If you're at all into synths and house music (and, really, why else would you still be reading this blog?) you'll have heard of the XoXBox. I pronounce it "zox-box", please inform in comments if you've heard another way of saying it. It's always interesting to hear people's takes on something that exists, essentially, as a wholly internet-based phenomenon.
The XoX is the apotheosis in a long line of TB-303 emulators, starting with the rackmount bass monosynths of the 90's like the Novation BassStation and the FreeBass FB33 (the latter the more explicit 303 emulator, the former more generic and closer to an SH-101). A friend of mine recently bought an old Roland Alpha Juno 2 from an old skool Brooklyn techno producer (greets to 8-bit, need to get a round and hear more stories one of these days). The Juno 2 has enough proper hoover stabs in memory to back up the claim that it is the original Alpha Juno which Beltram sampled for Mentasm, and the pics he pulled up when I mentioned that I had a XoX (on 8-bit's site, sadly down for maintenance this week) were very interesting. Apparently, there was an earlier attempt at a XoX-style 303 emulator in the early 90s, which was hand-built and almost entirely transistor-based synthesis (think Jupiter 4). The builder passed one over to a brooklyn producer friend who didn't quite know what to make of it, and it languished in his collection for a few years until someone realized what it was. The story ends there, since I, like a fool, never followed up, and dude's site is down. EDIT: hold on a minute, Check This Out.
The XoX itself, however, is effectively the be-all, end-all TB-303 emulator. The design requires the original chips from a 303 or NOS of the same[1], and the sequencer is designed to act similarly to the original 303 sequencer, though slightly better in the basic version. The arduino(?)-based OS/sequencer can be upgraded via a USB connection built into the basic design of the XoX, which also includes MIDI I/O/T as well as independent DINSYNC, switchable in/out, and CV + Gate outputs. This utterly outclasses the Acidlab Bassline 1 I owned a few years ago, which had severe difficulty syncing via MIDI to my TR-707 and would only work when synced via DIN, and I won't even mention the hilariously terrible programming method (hint: it involved two knobs and an INPUT button). The XoX drops in beautifuly with a MIDI setup, and performs like a dream. Compared with the TB-303, it's a bit like getting an East German BMW from the 60s vs getting a newly produced BMW today. The old one looks nicer, but the new one performs just as you'd like it to.
The configurability of the XoX with new firmware is fairly impressive, although hampered by the original design of it. There are OS upgrades which allow arpeggiation and various other sequencer-oriented re-purposing mods, check this thread on SOKKos (the oldest and most advanced) for more info. There are also several hardware mods which mirror the basic modifications which were often added by 303 users in the 90s, such as the overdrive knob and the filter expanders. However, in a 303 emulator, the most important issue is the accuracy of the sound.
XoXBoxes are known for their variation in sound, just as the original 303s were (though, if you bought a 303, you usually wouldn't question the variation quite so much as with those who buy a XoX). Some of the XoXen have a sound which is very mild even compared to other unmodified XoXes, so you should keep that in mind when shopping for one. There's no way of knowing what the XoX you buy will sound like, no matter who builds it. My XoX was built by a Taiwanese hobbyist who no longer sells them, but it sounded the closest to a vanilla 303 of any XoX I've ever heard. The pop in the filter-envelope reaction to the accents was the most beautiful I've ever heard from anything approximating a 303. The knobs on my XoX were, unfortunately, a bit too slow for my taste. Ideally, they should be like the original 303 knobs, and fast spins shouldn't feel any resistance. Luckily, the standard design of the XoX requires that the circuit boards be fitted well, so the varying button or knob resistance doesn't mean an increased level of wear to the top interface circuit board, and barring truly homebuilt versions, should stand up to a reasonable amount of live performance wear-and-tear as well as whatever you may throw at it in the studio.
One interesting issue I ran into with my XoX lies within my recording setup, which is MIDI-based and relies on a Roland MC-50 hardware sequencer and a Yamaha MJC-8 MIDI router: On two different tracks where I attempted to record the MIDI output of the X0X to the MC-50, there was a strange sense of lag, possibly introduced through lag from the MJC-8 (though I doubt this). The X0X syncs perfectly to a MIDI clock input for it's internal sequencer, which is more than capable of providing for 303-type sync usage. That is, when syncing the internal sequencer in tandem with a MIDI setup, it is bang on to the timing of the track. However, when I recorded the XoX sequence into my MC-50 and set the XoX to MIDI Play, it would drop notes in a strange (but highly usable) way. I think this might have more to do with the firmware than with the ability of the XoX to comprehend MIDI messages when played with an external keyboard. Mine was never upgraded after I got it two years ago, nor did I upload any second party OS to it, so your mileage may vary. Like I said, though, this strange issue of slightly mistimed sequencer messages can be very usable in certain situations, especially when the recorded XoX sequence is sent to another synth with a 303-ish patch.
Though I've sold my XoX recently (for reasons which have nothing to do with the sound/hardware), I'm hopeful of future projects with the same mindset as the XoXBox team had, such as the MB-808. It's a phenomenal approximation of the 303, and no other emulations have come so close to not simply reproducing the sound of the 303, but the interface as well. Drums are another story though, and I think that the next review I'll write up will be on the Korg DDD-1 plus some thoughts on the add-on cards available to it, both the old ones and the newer models which should place it heads and shoulders above the other similarly 12-bit generic drum machines.
[1] I have a theory that at least one plant in China has devoted a few lines to stamping out limited new chips, backed up by the fact that several of the original chips were literally the faulty versions of chips intended for more professional Roland synthesizers (18db filters? really? I've read several sources over the years claiming that either they are all faulty 24db filters or were based on the faulty versions, but given the short production life of the 303 that seems unnecessary) and thus can't possibly be that hard or expensive for an aging through-hole chip factory to replicate on the side.
Further note: The demonstration tracks I've included are my own music, and I'd be happy to describe the synths accompanying the XoXBox for any of them for those who are curious or confused.
