PAIA 2700/4700 MODULAR ANALOG SYNTHESIZER

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"A few years ago I decide to take my 1974ish PAiA synthesizer and rebuild it. I researched components by consulting with Scott Lee of PAiA. I designed custom panels through Front Panel Express. To keep the engraving costs down I went with a minimalistic look that was reminiscent of PAiA yet totally original with a vintage vibe, especially the knobs.

I had Steve Wood, a former PAiA Tech from back in the day, do all the module refurbishing. Most of the major components on the boards were replaced & all ICs socketed. The audio path has upgraded caps and Burr-Brown op-amps. All front panel parts and hardware are new. Taking Marvin Jones’ advice, I replaced all the control voltage “pin jacks” with 3.5mm audio jacks. These are grounded so I could interface the PAiA with my other modular gear.

Multi-turn pots are used for VCO frequency tuning (they look like the pots on the old “Putney” synth!). The “bouncy” push button switches are replaced by momentary toggle switches and all of the switches are now toggle switches with vintage looking paddles.

Perhaps the biggest improvement was replacing the weakest link in a PAiA chain: the power supply and distribution buss. While the 4700 regulated power supply was a step in the right direction, the +18V line was never regulated. The “buss-bars” used for power distribution were difficult to get a solid connection and were prone to problems. Plus, it made removing modules extremely difficult. This was solved by Frankensteining the newer 9771 power supply, dropping the power to +/-9 and adding a PAiA K60 regulated power supply for the 18V line . The 9771 power strips are connected to Blacet PS-CONN distribution boards and the modules power wires terminate into a 0.156” header to plug into the new power buss (see pictures). The result is clean and stable power with a hefty 1A supply.

One other thing to note is the custom patch bay. The bottom jacks are RCA and labeled CV, Gate & Vel. I would hook up my FatMan there to control a couple of the VCOs and use the Keystep 32 to play another line, all under MIDI Control! If you don’t have a FatMan I have a heavily modded-out one that I wasn’t planning on selling yet. If there is an interest I can add it to this listing and adjust the price.

Here’s the list of major improvements:
• Thicker, custom panels that are clean and minimalist yet reminiscent of the originals with their own vintage vibe
• All modules have been recapped with audio grade components (except for ceramic disc caps)
• New 3.5mm jacks for both audio and control voltages (grounded)
• All new panel/PCB hardware
• All audio op amps replaced with Burr-Brown
• Push button switches replaced with toggle paddles
• All potentiometers have been replace
• Original PAiA knobs throughout except the filter Q and LFO speed switch (noth with a "Moog" look!).
• VCOs have 10-turn pots for greater accuracy
• AD(S)R pot values have been increased to maximize rise and fall times while keeping the minimum settings
• Fully regulated power supply and power distribution is through Blacet P-CONN power strips for greater voltage stability.
• +/- voltage bias control on Power Supply panel.
• The road cases were re-tolexed with new hardware

Modules Include:
• 4 4720 VCO
• 2 4730 VCF
• 2 4740 ADSR Envelope Generators (Extended Range)
• 1 4750 LFO/Noise
• 1 4710 Balanced (Ring) Modulator/VCA
• 1 4711 Mixer
• 1 4712 Reverb (Tank Mounted on Rear of Case)
• 1 2701 VCA
• 1 2711 Envelope Follower
• 1 2712 Inverter/Buffer
• 1 4771-R Power Supply (Custom)
• 1 4700 Patch Panel 2 (Custom)"