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Actually, yes this is an ARP 2500. The 2003 is the synthesizer and the 3003 is the keyboard controller.
"This is a very rare and early version of the ARP 2500 Modular Synthesizer. It has a larger cabinet with 3 x 5 Modules (instead of 2 x 6 Modules on standard ARP 2500s) and the switch matrix in the top section has 10 positions (instead of the 20 positions on later ARP 2500s). You will probably not miss the extra 10 switch positions as most patching is done on the lower matrix.
The ARP 2500 for sale here has the serial number 014 (model 2003, serial 70 - 014).
I have been told that these very early 2500s were hand-built by the ARP/Tonus crew to the most exacting standards, they are probably better than later models (which of course are excellent as well).
The synthesizer is in technically beautiful condition with all modules working 100%. It has a very powerful and clean sound and is set up for 3 voice multitimbral operation.
I haven't been able to locate the cables for connecting the keyboard to the main cabinet, so I can't guarantee full functionality for the keyboard. Last time I used it (about 10 years ago) it worked fine though.
The ARP 2500 can produce a huge range of sounds from fat to bold to shimmering to weird modulation extravaganzas. It also makes a great companion to a sampler with the capability to filter and modify up to 3 external sound sources. Samples with FM-modulated filters? Very crunchy!
There will be no sound degradation when inserting any external sound sources, the signal path is very quiet and clean sounding.
It has 4 oscillators (2 of them with invertible waveforms), 3 excellent 24dB Filters with resonance and built-in mixers for up to 4 audio and 2 CV signals (5 CV inputs per Filter total), 3 VCAs with built-in mixer for 2 CV signals (plus another 3 fixed voltage CV inputs), 6 Envelope Generators (4 of them with Gate Delays and normal & inverted outputs. All 6 Envelope Generators have a switch for single or multiple triggering), a fixed voltage source (i.e. to shift all Oscillators at once) and a pink/white noise source with built-in filters.
There is also the rather lovely model 1027 analog sequencer with 3x10 steps and individual trigger outs for each step. Voltage controllable pulse width. The internal clock is very fast and can be driven into the audio range. You can modulate it from any source and use it as a signal generator/VCO with a user definable waveshape (by setting the 10 steps of the sequencer to different voltages).
All oscillators/filters/etc. are very stable and easy to tune, very much unlike the modular systems built by Robert Moog (even Wendy Carlos found the ARP oscillators to be far superior to the Moog ones).
I have occasionally heard the complaint that the ARP 2500 doesn't have any "special" or more "esoteric" modules as seen on other modulars. The truth is that EVERY module on the ARP 2500 is special, only that this is not so obvious. The oscillators for example first of all sound excellent, they must rank among the best oscillators ever built. They have a very rich and nuanced sound, full of harmonics. They have an extremely wide audio range, from the lowest frequencies (they can also be used as VC-LFOs) to sounds well beyond the human hearing range. They don't start to "jitter" at any frequency like many other oscillators, even ones on quite expensive modular synthesizers. When cross-modulating or using them for FM, they remain stable and powerful sounding.
Another example for the ARP sound philosophy is the 1027 sequencer. This can function as a standard analog sequencer, but also works as an audio generator by driving it up into the audio range - this can be voltage-controlled, of course.
The closest comparison to an ARP 2500 is probably the Serge 79 modular system, which was built with a similar idea of technological excellence at the service of a great sounding musical instrument.
The power supply has been profesionally modified to work with 220-240 Volts, but can be reverted to 110-120 V operation.
1 - Module 1004-T Oscillator
2 - Module 1004-T Oscillator
3 - Module 1023 Dual Oscillator
4 - Module 1006 FiltAmp (24dB Filter & VCA)
5 - Module 1006 FiltAmp (24dB Filter & VCA)
6 - Module 1006 FiltAmp (24dB Filter & VCA)
7 - Module 1033 Dual Envelope Generator (each with Gate Delay and inverted Outputs)
8 - Module 1046 Quad Envelope (4x Envelope, 2x with Gate Delay, 2x inverted Outputs)
9 - Module 1027 Clocked Sequential Control Module (Double width Module)
10 - Self-built Output Module w/headphone amp
11 - Self-built Pink/White Noise Generator w/Filters & fixed voltage (very useful!)
12 - Module 1002 Power Control Module
Main Cabinet for a maximum of 19 modules, 15 modules with access to modulation matrix.
Keyboard w/ 5 octaves, lower octave with inverse colored keys.
The cabinet is in good condition but has some surface marks and scratches, as can be expected on an instrument close to 40 years old. On the top of the cabinet was a small spot were the surface was damaged, but this has been fixed with antique furniture wax (the wax is fully removable). There was some other small damage to some of the corners and edges of the cabinet, but this has been also fixed in the same way and looks o.k. The previous owner had scratched his initials "RMS" in small letters into one of the Keyboard Modules and into the Power Module of the main cabinet. This is not too visible and has never bothered me.
The keyboard cabinet is in similar condition to the main cabinet, there is some surface damage to the lower left hand corner. Please have a look at the photos below. It shouldn't be too much of an effort for a good carpenter to return the cabinet to its original condition.
This instrument was used in the last 15 years in a non-smoking studio environment and has performed beautifully and flawlessly during this time. I'm sure the next owner will enjoy it for a long time to come."