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Synthchaser Update August 2020

Since my video posts have slowed down during this pandemic (more on why below), I thought I’d start making monthly blog posts just saying what I’m up to and working on. 

For the past few weeks I’ve been doing a double header restoration of 2 ARP Quadras.  One is a customer’s machine, the other is one of mine that I’ll be selling when I’m done (if you want a nice Quadra, drop me a line!).  I thought the LED sliders that I made for the Jefferson Starship Quadra turned out really well, and I’m putting them in these new Quadras as well.  I’m going to try hooking in a PWM module, so the LEDs can be dimmed or disabled with the turn of a knob.

Oberheim owners might want to follow this one.  I recently picked up a 4 voice OB-Xa and decided it was time to make replacement voice cards.  So I’ve laid out a circuit board (I teased this on Facebook and Instagram and was surprised people could identify it from a low-res CAD drawing), and had a few blank circuit boards made.   I need to find some time to build and test one, but the plan is when I’m done, I’ll make these available as pre-built boards, and possibly blank PCBs for those interested in building their own.  I’ll also be making voice cards for the OB-SX because the OB-SX voice cards are a subset of the OB-Xa cards (and I also have a 4 voice OB-SX!).

As most of you know I’m in California.  I’ve got kids and the lockdown and school closures really cut into the time I had to work on synthesizer repairs and shooting videos.  Many of you have asked over the past few months if I could repair some gear and I’ve turned you away for this reason.  I know there are people who will take your gear and sit on it for months or years before fixing it (or before you demand it back and get it back in worse shape than when it went in…), but that’s not how I roll.  If I can’t turn your repair around quickly, I’ll be up front about it and I won’t take your gear in.  Anyway, we just found out that our schools aren’t opening to in-person learning until at least January 2021.  So definitely feel free to ask about repairs, but please be understanding if I can’t take your gear in now.  I am still shipping parts orders, and I still ship parts internationally, though I’m seeing that most international mail is significantly delayed due to COVID-19.

Thank you all for your continued interest and support, and stay well!

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ARP Quadra Replacement Membrane Panel & LED Sliders – Synthchaser #132

I ripped the membrane panel off my ARP Quadra and then THIS happened…

Finally! A replacement for the legendarily flaky ARP Quadra membrane panel! Many an otherwise good Quadra have been turned into doorstops or scrap metal due to failed or damaged membrane panels.

In this video I briefly introduce two new goodies for the ARP Quadra. One is a replacement membrane panel, and the other is a set of LED illuminated sliders.

Both of these products, and the ARP Quadra shown in the video are available below:

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Repairing LEO’s ARP 2600’s with Don Lewis – Synthchaser #130

It was a huge honor and incredibly fun to work on the ARP 2600s from Don Lewis’ LEO (Live Electronic Orchestra) with him this weekend. LEO was a groundbreaking historic synthesizer that served as an inspiration for MIDI, having vintage synths from many different manufacturers (ARP, Oberheim, Roland, etc) all connected and working together. In this video, Don talks a bit about LEO, we show the problem with one of the oscillators in the ARP 2600, and then we troubleshoot and repair it.

There’s a new documentary, The Ballad of Don Lewis, which is available for pre-order on Amazon or On Demand from your cable provider that tells Don’s amazing story, which goes much deeper than just LEO. LEO will be on display again the the NAMM Museum of Making Music in Carlsbad, California starting in 2021.

The Ballad Of Don Lewis DVD:

https://www.amazon.com/Ballad-Don-Lewis-Various/dp/B083VPRQRT/

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ARP Omni & Quadra Master Oscillator – Divide Down Polyphony – Synthchaser #128

In this video, I explain how polyphony is achieved on the ARP Omni 1, Omni 2, and Quadra synthesizers using a master oscillator, top octave divider and frequency dividers. I discuss how this type of polyphony is different from the type of polyphony on the type of synthesizers with fixed number of voices, like the Prophet 5, Oberheim OB-X, and Memorymoog.

I also introduce 3 of my new retrofits–a drop in replacement for the Master Oscillator, a replacement for the TDA0470/TDA0470D gating IC chips, and a replacement 4075 voltage controlled filter.

00:00 Polyphony discussion
03:40 Master Oscillator replacement
09:10 TDA0470SC
10:06 4075 VCF Replacement

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ARP Omni 1 Replacement Switches – Synthchaser #127

The pushbutton switches on the ARP Omni 1 synthesizer suck. The mechanical latch often breaks, leaving us unable to turn on sections of the synth. Other times, we need to press the switch at just the right angle to be able to get it to latch. And yet other times, the switch contacts get dirty and the switch gets stuck off or stuck on.

The originals have been obsolete for decades and are unobtainable. So I’ve created a drop-in replacement switch, that fits the old switch cap! Check it out!

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Sad ARP Quadra Repair & Restoration – Synthchaser #124

It’s time to dig into my stash of ARP Quadras and get a couple of them overhauled and back out into the world. This Quadra was looking really sad, all of its slider shafts were sheared off, and it was shipped to me partially disassembled and in disarray. But the seller said it was working… NOT!

In this video I share (just some of) the ordeal it took to get this Quadra awesome again. Including refurbishing sliders, replacing broken slider shafts, repairing battery corrosion, replacing a dead CPU chip, dead oscillator, dead bass section, no output, broken phase shifter, and the list goes on.

This ARP Quadra is now for sale below.

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Attempting to Re-Silkscreen a Vintage ARP Odyssey – Synthchaser #122

I bought several broken ARP Odysseys, and as is common with the Black & Gold ARPs, a number of them had heavy wear to the gold lettering on the panel. After meticulously restoring the electronics of this one, I decided to risk it all to see if I could successfully re-silkscreen the panel graphics myself. The result wasn’t impressive. Though it made usable again a synth that was otherwise unusable since you didn’t know what slider did what.