Michael A. Firman
Electronic Music Connectors

In the late 1980's I built a full blown modular synthesizer from kits. The manufacturer was a company in England called Digisound, and the particular set of modules that I had selected from was called the Digisound-80 series. I had owned semi-modulars previously. In particular I had an ARP 2600. Now the ARP and the Digisound both used mini-jacks (1/8" "phone" jacks) as their patch interface. This was a perfect situation for me during the building process for a number of reasons. First I was able to "bootstrap" the Digisound as I was building it. I could use the ARP to easily plug up, test, and calibrate any new module that I built (plus the ARP had a built in amp and speakers, and could easily be dragged out of my studio and into my basement where I had my soldering station and work bench.). Second, when I got a nice little collection of Digisound modules built I could put them immediately to work up in the studio as extensions to the ARP, using the same patch cords that I had always used.

Once a full complement of modules was complete I wanted a nice analog sequencer to drive the thing. Digisound didn't have a complete sequencer in the catalog so I began looking for alternatives. At the time, the only other (to my knowledge) analog modular manufacturer still in business was Serge Tcherepnin (and I wasn't really sure he was still selling products). I managed to get a phone number and, by calling Mr. Tcherepnin, confirmed that he was still selling Serge synthesizers. I got a catalog and, after some thought came up with a layout for a sequencer panel (that was in my budget!). I called Serge back to place the order and I told him I wanted to interface this panel with an ARP 2600 and the Digisound. At that point I asked him if he could equip the sequencer with mini-jacks for the CV outputs (the catalog, at the time, mentioned that one could request custom connectors if desired). By the tone of his voice I could tell that Mr. Tcherepnin became agitated. He launched into about a fifteen minute lecture on the great benefits of banana connectors (some of which was actually in written form in the Serge catalog of the time), and how the nature of the piece of equipment that I was ordering would be greatly compromised by making the modifications that I had requested. By the end of the conversation I had settled on three rows of banana-to-mini jack adapters to be placed at the end of the panel. I was a little shocked at how important this issue was to this fellow (although, in retrospect, I should have guessed it was a hot button issue from the space he devoted in the catalog to the explanation I mentioned earlier). The point of this little story is that, this was the first of what became many discussions/arguments on this topic, with a variety of people. Furthermore, the arguments still haven't ended!

Let's first look at the benefits of banana jacks/plugs.The most significant benefit of this type of connector is that the banana plugs themselves stack. On the surface this might seem a bit benign. What this gives the synthesist, however, is the ability to fan the outputs of any module out to many modules without the need for "multiples". If you have a moderately complex system and are trying to put together a non-trivial patch then this becomes very important (one can quickly run out of multiples but the banana cables can be hooked together in seemingly limitless ways). Another benefit to banana jacks is that they come in a variety of colors and hence can be used by the synth designer to organize the system's I/O [Side-bar: the Serge system uses (roughly) red for gates, (both in and out), black for "audio" (both in and out), blue for control voltages, and yellow and white for other functions (like triggers, adapters, etc.)]. Now there were and are several manufacturers that utilize banana jacks; STS (Serge), Modcan, Fenix, and Buchla being the most well known. The early Buchla systems actually used both banana jacks and mini jacks, the former for control signals and the latter for audio.

On to the the benefits of mini jacks/plugs. Okay, I've already alluded to one of the benefits of mini jacks, namely that they seem to be ubiquitous and universal amongst synth manufacturers. This allows the synthesist to mix and match modules from different manufacturers (given, of course, that the signals follow some sort of standard). Many manufactures indeed have chosen this route; Doepfer, ARP, Wiard, Digisound, Roland, Blacet Research to name a few. Another benefit is that the connectors are small, smaller than both banana jacks and 1/4" phone jacks. This allows manufacturers to pack them into smaller areas (or pack more of them into an area) than would be the case with the other alternatives. A third benefit is that mini-jacks (and their big brothers, the 1/4" phone jacks) can be switched, i.e. the jacks can contain a small switch that is closed when there is no plug inserted and opened when there is a plug present. This allows the manufacturer to "normalize" connections within a given module (or between modules in semi-modular systems like the ARP 2600 and Korg MS20). What this means is that the manufacturer can "pre-patch" common connection points (like the output of a mixer going directly into a filter input) that can be over-ridden when the user inserts a patch cord. This saves the synthesist patch cords for commonly used connections.

Most of the same benefits of mini jacks apply to 1/4" phone jacks as well. The only exception being the size (they are bigger than mini jacks and banana jacks) benefit mentioned above. Phone jacks have one further benefit however. The patch cords for phone jacks are available everywhere (this is the standard for Guitars and Guitar/Keyboard amps). This also means that your 1/4" equipped module can be plugged directly into your Mackie mixer, or Guitar amp, or effects box, or whatever, you get the idea, using just a standard Guitar cable. Many significant manufacturers have used 1/4" phone jacks; Moog, Synthesis Technologies, and Korg being the most well known.

A final benefit to using either mini jacks or standard 1/4" phone jacks is that the patch cords used with these connectors are shielded coax. This has two advantages, first the cords can carry a signal ground from one module (or system) to another, making it unnecessary to provide a common signal ground for all the modules (or systems). Second, the shielding can cut down on noise in the audio signal when longer cable runs are needed.

Are there disadvantages to banana jacks? Well, I've already mentioned and alluded to a few; they are somewhat large, modules using them must be carefully grounded, since the patch cords don't carry a signal ground with them, for long cable runs they can be effected by noise, the patch cords aren't as available as the cords for the mini or phone jacks, and systems using them can't take advantage of normalized connections. One disadvantage should also be mentioned, the commercially available cables (ITT Pomona being the big manufacturer) are a bit stiff, i.e. not very flexible. This causes some storage problems - unless carefully stored, they can take up more space than one would at first think.On to the the benefits of mini jacks/plugs. Okay, I've already alluded to one of the benefits of mini jacks, namely that they seem to be ubiquitous and universal amongst synth manufacturers. This allows the synthesist to mix and match modules from different manufacturers (given, of course, that the signals follow some sort of standard). Many manufactures indeed have chosen this route; Doepfer, ARP, Wiard, Digisound, Roland, Blacet Research to name a few. Another benefit is that the connectors are small, smaller than both banana jacks and 1/4" phone jacks. This allows manufacturers to pack them into smaller areas (or pack more of them into an area) than would be the case with the other alternatives. A third benefit is that mini-jacks (and their big brothers, the 1/4" phone jacks) can be switched, i.e. the jacks can contain a small switch that is closed when there is no plug inserted and opened when there is a plug present. This allows the manufacturer to "normalize" connections within a given module (or between modules in semi-modular systems like the ARP 2600 and Korg MS20). What this means is that the manufacturer can "pre-patch" common connection points (like the output of a mixer going directly into a filter input) that can be over-ridden when the user inserts a patch cord. This saves the synthesist patch cords for commonly used connections.

Are there disadvantages to mini jacks? Again, I've indirectly pointed out a few, namely that one must use multiples for complicated patches (not a small problem) and that manufacturers can't easily color code the patch points. I should mention a philosophical point here. Because the mini jacks allow manufactures to easily normalize connections, they do normalize connections. What this can lead to is a sort of de facto programming method that the manufacturer dictates to the synthesist. A lot of people would argue that this is a way the manufacturer prejudices the synthesist, preventing him/her from more easily expressing creativity.

Are there disadvantages to phone jacks, beyond the ones mentioned for mini jacks? Well, yes, sort of a big one in my book actually. The patch cords for this type of connector are big and HEAVY! This makes them difficult to store and lug around.

Now, with all this said, it might seem like I'm leaning toward the mini jack side of the war. Actually, if anything I'm a bit partial to the banana jack system. I'm not very big on using normalized connections (I often forget what is normaled to what, and unless the manufacturer supplies an easily accessible diagram, I get pretty lost) so that isn't a big issue with me. I like the color coding on Serge systems and I really like the ability to stack the patch cords. When it comes to lugging boxes of patch cords around (particularly up on a stage) I like the convenience of the mini plug cables.

What determines which route a particular manufacturer will take, well, that's really a design consideration (probably one of many interconnected design issues) that has to be weighed in the early phases of product concept. In a perfect world, maybe it would have been nice to have one type of connector (I own systems with each type) but there seems to be situational advantages and disadvantages to each.

— Michael A. Firman 11/27/2000