Roland TR-66 Rhythm Arranger
The Roland TR-66 Rhythm Arranger is an analog rhythm machine from 1973. The following are my notes on it, including how to open it up and sample it.
In general, I find the sound quite pleasing in that it’s more “rounded” and “lounge” than the tight and snappy CR-78. The kick is mellow but with a cleanly defined thump at 60Hz (decay is tunable via an internal trimmer, but not the pitch). The high conga, low bongo, and high bongo are simple but recognizable classics (both decay and pitch are tunable via internal trimmers). The rim, clave, and cow bell are all tight and highly usable (they take reverb well). The snare is okay but can be a bit crude unless you get a well-tuned sample (the amount of white noise is adjustable via an internal trimmer). The hat and cymbal are a bit trashy sounding; they need processing to get rid of annoying frequencies. The top end on this unit extends beyond 40kHh!
VOICES (10): bass drum, low bongo, high bongo, high conga, rim shot, snare, cow bell, clave, cymbal, high hat.
PATTERNS (27): each with A and B variation. "Auto" mode alternates between variation A and variation B. You can press multiple pattern buttons at once to combine rhythms.
Notable Use: Dust Brothers Fight Club score "Corporate World." Roxy Music "Dance Away."
Controls
BALANCE KNOB: This adjusts the relative levels of the kick and hat/cymbal (it’s not an EQ tone knob), while holding the midrange sounds constant. So if you turn counterclockwise you get more kick and less annoying hat. Around 9-10 o'clock is a balanced sound between the kick/hat, that's pretty much the usable range of this knob. Note you can not get isolated hits this way, as the hat/cymbal will not mute.
IN/OUT: The low impedance out (10k Ω) gives “semi-pro” line -10 dBV levels for recording, and there’s also a high impedance out (100k Ω, lower-gain). Additionally there’s a “start” input for connecting a foot switch.
How to Sample It
The 1973 service manual can be a bit hard to decipher, here is how you trigger individual sounds for creating your own samples. First remove the four screws on the base. The TR-66 will then slide out the rear of the wood case.
Conveniently located on top you will see the Sound Generator Board. There is a cut out section in the metal platform on which the Sound Generator Board is attached, which allows you to access a small portion of the Rhythm Switch Board below. That is where you will find "terminal 5" (which is referenced in the service manual). Term5 is outputting a trigger at the tempo set by the front knob. Put the box in play, no rhythm buttons engaged, and run a wire from term5 to the sound you want to trigger. This generates a waveform at the 1/4" outs, at the same volume and sustain as the box normally outputs (I experimented with using my own trigger, but it produced erratic results for level and sustain).
Situated around the edge of the Sound Generation Board are nine terminals, which trigger ten sounds. Moving clockwise starting with the snare drum you will see terminals labeled: SD, HH, CY, C, RS, HB, LB, HC, BD. The RS terminal normally outputs a cow bell, but if you push the "bossa nova" button in around 3/4 (without actually making it click in) this terminal will output a rim shot (the service manual mentions something about grounding/ungrounding the CB SHUNT terminal to get these two sounds).
Tuning
On the sound generator board you will find eight off-white trimmers for tuning the sounds. These are labeled: BD DT, HC DT, HC FRQ, LB DT, LB FRQ, HB DT, HB FRQ, and CY.HH.SD VAR.
"FRQ" trimmers: these give you some control over the pitch of the three toms (HC, LB, HB), however the available range is narrow. If you go too low the drum may start to become a lump of noise with no definitive pitch, and if you go too high it may start feeding back. Interestingly the snare sound contains the low bongo sound within it (the SD fundamental is fixed at around 280hz, and the LB is adjustable around 400hz). So tuning this bongo also changes the sound of the snare (I tune it to a just intonation relationship).
"DT" trimmers: these give you control of the decay time of the bass drum and the three toms. It is especially useful for the bass drum; you can get anything from a tight 65ms snap, and a long 650ms boom.
"CY.HH.SD VAR" trimmer: this controls the level of the white noise. Turning this adjusts the snappiness of the snare, from completely muted (this could be considered a secret 11th sound!), to bright and raspy. Also, when sampling the HH/CY turning up this trimmer gives you a better signal to noise ratio.
