LARGE MFOS System

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southphillysynths
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LARGE MFOS System

Post by southphillysynths » Mon Jun 22, 2020 6:22 pm

Wanting to get some thoughts on building up a large MFOS system. There are two main issues I'd love insight on:

1. POWER

I recently acquired the following, all of which seems to be working properly!

Sound Lab Ultimate (actual draw between 90-100, doing more than that for safety is recommended on the website)
Sound Lab Ultimate Expander (actual draw between 90-100, doing more than that for safety is recommended on the website)
Delayed Modulation (~+/-20)
Wave Freaker (~+/-40ma)
Phase Shifter (~+/-20)
Analog Sonic Multiplier (~+/-30)

I hope to add:
Weird Sound Generator (not sure, most likely ~35ish)
Ecko Rockit (35ma)
Noise Toaster (30ma)
Alien Screamer (maybe) (10ma)

It is all currently using one of the MFOS DIY Walwart supply with 6 caps. I'm not sure that this would add too much current draw to that supply by adding the above circuits. I have listed the current draw from each of the modules as stated on the MFOS Build site.

I feel like for a project like this, I might rather buy robust off the shelf type of supply, just to be sure. The current set up is an absolute nest and I want to do these things justice!

Now that I think about it, the additions I want to make run on 9V batteries normally...

2. CASING

I see 3 options:

1. I wanted to try to make this rack mountable but any way I would go about it, these front panels are extremely strange sizes to accommodate home face plate printing. I'm not sure how to position them to get it to fit in 19'',

2. Grab a Haliburton suitcase and built it all into that.

3. Build a large slanted wooden case with everything mounted inside (ala .com studio systems)



All of this may be polishing a turd, BUT I have built of few of his circuits in the past and was a great inspiration. Only interacted with Ray once, but he was the absolute nicest and want to honor him as best I can at least by building this all up to be more robust than it is now! You can really tell he put a lot of listening in on these modules, they just sound great!
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Re: LARGE MFOS System

Post by Elahrairah » Mon Jun 22, 2020 7:09 pm

An easy way to see if your little powersupply is getting overworked is to see how hot the linear regulators are. If you can't touch them for more than a second, then they're working too hard already.
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Re: LARGE MFOS System

Post by Bodo1967 » Tue Jun 23, 2020 2:47 am

southphillysynths wrote:
Mon Jun 22, 2020 6:22 pm
All of this may be polishing a turd
Not really, the stuff sounds great and can be lots of fun :tu: .
southphillysynths wrote:
Mon Jun 22, 2020 6:22 pm
Only interacted with Ray once, but he was the absolute nicest and want to honor him as best I can at least by building this all up to be more robust than it is now!
I was likely among the last builders to order directly from him, and I can absolutely confirm this. I still have the e-mails from (iirc) September 2015.

Re: power supply
I built a linear regulated PSU for the MFOS Ultimate + Expander:
32025_01imgp1765_1.jpg
And if you haven't found it already - here's a ton of info and pictures by several builders including myself.

This is how my Ultimate w/Expander and modular looks now:
01IMGP3620.jpg
The modules are not all MFOS, but many are - including "Delayed Modulation", "24dB/oct VCF", "Triple Triangle to Saw Converter", "Dual Lin/Log VCA", "8 Stage Phase Shifter", "Dual* 3 in 1 Audio Mixer", "Noise Cornucopia", "CV & Gate Distributor", "Echo Rockit". "Wave Freaker" (still) needs troubleshooting but is intended to go into the gap in the second row from the top.

* Half-built Quad, because I didn't have enough space for a quad panel in the case :mrgreen: . I do have a fully built "Quad 3 in 1 Audio Mixer" plus two "Auto Stereo Panners" in a separate desktop box though.

The module cases also have linear regulated PSUs.
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... why buy it for $100 when you can build it yourself for $150?

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Re: LARGE MFOS System

Post by Jarno » Tue Jun 23, 2020 7:03 am

I would chuck in a few Meanwell supplies, hefty ones for +12v and -12v, smaller one if you have stuff that runs on nine volts. Maybe make sure that all modules have good supply filtering (because the SMPS supplies are a bit noisier than linear ones).
But yeah, those Meanwell supplies are really low cost, and work well.

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Re: LARGE MFOS System

Post by southphillysynths » Tue Jun 23, 2020 7:44 am

Thank you all!

To be clear, my initial tests I'm very surprised about how good it all sounds!! I've always loved the filters on MFOS gear, even the WSG has a super great filter, you can tell Ray really took the time to tweak values to dial it in.

I have looked through that thread in preparation, I'm still not sure how I would go about making this rack mount, I think the expander would have to go under the ultimate, unfortunately if they were next to each other it ends up being 21"
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Re: LARGE MFOS System

Post by EATyourGUITAR » Tue Jun 23, 2020 7:49 am

The WSG was such a one trick pony and they get decent money on ebay. I could never keep an WSG. My advice would be to keep the sound lab ultimate. Build a matching case for expansion.
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Re: LARGE MFOS System

Post by southphillysynths » Fri Jun 26, 2020 9:11 pm

Jarno wrote:
Tue Jun 23, 2020 7:03 am
I would chuck in a few Meanwell supplies, hefty ones for +12v and -12v, smaller one if you have stuff that runs on nine volts. Maybe make sure that all modules have good supply filtering (because the SMPS supplies are a bit noisier than linear ones).
But yeah, those Meanwell supplies are really low cost, and work well.
Thanks for that, can you recommend one? Larger amperage would be better so I can power the ultimate, expander, and 4 other modules I got as an expansion. I think I will do something else with the noisebox/9V stuff.
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Re: LARGE MFOS System

Post by EATyourGUITAR » Sat Jun 27, 2020 5:54 pm

RDDW08F-12
this meanwell outputs 333mA per rail. you will need a DC power brick at least 2A to be safe. power brick ratings may not tell you what is continuous or max. a cheap 4A brick may actually be a good match. 12v or 24v anything will work with this meanwell as long as you get the polarity right.
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Re: LARGE MFOS System

Post by southphillysynths » Sun Jun 28, 2020 12:28 pm

Wonderful!

Thank you for posting that, I will look further into it EATyourGUITAR

As I look further into the innards of what I have, I am going to try and stick with the ultimate + expander and the modules above as a single system (minus the midi, no need for it)

I found an almost perfect rackmount frame to use that will fit the ultimate/exp vertically

(https://www.odysseygear.com/product/ars ... 10u-shelf/)

The only issue being it is EXACTLY the height of 10U, so not sure if it will really work out. I plan on mounting the other two panels in a 4U serge type budboat and some how affixing it to the above mentioned rack frame. This will end up being 14U, really wish I could find the above type frame in exactly 14U!!

Anyone know of such a frame of that size?
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Re: LARGE MFOS System

Post by southphillysynths » Sun Jun 28, 2020 5:11 pm

Also,

There are two of these boards made by whoever built this, only present in the Ultimate, and the delayed CV box.

Anyone know what they could be for?
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Re: LARGE MFOS System

Post by EATyourGUITAR » Sun Jun 28, 2020 7:33 pm

LM324 is an opamp. There is one resistor and one capacitor. The cap is probably across the power rails of the opamp. Check what pin number the resistor is on. Check if the opamp connects to some input or output jack. Count pins from pin 1 counter clockwise. Start at the indent.
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Re: LARGE MFOS System

Post by southphillysynths » Mon Jun 29, 2020 7:46 am

Right, so to clarify there is one in the expander box and another one of these boards in the delayed modulation/wave freaker box.

The resistor goes to ground, it looks like the one in the expander is slightly different from the one in the other box.

The one in the expander is a tlo74 with +12V to pin 4, -12V to pin 11, a resistor to ground from pin 3.

The wavefreaker has lm324, to pin 11 through a cap from .12V. +12V to pin 4.

Does any of that make sense?
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Re: LARGE MFOS System

Post by EATyourGUITAR » Mon Jun 29, 2020 8:44 am

the opamps have pins 4 and 11 to power the opamps. this is the case no matter what purpose the opamp serves. resistor from pin 3 to ground with no resistors on any other pins would make me think it is wired as a comparator. without seeing what else is wired to the opamp, I can only speculate. anyway, opamps have inputs and outputs. the TL074 is a quad opamp made of 4 identical opamps. each opamp has 2 inputs and 1 output. usually one of each input is connected to a voltage that will never change. the other input pin becomes the actual input. if you were to look at the pinout for each IC, then follow the wires to the sources and destinations, you will know exactly what is going on.
tl074-pinout-diagram.png
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Re: LARGE MFOS System

Post by johnstilton » Mon Jun 29, 2020 9:59 am

Good Luck with your Large MFOS build!

I am also in the process of a Large MFOS build (which is currently on-hold because I am moving) and have been documenting my progress in the MFOS board hosted here on Muff Wiggler. Please also share your progress there so it can be easily found in the future!

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Re: LARGE MFOS System

Post by Schlumpfhut » Tue Jun 30, 2020 7:35 am

Soundtronics in the UK offers an semmingly easy to build bipolar power supply which might be one of the more simple way to power a MFOS system.

https://www.soundtronics.co.uk/modular- ... er-supply/

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Re: LARGE MFOS System

Post by southphillysynths » Fri Jul 03, 2020 10:02 am

johnstilton wrote:
Mon Jun 29, 2020 9:59 am
Good Luck with your Large MFOS build!

I am also in the process of a Large MFOS build (which is currently on-hold because I am moving) and have been documenting my progress in the MFOS board hosted here on Muff Wiggler. Please also share your progress there so it can be easily found in the future!
Absolutely, I will do that! Want to keep it on DIY for now just to get the most help possible, then I'm happy to cross post it back to MFOS.
Schlumpfhut wrote:
Tue Jun 30, 2020 7:35 am
Soundtronics in the UK offers an semmingly easy to build bipolar power supply which might be one of the more simple way to power a MFOS system.

https://www.soundtronics.co.uk/modular- ... er-supply/
Thank you very much for that, this was insanely helpful! So, I already have the MFOS supplies, I may use their busing boards for example which will make power distro easier...

BUT the front panels are amazing!!! This would actually cut out a ton of work on drilling and re-paneling the boxes you see above. They even have an Echo rockit panel!! I will most likely end up using that, very reasonable prices for panels as well. I don't really understand the plastic front panel, then metal back panel but if it works...

I also hope I can use Banana Jacks on the holes, can't find a spec anywhere on their site about what size the holes for jacks are drilled. I know 1/4'' and nanners are interchangeable on a 3/8'' hole.

I am going to take a closer look at everything to figure out those mystery boards and will post momentarily.
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Re: LARGE MFOS System

Post by southphillysynths » Fri Jul 03, 2020 10:43 am

These mystery PCBs look to be daisy chained off of the power connections on the expander and Delayed Modulation/Wavefreaker box. It looks to be carrying CV to either box.

I think it best to remove these boards entirely, wire everything as it should be and see what happens.
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Re: LARGE MFOS System

Post by EATyourGUITAR » Fri Jul 03, 2020 7:49 pm

can you follow the wires with your finger to see where exactly they go? we can help you before you disconnect it. after you disconnect, it will be harder to see what was modified. if you also need to repair something, we need to know what the other technician did.
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Re: LARGE MFOS System

Post by southphillysynths » Tue Jul 07, 2020 7:32 am

They were really causing more issue and confusion than was worth it to be honest. They looked to be carrying CV from the jacks on the expander's analogue multiplier to the CV distribution in the bottom left box. Most likely carried buffered CV from the expander to the other boxes, the previous owner couldn't tell me how they worked. They were also tacked on to grounding and voltage wiring with shredded wire in between.

The analogue multiplier on the expander was not even wired, so I wired that up once I removed those other PCBs.
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Re: LARGE MFOS System

Post by EATyourGUITAR » Tue Jul 07, 2020 7:48 am

Right ok. as long as you know how to put it back together. Beware the mfos schematics do not match the PCB exactly. After you do a mfos project one time, the rest become easy when you figure out how it is written.
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Re: LARGE MFOS System

Post by southphillysynths » Wed Jul 08, 2020 6:35 pm

I will figure it out!!

As I dive deeper, wondering a few things.

I ordered and received the odyssey rackmount tray. It's perfect! I may end up using it for more projects.

https://www.hollywooddj.com/odyssey-ars ... shelf.html

1. Would I be able to add a transformer and fuse to the main power supply? I would hope I could then just use a 3 prong power cord at the back, rather than a large wallwart type power connection. I like to keep my system pretty universal as far as power cables.

2. If I do use the soundtronics panels, I would want to build more than I already have listed above. They have panels for echo rockit, WSG, Noise Toaster, and many more. I feel like I may get into the slippery slope of building 10U more modules than just the phaser, delayed modulation, wavefreaker, and ring mod. Maybe this isn't a bad thing... but still!
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Re: LARGE MFOS System

Post by EATyourGUITAR » Wed Jul 08, 2020 6:47 pm

You can use a switching supply if you don't care about noise. Something like a meanwell. Then wire that to a fused IEC mains. The switching supplies are usually global automatic. I think that's the simplest most compact solution. You need to post your power requirements exactly.
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Re: LARGE MFOS System

Post by southphillysynths » Tue Jul 14, 2020 9:38 am

EATyourGUITAR wrote:
Wed Jul 08, 2020 6:47 pm
You can use a switching supply if you don't care about noise. Something like a meanwell. Then wire that to a fused IEC mains. The switching supplies are usually global automatic. I think that's the simplest most compact solution. You need to post your power requirements exactly.
Sound Lab Ultimate (actual draw between 90-100, doing more than that for safety is recommended on the website)
Sound Lab Ultimate Expander (actual draw between 90-100, doing more than that for safety is recommended on the website)
Delayed Modulation (~+/-20)
Wave Freaker (~+/-40ma)
Phase Shifter (~+/-20)
Analog Sonic Multiplier (~+/-30)
Ecko Rockit (35ma)

So looks like ~ +/- 310ma in total if I'm understanding things correctly.
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Re: LARGE MFOS System

Post by EATyourGUITAR » Tue Jul 14, 2020 12:19 pm

RDDW10H-12

ok I would write that as 310mA per 12v rail but I understand what you are saying no worries. here is the new part number for a dual 12v supply max load 410mA per rail. this puts it at %75 load which is perfect if you ask around. look for 19v or 24v DC laptop power supplies rated 3A to 4A. I found one from a breathing machine. medical quality. people throw this stuff in the trash. dumpster dive. get a job at a recycling station. ask around. if it is an HP laptop power supply, there is a problem, you need a 3 terminal socket and you need to set the max current of the laptop power supply with pullup and pulldown resistors. basically don't use HP laptop power bricks!
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Re: LARGE MFOS System

Post by belltones » Tue Jul 14, 2020 7:50 pm

OK, you don't have to dumpster dive a medical power supply or use a stack of Meanwell switchers, there's a very concise, affordable and neat way to get/build a *linear* power supply for this.

Start with the MFOS Adjustable Bipolar Power Supply (PCB on Synthcube: https://synthcube.com/cart/MFOS%20Adjus ... Bare%20PCB)

This is a real linear power supply where you build the board and then buy your choice of a transformer which you just wire to an IEC connector and power switch in your enclosure. You get clean, regulated DC and you have complete control over your wiring. It's not just the "official MFOS" way to do it, it's actually, as far as I know, the most convenient/concise path to a bipolar linear power supply for any synth. It was basically just adapted from the datasheet for the regulators. It's so convenient but good that we've actually used it to replace PSUs in vintage synths with terribly designed PSUs multiple times. I also have one to power the 5U system I'm trying to build for the shop (which includes some stuff you gave us, Stefano ;) We still have some MFOS boards of yours we haven't used! let us know if you want them back )
It can supply up to 1.5A and if later you decide you need more current, you only have to replace the transformer!

Here are some transformers that work well with it.
24VAC / 12VA, so up to ~250 mA per rail: https://www.digikey.com/product-detail/ ... -ND/952960
This one is only $12 and quite small. I've used it a bunch of times. If your total current draw is 310ma it's not drawing *all* of it from the positive rail so it would probably be fine now, but it would not leave you much room for expansion.

24VAC / 24VA, so up to ~500mA per rail: https://www.digikey.com/product-detail/ ... ND/5032175
This one is less than $14 for twice as much juice!

The above 24VAC output ones are good if you're doing +/-12 but if you want to do +/-15V you need about 28-32 VAC as your transformer output.

Here's one: 28VAC / 30 VA, so up to ~600 ma per rail: https://www.digikey.com/product-detail/ ... -ND/270148. about $16? I think this is what I used for the 5U system.

Another thing to note though, is that if I remember correctly, the Echo Rockit at least (and possibly some of the other MFOS 9V-friendly boxes) uses a positive voltage as a virtual ground so it's a little complicated to integrate it with bipolar-powered things like the SoundLab and virtually every other synth module on earth. You will need to reorganize the Echo Rockit power supply scheme a bit to power it with a bipolar supply, you can't just connect it to +12 and 0V in a +/-12V system; otherwise it will stop working when you try to patch it to the other stuff, because its virtual ground will get pulled down to 0V.
Last edited by belltones on Wed Jul 15, 2020 8:42 pm, edited 4 times in total.

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