Eurorack fever continues to spread. The ease of making musical electronics fit the standard, pioneered by Germany’s Dieter Doepfer, and the growing appetite from a small but passionate audience, seems to make producing new modules irresistible. The entire design equation is different: a single task or handful of tasks can become a product.

Dave Smith Instruments is the latest entry. And the product is the perfect choice for DSI. It’s a module built around on the Curtis filter, the signature filter found on everything from the 1980s Prophets (back when Dave’s company was Sequential Circuits) to the latest Mopho and Prophet 12 – as well as instruments like the Oberheim Xpander and Rhodes Chroma.

Putting the Curtis filter in a module gives you a range of features:

  • Switchable 2/4-pole, resonant low-pass filter
  • -12 dB, -24 dB switchable filter slopes
  • Dedicated voltage-controlled amplifier (VCA)
  • Audio input jack, filtered audio output jack (well, of course, though you can choose signal from either before or after the VCA)
  • Control voltage inputs for frequency, resonance, and amplitude
  • Self-oscillation in 24 dB mode

Street (MAP) US$179.

And yes, it’s actually as far as I know the first time in quite some that Dave Smith, known as the father of MIDI, had his name on something without MIDI built in. But that’s not in and of itself news; a module is by definition different from a standalone synthesizer.

What I think is worth discussing is what the value proposition is. In the context of a modular system, having a Curtis module makes perfect sense. On the other hand, modular isn’t a format that makes sense for every application. You can get this same filter in a DSI Evolver for not much more than the module costs (on the used market) – and sort of get an entire synthesizer free in the process. So if you’re just looking to route your sound through a filter, that remains an option. Apples to oranges? Absolutely. Sometimes you want an apple; sometimes you want an orange. (Sometimes you want both. Or a juicer. I’m off topic.)

The other question I have is how the DSI module fits in with the DSI lineup, whether we’ll see more from the maker. Maybe just a one-off filter module is enough, because of the abundance of great modules now in the Eurorack ecosystem. We’ll have to watch to see if Dave Smith is just testing the waters, with more to come.

But as this ships, I’ve no doubt it’ll please a lot of Eurorack lovers. And it should make a great addition to modular setups – I could see it even in a fairly small suitcase rig. Full details:




1 CV In – Frequency (3.5 mm jack) Range: 0 to 10V
1 CV In – Resonance (3.5 mm jack) Range: 0 to 10V
1 CV In – VCA (3.5 mm jack) Range: 0 to 10 V
1 Audio In (3.5 mm jack) +/-5V or 10V p-p
1 VCF Out – pre-VCA (3.5 mm jack)
1 VCA Out – post-VCA (3.5 mm jack)
Self oscillation in -24 dB/octave mode, tracks at 1V/octave

Internal power connector (ribbon cable included)
Current draw: +12V @ 36mA, -12V @ 25mA

Physical Specs
1.59″ W x 5.06″ H (40.3 mm x 128.5 mm)
Depth (measured from back of panel with power cable installed): 1.06″ (27 mm)
Mounting screws included

Compact, too – 8 HP.

DSM01 Curtis Filter [Dave Smith Instruments]