KORG Rhythm 55 (KR-55) Drum Machine

Korg released both the KR-33 & KR-55 in 1979. They are the successors to Korg's successful Mini Pops series of drums. The KR-55 looks a bit like a old school calculator, but don't let it's appearance fool you.
 This was quite cutting edge for its time.  There is a micro-processor involved in rhythm making. Gone are the days of the old diode matrix.

Its built in sequencer has 48 preset patterns (Waltz, Samba, Cha Cha, Afro, Enka, Rhumba, Bossa Nova, Tango, Slow Rock, Swing, Rock, etc.). There are 16 Intro patterns & 16 Fill-In patterns though sadly you can't  program your own patterns. (Roland had  just brought out the CR-78 one year earlier which had this feature as did the Roland TR-606 which  wouldn't come out till 1981).

There are 12 analog sounds: Bass Drum, Snare Drum, 2x HiHat, Cymbal, Low Conga, High Conga, Rim Shot, Claves, Cowbell, 2x Tom Tom. The sounds are commonly described as snappy & metallic.

Here is a great video I found on youtube which gives a really good example of these sounds.

The rhythms are not mixable like on some of the old Minipops drums, but the tempo and volume knob do allow for a little tweaking. There is also a "swing" control to add a bit of spice to the groove.

 In his excellent SOS review, Gordon Reid discusses the TR-33 & TR-55 "History of Korg - Part 1"

"More successful [than the Sigma] were the KR33 and KR55 rhythm units, which replaced the ageing Mini Pops series. These were more sophisticated than their predecessors, generating analogue sounds that were far more realistic than the noise-based thumps and hisses offered by the earlier DoncaMatics, Mini Pops, and units from competitors."

Here is the Korg KR-55 manual

There is a Trigger out , but no trigger in. Thus un-modded, it's impossible to sync with external gear. There are several triggering modes: I understand that The KR-55 runs at 8ppqn so you will need to use a clock divider if you wish to sync it to midi or sync24.
  
It can also be externally controlled via the footswitch jack for the Start/Stop & Intro/Fill switches.

There are no individual outs for the 55 but there are faders for most of the drum sounds.that allow you to mix the volume levels of the bass, snare, cymbal, hi hat, conga/TT, Rim Shot/Cow Bell/Claves.
There are lots of mods on the net on how to get individual outs.

The Korg Rhythm 55 was used by Jean-Michel Jarre (Magnetic Fields) and Depeche Mode  in 1981 (Speak and Spell) & Cabaret Voltaire.

Modding:
Analogue solutions midi kit looks nice but has a fee of £109 for the kit.  I may end up doing it but would love individual outs along with it.
http://www.analoguesolutions.org.uk/mods/kr55.htm 
http://www.youtube.com/watch?v=33zfpZ9RBK8

Here is a great place for some modding (esp for multiple outs) :
http://alienatedsynthesist.blogspot.com.au/2011/10/kr-55-clock-in-mod.html
https://www.flickr.com/photos/31603983@N05/sets/72157628641466671/ 

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For more info on the history of Korg Drum Machines Click Here