images via this auction"ARP 2600 semi-modular synthesizer, with full complement of CMS modifications and upgrades.
This auction includes the 2601 Console (s/n 26010788) and 3620 Keyboard Controller (s/n 36200788). Not only is this 2600 in outstanding cosmetic and functional condition, the numerous modifications and upgrades performed by Phil Cirocco at C.M.S./Discrete Synthesizers make this a truly phenomenal instrument. Here is a list of the work performed, with descriptions from the CMS web site:
AUDIO PATH UPGRADE PACKAGE
This mod replaces all gain stages in the 2600 console with audiophile grade components for crystal-clear highs and a deep low end, while still maintaining the distinctive character of the 2600. Upgraded sections include: lag processor, voltage processors, reverb stages, preamp, VCF mixer, output mixer, output buffers, etc. We also fix the annoying VCA thump. Noise in the reverb section is reduced by 35%. Filter headroom is increased by a factor of 2! Stability and sound improvement guaranteed. Later model 2600s (almost all wood / tolex 2600s) use inferior sounding gain stages that severely impede the true sound of your 2600. Earlier 2600's (Blue Marvins and Gray Meanies) use "high slew rate" chips that sound much clearer. Restore your 2600 back to the specs that the original ARP engineers intended! Don't be fooled by imitations from "noob techs" or DIY attempts. If the Audio Path Upgrade is not performed correctly, it can become unstable and lead to high frequency self oscillation of all the amplifier sections!
MOOG STYLE FILTER MODULE - 4012cx
The 4012 filter was used from 1971 (blue Marvin) to the middle of 1976. If your 2600 is a gray face, It probably utilizes the 4012 module. The 4012 is a ladder type filter using discrete transistors. The original 4012 made by ARP is prone to instability. The 4012 replacement filter by CMS is guaranteed stable yet uses the exact circuit that ARP used. Better quality components and personal attention to craftsmanship yield a filter of superior sonic characteristics! See the Sub-module section for more info.
VCA MODULE UPGRADE - (4019)
If your VCA module is unencapsulated, we can give it crystal clear highs and a deep low end. Also provides lower distortion and a faster slew-rate. If you have an encapsulated ARP VCA, this upgrade is not available, but improved unencapsulated replacement modules are available, see submodules page, model 4019cx.
POWER SUPPLY UPGRADE
The power supply in your 2600 is about 20 to 30 years old. Chances are that your power supply is not up to spec. This can result in excessive noise, ripple, and instability. This mod replaces your unit with a high power, highly stable, military spec power unit with remote sense regulation. The overall sound quality and oscillator purity are noticeably improved. Rebuilt ARP units are available for 125.00 (50.00 core charge).
17 INCH REVERB TANK
Ever wonder why later model 2600s have such a lame reverb. Later model 2600s use smaller reverb tanks with a shorter delay time than earlier 2600s made by ARP. The only reason I can find for this change is economic. Our brand new reverb tanks use 6 springs, counter wound and placed in parallel for a rich, full sound. This mod restores your reverb sound back to the original "Blue Marvin / Gray Meanie" configuration.
1/4 INCH LINE LEVEL JACKS
Professionally installed 1/4 inch Switchcraft jacks at line level (designed to interface with your studio mixer etc.) on both main outputs, VCA output, and preamp input. 4 jacks total.
SYNC SWITCHES
Two independent miniature toggle switches that sync vco-2 to vco-1, and vco-3 to vco-1 This setup enables dual sync (two separate harmonics) if desired.
ENVELOPE GENERATOR RANGE EXPANDER SWITCHESMiniature toggle switches that provide 2 additional time ranges for the attack, decay and release time of the ADSR generator and the attack and decay time of the AR generator.
VARIABLE VCF KEYBOARD TRACKING
The filter tracking on a 2600 is fixed at 1v per octave. This is quite limiting especially if you are shooting for natural textures. This mod provides a miniature rotary potentiometer that adjusts the tracking ratio from 0 to 1v/octave
LED INDICATORS
providing visual feedback on both E.G. outputs (red), s/h clock (green) and envelope follower (yellow). Requires power supply upgrade.
24Db DUAL MODE FILTER - MODEL 2621The one key element missing in a 2600 is a highpass filter with resonance and associated coupling circuitry. The CMS 2620 is a dual mode, 24Db (Lowpass/Highpass), discrete, transistor ladder filter from the CMS 9000 series modules, Installed in the left speaker section. This original CMS design features a beautiful "raspy" resonance. Complete with anodized face plate, high quality controls, 1/8 inch Switchcraft normalized patching. Special switch links both filters in your 2600 together for a truly remarkable sounding bandpass function (24Db x 24Db). The resonance on the highpass function is also very unique and distinctive. Requires power supply upgrade. Now comes with voltage controlled resonance.
VCO / 4 CHANNEL MIXER / INVERTER - MODEL 2627Installed in the right speaker section, this VCO utilizes the same exact circuitry used in the other VCO's in your 2600 to assure exact tracking and pitch stability characteristics. All four waveforms are available as well as pulse width modulation. Low frequency mode and normalized patching are also provided. The mixer section serves as a high quality audio mixer with the inputs either normalized to all 4 outs of VCO-4 or externally patched. The mixer can also be used as a voltage summer or inverter. Requires power supply upgrade.
In addition, the following mods are present:
• The AR has been converted to an ADSR for even more CV potential;
• All three oscillators have been fitted with -1/0/+1 "octave" switches. This switch will transpose the oscillator by the amount predefined by the "Interval" pot (up to one octave)
• An additional set of multiples have been added in the lower left, now giving you 2 x 4 mults;
• Voltage Processor sections 2 & 3 have positive outputs available as well as the conventional negative;
• External trigger input for the Sample & Hold."
>>Later model 2600s (almost all wood / tolex 2600s) use inferior sounding gain stages that severely impede the true sound of your 2600. Earlier 2600's (Blue Marvins and Gray Meanies) use "high slew rate" chips that sound much clearer.<<
ReplyDeleteAs a former owner of three 2600s, I have a problem with these "upgrades". almost NO ONE has really heard or owned the Blue Marvin or Gray Meanies - people only KNOW them because they're rare!
When you change the opamps to a faster slew rate, you make the synth a lot BRIGHTER which is not its original sound. It no longer has the famous 2600 sound - the one Stevie Wonder, Edgar Winter, and Pete Townshend used! The 2600 sound we know. (Unlike an added filter or mixer module, this "upgrade" takes away from the original sound almost ALL 2600s have, it is gone.) Good or bad - it is what it is, and the ONLY people who have said "You should do this" are always techs (hmmm) who are looking to improve something they find technically wrong - no one I know has ever said "My original 2600 sounds BAD, I wonder how this can be fixed?!" Same as with Fender amps - they kept working to get RID of the distortion, which the players really liked.
My friend had his 2600 modded and (yes) it was cleaner and brighter, it no longer had the old sound of the classic 2600. Why not just use a plug-in then?
I have an extensively modded Arp 2600 done by Phil at CMS. In fact I have a few classic synths( arp 2600, EMS AKS done by Robin of EMS, and a Rivera modded Minimoog) that have extensive mods. I guess I'm not a purist. For the most part they improve the options available on each synth, but yes some mods change some fundamental characteristics as in the stabilized oscs. on my EMS AKS or the modified signal path of my Arp 2600. My Rivera minimoog has an extra LFO and osc sync etc and these are great in enhancing sound creation. My AKS has extensive mods that are incredible tools: sync, 18/24 filter, inverter, hi/lo osc switch etc. Of course it is best to find the right person to mod ones synth. I think my Arp 2600 modded by CMS is much more useful than w/o the mods. So yes it may diverge a bit from the original sound but has more potential for sound creation overall. Ideally it is best to have two of the same synth, one unadulterated.
ReplyDeleteI also have a 70 Fender princeton reverb that I have had some minor mods done to increase headroom etc. and a Fane Alnico speaker thrown in; and I must say these have turned out to be nothing but improvements on the original design, different yes, but the sound of my guitars through it is perfect. But once again, I brought my amp to a very very good tech, after bringing it to a so so one who could barely make it work. My new amp tech turned out to have great ears, taste, and experience. So any tech will not suffice if you are really searching for improved sound.
ReplyDeleteAgreed - many people think this is an improvement. It is - on paper. Just a question of what you WANT the synth for, what it is/was or what it could be. Same with old cars or guitars - do you put new pickups on, or a new engine in?
ReplyDeleteMaybe these signal path upgrades actually bring the synth back to the original sound it had 30 years ago (?)
ReplyDeleteI had a 2600 similar to that with CMS mods and I could do spot on recreations of my fav Edgar Winter / Wonder patches and it still had a character unlike any other synth.
Also, if you like your filter cut off at 12K like the faulty 4075, you can set it lower.