Sunday, October 19, 2014

Fetishizing the Moog modulars

Lately I'm noticing a big surge of interest in the vintage modular Moogs. Now, this in itself is not a bad thing. It's a good thing, and not only from the historical preservation sense.  It's always good to have a perspective of history, and to see how Bob Moog and his compatriots made their decisions and went about doing things without access to all of the technology we have today. Remember, in 1963 when Moog and Buchla built their first modules, the integrated circuit was still largely confined to Fairchild Semiconductor's labs. The commercially package operational amplifier was a big ugly box that plugged into a tube socket and contained a pair of 12AX7 tubes inside it. There were no OTAs, no 4000 CMOS logic; Doug Curtis was in elementary school, and Ron Dow had not yet gone to Dave Rossum and Scott Wedge to beg for money (which was a good thing, since Rossum and Wedge were themselves high school students and didn't have any money).

Yes, things were different back then. Moog (and, independently, Buchla) had just thought of the idea of “voltage control”, in which he imagined that a generated signal might be able to remotely control the functioning of another circuit, thereby increasing the possibilities for more animation in electronic music, e.g., that the output of one oscillator could control the frequency of another in order to introduce vibrato, without a person having to constantly turn the frequency knob up and down. This was new territory; at first Moog had no idea how to do it with components that were available to him. As he attacked the problem, he made it work, but there were a lot of compromises: many components being made to do things that they weren't designed to; use of some expensive components which forced cost cutting in some other areas, and the necessity to keep the circuits confined to a reasonable sized package. There were also things to consider like what we now call the “user interface” was to function. (We all know the story of how the synthesizer came to be primarily a keyboard instrument: the switches of an organ keyboard, wired to a resistor grid, worked a lot better than primitive pitch-to-voltage converters and provided an interface that looked familiar to musicians.)

Consider Moog's first voltage controlled oscillator, the model 901A/B duo. At a list price of several hundred dollars in 1964, what you got for a 901B VCO was a basic oscillator with four waveform outputs. If you wanted volts/octave response (which was essential for any kind of tonal music), you had to also buy the separate 901A driver module which contained the exponential converter. And oh by the way, the VCO contained absolutely no temperature compensation, which meant you had to constantly re-tune as the circuits warmed up and/or the room temperature varied.

As another example, consider the Moog 904B VCF. Here's a photo of one:

Moog 904B.  Photo courtesy of David Brown at

Note that it's a 2U wide module and how big it is and how much empty space there is on the panel. Why is it so big? Because the circuit board behind the panel needed to be that big in order to cram all of the circuitry in.  Here's another, more drastic example of that sort of thing:

Moog 905.  Photo courtesy of David Brown at
This is the 905 reverb.  Lots of wasted panel real estate?  You bet.  It's that large because it uses a spring reverb tank, which is mounted in the module itself, right behind the panel.  Modern modulars that offer spring reverb modules mount the tank remotely, somewhere in the rear of the case.  Although, oddly, the Club of the Knobs reproduction of the 905 retains the same 2U wide panel design, even though it uses remote mounted tanks:

Club of the Knobs C905 reverb.  Photo from COTK's Web site.
This is taking authenticity to a bit of an extreme.  Clearly, a 1U panel would have been sufficient.  The Eurorack users always say that all of the large format modulars take up too much space, and this sort of thing doesn't help.

There were a lot of things about the Moog modulars that were different from today's modulars and made them not so easy to interface to or work with. Most Moog VCOs and other signal generators output a signal that is only 1.5V peak to peak. This I assume was a choice made based on typical use of signals as modulation sources, but, for example, it means that the output of a VCO or an envelope generator can't be made to drive a VCF though its full frequency range without being amplified.  For reasons totally unclear to me, MOS-LAB recently decided to go back to Moog's 1.5V standard for its reproduction of the 901B and 921B VCOs. 

MOS-LAB 921B VCO.  Photo courtesy of
And there's the infamous S-trigger signals. On a Moog modular (and other vintage Moog synths such as the early Minimoogs), something that generates a trigger or gate signal does not output a voltage pulse. Rather, the output is a simple transistor that is saturated in the “low” or “off” state, shorting the output to ground, or cut off in the “on” or “high” state, which leaves the output “floating” electrically. The output expects that whatever trigger/gate input it is patched to will “pull up” the output by applying a voltage through a resistor. When the output is in the high state, its voltage rises to the pull-up voltage; when it is in the low state, it shorts the output to ground, and the pull-up resistor limits the current that flows to ground. We've all seen that the modular Moogs use the infamous “Cinch-Jones” two-bladed connector for trigger outputs and inputs, requiring a separate type of patch cord to connect them (and thus the modular Moogs do not have fully unified patching). This is why; if a trigger/gate input, with its pull-up, were inadvertently connected to a signal output, it could potentially damage the output circuit.  But it's a pain because of the special cable needed, and because you need an adapter to interface any external trigger or gate source.  Mercifully, neither MOS-LAB nor COTK has chosen to use the S-trigger on their Moog reproductions, even though the connector itself is still available

Moog 911 envelope generator; note Cinch-Jones gate input connector at bottom left.  Photo courtesy of David Brown at
And last but not least, there's the cost of construction using those "authentic Moog" methods and circuits.  As I wrote above, there were a lot of places where the Moog designs had to use methods and techniques that were a lot more expensive (such as building op-amps out of discrete circuitry) because more capable components weren't available at the time.  Consider: offers two step sequencers -- the Q119 and the Q960.  The Q960 is a fairly faithful recreation of the Moog 960 sequencer design, up to and including the incandescent lamps which indicate the active stage (which most users replace with LEDs because the lamps burn out frequently).  The Q119, on the other hand, has most of the same capabilities and controls but is microprocessor controlled, and all of the indicator lamp are LEDs.  The two share many capabilities -- but the Q119 is about $300 less expensive, plus in order to duplicate the Q119's 24-step mode with the Q960, you need to add a Q962 sequential switch, at an additional $160. 

Moog 960 (top) and Q119 (bottom).  Top photo courtesy of David Brown at; bottom photo courtesy of

So given all of the above, I'm starting to wonder if the current market isn't fetishizing the modular Moogs a bit much. Of course, the Dotcom/MU format was based on the physical dimensions of the original Moog modulars, and Roger Arrick's designs continue to take certain design cues from the Moogs, such as the black panel background and the knob style. But Arrick started out with fresh circuit designs using contemporary electronics technology. And he's no slave to the Moog look and feel; he has never hesitated to make a module smaller than the functionally equivalent Moog module when the circuit design allowed for it. The other notable thing was that Arrick avoided both the weird mix of power supply voltages and the edge connectors that Moog modules used; set the standard power for the MU format at +/- 15V and +5 volts, and the flexible power supply harness doesn't limit the modules' board mounting geometry the way the Moog edge connectors did. (The Dotcom MTA-100 power connectors are also a lot less prone to corrosion problems than the Moog edge connectors are.)  As for Club of the Knobs, they started out copying the Moog modules, but soon realized that simply duplicating the Moog lineup would be too limiting.  And although they continue to stick to the general Moog format, they have long since blown past the limitations of the original Moogs with module designs that Moog could never have thought of or implemented with the technology available at the time, such as the C950A MIDI interface / arpeggiator. 

That's why, to be honest, I really don't want to see a big comeback of slavish Moog-modular clones. Even putting aside the difficulties of obtaining exact replacements for the vintage Moog parts, the 1960s Moog modulars were just all-around limited compared to what is available today. Yes, it's great that Moog has been able to sell several of the $1.5M copies of the Keith Emerson modular; the units will instantly be valuable collector's items as well as being highly educational, and more power to Moog for being able to build them and sell them at that price. What bothers me is the people might get the idea that the 5U formats are all about duplicating what has been done in the past, with the implication being that you have to turn to the Euro format to find any modern or fresh ideas. That would be a self-limiting move for 5U.  And as someone who wants modern capabilities but prefers to work with 5U formats, I don't want to see that happen. 

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