Gear Change: Siel DK-70

Before I move on from Siel products, I've got to talk about a synth I truly adore, and am sadly parting with. The Siel DK-70 is an 8-voice DCO analog polysynth in the vein of the Korg Poly-800. It has a built-in two track polyphonic sequencer (real time key-presses only, though it does apparently output MIDI) and a wonderful, though strangely implemented, chord memory function. It runs on 6 D-cell batteries (or C? It's been too long since I used batteries), and has guitar-strap pegs on each end. These are the only part of the construction which are actually made from metal, the case itself being manufactured plastic of a quality similar to a Roland SH-101.

The programming interface on the DK-70 is, again, similar to the Korg Poly-800. The parameters are listed on the upper right of the synth (same as the later CTS-2000, except without the membrane button/menu system), and one selects the parameters to edit via the same membrane push-button phone-style pad that one uses to select a patch. The membrane buttons of the pad, I should mention, are surprisingly high quality given the obvious budget mindset of the design, and have been in good shape on both of the DK-70's I've owned. I compare this to the two Sequential Sixtraks and the Sequential Split-Eight I've had, where the membrane buttons were in absolutely abysmal condition despite the fact that the hardware appeared to have been well cared-for. Age is probably not an issue with the DK-70's interface, although this brings us to the memory issue.

The internal memory of the DK-70 was obviously designed as a consumer keyboard, with the lions share of patch save memory reliant upon a cartridge which was offered with the keyboard, which apparently nobody bought, or at least kept. The internal patch memory consists of 40 preset patches, which are very same-y, though usable if the Siel sound is something you're looking for (i.e. if you bought the thing), and 10 user patches, which are not battery backed-up internally and require that one keep the D-cell batteries in the synth, similar to the Casio CZ-101. Keeping it plugged in via the power supply does not ensure that your patches will be saved. When the 10 user patches are reset, the internal rom refills them with the remaining 10 of the 50 preset patches.

That's not so bad, since the final ten patches of the 50 are quite good with a little editing, and editing is extremely easy for anyone familiar with analog synthesizers. The built-in patches are best described as 'standard analog fare' for 1985, though they do exemplify why Siel and other Italian manufacturers were relegated to a sort of ghetto compared to their Japanese and American competitors. The quality of the piano patches on the DK-70 is horrid even in comparison with the standard synth piano patches of the Korg Polysix from four years prior to the release of the DK-70. Strings, perhaps unsurprisingly given Siel's background with the SCI Prelude, strings are where the DK-70 shines. The oscillators have a warm quality which is immediately comparable to the Korg Poly-61, but the Curtis filters paired with the unique design Siel employed give it a clarity and subdued warmth which totally destroys any possibility of comparison with the Poly-800 in terms of sound. Pair this synth with a cheap 80's reverb unit, and you can create the warmest, most enveloping wall of strings, or the most proper techno bleep bass you've ever heard (especially with the Moog Killer modification on the filter which expands the resonance and gives you knob control for that and the Cutoff).

I've owned two of these, and just sold the last one due to money issues, so let me describe some of the issues I've run into.

First, the power supply is a terrifically oversized 12v ungrounded brick, similar to the bricks which came with the Atari ST 520. It can be very noisy, but since I'm not too familiar with electronics I couldn't explain the factors which contribute to this. My building has a truly terrible electrical system, but behind a surge protector power-strip which shared power with my mixer and most of my other equipment, there was very little noise (caveat: my mixer is a first-gen Makie CR1604, which may have a noise floor above that of the DK-70, or there may be some kind of electrical equivalent of audio frequency cancellation, the correct term escapes me but it's the sort of thing that you deal with when miking a drum kit in the studio). However, when I brought the Siel into the audio studio at my university to allow my friend to use it as backing for a track we were working on, it had a terrific amount of hum. Here again, the caveat would be that I don't know how well that studio is wired and we were using it for something which they apparently never anticipated it would be used for.

Second, the keys tend to degrade over time in a fairly common but strangely unpredictable way. In most of the analog synths that I've owned, keys degrade and fail because the mechanism of the key contacts degrade a very slow rate between the contact and the conductive rubber plunger which the key presses down upon them. It can happen through frequent playing, where the rubber plunger wears down simply through overuse, or, more often, because dust accumulates on the conductive plunger and prevents full contact. However, the DK-70's keyboard is, and I state this having only used two of them, very, very cheap. There seems to be about a millimeter of space between the keys. I've only seen something similar with a quite well-worn Korg Polysix, and on that a simple cleaning of the contacts worked perfectly. With the DK-70, it seems to have been a point of the inexpensive design, possibly reusing a keyboard structure from another more expensive synth. The keys are slightly more mushy than other keyboards, probably due to the cheap feel of the keys themselves, which allows dust to act in different ways on them. A key pressed a certain way will not connect, but if massaged enough or if pressed in a different way will connect perfectly. Further caveat would be that I never bothered to try to clean the contacts, as the DK-70 responds very well to MIDI and I have been using another synth as a controller keyboard the whole time I've owned them. I don't think this problem poses any real issue, and if it does there are several cheap fixes in the case that a simple disassembly and cleaning with a q-tip doesn't work. If you have this problem with this synth or any other, look around for some Wire Glue or Conductive Paint (the former is cheaper and just as effective in my experience).

I would highly, highly recommend the DK-70 for someone in the market for a new analog synth to add to their established MIDI rig. On it's own, it provides wonderful sounds, but sampled it can provide an entire palette of analog-style patches to warp and alter which will sound like nothing which has come before.