Digisound 80 refurbishment

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nerdware
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Post by nerdware » Tue Aug 27, 2019 11:43 am

StateVariable wrote:I have the 80-6A low-pass and the 80-7A SVF. My SVF is still out of action waiting for the switch to get cleaned up, but I remember the 4-pole LPF mode sounding the same as the 80-6A to my ears. I used to have them patched on two voices and they sounded comparable to me. I never liked the 2-pole modes on the SVF and never used anything but the the LP-4 setting, but my tastes have changed a bit since it was last powered 25-30 years ago so I'll have to try it again and see.
I never liked the 2-pole modes either. Even today I rarely use them, on any filter in any format I've used. That's just my individual taste. Other people clearly love them, and they may well love the 2-pole modes on the 80-7A. However, I don't mind using them on some signals, like noise.

Also: thanks for reminding me that my SVF modules are the later 80-7A version. They definitely use different chips, so this is an important detail. So my "disappointment" is clearly being unfair to the 80-6A and I don't want anyone to take it too seriously. This is just personal taste.

Thanks.
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StateVariable
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Post by StateVariable » Thu Sep 05, 2019 6:56 am

snufkin wrote: What modules did you add whilst restoring StateVariable ?

Seems there are quite a few systems being resurrected here

would love to hear more about module selection :)
None of the ones I added were Digisound modules so I don't know how much help I can be with module selection. My system is small, I started in the early 80s with three 80-2 VCOs, one 80-6A LP VCF, one 80-7A SVF, one 80-9 dual VCA, one 80-18 dual ADSR, the 80-1 PSU and two 80-15 DACs running from the keyboard controller and from a Tangerine computer I had at the time. I wrote lots of machine code and wanted to be Chris Franke or Thomas Dolby, so two simple subtractive voices worked fine for me and I was very happy with that set of modules. A bit later I decided I wanted to be Robin Guthrie, and later still played with making digital synths so the modular got put away.

Since I've got it out again I find I'm much more interested in playing with generative patches, algorithmic composition and more complex sounds. Here is what I've built so far to go with the originals, I kind of followed what I felt I needed to make what seemed like interesting music:

- Made the 2 DACs into a single MIDI input module with a couple of arpeggiators and simple step sequencers, so I can still play at Tangerine Dream when I want. I have an old K1 that makes a much better keyboard controller than the Digisound one and I added velocity, pichbend, mod LFO etc.

- Clouds (yes, I know). That came out of simply wanting some delay and reverb, and realising Clouds would be much cheaper to DIY than a spring reverb and a PT2399 and would be more flexible. I think it cost about £50 in the end so maybe I was wrong, but it is fantastic as a sound source so now I'm back to designing separate reverb & echo... I built it on perf board and there are a couple of pics in the DIY forum from a year or so back.

- A quad LFO that can also work as 4 AD envelopes and goes down to several minutes period. This has been a lot of fun to play with, you can set up a whole piece to evolve over a couple of mins. (Arduino based)

- An interface to an old digital drum sound module from an electronic drum kit. It just puts out very short 12v pulses when it gets gates on 9 inputs, and amplifies the output to modular levels.

- A quad Euclidian pattern generator (also Arduino based). I didn't really like the look of most of the versions that are out there, I found having numeric displays of length and density for each channel was much more useful than led matrices or circles, and I wanted VC of density. This one really is a lot of fun to play with. It has a bunch of red 7-seg displays and looks pretty good too. I should do a write-up of it sometime.

- Output mixer with headphone amp. Much more useful than I thought it would be. I don't use the mixing aspect much but the headphone amp is great to have in the rig. I think 2 or 3 separate mixers elsewhere in the rig will be more useful.

I also find I need a bunch of passive attenuators and multiples. I'm toying with the idea of Plaits once I start my second rack, it seems very much in the Digisound spirit.

Don't know if that's any help. I love the Digisound designs and aesthetic but I don't seem to be gravitating towards more Digisound modules right now.

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Post by ianski » Tue Dec 03, 2019 6:36 am

Thought I'd finally post here and stop lurking after making an account recently... I'm responsible for the (pretty dry) YT video from the Synthesized event at the Cambridge Museum of Computing History.

It's great to see the old Digisound still getting some love, mine's still going strong. I have a bunch of work to do on the system next year... general servicing, another cabinet to make, modules to repair, modules to build, changing one of the VCF-L's to an "H" and trying to get the Alphadac system working. I'll post up my progress when it eventually gets going.
Hopefully the expanded system will be at the Synthesized event next year.

I really like the 80-6 but the complete lack of resonance on all my SVF's is annoying - I still can't work out if they have faults or if that's as good as they get. Maybe I should post up some demos for comparison? I think all my SVF's are the later CEM type, need to double check that!

I'll get some photos online of how it looks currently soon. Cheers.

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Post by nerdware » Tue Dec 03, 2019 6:56 am

FWIW, my 2 SVF (80-7A) modules don't oscillate either. I've always assumed that's a feature and it doesn't bother me. Whenever I wanted a filter to oscillate, I've used the VCF-L (80-6L). So I don't think your modules are unusual.

BTW, one of my regrets now is not getting a VCF-H and VCF-B. I have a VCF-P instead, which I still love.

Also: welcome to Muffs! :tu:
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Post by StateVariable » Tue Dec 03, 2019 9:19 am

I know that video ianski - not dry at all :) - lovely system! Welcome to Muffs! Keen to hear about any Alphadac progress, I lusted after one of those in my teens!

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Post by ianski » Tue Dec 03, 2019 10:02 am

nerdware wrote:FWIW, my 2 SVF (80-7A) modules don't oscillate either. I've always assumed that's a feature and it doesn't bother me. Whenever I wanted a filter to oscillate, I've used the VCF-L (80-6L). So I don't think your modules are unusual.

BTW, one of my regrets now is not getting a VCF-H and VCF-B. I have a VCF-P instead, which I still love.

Also: welcome to Muffs! :tu:
Thanks!

That's what I'm hearing in general, but the resonance is SO weak I don't see the point of being able to CV it at all. I'll make sure to check any op-amps or other components though as I've had VCO's not working but using a known good CEM, which turned out to be something else.

One of my filters is the "B" version - it's really great and very 'squealy', and I have two set up as "P's" - yes very subtle but still nice sounding. I need to try out that idea of feeding back the input though.
I have the parts to swap one of my other "L's" to a "H" already, I just haven't got round to it yet (my growing Eurorack system is taking up a lot of my time recently outside of work). :oldmanureuro:

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Post by ianski » Tue Dec 03, 2019 10:06 am

StateVariable wrote:I know that video ianski - not dry at all :) - lovely system! Welcome to Muffs! Keen to hear about any Alphadac progress, I lusted after one of those in my teens!
Thank you, glad someone liked it!
I keep threatening to sort out my own channel and do more videos, I've got a decent amount of cool musical gear. Maybe next year...

I did have a look at the Alphadac bits when I first got them, and read all the documentation etc. but it looks like the PCB inside the keyboard has some wires off. The trouble is that the case of the keyboard is glued together so I might have to split it to fix it which I'm not looking forward too.

My Alphadac has a separate EEPROM with a "REC" label, so assuming it's the one supplied by Digisound with recording facilities. I'll try to get that dumped at some point. No idea how it actually works beyond what the documentation says though.

I have the 80-25 MIDI interface which is a rack mount device as well as a Kenton Pro 2K so I can control the synth no problem, but I'd very much like to get the Alphadac working as it was kind of ahead of its time, and I really like using equipment as it was originally designed to operate, plus it's a bit of history too.

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Post by nerdware » Tue Dec 03, 2019 12:31 pm

ianski wrote: Thanks!

That's what I'm hearing in general, but the resonance is SO weak I don't see the point of being able to CV it at all. I'll make sure to check any op-amps or other components though as I've had VCO's not working but using a known good CEM, which turned out to be something else.
Yeah, maybe that'll be it. I have no idea. The feedback trick really helps the SVF, I find.
One of my filters is the "B" version - it's really great and very 'squealy', and I have two set up as "P's" - yes very subtle but still nice sounding. I need to try out that idea of feeding back the input though.
I have the parts to swap one of my other "L's" to a "H" already, I just haven't got round to it yet (my growing Eurorack system is taking up a lot of my time recently outside of work). :oldmanureuro:
I have the same problem with Eurorack...and most of mine is video modules. :lol:
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Re: Digisound 80 refurbishment

Post by micromusic » Sat Jan 25, 2020 4:58 am

Here a pic of mine still lots of work in progress
A mix of Digisound Yusynth and MFOS all built from scratch by me over the last six years

From the bottom up
2 Digisound PSUs plus a 12 volt one for the MFOS modules and Sequencer plus a 5 volts PSU for the Voice card and VCDOs

On Off switch (very handy for turning on and off)
MFOS variclock sequencer
In progress with the next module a Yusynth Dual gate delay,Pulse delay,Comparators,Logical and random gates all on one panel
Yusynth Clock Divider
2 Digisound Sample and Holds
Oscilloscope (Cheap Bangood one mounted on a panel)
MFOS delay

2 VCDOs with AS3340s
3 VCOs original CEM3340s
3 Yusynth VCOs
MFOS Wavefreaker
2 Dual VCLFOs CEM3374 and AS3360s
Processor

Processor
VC Mixer AS3330s
2 Yusynth mixers
Waveform Multiplier
2 Dual Ring Mods
Yusynth Metalizer and Wavefolder on one panel
VCF-L CEM3320
VCF-H CEM3320
VCLFO AS3340
Yusynth Dual Quadrature LFO
Digisound Quad LFO
Yusynth Dual VCLFO
Another Quad LFO still to make
VCF-B and VCF-L still to be made
VCF-P CEM 3320
2 80-7s SSM2040 version


Voice Card Still cant get this to work properly!!!!!!!! using AS chips except for the CEM3372
2 DRFs CEM3350s
Yusynth VCS-3 filter
Yusynth Moog filter
Yusynth Steiner filter
MFOS Phaser

Yusynth EG
Yusynth VCA
Yusynth dual EG
Dual VCA CEM3330
Dual EG CEM3310s
Dual VCA still to make
Attachments
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Re: Digisound 80 refurbishment

Post by alfa » Sun Jan 26, 2020 1:42 pm

Dear Micromusic
Why not to use in Your project AS3372E which "covers" functions of CEM3372 ,
CEM3378 , CEM3379 and gives additional opportunities?
http://www.alfarzpp.lv/eng/sc/AS3372E.php

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Re: Digisound 80 refurbishment

Post by jorg » Mon Jan 27, 2020 9:55 am

alfa wrote:
Sun Jan 26, 2020 1:42 pm
Dear Micromusic
Why not to use in Your project AS3372E which "covers" functions of CEM3372 ,
CEM3378 , CEM3379 and gives additional opportunities?
http://www.alfarzpp.lv/eng/sc/AS3372E.php
The PDF link on that page is dead.

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Re: Digisound 80 refurbishment

Post by alfa » Tue Jan 28, 2020 4:46 am

Dear Jorg
Thanks! Now working:
http://www.alfarzpp.lv/eng/sc/AS3372E.php

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Re: Digisound 80 refurbishment

Post by ianski » Fri Feb 07, 2020 6:29 am

@micromusic That's a great system! Love the voice card... I would seriously like to have one of those but finding one isn't exactly easy.
I do have populated boards for the 80-22 patcher and the DEV-91 modules - I need to get some faceplates made up for those.

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Re: Digisound 80 refurbishment

Post by micromusic » Tue Feb 18, 2020 12:35 pm

Hi Ianski

I thought your youtube vid was rather good!!
My voice card does work but only for a about 2 mins then it slowly fades in volume frustrating that I cant find the issue with it!!!!
You should be able to knock one up, if I can anyone can, If I can get it to work I will build another as I have a spare CEM3372 I would still like a photo of a proven working one (both sides of PCB) as I still seem to think the EGs are wrong on the PCB tracks in the way it feeds the VCAs etc
My 2 multimode filters are SSM2040 based and their resonance is also very weak but from memory the one I made in the early 90s had much more resonance almost into self oscillation, maybe more modern components are to accurate???

Anyway the first person that posts a working voice card PCB picture back and front I will send an 80-7a PCB and an original CEM3335, rather generous me thinks!!!

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Re: Digisound 80 refurbishment

Post by ianski » Wed Feb 19, 2020 8:52 am

That's a very generous offer! Sadly I don't have a module so can't help out. Hope someone steps in though.
If something gradually changes that kind of hints at capacitors not holding their charge or something else that's dragging the voltages down, but I'm not familiar enough with this module to answer with any authority. I will say though that the exponential responses on my VCA's are very poor - I can't really use them for audio unless I stick with linear response.

I'm still looking for the remaining 3 Digisound items to complete my collection (80-23 Quad LFO, 80-24 Poly keyboard controller and 80-C9 voice card) just in case any turn up...

Good luck with getting it sorted out.

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Re: Digisound 80 refurbishment

Post by snufkin » Fri Feb 28, 2020 1:29 pm

Hi micromusic,
I am not sure how much this will help as I am only part way through the build of the voice card. Simon Bailey one of the original designers sold me his last board and panel, I have made up some brackets, filled in the remaining physical components on the panel and a friend is trading me some CEMs. What you see in the pics below is the board waiting for the off board wiring CEMs and a few other bits and bobs. You will also see a really cool hand drawn board layout by Charles Blakey that Simon also kindly sent me (which I want to frame). Anyway I hope it helps, hopefully someone chimes in with images of a working unit at some point. I am also building up a bunch of other panels I recently nabbed from various people, the next job is to build a case before I go any further ;)
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micromusic wrote:
Tue Feb 18, 2020 12:35 pm
Hi Ianski

I thought your youtube vid was rather good!!
My voice card does work but only for a about 2 mins then it slowly fades in volume frustrating that I cant find the issue with it!!!!
You should be able to knock one up, if I can anyone can, If I can get it to work I will build another as I have a spare CEM3372 I would still like a photo of a proven working one (both sides of PCB) as I still seem to think the EGs are wrong on the PCB tracks in the way it feeds the VCAs etc
My 2 multimode filters are SSM2040 based and their resonance is also very weak but from memory the one I made in the early 90s had much more resonance almost into self oscillation, maybe more modern components are to accurate???

Anyway the first person that posts a working voice card PCB picture back and front I will send an 80-7a PCB and an original CEM3335, rather generous me thinks!!!
WTB: any Digisound80 / Digisound 80 faceplates/pcbs/kits.

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Re: Digisound 80 refurbishment

Post by SynthFreq » Mon Jun 15, 2020 3:28 pm

Hello all, just joined to post another survivor, poor quality pic, but this is when it was last used.

Image

and another from about 14 years ago after restoration and a new psu,

Image

Sadly I lost a couple of modules along the way, never retrieved them from a repairer :( and it's been mostly unused since moving home, but my interest has been rekindled. I used to own a large walnut cabinet synthesizers.com modular and an Andromeda A6 but sold those. I couldn't part with this though. It's in a solid mahogany case and I built a few of the modules myself. I remember pestering Mr. Blakey with problems back in the day, what a patient gent he was. So was his engineer Mr. Massey, who once did a house call to repair this example. Obviously I deeply regret missing the modules I always wanted and failed to acquire, like the VCDO and voice card. I have quite a few spares though, 33 modules including 8 VCO altogether, but i'm only using the white ones :) an Alphadac controller, even some circuit boards, panels and cem's and heaps of correspondence & documentation. I hope to gradually build everything into a bigger all white module cabinet with a full service, eventually. Hence my presence here, as my expertise is rudimentary. Thanks to this thread I now have a source for CHIRI connectors anyway. Liking the other examples, especially the voice card and it's nice to see enduring interest in the brand.

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Re: Digisound 80 refurbishment

Post by KSS » Mon Jun 15, 2020 4:38 pm

Welcome to Muffwiggler SynthFreq!

What a very nice system you have! Thank you for sharing.

Of course we're always interested in any 'new' documents related to Digisound80. I hope you will see if any you hold are so far not represented online.

The re-issue of CEMs and SSMs make it again possible to resurrect once latent projects.

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Re: Digisound 80 refurbishment

Post by nerdware » Thu Jun 18, 2020 5:47 am

Yes, welcome to Muffwiggler, SynthFreq! I've enjoyed your Youtube videos for years. My own Digisound 80 is a similar size, built and maintained during the 80s my Roger Massey. Alas, mine too needs refurbishment, but on the recommendation of Roger, I made sure I had some spare parts, like knobs. Now I wish I'd bought a couple of those 2-pole 7way switches needed for the SVCF.

I regret losing contact with Roger in the 90s. I got to meet him - and his family - a number of times. Eventually the visits were replaced by phone calls. Now I don't even have his phone number. When I last saw him, in the early 90s, he didn't seem at all interested in the online world, altho he had a modem.

I never met or spoke with Mr Blakey, but I did chat once with Tim Higgins on the phone. It sounded like the company was in safe hands with him. I liked the direction he was taking the company. I think Mr Blakey would approve.

Something Roger told me once has stuck with me over the years. He said that people in this business do it for love, not money. This forum is a testement to that. Welcome, SynthFreq!
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Re: Digisound 80 refurbishment

Post by cretaceousear » Thu Jun 18, 2020 7:29 am

Another welcome to MW SynthFreq!
And thanks for the reminder to get my act together and sort mine out. It was last out a year ago with my mates for a jam, but it got noisy and scratchy in a bad way. Not unlike its builder.
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Re: Digisound 80 refurbishment

Post by Licudi » Thu Jun 18, 2020 2:04 pm

Anyone got a link to the SOS artice on Digisound from about 20 years ago? Can't find it in Wayback.

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Re: Digisound 80 refurbishment

Post by werock » Thu Jun 18, 2020 2:16 pm

Have you tried Muzines, they have a lot of the early SOS issues scanned?

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Re: Digisound 80 refurbishment

Post by Licudi » Thu Jun 18, 2020 2:19 pm

Cheers, I had a look, but it's all pre-2000 content as far as I can see.

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Re: Digisound 80 refurbishment

Post by werock » Fri Jun 19, 2020 8:00 am

This is the link to the article, which I chanced upon while looking at something else, but it only works through archive.org

https://web.archive.org/web/20040226205 ... ound80.htm

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