MATRIXSYNTH: Original 1971 ARP Soloist Model 2700 ex Dennis P. Colin

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video upload by Synthchaser

via this auction

Some pics of the inside bits below.

Pics and video for that one captured below.

"Offered here is an exceptionally rare early ARP synthesizer, with a remarkable history. The ARP Pro Soloist, with its expressive leads and effects, was made famous by Tony Banks of Genesis.

But in 1971, before the Pro Soloist, ARP introduced its 3rd synthesizer (after the 2500 and 2600), the model 2700 Soloist. These original Soloists are rare enough, but this one had been extensively customized personally by ARP engineer Dennis P. Colin (the designer of both the Soloist and the ARP 2600).

Mr. Colin had made all kinds of modifications to this Soloist, including adding a 2nd oscillator (perhaps this was a feature they were considering for a future revision), extra knobs and controls, and CV in and out jacks. Sadly, these modifications were done with a "prototyping" level of quality and 50 years later were broken and needed to be removed to get the synthesizer working again. Traces of these are left behind inside where Mr. Colin wrote his initials in many places, and outside, where the extra jacks and controls were located and (sometimes) labeled. Included for the buyer are most of the parts removed from backing out the customization.

The ARP 2700 Soloist is a fascinating synthesizer. Like its successor the Pro Soloist it is a preset monosynth with six assignable aftertouch effects, plus repeat and portamento. The Soloist has fewer presets than the later Soloist, but includes a couple that didn't make it to the Pro Soloist (Piccolo and Vibes).Inside, the Soloist uses the same 4027 Oscillator and 4012 Voltage Controlled Filter modules that the ARP 2600 does. While there are no CV ins or outs on the Soloist, the design is more easily modifiable to interface with other devices than the Pro Soloist.

There is a video demonstration of the synthesizer that is for sale at the end of the pictures list.

This ARP Soloist was serviced in 2023 by Synthchaser. Work done included:

Recap all Tantalum & Electrolytic capacitors (except those in epoxy sealed submodules)
Replace all sliders
Revert Dennis P. Colin prototype modifications to original
Replace touch sensors
Clean key contacts & buss bar
Tune/calibrate.Presets are reasonably well tuned.Due to the design and construction of this synthesizer, perfect tuning and scaling across all presets isn't likely to happen.
Condition: A few holes that were drilled in the top for the Dennis Colin modifications have been plugged with plastic hole plugs.Many extra jacks were added to the back panel, but these are disconnected. Original epoxy sealed 4027 VCO module was dead, replaced with Synthchaser 4027-1 VCO submodule. Audio output is not as clean as the other Soloists I repaired, see video demo for example of what I mean.

In the listing I've included some photos of the places Dennis Colin marked his initials on this synthesizer, as well as pictures of the schematic for the Soloist and the 4012 VCF Module where you can also see his writing. No schematic or manual is included. An Oval PH-163 power cord is included."