Friday, 12 June 2015

ARP 2500 & NLC

Wow - Andrew F of Nonlinear Circuits is restoring this baby.

It's another ARP2500. There are now three of these babies in Australia (as far as I know).
These pics were taken in Japan.

Here is the link to his blog about its restoration.
Have fun Andrew.

Some close ups:
 The modules from left to right are:
1023  x 2 - Dual Voltage Controlled Oscillator
1004-T - Voltage Controlled Oscillator
1047 - Multimode Filter/Resonator
1006 x 2 - Filtamp
1046 - Quad Exponential Envelope Generator
1016 - Dual Noise/Random Voltage Source
1045 x 2 - Voltage Controlled Voice
1036 - Dual Sample & Hold/Random Voltage Generator.
1027 - Ten-Position Sequencer
1050 - Mix/Sequencer
1002 - Power Supply.

Notice the ribbon controller...It's a Moog 1150.

Side cabinet 1.
The modules are (from left to right):
1023 - Dual Voltage Controlled Oscillator.
      (It has had 2 switches and 2 pots added to the panel.
       Neither of the switches were wired to anything.)
      More info and pics of this module can be seen here
1006 - Filtamp
1033 - Dual Delayed Exponential Envelope Generator
1027 - Sequencer:
1050 - Mix/Sequencer
1002 - Power Supply.

Side Cabinet 2:
The modules from left to right are:
1004-T - Voltage Controlled Oscillator
1047 x 2 - Multimode Filter/Resonator
1004-P - Voltage Controlled Oscillator
1005 - Modamp
1046 - Quad Exponential Envelope Generator
1002 - PSU

The 1004 VCO comes in two varieties, the T & the P.
The 1004T is the same as the 1004P, except the P also has inverted waveforms.

This is a mystery at the moment. It's obviously a home brew 2500 addition (as if the current system wasn't already big enough). Andrew is currently working out what these modules do.
Some of the DIY modules are just a panel with no PCB behind. So the question is what to
do with the empty spaces?? Maybe add some NLC modules???

So far he has identified (from right to left):
1.  Reverb (extreme right) - the one with the big black dial.
2. Matrix mixer ??
3. DIY modules #4 - dunno - so far a mystery (3rd from the right)
4. Fixed Bandpass Filter (4th from the right)
5.  Clock (5th from the right) - this one uses numitrons -- how cool is that :-)

I love this old skool technology.
Numitron tubes are like Nixies, but instead of the ten number-shaped filaments in each Nixie, Numitrons use eight tiny incandescent filaments arranged in seven to make the number plus a decimal point. When a current is passed through the filaments you want lit up they literally light up just like a light bulb.  
Nixies use high voltages, but Numitrons generally use low volatges.

I'll update this as Andrew unravels the truth.

Finally, on it's way to Australia

1 comment:

  1. Cool stuff. I would love to restore / use a 2500 system! I'm currently attempting to build some of the modules based off of documentation I've found on line.

    Question: Do you have any documentation regarding the physical dimensions of ARP 2500 modules, i.e. how big is the housing and how big are the PCBs?