Practical Electronics Minisonic (or is that Minichronic?)

[abstraktor]

First DIY synth project I ever undertook (well with a lot of help from a cousin) was the PE Minisonic mini- modular synth which was published by hot mag of the times, Practical Electronics. As we never got our amateur build to make a sound (which broke my teenage heart), I just wondered whether anyone else out here in EM land ever constructed this box and how it sounded.
I had decided to replace the stylophonesque keyboard with a proper kimber-allan based job, but apparently the design was so crap that few people ever got it to work anyway. I spent a fortune on it at the time and left it in a cupboard in a rented flat, but it still haunts me to this day.
Any thoughts?
Should I try again, to prove fate wrong and attempt a 2010 build?

[v-un-v]

I never constructed a minisonic, but I lusted over the original mk1 for many a year! The Soundlab that I started to build (but never actually finished ), its panel was based on the Minisonic Mk 1's panel design (it was LOVELY wasn't it??). My studio for the ice cream vans LP was also named "minisonic"

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[abstraktor]

yes indeed senor V-un V that is it! Let's wait and see whether anyone has still got one operational (I doubt they'd have the same pop art panel though). Your design for the Soundlab is great...I was thinking of undertaking the Minisynth build but.....

[magman]

Must say that I practically wore out the editions of PE that had this project in (I ended up buying replacements for my collection).

It might be worth asking in the DIY Hardware and Software forum to see if there were some more young adventurous souls who tried to get this working.

I've got a hankering to try for the Minisonic 2 design, but a few of the components are almost impossible to source now. If I find these missing parts though, I suspect I would add it to my project stack for historical interest.

Regards

Magman

[Danno Gee Ray]

Anyone by chance have scans of the article?

[ian-s]

[magman]

[abstraktor]

yes, I had found that minisonic 2 website -which is great, although I'm not sure if the sound samples give much away as to the synth's potential...or maybe it does, and atonal cross modulations and burps are the best that it could do! If the mark 2 was a revised design then the original wasn't going to win a "vintage classic" label for sure, much as I love Forbidden Planet sqwonks and cronks. I think I knew back then that the Minisonic was never going to be a Minimoog...but if it could have gone some way towards being a poor boy's VCS3 (just add tape echo!) then I would have been a happy twiddler!
Good idea about moving this topic over to the DIY forum, btw.
cheers guys.

[MirlitronOne]

Gosh, I remember that edition of PE coming through the letterbox. I was excited by the possibilities - until I saw the complexity and my heart sank - especially as I was never going to be able to build a PE modular. Luckily, I never even tried to build the Minisonic. Even then, I thought that the front panel design was awful.

A couple of years before I had built the PE stylophone-clone and failed to get that to work. I could kick myself for throwing it away as the circuit is now trivial to me and I'd be able to troubleshoot it no problem. NEVER throw any electronic builds away - after all, it only took me ten years to get my PE 'Treasure Tracer' metal detector into full operation

Tim Orr's 'Transcendent' synthesizer kit came on to the market just as I left University and entered the world of work. I still kick myself for not buying one of those.

[magman]

I've recently noticed that someone else has posted scans of the original Minisonic articles on the Web, here:

http://www.timstinchcombe.co.uk/synth/pe_mini/pe_mini.html

Regards

Magman

[Danno Gee Ray]

Thank you.

[Don Erskine]

I remember the November 1974 edition of PE well ( I think I still have it somewhere!) and as the previously published Wireless World Synthesizer was way beyond my means (and skills) the Minisonic was my first 'proper' synthesizer.

The front panel artwork was awful, and made it look like a toy - it wasn't.

The VCO was sophisticated, with a serious stab at thermal stability, though the transistors used for the 'transistor oven' weren't ideal for log-law tracking over a wide range.

The VCF had a decent diode ladder too.

It was designed down to a price, and the quality of the components in kits did not help - precision components would have been an improvement.

Bearing in mind a lot of the constructors were inexperienced, and it was battery-powered, it is not suprising it is disregarded my many enthusiasts. It did work though.

I got mine working quite well, the worst bit being the novel high-frequency oscillator design used in the keyboard - I lashed out on the expensive FET op-amp option on the track & hold, but it did tend to drift no matter how much I adjusted it.

I added a 'proper' keyboard and made some passable noises with it. I skipped the built-in amp as I already had a guitar amp.

I think the design is well worth revisiting - especially the Mk2 version with a proper PSU. It's basic, cheap, and I'm sure it could be improved with a few more modern components would form the basis of a good cheap analog synth.

I think replacing the 741s with higher slew-rate op-amps would be an improvement, and no doubt other tweaks could be made. It's a simple design, and easily adapted.

I re-used the modules in several builds. I may still even have the PCBs... I know I kept the ICs.

The MiniSonic played a great part in my deciding to become an electronics engineer. Thanks, Mr Shaw, wherever you are now.

As for the Transcendent.. that is worth another post in itself.

[abstraktor]

forgot about this thread -thanks for all the contributions - the pdf's of the original PE article are just what I had been looking for. I'm starting on a MFOS WSG as a warm up for the MS, but version 2 sounds better -perhaps with mods.

[TheProf]

If anyone is having a go at a Minisonic, or Minisonic 3, I've just got lucky and found a batch of MFC6040 chips, (the 6 pin VCA from Motorola).

You need 2 for a Minisonic 2.

I have 20 to spare, PM me if you're interested.