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The "DG 2500" synthesiser

When I was in my teens I had the privilege of using and demonstrating some of the world's most fabulous music synthesisers. This synth build is my attempt to recreate one of my favourite synths of all time.

The ARP 2500 modular synthesiser was a wonderful design and it should have been, it cost as much as two houses! It was futuristic looking and very well thought out. It was also a bit quirky in places and suffered from breakthrough, a kind of noise interference where one part of the synth picks up noise from nearby circuits (a bit like having noisy neighbours). There was however, an upside to this in the form of added richness which often enlivened the the final sound patch.


Above: Phil Dodds using an ARP 2500 with additional side wings during the filming of "Close Encounters of the Third Kind". The synth was mounted in a unique housing to make it look even more massive on the set.

The "DG 2500" project from the beginning

It is not made from a kit
The first stage

1. The first pieces. Aluminium extrusions are bolted onto pieces of wood which will make up the inner module housing. These extrusions will eventually form rails to which the modules are attached. A small but very important start of a huge project. This synthesiser is being built outwards from the very centre.

Inner module housing

2.The inner module housing (I.M.H.) starts to take shape. It's a cabinet which no one will see when the synthesiser is complete. The picture shows one of the temporary formers which hold the wooden sides to the top and bottom of the I.M.H. at an angle of 90 degrees while the glue sets.

The first stage

3. The I.M.H. on it's side. It is now a long rectangular box with a closed back secured by brass screws for future access. The wood has been carefully trimmed, sanded and sprayed with a protective finish.

Inner module housing

4. The inner module housing is now almost complete. It only requires a long oak mounting platform for the power distribution arrays and some wiring. You can see the aluminium extrusions fixed at the bottom, top and half way point of the housing. The blank panels at either end are just resting in place to help keep the shape of the structure as true as possible until it's populated with modules.

The mounting board

5.This long piece of oak is the mounting for the power distribution arrays. There will be 4 of them fitted along the length of the mounting. The whole unit will then be fitted inside the I.M.H. at the back so there will still be plenty of space for module circuitry.

Inner module housing

6. The power distribution board is now complete with its 4 arrays. At this point I have yet to make the wiring looms and connect them to power supply and the arrays but this will soon be done. I can then test the three modules I already have.

Latest progress
Cutting aluminium

7.Precision cutting for the module front panels. The angle had to be exactly 90 degrees to make a good fit.

All cut to size

8.The aluminium sheet ready to cut to size for the matrix panels. There are 12 needed for the synth. As you can see, it's not a kit.


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