“For sale is an ARP 2600.
It was restored by Kevin lightner ( http://www.synthfool.com/ ) and is in great condition, everything works perfectly, great shape, it is not included the Keyboard.
It has some very interesting modifications that you can check in the info sheet explained by Kevin ( will be sent with the unit).
Many hours have been spent in upgrading the audio and cv path in critical areas.
Part of the list;
It was changed every 1/8″ jack.
New and larger spring tank rever with lower noise circuits.
New power supply stable and accurate international power linear supply, currently, the AC input is hardwired for 230 volts.
Unit will operate with 220, 230 or 240 volts AC, but internal jumpering is possible for 110 operation.
The filter is an unmodified ARP 4012 design, (the MOOG FILTER).
The internal amps are modified for lower noise and faster slew rates.
1/4″ output jacks, these jacks carry the left and right signals as provided by the output pan mixer, same as the 1/8″ jacks below them.
The envelope generators have been modified. Lower offsets( output voltages when not being used) than stock. The AR gen has considerably fasters attacks
and added gate input not normally provided by Arp.
The ADSR has much faster decay and release times available than stock.
The gate button is a high reliability type ( used in Neve and Api consoles) and provides a larger surface and a softer feel tahn stock, in addition to lightning up with a gate signal.
This circuit mod takes its input from the envelope follower input jack (not the EF output jack) and produces a very fast risetime gate for its output. This gate is dependent upon the level
of the ipunt signal and the setting of the threshold control (grey knob). The blue Led provides visual status operation.
This circuit has been modded so no offset voltages are present during usage. Can now be used for pitch voltages (glide) without tuning
problems when adjusted, can smooth out gate signals from the comparator gate output…etc. ” Link