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 Forum index » DIY Hardware and Software
E&MM Spectrum Synth build
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magman



Joined: Feb 04, 2009
Posts: 363
Location: Liverpool, UK

PostPosted: Tue Mar 17, 2009 11:17 am    Post subject: E&MM Spectrum Synth build
Subject description: Long delayed project resurrection
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I've had a set of PCB's stored away for the Electronic & Music Maker Synth, like this one http://www.colinfraser.com/spectrum/spectrum.htm since the 80's when I bought them new. Since I decided to get back into electronic music, I remembered where I had hidden these bits but the CEM chips are like hens teeth to get hold of, especially the 3340 VCO chips, so I started collecting parts for other projects instead.

As luck would have it, a couple of weekends ago, a trawl on eBay saw some CEM3340 pulls appear for a very short while and I was fortunate to grab a pair before they all went. This gave a whole new impetus to this project and put my other project (the Wireless World synth) on the back burner as the Spectrum would be likely to deliver a working synth much more quickly. A couple of hefty orders from CPC and Rapid and I now have a nice synth construction project for the next few weeks. Another hefty order to Vintage Planet should see me with the last few critical parts to get the full synth working.

I thought I'd ask on the forums to see if anyone else has any experience of this synth, especially any gotchas to watch out for.

I'm also tweaking the design a little bit, mostly on the mechanical side to try and reduce the birds nest from the front panel to the PCB's. I've also got a quote out with a local supplier for the bulk of the metalwork I'll need.

I'll keep you posted as my new toy develops. Very Happy

Magman
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fonik



Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23

PostPosted: Tue Mar 17, 2009 11:48 am    Post subject: Reply with quote  Mark this post and the followings unread

that's special! awesome you stored the PCBs all the time - and find them again Laughing - i allways find myself thinking: where is it? i put it in this box, why isn't it in this box now?

just curious, in what condition are the PCBs after all that time?

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matthias
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magman



Joined: Feb 04, 2009
Posts: 363
Location: Liverpool, UK

PostPosted: Tue Mar 17, 2009 2:38 pm    Post subject: Reply with quote  Mark this post and the followings unread

I must admit that I'm a bit of a hoarder.

The PCB's are in good condition, they were store flat in a plastic crate. though not in any special conditions (loft then garage if I recall correctly).

They were slightly warped when I dug them out, but luckily they are fibreglass so they haven't warped too much (You should see the PCB in my old Synchime that I found at the weekend, now that's warped).

Magman
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magman



Joined: Feb 04, 2009
Posts: 363
Location: Liverpool, UK

PostPosted: Wed Jul 29, 2009 11:37 am    Post subject: Reply with quote  Mark this post and the followings unread

It's been a while since I mentioned this project and there has been quite a bit of progress in the last few months.

All of the PCB's have been stuffed, as in the photo's below.

I've also managed to source all of the chips, including a few spares of the elusive CEM chips, mostly via eBay.

The best news though is that I have managed to find a local supplier (Ironically via eBay again) who has made the main metal panels for the synth, though I did have to re-learn some CAD to produce suitable AutoCAD compatible DXF files for this to work out. The three main panels worked out at 115 GBP including taxes - including supply of the metal and bending the panels.

There is still loads of work to do on this synth. Painting the panels to a good finish is important to me (and I'm still learning the lessons from previous rushed attempts) and it will no doubt be fun labeling up a panel that is 820mm wide to a good standard. Wiring is going to be fun (25 pots and 14 rotary switches) and I've also decided to use high quality pots for the panel now. Then the fun of testing and calibration.

Should be fun

Magman


Spectrum VCO's.JPG
 Description:
Spectrum VCO's PCB Stuffed but not tested yet
 Filesize:  2.76 MB
 Viewed:  182 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

Spectrum VCO's.JPG



Spectrum Keyboard Ctrl and VCF PCB's.JPG
 Description:
Spectrum Keyboard Controller and VCF PCB's
 Filesize:  2.89 MB
 Viewed:  163 Time(s)
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Spectrum Keyboard Ctrl and VCF PCB's.JPG



Spectrum LFO & ADSR's.JPG
 Description:
Spectrum LFO and ADSR PCB's
 Filesize:  2.96 MB
 Viewed:  177 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

Spectrum LFO & ADSR's.JPG



Spectrum Chassis Assembly.JPG
 Description:
Two of the main Spectrum Panels, temporarily mounted on their support frame.
 Filesize:  3.19 MB
 Viewed:  164 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

Spectrum Chassis Assembly.JPG



Spectrum Chips.JPG
 Description:
A nice collection of chips, including a few spare CEM's.
 Filesize:  2.93 MB
 Viewed:  161 Time(s)
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Spectrum Chips.JPG


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v8pete



Joined: Jan 27, 2008
Posts: 43
Location: UK

PostPosted: Fri Jul 31, 2009 2:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

Great project! I remember getting the Spectrum Synth book from Maplin all those years ago & being frightened by the apparent complexity at that time, also the fact that it used these weird CEM chips that you had to buy from Digisound!!
Just wondered also if you've considered having a front panel professionally screened by Jeff Toman at custom synth?

Pete
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magman



Joined: Feb 04, 2009
Posts: 363
Location: Liverpool, UK

PostPosted: Fri Jul 31, 2009 2:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm going to have a go at the legends on the front panel myself (learning techniques like this is all part of why I got into synth DIY anyway).

I've got an idea I'm going to try of using copper foil and etching it to make templates, then spray the legends using an airbrush (A kind of poor mans silk screening). If this fails, I will probably try one of the laser transfer systems (we've got a colour laser in work that should work).

I went one step further than you years ago, I actually bought the PCB's along with the book (I already had the magazine articles, but I bought the book anyway), that's why this whole project came back to life.

Regards

Magman
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