
via this auction
"The “orange and black” 2601 is the last 2600 version produced by ARP. It is the most reliable version, an update to the more common grey version. None of the modules are set in epoxy, making it more serviceable in the long run...
Here are a list of the specific repairs:
4 slider tips were repaired with identical replacements.
NOS power connector was re-fitted (comes with original cable)NOS handle was fitted (quasi-identical)
NOS keyboard connector was fitted
Some Polyfusion-specific internal normalization was removed
Polyfusion front panel gate input removed and capped
2 Polyfusion connection inputs removed from the left side and patched
(one tiny hole on upper right panel left (see pics)
new orange LED in the power indicator
New capacitors on the power supply
Tolex on both cases was cleaned and refinished.
Additionally, my tech performed some great modifications :Filter upgrade :
the 4072 filter was upgraded to correct the “error” causing the filter to open to a maximum of around 12k, now it's nice and bright when fully open (28k apparently). The filter kept its original character, just with extended range. The upgraded 4072 is a very nice sounding filter, just as good and useful as the previous moog-like filter Arp used, but a bit more unique and exclusive!
Reverb upgrade :The reverb tank was changed top a looong type 9 NOS replacement. The first 2600s' had this type of tank and are known for their longer, fuller reverb.
The original reverb tanks were made by Hammond, their reverb division then took the name Accutronics. Thankfully I was able to purchase a remaining american made Accutronics tank (now made in Korea). The original small tank is included in the auction as well. My tech also performed a modification to lower the noise floor, and made the connections balanced using good quality cables (Canare). I am a fan of spring reverb and own a few and was very pleased with how this one sounded! The tank has been mounted vertically to avoid interference with the speakers at max volume but can still occur if you try hard. These mods, along with new caps on the power supply and proper calibration, greatly improve the 2600's signal-to-noise ratio." Additional pics here.












































