The Rhythm Fever is basically a repackaging, with a ‘stylish-modern-turn-of-the-eighties’ enclosure, of classic Rhythm Ace units such as the FR-6, minus the wood. A few of the rhythm patterns are different (this one has ‘disco’!!), but the internal circuitry hasn’t changed much, if at all. In fact, after comparing the voice board for a few Ace Tone drum machines, I realized that they were all the same!

I don’t know how many of the Rhythm Ace models use the same voice board, but I wouldn’t be surprised if there were many, many of them… This is interesting, because it means you can probably interchange voice boards between units with no extra modifications whatsoever (the wires attached to the board are exactly the same, see below), which makes for quick repairs provided you have an Ace Tone drum machine you don’t mind cannibalizing…

Main voice board of the Rhythm Fever. Almost identical to the Rhythm Producer and FR-6 boards

Rhythm Producer voice board

The Rhythm Fever is probably one of the last models designed and manufactured by Ace Tone before the company closed down. The design and enclosure of the Rhythm Fever, as well as the presence of a ‘disco’ preset, can attest to this; while most Rhythm Ace units were built in the late sixties / early seventies, the Rhythm Fever clearly belong in the latter half of the decade.

Like many Rhythm Ace models, the Rhythm Fever has the standard ‘rotary preset selector’ for two of its button, which can be found on many Rhythm Ace units. The bass drum, like all Rhythm Ace units, is a very low frequency thump (around 60Hz) without much snap or attack, which makes it a bit tricky to use in a mix, but with a lot of tweaking and EQing, it’s definitely usable. Just don’t expect a snappy early eighties analog BD sound, you just won’t be able to coax it out of this machine!

By the way… Did I mention it has a DISCO beat ? 🙂

Technical Info / Service Notes

When I first received my Rhythm Fever, it sounded great, and every button worked fine, except after a few minutes the tempo started drifting like crazy, which made it totally unusable. I poked around the circuit for a while, trying to find the source of the problem, but couldn’t locate the cause easily, so I just put the drum machine on a shelf and forgot about it.

A few months later, I got my hands on an Ace Tone Rhythm Producer which had exactly the same problem. That motivated me to find the root of the problem, because I figured if I could fix one of them, I could easily and quickly fix the other one as well… The ‘two birds with one stone’ kind of thing… So I poked around the Rhythm Producer for a while, did some research on the net on vintage drum machine clock circuits, and found the problem: two leaky capacitors in the clock circuitry. (Read the full story on my Rhythm Producer page)

After I’d found the problem on the Rhythm Producer, it literaly took me 30 minutes to fix the problem on the Rhythm Fever. You see, Ace Tone products from the seventies have EVIL tantalum capacitors, the great majority of which have gone bad over the years. Don’t trust ’em! They’re nothing but trouble! They were responsible for malfunctions on three of my Ace Tone machine, so far… (Check out the Ace Tone PS-1000 monosynth page for another example)

If you own a faulty Ace Tone instrument, this might be the best piece of advice you’ll ever get… Replace those brown tantalum caps with electrolytic capacitors, and all your troubles will go away!

Faulty capacitors before replacement

After replacement

If you’re interested in modifying this drum machine for multiple, individual voice outputs, check out the Rhythm Producer page, where I describe this mod in detail. The voice boards are almost identical, so the procedure should be the same.

Specifications

Gallery

After replacement

Faulty capacitors before replacement

Main voice board of the Rhythm Fever. Almost identical to the Rhythm Producer and FR-6 boards