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My DIGISOUND 80 modular build project
MUFF WIGGLER Forum Index -> 5U Format Modules Goto page 1, 2, 3, 4  Next [all]
Author My DIGISOUND 80 modular build project
So I've made a start on my DIGISOUND 80 modular build from scratch.

Today I etched the PSU PCB and starting adding components, still lots of parts to arrive, I'm getting about 15 parcels a day of bits from Ebay.

Here are some pics of the PSU build.

Some parts missing off the board, but they will soon be here.

Just starting on a VCO board now.
Eric the Red
Wow. Just wow. I have read a lot about this system and this is a wild build yu ar getting yourself into.

Keep it u and I look forward to reading about it here.

How interesting! I will monitor this closely.

Out of curiosity why did you use a marker for the pcb mask? You could have just printed it since it's available.
Welcome to Muff's, craigyb! w00t

That's impressive you are going "old school" and drawing the PCBs by hand! eek! we're not worthy How do you make sure the IC pads get aligned correctly?
That looks so cool.

And there's your answer ppkstat :-)

Thats how I started out, except I used a technical drawing pen and ink. Unfortunately I attempted a guitar amp and I could never figure out why it wouldn't work.
But with craigyb's example I'm tempted to try again. Looking forward to more.

Thanks for your input guys, I didn't know I could print out PCB layouts onto copper or transfers, so I kept it simple.

Chip alignment, trial and error, I printed out multiple copies of the PCB to paper until I could fit the DIL sockect onto the paper perfectly, this was then laid over copper board and dot punched every single hole. Just a case of joining the dots then etching and drilling. It's a method I perfected when I was 16/17 years old and is quick for board production.

I did a VCO board shortly after this and her is what I have so far, as I said, still waiting on a lot of parts to arrive. I only started the project 4 days ago.

a lot of modules used CEM chips. i imagine the recent clone of the 3340 will help with the VCO and LFOs?
holy cannoli! Truly a labor of love here. Interested to watch the progress.
fluxmonkey wrote:
a lot of modules used CEM chips. i imagine the recent clone of the 3340 will help with the VCO and LFOs?

I had a drawer full of CEM chips from my synth repair days, that's what inspired me to start building again.
So you need to give us a full life biography now.. or at least the synth related bits.
I hand drew/etched /drilled quite a few PCBs last century but it's hard work - kudos to you!
(I saw the PSU PCB on eBay a few months ago - the PCBs do turn up.)

When I built my Digisound 80 I got PCBs from Charles Blakey - long time ago!
If you insist. smile

I've been into electronics since I was 11, taking stuff apart and building projects from magazines. I got into electronic music at the age of 16, I started building various synths from magazines.

A full blown Elektor formant modular (cheated by using Digisound VCO's based on SSM chips) was a project I completed when I was 17. Foolishly I swapped that for a stage organ as I needed to gig and the Format was not really a gigging synth.

Lots of other music projects undertaken, Transcendant DPX which was a waste of time and money, it never worked properly and sounded awful (Thanks Tim Orr).

I started with a Korg Sigma a preset synth with some controls and I've had various pieces of kit over the years. Arp Quartet, Crumar Trilogy, Yamaha DX7, Roland JX10, D70, JV1080, Sound Canvas, TD7 and many others. I preferred Ensoniq gear as it was performance and sequencer based. I had the ESQ1, SQ80, TS10, ESQm. Finaly I got fed up of lugging stuff around and went with a Korg Trinity and hard disk recording system.

I put all my stage gear into my studio and recorded my shows to the Trinity and sequenced all the effects and lighting over MIDI. It was a pretty cool show in it;s day.

I gave up in 2002 and although I still have all my kit I didn't really have the time to play. But recently I have been updating the studio and getting things working again, replacing batteries in older stuff and testing everything. I had to buy a new midi interface to support later operating systems.

It was whilst chatting with my boss at work about the new OB6 and analogue sounds I decide to get back into analogue and build a synth, we were talking about the formant and I started looking for kits to build.

As I had a draw full of CEM chips it seemed sensible to start to build a digisound 80 and about 10 to 12 modules will be enough. I can't go mad. I'm going to MIDI to Cv control it and that should keep me busy for a month or so knocking it together.

I' away until the new year, so very little more will be done until Jan, I wish you all a merry Xmas and a happy new year.
Wow that's quite a list - you must be a similar vintage.
I remember seeing the Transcendant 2000 in whatever mag it was and thinking one day..
Brave man for not taking the Eurorack train and merry chrimbo to you too!
Couldn't resist a bit more work, I etched all the remaining boards bar 3 tonight. I ran out of PCB board after 10.

This is my VCF circuit coming along nicely.

Next module along as more parts have started arriving....

QUAD LFO, Saw, Square, Triangle and inverse of each X4

Circuit board

Home made aluminium front panel.

Had a spare day before the hols and started VCA and processor boards. H ad a bit if a scare as I started building the VCA with an older doc, 80-9 instead of 80-9A, I couldn't understand why the parts wouldn't fit the board layout.

Dual VCA board

Processor board

Time for a break now, happy hols
Very nice! I'm envious - I build my 11 module 80 from boards and parts I bought from Blakey in '82. Still works but needs some love which I am taking on now. I wondered about making my own boards too. Though maybe a little long in the tooth now, so looking for compatible units to add. But who knows - I need to get my soldering chops back. Good luck to you - it will be rewarding!
Back from my hols now and restarted the project.

Tonight I completed the QUAD LFO board and attached the front panel ready for wiring.

I think the knobs are too small, but they came with the pots so it seemed sensible to use them whilst I look for more suitable knobs.

Just a quick update

No sound yet as I've not finished a case for all of this.

The PSU is built and working, it's a long time since I've done anything like this and got the tantalum capacitors the wrong way around and blew a couple up. Other than that it worked fine.

And I've just finished wiring up the first VCO and a QUAD LFO, the VCF is just mounted and not wired yet.

Will hopefully have more done tonight and my case should be ready tomorrow to mount and test some modules and the MIDI to CV interfacel
craigyb wrote:

The PSU is built and working, it's a long time since I've done anything like this and got the tantalum capacitors the wrong way around and blew a couple up. Other than that it worked fine.

Nice to see all your progress, good job! thumbs up

Just curious, how are you going to do the power distribution from the power supply to the modules?
Nice to follow this!
I think general advice nowadays is to use electrolytics instead of tantalums - I believe size/capacitance of elecrtolytics has improved since then and if they fail electros don't short out.
JohnLRice wrote:

Just curious, how are you going to do the power distribution from the power supply to the modules?

I'm using 4 sets of 75cm 3 way Molex distribution cables for PC drives, I have soldered power sockets onto each board and can power them up indivdiually.

I've doubled up a few modules, the Noise board seemed to be a waste of space so I've built a combined noise and ring mod panel. The VCA was also rather bare, so I put 3x 6 way junctions into the unused space. Simply modifying the front panel designs to hold the extra bits.

I have one spare slot in my system, I was planning to put the Elektor formant 24dB/Octave VCF in there as an alternative to the standard VCF, but I might look at building a simple sequencer in there.
Finished off the VCF and Dual VCA with 3x 6 way patch panels

Starting to come together now, of course all of these is untested....

I'm so excited to see how this will all turn out! It looks awesome. I don't understand why you are doing the PCBs by hand, but that's what makes this build thread so interesting. First time I've seen a Digisound build too, can't wait to hear it! How big do you plan to go?
I wasn't sure if you knew that Rapid Electronics sells the power connectors that Digisound used to use. -housing-pcb-connector-female-22-0042

This might allow you to use a more bus board to connect your modules to your PSU if you prefer.

[edit] Just noticed that the male connector has a Minimum Order Quantity of 200, which is a bit odd when it's only 10 for the female connector. Might be worth contacting Rapid to see if this is in error. [\edit]

Also, if you need it, I have all of the original magazine articles for these projects, so can sort out high-res scans if they are of any use.

I have a couple of Digisound PCB's in my workstack, a VCDO and a VC-ADSR, though I will be building these in MOTM format. I might get round to building them in the not too distant future hopefully.


Not had much time to carry on with this, but managed to build the Elektor Formant 24dB/Oct VCF and the ARP Odyssey MK3 dual VCO's.

Will hopefully get things into the case that has arrived this weekend and start testing and making some sound.
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