Giving An Analogue Mixing Console Some Love

May 03, 2020

This lovely analogue mixing console, a Soundtracs PC-MIDI 24 track, was fully restored, and then purchased by a well known Electronic Dance Music producer based in Amsterdam. An audio mixing console like this can be a great value investment for musicians and producers that appreciate working on an analogue mixing desk.

At 120 x 90 x 25cm, the Soundtracs PC-MIDI 24 track is a nice size for one person to operate. Inline means that both mic/line input, tape output and tape return are all in each channel strip. There is also MIDI mute automation of mutes, which makes it an excellent partner for recording and mixing from a DAW. Mutes can be recorded in real time or recalled by using patches. The onboard computer can also send commands to control other MIDI devices. There are 24 channel modules, one master and two FX return modules with four channels each, as well as a separate power supply. The console also has 18 channels of LED metering on the overbridge.

("Back in the day" - until the 1990s I guess - there were quite a few British manufacturers of audio mixing desks. Of course, Neve and SSL are the best known and most legendary, but manufacturers like Soundcraft, Soundtracs, TAC, DDA all produced very good quality analogues desks at a slightly less eye-watering price. These days Soundtracs, like most of the others apart from Soundcraft, who don't as far as I know, do manufature in the UK now, don't exist anymore, but Tim at Studio Systems was able to supply me with tech info and a few special components that I could't find elsewhere.)

Features:

24 Mic inputs with up to 60dB of gain, 20dB pad and +48V phantom power. Line inputs with up to 30dB gain.
24 Four Band Equalisers, with two swept mids, high and low shelving. Equaliser can be split between Channel and Monitor sections.
4 auxillary sends. Aux 1 and 2 can be switched pre/Post fader. 3 and 4 are Post (but can be altered by setting links on the board).
16 subgroups (on the first 16 modules).
Direct outputs from last 8 modules.
MIDI mute automation on both channel and monitor sections of each module, as well as the 4 aux masters.
8 FX returns (two separate modules) with MIDI muting.
LED metering on overbridge for groups, Mix bus and SOLO.
External low noise linear PSU.
Comprehensive (and very useful) User Manual in PDF form (54 pages).

Testing the console

This analogue mixing console was fully overhauled. A number of repairs were carried out, and of course it was fully tested. This is what I did:

Full rebuild of PSU : new mains transformers (it looked like the original had failed and a horrible attempt at repair carried out), upgraded rectifiers for audio rails (mounted on chassis for better heat dissipation), replaced and upgraded smoothing capacitors, rewired (adding an earth busbar internally and replacing possibly unreliable crimp connections with solder).
Inline fuses added in PSU to protect desk wiring in case of a short.
PSU load tested at 2 amps (desk requires a little over 1.5A), and checked for stability. Power lead checked and resoldered.
Cleaning : buttons and knobs removed and washed, faceplates cleaned.
Broken earth terminal on rear of desk replaced.
Mechanical damage to overbridge faceplate repaired.
Battery on computer board replaced.
Pots cleaned with Caig Deoxit. Faders opened, cleaned and lubricated with Caig Fader Lube where necessary. 1/4" jacks cleaned with Deoxit.
Broken potentiometers and missing control knobs replaced.
Main audio paths (mic/line in to tape out, tape in, routing to mix, auxs) checked with oscillator, also tests of frequency response and noise carried out.
Operation of peak LEDs and test of Maximum Output Level (headroom) carried out from Line In to Insert Out for each channel.
Burnt out lamps in overbridge behind logo replaced with white LEDs, which last for decades. (Cosmetic, but that matters too.)
Various missing screws in frame replaced.

The Soundtracs PC-MIDI power supply (fully rebuilt)

Back in the 1980s and 90s, British manufacturers of mixers like Soundcraft, Soundtracs, DDA, and so on were making a lot of great audio mixing consoles and selling them all over the world. They can now often be purchased for quite a low price and anyone looking to restore one could use the above list a a checklist. You will need a decent audio test bench to get the job done though!

This is a very capable and well featured piece of vintage pro-audio gear, perfect for a growing project studio or compact commercial studio that appreciates the benefits of an analogue mixer with mute automation and the classic “British” sound. The desk sold very quickly after restoration.

More pics:

Soundtracs PC-MIDI console - audio connections

Soundtracs PC-MIDI console - EQ section

Soundtracs PC-MIDI console - Routing section

Soundtracs PC-MIDI console - Master section

Soundtracs PC-MIDI console - MIDI and power connections

Soundtracs PC-MIDI console - audio connections

Soundtracs PC-MIDI console - onboard computer