The MODCAN Quantizer 55B - a mini review
2007-04-15 by Richard Brewster
I have used my Blacet Miniwaves mostly for quantizing, since I like to use scale tones in my aleatoric musings. I've looked around for a dedicated quantizer, but never found anything well suited to a standard MOTM setup until this. Not sure when it was added to the Modcan B lineup, but the Dual Quantizer 55B fills the bill. I've updated my website with some photos and a two minute MP3 demo. http://www.pugix.com/top-cabinet.htm#quantizer The Miniwave does well as a quantizer. Modcan offers a version of the Miniwave, too, with a built-in VCO. There's a quantizer bank in the standard Blacet ROM. The Davidson SCALE Quantizer ROM is excellent, too. I'll speak to the differences between the quantizing with the Miniwave and the Modcan 55B in a bit. First, about the physical Modcan 55B module. As you can see from the photos on my site, the 55B fits perfectly into my MOTM rack. Although it's a thinner panel, the 1/16-inch difference of height (shallower than the 1/8-inch MOTM panels) is barely noticeable. What *is* noticeable of course is the color. The panel design is nice and clean. The jack spacing and locations are different from MOTM. The switches are mini-toggles, not bat-handles. Alpha pots are used. I replaced the knobs, not just because of the look, but because Modcan knobs have a gap in the flute that the set screw goes through, and your finger catches on it. It's annoying. Otherwise, build quality is very good; it's clearly assembled with care. You'll notice that the hardware consists mainly of a large PIC microcontroller. The six trimpots are labelled, but there's no mention of them in the instruction manual, which is very short. It would be nice to have a calibration procedure. Lead time on this was two months from placing the order and payment and receipt of the module. I never ordered from Modcan before, but this seems about normal. When I placed the order, Bruce Duncan responded quickly and asked what power cable I required. He supplied a MOTM power cable adapter at no extra cost. The 55B features. There are two identical and separate quantizers. Each has an input for the CV to be quantized, an output, a clock input and a pulse output, and three control inputs. There are four parameters, three of which are under voltage control. You manually select one of three fixed scale banks. This isn't under VC like the Miniwave bank is. Each bank has 16 scales, selected by the sum of a pot and a SCALE CV input. There is also a TRANSPOSE pot and CV input; the Miniwave has nothing like this. It is a key transposition, not just an offset. (I don't really understand the difference. Maybe one of you will explain it.) Finally, there is an INVERT input that responds to a gate. This simply inverts the output around ground. If your input is all positive, when inverted it is all negative. I didn't quite see the utility of this until I realized that negative inputs get quantized just fine, unlike the Miniwave, which needs a zero to +10V input in quantizing mode. So you can merrily quantize a MOTM-320 LFO, using any of its waveforms. You'll normally want to use an external attenuator on the input for overall scaling. None of the inputs has a pot for attenuation, due to lack of panel space. With nothing patched to the CLOCK input, quantizing happens when the input crosses a quantized boundary, just like with the Miniwave. On each transition you get a short pulse out of the PULSE output. It's something I have wished the Miniwave had. (I saw a schematic somewhere describing a pulse output Miniwave modification.) My demo MP3 shows this off by using it to trigger an envelope generator to make a new note on each transition. Now, I found that when quantizing the output of a sample and hold, the 55B works better if you clock it with the same clock used for the sample and hold. It's cleaner, because with large jumps without clocking there can be a zipper effect as multiple transitions are crossed. The 55B makes a nice sample and hold by itself, with a no-droop digitized output. I admit to general ignorance when it comes to scales. But I can say that the choice of scales in the three banks has a good variety. My favorite is the B bank, which includes Algerian, Altered, Aux Diminished, Balinese, Byzantine, Diatonic, Spanish, Double Harmonic, Hindu, Sixtone Symmetric, Nine Tone, Overtone Dominant, Pelog, Prometheus, Enigmatic, and Octatonic. (These are listed on the Modcan website as being in the C bank, but the downloaded manual puts them in bank B and to my ear this seems right.) Overall impression is of a very nice module that I will use a lot. Now maybe it needs a few Modcan siblings in my cabinet. The Clock 53B looks very interesting.... -Richard Brewster http://www.pugix.com