If you spend any time browsing synth builder forums, DIY groups, or Eurorack threads, you’ve probably run into the debate: Should you hunt down a vintage original CEM3340 chip, or just use the modern AS3340 reproduction?
It’s a question I get asked regularly by builders working with the 3340 VCO PCB and FRont Panel Kit. The short answer? Go for the AS3340. Here’s why.
The Price of "Vintage"
The original CEM3340 (designed by Doug Curtis in the late 1970s and used in legendary synths like the Sequential Circuits Prophet-5, Roland SH-101, and Memorymoog) is expensive, hard to source, and often comes with the risk of buying counterfeit or degraded vintage stock.
The AS3340 (produced by Alfa Rpar) is a modern, pin-compatible reissue of that exact same architecture. It drops right into the same circuit, tracking pitch reliably and outputting the same core shapes—at a fraction of the cost.
To be honest, I’ve never even used a vintage CEM3340 in my builds—and I’ve never felt the need to.
A Square Wave is a Square Wave !
There’s a lot of "cork-sniffing" in analog audio, but let's be real: a square wave is a square wave, no matter how you produce it.
Sure, subtle non-linearities and tolerances in different oscillator topologies can give a VCO a tiny bit of subtle character. But at its fundamental level, the raw output from a 3340 core is a geometric waveform meant to serve as pure raw material.
The design philosophy behind the 3340 VCO chip wasn't to create a "warm, colored, quirky" sound source. It was designed to do a few specific jobs perfectly:
- Generate core waveforms accurately (sawtooth, triangle, and pulse/square).
- Provide rock-solid 1V/Oct pitch tracking across multiple octaves.
- Offer clean modulation inputs for Exponential/Linear FM, Hard/Soft Sync, and Pulse Width Modulation (PWM).
Where Tonal Character Really Comes From
If the raw oscillator is just the solid foundation, where does the actual "magic" in a patch come from?
It comes from the tools you use to process it.
The real mojo in a modular patch happens after the raw waveform leaves the VCO output:
- The non-linear drive and resonance slope of your Voltage Controlled Filter (VCF).
- The subtle harmonics introduced by wavefolders, saturators, and distortion circuits.
- The complex movement created by LFOs, envelopes, and cross-modulation.
Saving money on your VCO ICs means you have more budget to invest in unique filter topologies, creative modulators, and interesting signal-shaping tools—which is where 90% of your patch's sonic personality is actually born.
The Verdict
If you’re restoring a rare 1980s synth to 100% factory-original specs for museum collector value, buy the CEM3340.
If you are building Eurorack modules to make music, design patches, and tweak sound, stick with the AS3340. It’s stable, readily available, affordable, and delivers the exact core performance the 3340 architecture was meant to provide.
Ready to Build Your Next Oscillator?
Whether you prefer sourcing your own components or building straight out of the box, we have you covered with the Guru Gara Synth 3340 VCO:
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PCB & Front Panel Kit – Includes our high-quality circuit board and signature hand-printed front panel featuring exposed gold-plated ENIG artwork. Perfect for DIYers who have their own parts bin ready.
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Complete Hardware Kit – Includes the PCB, gold-plated ENIG front panel, and all the components needed to complete the build, including the AS3340 IC chip, jacks, potentiometers, and hardware.
Pair your 3340 VCO build with our 3320 VCF or 3310 ADSR for complete signal sculpting.