Jeffrey Paul

I’m a big fan of analog bass synthesizers. Analog synths and the music that they create are right up there in my top five favorite things in the world, right next to cheese, boobs, beef, and guns. (I never claimed to be anything but a simple man.)

The most famous analog synth in the world is undoubtedly the TR-808 drum machine, now that Kanye’s gone and made it a pop-music phenomenon. They sound awesome, but, in my opinion, they’re not really that feature-rich, considering all the hype. Push buttons, enter sequence, and drum go boom, click, and crash, and all the other noises you’ve been made familiar with from the last 25 years of hip-hop. Narrow the search range down to analog bass synths, and you’ll find yourself looking at the number 2 spot, the classic Roland TB-303 “bassline”. Due to awesomeness and general techno-fetishization, this thing’s been (rightfully) documented to death, in case you care.

(Some might say that my argument against the 808 could also be made against the 303, at least in stock form.)

Unfortunately, they’re kind of expensive these days, being old and rare and highly sought-after, so various others have taken it upon themselves to make sound-alike synths, with varying degrees of success. My favorite from this group is called the x0xb0x, a schematic clone* created by Limor Fried, better known as ladyada.

(*……meaning that the synthesis circuitry of the x0xb0x is as faithful as possible, down to the exact make and model of the transistors and other audio-path components, to the original TB-303.)

I built my first x0xb0x a few years ago when I was living in New York. Parts cost, then, was around $450, purchased as one big kit from ladyada’s then-relatively-new electronics kit vending business, Adafruit. I got kit number 400, the first from the fourth batch of 100. After number 999 went out the door a year or two later, she found it harder and harder to source the original transistors used in the 303 (remember, this thing was discontinued in 1984), especially in the quantities needed for making a hundred kits at a time.  These days, I’m not sure that you can buy a full x0x kit from Adafruit any longer, a turning point I hadn’t expected quite so soon.

Fortunately, she still sells the pre-made circuit boards (even if she decided to stop, the manufacturing files are open-source— anyone could ship them off to a fab and have a run (or just one) of them made). Same goes for the aluminum faceplate and backing plate, although that’s less important now for reasons I’ll explain in a second. Also, the case and the rest of the parts can be ordered from any electronics supply house. A 200KΩ resistor from 2010 is the same as a 200KΩ resistor from 1970.  It really boils down to those weirdo transistors that the engineers at Roland picked out back when they were designing this thing.  Being in the analog synthesis path, they are the soul of this machine, and are critical to an accurate reproduction of the sound.

I went out and about today to run errands (not the least of which was buying a 9VDC power supply for my Doepfer MIDI-to-DINSYNC box), and came back to the office, checking my mail on the way in.

Inside was this.

Contents: weirdo transistors!

This is how they look in use in a x0xb0x.  (These are the old ones from Adafruit, now in x0x #400, not the new ones that came today.)

I’ve picked up 3 full sets of the rare parts, just in case. I hadn’t really expected the Adafruit kits to dry up so fast, so when I found a reliable vendor for the rare parts (at a slight price premium, unfortunately), I decided to stock up. Mostly because I recently heard about an awesome new development…

The TB-303, as far as synths go, is relatively user-unfriendly. In addition to a notoriously difficult sequencing interface, it has only a few knobs with which to modify the sound. For a lot of acid techno enthusiasts, these six little silver knobs have proven to be more than enough. It’s got a lot more potential locked up in there, though, and so an Australian by the name of Robin Whittle decided to make an inboard modification to the TB-303, called the Devilfish, to add (among other things) several additional knobs and switches to adjust synthesis parameters formerly untouchable within the innards the device. Getting one of these things installed is not a trivial matter, and involves round-trip insured shipping to Australia, as well as parts and labor for the add-in board itself (not to mention the drilling of new holes in your treasured rare synth). Devilfish-modified 303s have sold for as much as $3,000 USD (albeit in perfect condition). Welcome to the cult of acid.

After (presumably) being hounded by a large percentage of the thousand people who built their own clones from kit form, he issued a statement that he wouldn’t be making any Devilfish mods for the x0xb0x. Enter Brian Castro, a x0xb0xer who made an add-on board for the x0xb0x, called the x0xi0. This adds most of the additional parameters of the devilfish mod, as well as a ton of additional input and output ports not included in the original x0xb0x design. The kit, at around $500, comes with two add-in boards (one for the top, one for the I/O ports on the back), all the parts, jacks, knobs, and knob-caps, a new faceplate (with the additional holes), and a new backplate (again, a zillion additional holes for I/O).

It looks really awesome (top and back) and sounds even better. For just around $1,000 USD in parts and the fun (for me, at least) of putting it together, it seems to me that this is just about the most bang for your buck you can find in the world of analog bass. Having already built one x0xb0x (with plans for more), this mod seemed like a no-brainer. It even brings down the total cost a bit, as I don’t have to order or have fabricated the plain x0xb0x faceplate and rear panel.

I’ve just ordered my x0xi0 mod (going into #400), and circuit boards for two more x0xb0xen. Holding off on the rest of the parts for now, as I don’t know when I’ll have the time to assemble more full synths, but you can bet that that x0xi0 is going in to the existing one within a day or two of arriving on my doorstep.

Audio samples and fresh pictures will be forthcoming.