to. I really tried to make it easy. The wiring page for each module also has a link to open it up in a PDF format for downloading and printing.

The wire kits range in price based on how many there are. The more cables, the more it costs. The noise generator only needs three but, the VC Mixer needs 15. For some reason, it takes me 5 times longer to make those. :eek:

They're offered as a convenience. People could always make their own.

George
Last edited by mmm on Fri Jan 08, 2010 11:04 pm, edited 1 time in total.

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Post by mmm » Fri Jan 08, 2010 11:01 pm

Oh, yeah.

I forgot. If you go to my cart there's a picture of about 7 or 8 of these cables in the cart. All the pix are the same for each wire kit even though the actual wire kit depends entirely on how many cables are needed. It gets the idea across.

I need to get that pic from my brother and put it on the wire and cable page.

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Post by Peake » Sat Jan 09, 2010 2:56 pm

Excellent. Best results to you! 8_)
This is not the place I'd imagined it to be.

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Post by Luka » Tue Jan 12, 2010 4:33 am

just grabbed 3 filters :)
good replacement for my motm440

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D/A A/D
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Post by D/A A/D » Tue Jan 12, 2010 7:06 am

Can the LFO's run in audio range???

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Post by mmm » Tue Jan 12, 2010 10:36 am

Luka wrote:just grabbed 3 filters :)
good replacement for my motm440
So you did. What a nice thing to see before the obligatory morning cup of coffee even kicks in.

Thank you Luka. I'll email you from that side of the computer shortly.

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Post by mmm » Tue Jan 12, 2010 10:43 am

D/A A/D wrote:Can the LFO's run in audio range???
The LFO's are set to run in different decades. LFO1 runs at a slower rate than LFO 2 with an overlap between the two.

LFO 1 can top out at 12Hz.

LFO2 can top out at ...I believe just off the top of my (still not enough coffee) head, around 116Hz.

But, if you have a particular range you'd like to play around with, it's just a capacitor change. Maybe, I can come up with a simple way for people to attach some caps to a panel switch and just have a range function.

It's actually easy to do if anybody is interested in implementing that. Just let me know when you order.

Thanks all! :mrgreen:

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Post by mmm » Sat Jan 16, 2010 12:01 pm

BUFFERED MULTIPLE SALE

I've receive a lot of requests for information about the 4-channel x 2 output cascaded buffered multi's

I have a bunch so, I figured I'd drop the assembled DIY board price in my cart to $64.95 for a week until midnight Sunday 1-24-10

That's squeezing it down as low as I can go so, here's your chance.

They work equally well on +/-15VDC and +/-12VDC

For those that wish to mount the boards edge-wise. I picked up some of those 1/4" angle brackets with 4-40 threads that was suggested to me on this thread and they work beautifully. Thanks guys!

So, if you need a couple with your boards, let me know.

Outboard components that you will need are:
N/C interrupting-type jacks(12),
The panel of your dreams :)
Wiring to the jacks
Board power cable

It's a simple project and a rewarding utility for any format.

Thanks

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Post by pugix » Sat Jan 16, 2010 9:38 pm

mmm wrote:BUFFERED MULTIPLE SALE

I've receive a lot of requests for information about the 4-channel x 2 output cascaded buffered multi's
I'm planning to order one of these (and a VC Mixer DIY board, too). I thought I would put an attenuator pot on each input. Then I'd have 4 buffered attenuators, each with two outputs. The cascading might be a little weird, if I cascade the output of one channel to the next input, since all pots along the path would be involved. But I could alternatively cascade all the inputs (with the drawback of a 25K ohm load if I use 100K pots). What do you think?

I'd like to be able to distribute precise 1V/Octave keyboard CV with this, if my attenuator pots idea wouldn't interfere with accuracy (probably OK, if I cascade each output to the next input). While on that subject, how precise are these buffers? Do they use better than 1% tolerance resistors?

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Post by pugix » Sat Jan 16, 2010 9:39 pm

Oh, and what is the output impedance?

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Post by mmm » Sat Jan 16, 2010 10:40 pm

Hi Pugix.

If you put the tip of the input jack to the top of the attenuator pot, The bottom to ground and send the wiper to the channel input, it will work as an attenuator for the channel.

Anything you do to an input will be reflected to the subsequent channel outputs if the cascade feature is implemented using N/C interrupting switched jacks. To not use that feature. Just don't hook up the white wire (pin 2 on the associated connector) to the jacks. That's the previous channel feed to the next channel input.

For Keyboard CV's. It's close but, not as precise as I would like it to be. I found a workaround that I implemented in a precision buffer that I haven't made into a module yet but, implemented it on my VCO 1V/octave feedthroughs for daisy chaining them.

These are OK within 4- 5 octaves if you tune the VCO's to unison at the highest frequency. Any deviation on down isn't as noticable as tuning unison low and going higher.

The input impedance is 100K and the output is 1K.

The precision isn't determined by the resistors. The buffers are configured as a hard line unity-gain buffer. The input and output resistors are primarily for impedance matching. The deviation is within the manufacturing tolerances of the op amps. For anything but uber-precision, they do a good cloning job.

Keep in mind that if you hook up a pot for an input attenuator, pot's don't necessarily go all the way to 0 ohms from the wiper to the terminals at either end of the stops. That would affect precision as well.

Did I forget anything?

G

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Post by mmm » Sat Jan 16, 2010 11:05 pm

Actually, now that I think about it.

I really over-designed these things. (My version of OCD) :)

the subsequent channel feeds are also buffered with impedance matching prior to the feed so, you could use the feed to the next panel jack switched input as a third output for the previous channel.

That gives you 4 channels with three outputs each except the 4th channel. Which would only have two outputs.

You could still run one of those through a 1K resistor to the input of the next channel and still cascade them, if desired.

The switched pin of the channel 1 jack goes to ground to ensure that the outputs are silent if there is nothing plugged into channel 1.

As a side note, because of the excess buffering, the parallel loading of 4 input attenuators is negligible.

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