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Modular synthesis intro, part 3: How to get started

Tue 31 Jan 2017 by mskala Tags used: ,

I will assume that you've already read part 1, which describes what a modular synthesizer is; and part 2, which says that you shouldn't buy one. Your spouse isn't allowed to kill me because I did warn you, and your cat has already formed an opinion on your intelligence anyway. In this final installment I'm going to offer some suggestions on how to get started with modular synthesis. Very much depends on your own reasons, which are ultimately known only to you, for why you've decided to do this. I can only offer some insights that may be helpful for what I think are typical newcomers.

This installment grew a lot as I was writing it and in fact I should probably have just split it into two or more and made the series more than three parts. Maybe someday I'll rework it into such a form. But, for now, what you get is a three-part series with a very long third part.

I'm writing this assuming the Eurorack modular format, which is really the only one I'd recommend to a newcomer today. By "format" I mean the standardized physical dimensions of the modules, their electrical connections, sometimes conventions on panel layout and visual design, and so on. Devices built for a given format should all work together. Other formats beyond Eurorack exist, including the formats of the original Moog and Buchla systems from the 1960s, but Eurorack is by far the most popular one today. It has the widest range of modules available; because of its popularity, prices are sometimes lower and it has a stronger community; and it's physically compact, making the equipment more portable, all compared to other formats. Eurorack originated with the Doepfer A-100 system in the 1990s; it is based on, but differs in some important ways from, the Eurocard standard used for some industrial electronics.

You should expect that getting started in this hobby is going to cost you between about $1000 and $2000 (US dollars - I'm in Canada but I think readers of this will be all over the world, and probably more familiar with the conversion from their local currency to US dollars than to Canadian). There are some ways to economize, which will be described in this article, but using those techniques will help you keep the price tag in that range, not really bring the low end further down. If you make modular synthesis a big part of your life you may well end up wanting to spend much more money in the future, but it's also possible to buy a starter system and just keep using it indefinitely without spending more money.

Plug in

Modular synthesis is a social hobby; a big part of the experience is connecting with others who are doing the same sort of thing you are, sharing ideas, getting into occasional flame wars, and so on. Even if you hate interacting with people, it's worth making the effort at least occasionally to exploit them as information sources, sell your old unwanted modules, buy fresh modules cheap, and so on.

The greatest, not the only, online nexus for modular synthesizer users today is a phpBB-based Web forum called Muffwiggler. The name discussion has already been done to death. If you're interested in getting started with modular synthesis, it's certainly worth creating an account there and taking a look around. Lurking for a bit will give you a much better idea of what this hobby is all about. Other relevant online fora include Electro-Music, the Synth-DIY mailing list, and the Mutable Instruments online forum.

There are often in-person events for modular synth users in large cities. Lurking on Muffwiggler is probably the best way to find out about these - there's a subforum specifically intended for planning and announcing them.

Modular Grid is an online "planning" tool for modular synthesis. You can drag and drop pictures of modules onto a picture of a rack and build up an imaginary synthesizer. In principle this is useful for deciding what modules you want to actually buy, or for deciding how to lay out your collection of modules in your case, but really, I think most people just use it as fantasy material, building on the screen a synthesizer they imagine owning. Anyway, it's coupled to a database of available modules, with remarkably good data quality considering that it's maintained on the Wiki principle, so it's a good resource for looking up what modules are available in a given category and so on. The rack planner also includes automatic estimates of the total price and power requirements for a setup.

When you're considering buying a module, you should look for "demo" videos of it on YouTube. People make such videos for nearly all modules, and they can give you a good idea of what the module sounds like and how it's used. It's a bit unfortunate the YouTube has become the standard venue for such things, because its sound quality is atrocious even in the best case where people recorded the signal directly from the synthesizer; even worse when they used the microphone built into a Webcam. But that's the world we've created for ourselves.

Learning synthesis

Some wigglers claim to have a lot of fun with their synthesizers just by plugging in cables at random without knowing anything about how the sounds are made. I think a disciplined approach of actually knowing what you're doing is likely to give better results. For that, you're going to have to learn a bit about sound and how synthesizers in general work. You can pick up some ideas just by talking to other modular users, but there are also plenty of things to read and play with.

The Synth Secrets articles from Sound on Sound magazine are a good place to start. This is a 63-part series covering a wide range of synthesis techniques. Early parts claim it'll just be about "subtractive" synthesis, but in fact the series also went to many other places in its five-year run. If you read through all of that, you'll probably be ahead of most of your peers in terms of technical knowledge.

It's worth getting Csound or another software modular synth and playing with it. I talked about these in more detail last time. They're a good way to try out different synthesis techniques, and they have some unique advantages over hardware. Using one for a while before you start buying modules will help you get a clearer idea of what modules you want.

The user manual for every North Coast Synthesis Ltd. module includes patch suggestions and technical discussion of the circuitry. Even if you don't buy the module, you may want to download and read the manual as a source of ideas. Some other module makers also offer patch suggestions.

Ready-made systems

As I discussed last time, if your main focus is on making music, then you may be better served by some other instrument than a modular synthesizer. Modular synthesizers appeal most to people who want to spend a lot of time tinkering and building up a customized system from individual pieces, possibly to the exclusion of actually making music with it.

Nonetheless, if you want to skip the part that most modular users find fun and just get started with a usable system with a minimum of fuss, it is possible to buy a complete modular system as a package deal and not have to think about it further. You may get a slightly better price this way compared to buying the pieces one at a time; and you'll certainly get up and running making music faster.

Doepfer makes a couple of different standardized complete systems, with prices ranging from around US$1200 to US$2400. Any of those would be quite reasonable ways to start off with a complete usable system. I favour the "Basic System 2" (which comes with a USB and MIDI interface, so you can drive it easily from a computer or keyboard synth) and the "Mini-System," which is a well-balanced small system. Any system built completely from Doepfer modules like these will probably be influenced by the Doepfer philosophy of splitting the synthesizer into many small, simple functions. This is more or less what people mean by "East Coast" synthesis.

If you buy one of the Doepfer ready-made systems, then for an extra charge you can have them install it in a bigger case, with an empty row for adding other modules in the future. It's a good idea to do that. Otherwise, you'll be facing another case purchase as soon as you want to expand.

MakeNoise offers the Shared System, a packaged collection of their own modules that form a complete instrument for US$4500. These are bigger, more complicated modules, and fewer of them, partaking more of the "West Coast" synthesis tradition. Most are also digital, with microcontrollers at their cores, should that make a difference to you. The Shared System also includes a small amount of empty rack space, which you can use for adding one or two extra modules of your choice (maybe from some other manufacturer).

The MakeNoise panel graphics are polarizing. Some people love the look, and some hate it. I'm in the latter camp. However, I must admit that when it's an entire system those graphics look a lot better, especially in the black-and-gold edition. My visual objection is to a single MakeNoise module in the middle of a system built out of other manufacturers' modules, where it tends to clash. It's easy to argue both sides of that question. One side: if you're making music, shouldn't you care more about how it sounds than how it looks? The other side: if you're spending thousands of dollars on a thing for your own amusement, why should you buy it if you don't love it?

If you get a ready-made system, you're basically done. The rest of this article is about the more complicated, and more modular, approach of building up a system from parts obtained separately.

Power supplies

Eurorack modules require +-12V DC power and sometimes +5V as well, so you need a source of such power. Most people buy power supplies designed specifically for Eurorack, which will usually come with either a rigid "bus board" that has male header connectors on it, or a "flying bus," which is a ribbon cable with such connectors attached directly to the cable. Then each module comes with a female-female cable of its own for connecting the module to the power bus.

Bus boards are preferable. Flying busses introduce enough resistance in the power distribution that they can cause crosstalk between modules. However, that's not a dealbreaker; you can still get very good results with a flying bus, especially in a small system. They're just maybe not the absolute best. Flying busses are often a fair bit cheaper, which is why they remain popular. I'd say, go ahead and get one if that's what comes with the power supply you want to use, but all other things being equal, it's nice to have a bus board.

There are a few different ways to get the power onto the bus. Some cases (see next section) come with built-in power supplies, which might plug with a cord directly into the wall (like most of the Doepfer cases), or have a low-voltage input supplied by a "brick" or "wall wart." The outboard component in turn might be a switching supply producing DC at a relatively high voltage to be regulated down by components on the bus board, or it could be AC at less than mains voltage, with the AC-to-DC conversion done inside the case. The connection to whatever cord there is, could be on the side of the case or through a panel that mounts like a module into regular rack space (like the 4ms Row Power or Tiptop μZeus).

Part of the reason for separating part of the power supply into an outboard device is that in most places, anything that plugs into the wall is required to go through an expensive "certification" process of safety testing before it can legally be sold. Manufacturers of these power systems make an argument (which may or may not be legally correct) that if the system consists of a wall-wart which plugs into a circuit board with a low-voltage connection between the two, then only the wall-wart has to be certified (ideally it can be a commercial product bought from some other manufacturer who already paid for the certification) and the circuit board doesn't need to be certified. Another reason for the two-part design is that the voltages and plug shapes needed for dealing with mains electricity are different in different parts of the world, so with some care it may be possible to design the system so the circuit board is usable everywhere and you just swap in different versions of the outboard transformer according to the local voltage.

Some people make a big deal of preferring "linear" power supplies for audio applications and turning up their noses at "switching" power supplies. The difference has to do with how the voltage regulators work - linear regulators are inefficient and unable to handle variable input, so by audiophile logic they must be better. My perspective is that a properly designed present-day switching regulator is perfectly acceptable in audio applications, and a badly designed regulator of any kind will cause trouble, so you should be looking for quality rather than looking for the word "linear."

Occasionally someone floats the idea of trying to use a PC power supply to power a modular synthesizer. That is usually not a good thing to do. PC power supplies are appealing because they are produced in huge quantities and therefore cheap, but they are not well-optimized for modular synth use. The average PC power supply is meant to supply massive quantities of power - often hundreds of watts - at a low voltage like 5V or even 3.3V. It will have +12V and -12V outputs too, but those will have much less current available, and the +-12V outputs may be poorly regulated. Those outputs are usually only meant for driving relatively undemanding mechanical things like fans and hard drive motors. On the other hand, a Eurorack modular synthesizer will usually draw most of its power on the +-12V busses; a few computerized modules may also want significant amounts of 5V, but not the huge amounts available from a PC power supply. And modular synthesizers are relatively sensitive to the cleanliness of the power, especially on the -12V bus because of the way op amps (a basic analog building block) are typically designed. So with a PC power supply hooked up to a modular synthesizer, the power supply's strengths are not being used, and its weaknesses are being sorely tested. The stuff you'll have to do to compensate for this situation is likely to cost you as much time and money as you wanted to save by using a PC supply.

Battery power is possible, but likely to be inconvenient. The voltages may be a problem. You need a total of 24V, which would be 16 standard dry cells at 1.5V each, and for anything but a very small system the current requirements will drain your batteries quickly. Synthesizer modules usually don't use huge amounts of power, but they're not designed with power economy in mind as let's say tablet computers today might be. Then you may also run into issues of controlling the voltage as the batteries drain, since a stack of 16 dry cells is really only approximately 24V when fully charged, and some modules may start to misbehave as the voltage decreases when the batteries drain. All in all, you're probably better off using some other kind of synthesizer for portable use (like maybe a keyboard synth designed to run on batteries); or else, let's say for an outdoor music festival, you could go the whole way with an AC generator and plug in your regular power supply.

Racks and cases

You're probably familiar with 19-inch equipment racks, sometimes called "telephone racks" or "server racks." There are two vertical rails, and equipment stacks vertically between them, screwed into the rails, usually consuming integer multiples of the "rack unit" (abbreviation U), 1.75 inches or 44.45mm. You might buy an industrial PC in a 1U or 2U case and install it in a co-location facility to use as a server.

[Racks of audio equipment]

For smaller pieces of equipment, you can have a "cage" that mounts inside the rack, with a couple of horizontal rails to which things mount in a horizontal stack. Sometimes there's a backplane built into the case, into which the smaller devices fit. Blade servers mount this way; so do 500-series modules used in pro audio. Eurorack synthesizers use a similar system. One row of Eurorack is 3U high; there are rails at the top and bottom of that space, and the modules screw into the rails. The standard rails used by Doepfer and most but not all other manufacturers have a lip at the top and bottom into which the module faceplates fit, so the module faceplates are a little less than 3U high. See the Doepfer mechanical details page for some pictures.

The horizontal width of each module is measured in units called HP, which I always want to read as "hit points" but it's actually meant to stand for "horizontal pitch"; 1HP is 5.08mm or 1/5 inches (exactly). Most but not all modules are an even number of HP. A standard 19-inch rack frame is 84HP wide.

But since Eurorack has become popular, it's become a thing that manufacturers have created cases specifically for Eurorack synthesizer modules with the mounting rails directly attached to the case, no 19-inch racking system in between. And in such a case, there's no requirement for the width to be 84HP. Eurorack-specific cases are built in many other widths, both wider and narrower than the standard 84HP.

So if you're starting out to build a Eurorack system, you have a number of choices. Probably the cheapest thing to do, and perfectly adequate for starting out, is to buy or build a wooden box with about 110mm vertical space inside and whatever width you want. Storage units intended for CD jewel cases may be about right. Then you can screw your modules into the wood at the top and bottom with wood screws. You'll need to add a power supply, maybe the kind with a wall wart plugging into the front panel and a flying bus behind; or you could use a bus board and screw it into the back of the box.

One 84HP row of Eurorack is enough to contain a decent starter system. I'd strongly suggest buying more case space than you need at the start, though, so as to have room to grow. If you're starting with one row, get a 6U case (two rows). People are always complaining about not having enough HP, or wishing that a given module consumed fewer HP, even without thinking through how there'd be no room to get their fingers onto the knobs if the panel were shrunk any smaller.

I think a depth of about 100mm from the front panel to the back of the box is probably ideal. That's about what's available in the Doepfer cases. Almost all modules will fit within 60mm, but it's nice to have some extra space for running cables and so on. If you use a shallower box, you may have to pay close attention to how deep your modules actually are and whether they will fit. ModularGrid's database can be helpful with that. Shallow cases are often called "skiffs," especially when you put one on the table in front of a larger synthesizer and use it to hold your control and sequencing modules.

A wooden box without rails saves some money, but the wood will get chewed up if you remove and replace modules a lot. A fancier option is to get a pair of rails and some "ears" that connect to the ends of the rails and make a simple frame, which you can then mount in a 19-inch rack cabinet (which in turn could be a do-it-yourself makeshift or plain wooden box, if you like). There's a thing called a Happy Ending Kit which is quite popular: it's a set of rails with rack ears that can rest on a tabletop if you don't screw them into a 19-inch rack, bundled with a flying-bus Eurorack power supply, for about US$160.

The next level up from rails and ears in a 19-inch rack is to use a complete case built with metal rails specifically as a Eurorack case. Doepfer offers several of these; so does Pittsburgh; Tiptop recently introduced the moulded-plastic Mantis case; and there are many others. At the high end, outfits like Lamond Design do bespoke wooden cases to whatever specification you can afford.

I myself started out with a dual-row Pittsburgh Modular Cell[90] case, but they don't make those anymore, and that may be just as well. I wasn't thrilled with it. It's a little on the shallow side; I didn't like the sliding nuts (more on those later) with nonstandard screws; there were problems with the power supply; and I didn't like the factory finish on the wooden end cheeks and ended up sanding it all off and redoing it myself by hand (with results that I liked, but it was a lot of work and more than zero expense). Anyway, here's a picture of it.

Eurorack synthesizer on a hotel desk]

Pittsburgh Modular makes several other kinds of cases now, which are probably worth a look - they seem to have learned from some of the mistakes of the Cell series.

I expanded into a rack case of the kind travelling acts use for mixing boards, with 10U of 19-inch rack on the top (into which I've put three rows of Eurorack rail-and-ears frames) and 4U at the bottom (where I hope to someday put in a Roland V-Synth XT). This is a very bulky case, with a lot of empty space inside, and it wouldn't be very practical for travelling; it also wasn't cheap. But it solves most of the things I didn't like about the Cell[90].

In a case that uses the standard Eurorack rails, there's a question of how exactly to fasten the modules to the rails. Modules have mounting holes on them. Rails may contain a row of threaded holes 1HP apart to accept the screws; or they may have a slot, into which slides a metal strip with the threaded holes; or they may have so-called "sliding nuts," which just fit inside the rail and can slide to whatever horizontal position you want.

I think sliding nuts are really annoying, but they're the cheapest option, and a few people actually prefer them. Sliding nuts have the small advantage that you can slide them to any horizontal position, so it's not so necessary to mount your modules perfectly on the 1HP grid (useful for the occasional module with nonstandard mounting hole locations relative to the panel). Holes directly in the rail are less often seen; they're the sturdiest way to do it, but if you strip the threads on one, too bad, there's not much that can be done about it. The threaded strip inserts are what I prefer.

The threads for the mounting holes ought to be M3 (metric machine screw), but a few oddball cases are built with M2.5 or American #6 machine screw threads. Since your modules will come with M3 screws included, you can have fun searching for the right kind of screws if your case uses a different size.

People frequently want Eurorack cases that can be taken on commercial airliners as carry-on luggage. I think it might really be better to buy an appropriately-sized Pelican flight case and send your equipment as checked baggage, with as much insurance as it needs. That won't be cheap, but travelling safely with delicate electronic equipment is not going to be cheap in any event. Demanding that your case should be carry-on means it can't be as large as you want, to begin with. It's going to be built with the bare minimum of padding and protective structure in order to squeeze in the maximum number of HP. You'll have to fight with other passengers over whether you can put it in an overhead bin, and probably also with the airline staff over whether it really meets the requirements even though you thought you had that in writing from them before you started. Fat chance of your being able to take advantage of the rumoured "musical instruments are ALWAYS allowed as carry-on" policy. And so on.

Note that transporting a Eurorack synthesizer is really no harder than, and not much different from, transporting any other musical instrument. More or less the same considerations apply.

If you want to buy just one module

You need a case, even if it's as simple as a plain wooden box, and a power supply, or else you can't do modular synthesis at all. But if you're really pushing the budget, first stop and ask whether you can afford this hobby, and then if you want to buy just one module to start with, my suggestion for most beginners would be the Mutable Instruments Braids. It's about US$400.

The Braids is a multi-function VCO (voltage-controlled oscillator); basically a DSP chip running a bunch of different signal-generating algorithms that can be selected from the front panel or via control voltages. It's a lot of bang for the buck. Using this module alone without any others to control it or process the result means that you can't generate much except "drones" (long sustained sounds rather than individual notes), but there's enough front-panel controllability that you can still have some fun with it. There's also a sensible expansion path: many other modules you'd add in the future can be used well in combination with the Braids.

Maybe, like many in this hobby, you suffer from digitalitis. That's an irrational aversion to anything seen as "digital," usually coupled with an inability to define clearly what exactly should count as "digital" or why it's supposed to be bad. I have given up arguing with such people. If you're one of them, and you don't want to buy a Braids because it's not "analog" enough for you, then you might consider a so-called "complex" analog oscillator module like the MakeNoise DPO (US$600). This is two analog VCOs in a single module, combined with some shaping, cross-modulation, and processing functions. The DPO is not quite as versatile as the Braids, but like it, the DPO can produce interesting sounds immediately without needing any other modules, and it won't be left behind when you expand to a larger system.

The DPO's manufacturer claims it is Vactrol-based, which if true means the module is probably illegal to sell in Europe. Vactrols are old-fashioned optocouplers made with cadmium sulfide photocells, and cadmium is banned by the EU Directive on Reduction of Hazardous Substances ("RoHS"), largely because of waste-disposal problems. Nonetheless, some European retailers have DPOs for sale. I don't know what to tell you.

If you want to do business with me as soon as possible

Thank you! But, again, make sure you can afford this before you start. If you just want to support me, as I said last time, I wish you'd help me with romance instead of module sales - and do that by telling women about me, not by telling me what I should do. "Teach a man to fish" is a bankrupt ideology.

None of North Coast Synthesis Ltd.'s currently-planned modules are much use all by themselves. They're designed to become parts in large custom systems, and to really get the most out of any of my products, you'll need thousands of dollars worth of other gear from other manufacturers. However, if you start out with a case, power supply, and a Braids or other complex oscillator, as recommended in the previous section, then it would be quite reasonable to make your second module purchase be a North Coast MSK 010 Fixed Sine Bank. It's a control voltage generator that produces slow sine waves at eight different frequencies; by plugging them into the modulation inputs of your oscillator, you can make the parameters change over time, giving a more interesting sonic texture.

[Fixed Sine Bank]

Preliminary panel art as of late January - the final version may look a little different. Currently planned to retail for about US$245 fully assembled, with do-it-yourself options available for less.

Patch cables and multiples

As soon as you have more than one module, you'll need patch cables to connect them together. These should be male-to-male cables with 3.5mm mono plugs on them; these are sometimes called "1/8 inch" plugs even though they're really a tiny bit larger than that. Don't use stereo patch cables - there's some variation in where the contacts in the mono sockets on modules actually touch the plug body, so that it's possible for a stereo cable connecting two mono sockets to fail to make the connection. You may still want to have a couple of stereo cables on hand for doing things like connecting to a computer's stereo line input; just keep them separate from the mono cables used within the synth.

Places that sell modules usually sell patch cables, too. It's nice to have a selection of different lengths and different colours; if your cables are all the same, it can be hard to keep track of what goes where in a complicated patch.

Sometimes you want to connect a single output to more than one input. You can get a thing called a "passive multiple," which contains several sockets wired directly together behind a small panel that fits into the synth rack like a module. Many manufacturers sell these; a typical example is the Doepfer A-180-2, with two four-way multiples (reconfigurable to a single eight-way) in 2HP for about US$40. The way it's used is that you patch your output into one of the holes, and then patch from the other holes to your multiple inputs.

Passive multiples are often recommended as beginner do-it-yourself projects, to practice soldering and general module construction, and many places sell kits for building them.

You can also get passive multiples as separate devices that don't take up rack space, such as the Intellijel Hub (single four-way, US$10). And there are specialized cables, like the Tiptop Stackcables, that allow multiple plugs to share a socket, providing the effect of a passive multiple built into the cables.

If you drive several inputs from a single output through a passive multiple, that places correspondingly more load on the output. It's possible, though not really common, for the increased load to interfere with the output's ability to maintain a consistent voltage; the effect tends to be most apparent with a pitch control voltage driving several oscillators, filters, and so on all at once. Too much load and all the pitches go a little flat. To guard against such problems, you can get a "buffered multiple," which is essentially a distribution amplifier that boosts the available current while keeping the voltage fixed. Plug the CV into the buffered multiple's input, and then it has several outputs available for driving other things. These cost more than passive multiples, but it's nice to have at least one or two, depending on the size of your system.

My suggestion is that it's good to have about one multiple module (containing two four-way multiples) per full row of Eurorack, and at least one should be a buffered multiple. So, for a small system, once you're near filling your first row, you should probably plan to get a buffered multiple, and then add some passive ones when you grow larger. You can substitute a few Stackcables, Hubs, or similar devices for the passive multiples, if you like.

You shouldn't patch two outputs into each other, neither directly nor through a passive multiple. The best case of what will happen is that (as seen by any inputs sharing the multiple) the resulting voltage will be the average of the voltages the two outputs are attempting to send, resulting in mixing of the signals; but that's optimistic. Both outputs are trying to have very low impedance and drive the signal to a specific voltage. If they aren't aiming for the same voltage, then they will fight over it, both drawing significantly more current than is normal. In the worst case, the weaker one could be damaged. That's rare, but what's fairly common is that you get an unpredictable unequal mixture, with maybe a lot of distortion. If you want to combine two outputs equally into a single signal, the right way to do it is with a unity mixer like a Doepfer A-138u (US$54), or a fancier mixer with adjustable levels.

Buying more modules

First, some words on budget and timing. You should know how much you're willing to spend, but you shouldn't spend it all at the start. It's pretty much a certainty that after you make your first purchase and start playing with it, you'll discover some module that you just have to have and didn't think of when you were starting. Set aside some money so that when this must-have module shows up, you'll be able to get it.

It's frequent advice to start with a small system and add modules one at a time, and if your budget is very constrained, you may have to do that whether it's what you want to do or not. I have some recommendations above for which module to buy if you're going to buy just one. But I think if your budget is a little less constrained, and you can afford to buy several modules right at the start (with some money reserved for your future lust module, as mentioned above), it's okay to buy a fairly complete system right at the start. There's not much point flailing around with a few modules that you can't really use properly yet, when you can already afford to expand. I wouldn't suggest buying more than about one 84HP row right at the start, though.

Play with different configurations in Modulargrid and see how appealing they seem to you. It's a commonly done thing - which some wigglers hate, but it remains commonly done and generally accepted - for newbies to set up the systems they're thinking of buying in Modulargrid and then post a link to it on Muffwiggler asking for advice and suggestions. You'll get both good and bad advice that way, and both can be interesting.

Here's a rundown of some of the common types of modules that might be of most interest to someone starting out.

Oscillators: Also known as VCOs (Voltage Controlled Oscillators). Waveform generators controlled by a pitch control voltage (CV) which would normally come from a controller or MIDI interface, as well as front-panel knobs. You really need at least one of these; having more than one allows playing more than one note at once, or connecting them together for modulation effects. Both my suggestions for single-module systems are so-called "complex" oscillators (one digital, one analog), which produce more or less complete sounds by themselves. The more traditional kind of synth VCO produces just a simple waveform like a sawtooth. Those don't sound good by themselves and really need other modules to shape the spectrum, so they become appropriate when you're building a system with more than one module.

I bought two Tiptop Z3000 oscillators (US$255 each) when I was starting out, and I like them a lot, but not everyone likes the digital frequency displays on these analog oscillators. The Intellijel Dixie II (US$220) is also highly regarded, and takes up very little rack space. (Don't make the mistake of planning with Modulargrid to use the earlier and even narrower "Mark I" Dixie - those have become hard to find.)

Controllers and interfaces: If you're not just going to twist the knobs on the oscillator and make drones, you'll need some way to play notes. I think for most beginners a MIDI interface makes the most sense; then you can plug in a keyboard synth or a computer. Many of these will accept both USB-MIDI and real DIN MIDI connections, like the Doepfer A-190-3, US$140. A fancier choice, with DIN input only but a bunch of special features, would be the Mutable Instruments Yarns, for about US$360. Mutable Instruments used to sell a do-it-youself kit for a very basic USB-MIDI interface called a CVpal, and those were really nice for anyone with a DIY bent, but unfortunately the kits have been out of production for a while. The design is open and in principle could be revived, but trying to build it without a commercial kit, including getting the chips programmed and the boards manufactured, is no longer a beginner project.

If you can afford just one module, I said the first should be an oscillator, but then if you can afford just two modules, for most people it would make sense for the second to be a MIDI interface. Be aware that most synthesizer USB-MIDI interfaces are USB devices, not hosts, and most USB-MIDI controllers (like the Akai MPK Mini I use) are also devices. That means the controller won't plug into the interface. You need a computer in between. If involving a separate computer is a problem, you should either look at controlling your rack through traditional DIN MIDI, or seek one of the rarer Eurorack USB-MIDI hosting modules, like the Expert Sleepers FH-1 (US$280).

Filters: Subtractive "East Coast" synthesis revolves around the voltage-controlled filter (VCF), which is used to remove higher harmonics from a harmonic-rich VCO signal. Much of the timbre of the sound in a subtractive synthesis patch comes from the filter. These are usually low-pass filters (LPFs) because that's the most useful type in making musical sounds, although other types available and one common family of circuit topologies routinely offers multiple different filter types on separate outputs. There are many filters to choose from. The first one I bought was a Tiptop Z2040 (US$205), which is generally thought to sound similar to 1980s Roland analog synths - a classic, middle-of-the-road synthesizer sound. The Z2040 also has a couple of built-in VCAs (see below), which can be very nice in a small system with few or no dedicated VCA modules. Doepfer makes a number of filters of which the A-124 "Wasp" (US$92) seems to be especially well-regarded, notwithstanding that it sometimes has reliability problems. Intellijel makes some fancier multi-function filters of note, including the Dr. Octature II (US$280, and the thing on which I spent the money I'd reserved from my starting-out budget) and Korgasmatron II (US$390).

Probably my favourite of the filters I currently own (excluding prototypes of future North Coast products) is the Erica Polivoks VCF (USD$113 fully assembled, but I built mine from a kit for a little less, and made some modifications). I like it because it has what I'd call a very expressive sound - much like an acoustic instrument and not a sterile "electronic" sound at all. However, it is electrically rather poorly behaved, cannot produce a "clean" sound under any adjustment, physically deeper than will fit in some Eurorack cases, and so on. I'm not sure I would recommend that as the only filter to someone who plans to buy only one.

It's in my business plan for North Coast Synthesis Ltd.'s third product to be the "MSK 007 Leapfrog VCF," a synthesizer filter with a fifth-order leapfrog topology, which as far as I know is unique in the modular synthesis world. The current plan is for it to be a 16HP module priced at about US$490 assembled (kits also available for less), with an extremely sharp low-pass cutoff giving it a unique sound. (Sharper cutoffs exist in digital filters, but I know of no other analog modular-synth filters that can approach the measured behaviour of my prototype.) It also has a built-in VCA. So, you might want to keep your eyes open for that later in 2017. But you can't get one today.

Voltage-Controlled Amplifiers (VCAs): VCAs allow one voltage to control the level of another. That is necessary in shaping continuous signals into separate notes - the output from an oscillator usually runs all the time, so you might patch it and the gate signal from your MIDI interface into a VCA to allow the sound to start when you press a key and stop when you release the key. With the addition of an envelope generator, it can also follow a loudness profile (envelope), typically loudest right at the start of the note and then trailing off. But VCAs also have many other uses, in modifying and routing control signals through a large patch; and they are often overlooked because of not being as "sexy" as some of the complicated sound generation and effects modules marketed by up-and-coming manufacturers. That's why it has become a cliche to tell newbies their proposed initial setups "need more VCAs," and Muffwiggler has actually configured its phpBB installation to include a customized emoticon for "You can never have enough VCAs!"

The Pittsburgh Dual VCA module (US$160) is a decent choice. Doepfer makes several variations of which the A-132-3 (US$113) seems like a good pick for a small starting-out system. At the higher end, the Intellijel Linix offers six VCA units in a single module for about US$330.

Other utilities: There are many small modules that do things with signals in ways that become more useful as a system grows: these include LFOs (Low Frequency Oscillators, which can be used for stuff like adding vibrato or creating a regular pattern of notes in a self-running patch); mixers (both for control voltages and audio signals); switches and clock-manipulation logic (again, useful for patches that run themselves); sources of random voltages (either to play notes, or as "noise" to add to a timbre, especially in percussion sounds); and many others. I think I'm going to leave detailed discussion of these for some other article, because they're less relevant to beginners just starting out, and this introduction has already become much longer than planned.

Effects: Once you have some sort of audio signal, there are modules specifically intended for modifying it. The Mutable Instruments Clouds (US$360) is one that has become very popular recently; it does "granular" effects, where you play a signal into a buffer and then small clips from that buffer can be played back, possibly with pitch shifting and other modifications, to create a sonic texture. Older, more classic kinds of synthesizer effects include "wavefolders" like the Topobrillo TWF (US$250) and "spring reverbs" (which send the signal through real mechanical springs) like the Intellijel Springray (US$240 plus one or more "tanks," which range from US$12 to US$25).

Saving money by buying used

Modules, if kept in decent condition, usually retain most of their value on the used market. Some modules actually command a premium over their new price, either because they're no longer available new (for example, Modcan) or simply have limited supply (for example, Cwejman). On the one hand, the low discount for used modules means you're not likely to find many extreme bargains, and if you do, you should be careful that they're not too good to be true. On the other hand, it means buying a module you're not sure you will like, is safer - you can expect to sell it later and get back some of your investment, maybe even all of what you paid for it if you bought it used yourself. So buying used modules can be a good way to build up a system. It reduces the financial risk connected with whether you want to keep the modules.

Muffwiggler has a buy-and-sell subforum which is one of the better places to buy and sell used modules; if you're looking to build a system on a budget, that can be a valuable resource. Be aware that they have a rule, pretty strictly enforced, that you're not allowed to sell modules on the forum until after you have written 100 forum messages (you may buy regardless of your message-writing status), and they ban people who seem to be trying to build their post totals by posting garbage. This descends from phpBB's practice of giving users "ranks" based on number of messages posted, and I don't really approve of it, but my opinion doesn't change anything. Whether it's the best way to do things or not, in practice the 100-message rule does cut down on scams.

Modulargrid also has a module marketplace. I don't really know much about it and can't give a solid recommendation for or against.

If you're in touch with other modular hobbyists in your geographic location, you can often buy, sell, and trade modules with them. That can reduce both the risks and the shipping costs associated with doing used-module sales over the Net.

Be wary of responses to "wanted to buy" ads, on Muffwiggler and elsewhere; scammers have been known to respond using photos copied from eBay auctions as "proof" that they have the item you said you wanted, then they collect payment and disappear. Someone who often uses the alias "gearaudio" or some variation is well known for this scam - each time he tries it and it gets reported, they ban the latest alias and warn everybody, but he just seems to keep coming back and trying again. With a wanted to buy ad, you want to be very sure that the person you're dealing with can not only send you a photo, but also talk with you about the item they're selling in a way that shows they know what it is and have actually used it; genuine hobbyists can, and scammers usually can't.

Sometimes you'll see somebody's complete modular system offered for sale as a package deal. Be cautious with that. Buying a complete system means you lose the opportunity to choose all the parts individually, so unless you're sure you really want everything in the package, you should evaluate carefully how many of the modules you actually do want; how much the discount really is compared to the used prices of the modules individually (often, it's not much); and whether the discount makes up for the fact you may be paying for modules you don't want. Often a package deal on used modules comes from an estate, divorce settlement, or similar. The seller may not be the original owner, may not be a hobbyist themselves, and maybe just wants to liquidate the asset for whatever they can get. In that case, on one side they may be willing to settle for a low price because they just want it off their hands, but on the other side, they may well have unrealistic expectations and little knowledge of the market.

I don't think you should pay money for do-it-yourself projects that don't work. People sometimes try to recover losses on failed projects by selling them, with the suggestion the buyer can either fix the problems or tear the project down for reusable parts. It's seldom worth it. For that matter, you should be wary of any equipment (not just do-it-yourself stuff) that is being sold in less than working order. If you don't know exactly what's wrong with it, it's hard to make any fair estimate of how much it's really worth.

Saving money by building your own modules

Many beginners think they're going to save money by building their own modules instead of buying assembled. That's often less true than they imagine.

First of all, the only thing that makes sense is to compare quality for quality. If you spend US$200 to build a module that is really the same as a commercial module priced at US$400, great, you've saved US$200. That calculation ignores your time if you put a price on that, but it may be fair not to count time. If you enjoy doing electronics work, then the time spent assembling the module can be seen as a benefit instead of a cost.

But maybe your DIY module has a front panel made of circuit board material instead of aluminum, and maybe you used the cheap potentiometers from Thailand that wear out really fast and will be scratchy until they do, and maybe your module isn't calibrated accurately because you don't have the test equipment that the commercial factory would have, and so on... maybe you've just spent US$200 to build a module that is really worth US$200. All the savings came from settling for a lower-quality module, not from building it yourself. That's what I see happening with a lot of the people who claim to have saved significant amounts of money by building their systems from scratch. On a closer look, it turns out they've really only compromised on quality.

If we're going to compare quality for quality, there are several factors that make it difficult to save real money by doing it yourself. First, there's setting up your workshop. Starting at zero, it costs between US$1000 and US$2000 to put together all the tools and electronic equipment you need to build modules of commercial quality - maybe also including some expenditures on books, training, materials used up during practice sessions, and otherwise building your skills to be able to make modules. That price tag is about the same as a starter Eurorack system built with commercial off-the-shelf modules. So even if you assume (optimistically) that you can save 50% on module prices when you're building them yourself, and you're committed to only have modules you built yourself, you still won't break even compared to buying commercial products until you have a system twice the size of a starter system and you have paid the equivalent of full price for that.

Then, there are quantity discounts. Someone who buys parts in quantities of 1000 may pay half as much as someone buying in quantities of 10 or 100. That means commercial outfits making large batches of modules will be getting their parts cheaper than you can, partly compensating for the fact they have to pay for labour and you don't. There are also issues of whether you, as a small player, are able to source parts in small quantities at all; many distributors and manufacturers simply won't sell except in minimum quantities that are too big for an individual. They also may refuse to sell to anyone who isn't a business. So you face extra challenges dealing with those obstacles, and may end up paying for more parts than you need, having to organize group buys, or convincing someone who does run a business to act as a middleman.

Quantity discounts mean you'll sometimes end up ordering more parts than you immediately need, to have some left over for future projects. That's great if you really do use the extra parts, but if you don't, the money you've wasted on them will probably erase the discount. And even if you eventually will use all the parts you bought, having to tie up your money in inventory, store the parts and keep track of them, and so on, adds to the cost of running your workshop.

Some of the quantity and sourcing issues can be reduced if you build from kits instead of trying to obtain all the parts for a design all by yourself. Whoever's selling the kits will want to take a profit, but because they have access to quantity discounts you don't, the price of a kit may still compare favourably to what you would pay in a pure do-it-yourself situation.

Some manufacturing processes are completely impractical outside a large factory. You can kind of do reflow soldering with an ordinary kitchen toaster oven, but that doesn't work perfectly and may introduce reliability problems. Lots of people etch their own circuit boards at home, but when you look closely, you realise that almost all of those are single-sided boards, with bare copper, no solder mask, no silkscreen, and no plating. Quality for quality again: at just a slightly higher price than those homemade boards, you can order boards custom-made in China that will be double-sided, with plated-through holes, solder mask and silkscreen on both sides, and gold over nickel plating. But you have to order at least 10 of them. It's not realistic for a hobbyist to do all that on a single-unit basis in the garage; it wouldn't cost less than the Chinese factories with their huge volumes and robotic equipment; and if you attempted to do it anyway, you'd quickly attract the wrong kind of attention from your local regulatory agencies regarding how you planned to dispose of the waste. This again favours commercial production.

Let's not even get started on the safety issues related to handling peroxide-boosted acid etching solutions, which some of the Muffwiggler crowd will cheerfully assure you must be perfectly safe because the granola people sell hydrogen peroxide at the health food store.

On top of all that, there can be issues regarding module designs. Most manufacturers of commercial modules keep the details of their designs secret. You can't just point at a module offered for commercial sale and say "I'll build one of those"; you're faced with trying to come up with a design for it either by yourself, from public sources and the hobbyist community, or by reverse-engineering the commercial one. That doesn't have to be a dealbreaking issue. Many high-quality designs are available in public sources, and some of the most innovative designs are born in the hobbyist community and only available as do-it-yourself projects. If you want a Turing Machine, for instance, you have to either build it yourself or pay someone to build it for you on a bespoke basis.

A few commercial manufacturers, including Mutable Instruments and my own North Coast Synthesis Ltd., make it a policy to publish all their designs. But these designs still may be optimized for commercial production - including the use of parts that aren't available in small quantities, or technologies like fine-pitch surface mount that aren't practical for hand assembly.

For modules with programmable digital parts (microcontrollers, FPGAs, CPLDs, and so on) there may be firmware required on top of the hardware design, with associated copyright issues, a need for specialized equipment to download it into the programmable device, and so on.

The bottom line is that it just doesn't make much sense to turn to DIY construction solely as a way to save money. It'll cost so much in both time and money that you won't really save. Nonetheless, DIY construction may make sense if you have other reasons to do it beyond saving money. For instance, if you already have an electronics workshop as a result of some other activity (like ham radio, say), it brings down the cost of applying that to synth building also. And maybe electronic construction is your real hobby, a goal in itself, and it's to do that that you got into modular synthesis in the first place instead of the other way around. That's a big part of my own story, and in such a case, saving money is beside the point.

Beware of "passive" modules

Some modules are powered entirely by the incoming signals on their inputs. They don't require a separate connection to a power supply. I'm not sure why, but a lot of people think that's a really, really, cool idea. It often isn't.

I'm putting the word "passive" in quotes because that word has a specific meaning in electrical engineering and the way synthesizer people use it, is not what it actually means. But I don't want to have to go into a lot of detail on that here, and it is the standard term people use for this concept in the synth realm, so we're kind of stuck with it. I'd really prefer to call them "signal-powered" modules.

The power for "passive" modules has to come from somewhere. So if your power supply is close to overload, you're not going to avoid overloading it by adding a "passive" module - it'll just (by virtue of its low input impedance) cause the module that's really powering it to draw that much more from the power supply. Running out of power isn't a big issue for most people, but this point seems worth mentioning. The laws of physics, conservation of energy in particular, remain in force. All you're saving is the need to connect a cable.

Whenever two pieces of electronic equipment are connected together, there's an issue of how much of the signal between them is supposed to be carried by current and how much by voltage. This ratio is called the impedance of the connection. Different kinds of interfaces place different requirements on the impedances of the inputs and outputs. In radio systems it becomes especially complicated because the impedance ends up being a complex number, with real and imaginary parts; people usually try to make it pure real (with imaginary part zero), and the same for both input and output to prevent signals from reflecting off the ends of the cable, but that can be complicated. Audio is usually a little easier.

Modular synths attempt to keep the impedance situation as simple as possible by demanding that outputs should always have very low impedance and inputs very high impedance. As long as those demands are approximately satisfied, we can approximately assume that the information on the cable will be carried entirely by voltage and the current will be negligibly small, and that makes a lot of interconnection issues simpler.

"Passive" modules mess with the assumptions. By having an unusually low input impedance (to draw more current from the upstream modules) and an unusually high output impedance (because they have no power of their own to supply to downstream modules), these modules are not playing by the rules. They usually work pretty well as long as the other modules in the system continue to pull their weight, but you end up having to face some of the issues that the standard way of doing things is meant to avoid.

With a lot of passive modules in your system, you'll run into unexpected behaviour. For instance, trigger voltages might not trigger envelopes when they should, if they've been through too many "passive" logic modules; and oscillators and tracking filters may end up flat and mis-tracking if their control voltages are being used as power supplies. You may find that there are restrictions on what you can patch into what, which (depending on your style) may break the "anything into anything" artistic flow of modular patching. Just consider: what if you want to patch module A into module B and they're both passive? Do you think that's likely to work?

Now if there's a module you're sure you want to use and it happens to be "passive," I wouldn't treat that as a dealbreaker. There are some circuits, traditional diode ring modulators being one good example, where it just happens to be the case that the circuit you would want for other reasons doesn't have a power connection. If you want one of those, fine, get it. Attenuators, if they are true attenuators and not mislabelled variable amplifiers, can also quite reasonably be made "passive": their only purpose is to absorb power and they don't need an extra power input to do that. Passive multiples (no quotes, they're the real deal) are a glorified type of cable adapter and don't need power. Some kinds of interface modules fall into the same category, including USB interfaces which take their power from the USB bus like other USB devices. And some highly-regarded low-pass gate modules are also traditionally built in a "passive" format, although for my own money I'd consider that design to be borderline and I would want to pair such a module with a buffered multiple to restore the level. I'm not saying you should never buy a "passive" module; only that I think you should regard a module's being "passive" as usually a disadvantage, not a positive selling point.

Also beware of the guy who tries to sell you "passive" microcontroller-based DSP modules. That's all I'm going to say about that; if you read the Muffwiggler forums, you'll quickly know what I'm talking about.

Don't buy an output module

Every new user thinks they need a module specifically for connecting the modular synth to wherever the sound is going (often speakers, headphones, a mixing board, or a computer interface). I bought one as part of my first purchase of modular gear myself. Getting one of these is usually a mistake. Popular unnecessary output modules include the Pittsburgh Outs (which is the one I got, US$100); the Makenoise Rosie (US$140); and the Intellijel Interface (US$260).

Most audio gear other than modular synthesizers expects an input voltage level considerably lower than the native level used within the synthesizer. You don't need to boost or preamplify the modular signal to make it suitable for your other equipment; instead, you have to attenuate it, and you can usually do that just by turning down a knob on one of your existing modules (such as a VCA). Some of your outboard equipment (most pro and semi-pro mixing boards, in particular) will already have enough headroom that it can take a modular signal at modular level without any special provisions for interfacing.

Speakers as such have a very low impedance, and synthesizer outputs (although they have plenty of voltage) may not be able to supply enough current to drive speakers. So if that's what you're doing, then okay, you need an amplifier somewhere. But it usually makes most sense to use speakers with the amplifier built in, such as people plug into PCs, rather than having a speaker amplifier module in your synthesizer to use with unpowered speakers. One reason is that because of mass production, using speakers with built-in amplifiers means you'll either get the amplifier for less money, or a better amplifier for the same money.

Driving headphones directly is an application where it may possibly make sense to have an output module in your modular. You can get acceptable results plugging headphones directly into many, but not all, of the signal-producing modules in your synth; it's a question of impedances again, because the voltage/current ratio the phones demand is a lot different from what the synth modules are built to expect, and not all outputs react the same way to the mismatch. So having a headphone amplifier module would remove some uncertainty. If you think you need one, I like the Doepfer headphone amp (US$60). But don't buy it first thing. Wait until you're sure you need it.

People who intend to do live performances are sometimes attracted to the MakeNoise Rosie because it's marketed as being specifically designed for live. I am unconvinced that it's necessary or valuable. I'd rather do the "smoothly add and remove signals without startling the audience" function using a Doepfer A-138e crossfader module (US$92), which can also do many other things, and add a headphone amp module if I really think I need a separate output for my headphones. The A-138e is a large module and it may not be appropriate for a small starter system, but I use mine in almost every patch since I bought it. There is a consistent pattern here worth noting: modules sold for a very specific purpose (like the Rosie) are less appealing to me than modules that have a more general function capable of being turned to that purpose or many others.

You don't want a stereo mixer built into a Eurorack module, either. You may think you want that instead of a standalone mixer for connecting your other gear. It's frequently at the top of people's "I wish someone would start manufacturing this kind of module" lists, and some manufacturers are starting to oblige with stereo mixer modules, but it really seems to be a bad idea.

One reason is that because they're mass-produced for a much larger market than any synth module, standalone mixing boards can offer lower prices for the same quality and feature set, or better quality and features for the same price, compared to what it costs to do this sort of thing in a Eurorack module. The constraints on panel size and shape for Eurorack, and the power supplies available, don't work for the usual layout of a mixing console and the signal levels it needs to handle. Another issue is that everybody has a feature they think a stereo mixer must have, and a feature they think it must not have. It's not enough to just choose not to use an undesired feature, because they don't want to pay the money or panel space costs. And your must-have feature will be someone else's must-not-have - which means any stereo mixer module can only satisfy a small fraction of the market, requiring many different models for different customers and further driving up the cost.

The traditional four-knob mono modular mixer, as sold by Doepfer, Pittsburgh, and many others, is much more appropriate for use within a synthesizer rack. If you want stereo, use two of them. If you want "sends" and "returns," use a matrix mixer (US$150). Each of these simpler modules can be used in several ways, whereas the "stereo mixer" as most people imagine it would be useful only as a substitute for a better and cheaper standalone board. After you have a final instrument signal from your modular synth, you can plug it, and the signals from whatever other studio equipment you have, into a traditional standalone board to do your final mix and panning, and that works a lot better than trying to do the final mix inside the Eurorack.

The red line

Traditional Eurorack power connectors are not polarized. It's easy to plug the cable into the module or the busboard backwards. Then you end up with +12V applied to the -12V bus and vice versa. Some modules will be instantly destroyed if you power them up in that condition, which can be heartbreaking in the case of modules costing hundreds of dollars each. Others contain one or another form of protective circuitry, which may prevent or at least reduce the damage. Some styles of module-protective circuitry (parallel diodes, in particular) may pose a threat to the power supply in case of a backwards connection, even though the module is protected.

All my own designs use series diodes for protection. If you try to power up a North Coast module with the power reversed, then it will not power up, but should not suffer or cause any other damage, and everything should be fine once you reconnect the cable properly. I can't promise, though, that it'll be immune to cases of misconnection more complicated than simply reversing the plug. Many other manufacturers do it the same way I do, but this isn't a no-brainer; there are tradeoffs involved, and other manufacturers who don't use protective circuitry, or use more dangerous types of protective circuitry, sometimes have important reasons for doing things the way they do.

Nowadays some boards and most cables are built with polarized connectors, and if all your power connectors are polarized correctly then it should be difficult or impossible to plug them in backwards. But it's also been known to happen for a cable or board to be made and sold with polarized connectors that are themselves installed backwards, so that the polarization causes the problem it should prevent. There's no real substitute for careful human attention to the power connections: whenever you plug and unplug power cables, make sure you have all the polarities right before you turn anything on.

Power connectors have a standard convention by which one pin is designated as "Pin 1," the reference pin. It will often be marked with a little triangle molded into the plastic body of the connector, for connectors that have a plastic body. There is also a standard convention regarding where the keying slots are in relation to Pin 1, so if you have polarized connectors, they will keep everything in the right relation.

The usual kind of ribbon cable used for Eurorack power is grey with a single red wire forming a stripe along one edge, and the red wire should be connected to Pin 1. You may rarely see grey ribbon cable with the special wire coloured blue or dark grey instead of red. There is also rainbow ribbon cable, where Pin 1 should connect to the brown wire; starting from one edge the wire numbers go brown, red, orange, and so on like the resistor code. Wire number 1 is one of the two wires carrying the -12V negative supply. On circuit boards, the connectors are usually oriented so that Pin 1 is at the bottom; and it is usually marked on the silkscreen art of the circuit board, either with text like "-12V" or "stripe here" or with a little line or bar; and if you look closely at the solder pads attaching the connector to the board, often Pin 1 will be different in some way. For instance, on my boards it has a square instead of round pad.

In general, then, you can usually get everything right by keeping all things that distinguish one end of the connector (markings on boards, markings on connectors, and the cable stripe) lined up with each other, and the stripe and the special end of the connector will usually be at the bottom, and any connectors that are polarized will agree with these clues. But double and triple check if you're not certain! It is unfortunately possible for any part of the system to have been manufactured wrong, in a way that will conflict and cause trouble if you trust a single indication when it disagrees with the others.

If you come into possession of an incorrectly-made ribbon power cable where the connector polarization doesn't match the stripe at both ends, throw it away! A properly-made replacement doesn't cost enough to be worth the risk of trying to keep the bad cable in service while remembering that its marking is backwards.


This article has ended up a lot longer than I originally expected, and I hope it hasn't worn you out; but it's all information that may be useful and should put you on a better footing if you intend to get involved in the modular synthesizer hobby. Starting out, at a bare minimum, you need a case and a power supply and one or more modules. If you buy only one module, I suggest a complex oscillator like the Braids or DPO. I've also given some suggestions on where to go when building a larger initial system, and pitfalls to avoid. As I said in earlier installments, I think getting involved with modular synthesis would be a mistake for many people who consider it, but if you insist on doing so, well, I hope you have fun.

And yes, please buy my products once they're available.


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