The original KR-55A included 48 preset rhythms, 16 intro, and 16 fill patterns, and the later KR-55B doubled this to 144 patterns, 32 intros, and 32 fills. You would think that the later version just added more patterns to the existing collection, but in reality they share very few patterns - almost all of the KR-55B patterns are different than the KR-55A patterns (even patterns with the same names are a little different). We've included all of the patterns, intros, and fills from both machines - believe us when we say that reverse-engineering these was no small task!
To play a preset pattern, make sure the Pattern Mode button is set to Preset. Each of the black pattern select buttons selects three rhythm patterns, depending on the the currently selected A, B, or C group buttons on the right. Once a pattern is selected, press the Start/Stop button. Get ready to blow minds and pack the dance floor when you punch up that sweet Foxtrot!
Don't let the silly names put you off - many are totally usable in modern music contexts, particularly when instruments are selectively disabled using the volume knobs or mute buttons on the Mixer panel.
55A Patterns
There are a total of 48 patterns when the Model switch is set to the 55A position. To select a pattern, click the corresponding black pattern button at bottom left, and choose the desired pattern row with the A, B, or C buttons.
55B Patterns
Choosing the 55B Model switch position doubles the available pattern choices to a total of 96 patterns. Pattern selection operates the same as 55A, however, two separate variations are available for each pattern by choosing the I or II position with the Pattern Group switch.
Note that the even though some 55A and 55B patterns share the same names, the patterns are almost all different. Someone at Korg must've really been trying to impress their supervisor when cooking up the new-for-1982 improved KR-55B.
Intro/Fill-In
KR-55C includes nifty automatic intro and fill patterns. These are all one bar long. Intros and fills can only be used in Preset Pattern Mode - they are not usable in User Pattern mode.
When in 55A mode, there are a total of 16 intro patterns and 16 fill patterns with preset rhythm groups sharing the same intro and fills. For example, in 55A mode, the Foxtrot, Shuffle, and March rhythms share the same intro and fill patterns. The easiest way to think about it is that there is one intro and one fill pattern for each black button.
In 55B mode, there are a total of 32 intro patterns and 32 fill patterns with preset rhythm groups (i.e. buttons) sharing the same intro and fills. These operate basically the same as 55A mode, but as with the preset patterns, there is an alternate set of intro and fill patterns depending on the Pattern Group switch position, so same analogy as above, but now there are two intros and two fill patterns for each black button.
The only exceptions are the 5/4 patterns, which basically work the same way, but there are not separate patterns for intro and fill - the intro and fill patterns are the same.
The Intro/Fill-In functions only works when Pattern Mode is set to Preset. When Pattern Mode is set to User, the Intro/Fill-In button turns into the Inst Trigger button, which can be used to play the currently selected instrument live when playback is stopped, or to insert drum hits for the currently selected instrument into patterns on the fly during playback.
Using the Intro Function
To begin a pattern with its associated intro pattern, use the Intro/Fill-In button to start playback instead of the Start/Stop button. The fill pattern plays in its entirety (1 bar) and the currently selected pattern begins on the downbeat.
Using the Fill-In Function
To trigger a fill pattern, click the Intro/Fill-In button while a pattern is playing. The way in which these play back is a little tricky, but makes sense:
When you hit the Intro/Fill-In button, you might expect the entire one-bar fill to play from that point , but that's actually not how it works. When the fill button is pressed, beginning at the next eighth note, the fill replaces the remainder of the bar, and on the next downbeat, the current pattern plays from the top. In order to make this work, the beginning of the fill gets shortened. The later in the bar the fill button is clicked, the more of the beginning of the fill pattern gets chopped off. Have a look at the diagrams below:
When the fill button is clicked, the fill begins at the next 8th note. For timing reference, the top green staff and dashed vertical lines represent this 8th-note "grid."
In the first example below, the fill button is clicked on the "and" of beat 1 (i.e., during the second 8th note of the bar), so fill playback begins on beat 2. This means the preset pattern plays through beat 1, then the fill plays through beat 2, 3, and 4. On the next downbeat, the pattern begins from the the top.
In example 2, the Intro/Fill-In button is clicked immediately after beat 3. This means the fill begins playing on 3-and. Not only does this cut off the first two beats of the fill, it also cuts off the first two 16th notes of the fill (in this case, the low tom).
Finally, In example 3, the Intro/Fill-In button is clicked on the 4-and; that is, immediately before the next downbeat. This allows the entire one-bar fill to be heard.
You may have noticed that all the examples above are one bar long, but KR-55C's patterns are all two bars long - fill behavior works the same whether a fill is initiated during the first or second bar of pattern playback, and following a fill, the pattern always restarts from the top regardless of whether it was initiated during the first or second bar of the preset pattern. There's one exception to this, explained in the Alternate Fill Pattern Substitution section below.
If any of the above is above your understanding of rhythmic notation, the important takeaway is that the fill length heard is always adjusted so that the downbeat lands on the 1 of the next bar, at which point the current preset rhythm begins again from the top. This means it's impossible to hit the Intro/Fill-In button at the "wrong" time and cause the downbeat to land in a weird spot.
Waltz, Ballad, and 5/4 Fill-In
The Waltz, Ballad, and 5/4 patterns (clustered at bottom left) are the only KR patterns that aren't in 4/4 time. Waltz patterns are in 3/4, Ballad patterns are in 6/8, and the 5/4 patterns are (you guessed it) in 5/4 time. The fill functions works the same as explained above - their associated fills are also one bar, but in the same time signature as their associated patterns.
Alternate Fill Pattern Substitution
Alternate fill what-a-wa-wha? In case all of the above wasn't confusing enough, the original KR machines had one additional feature, intended to avoid redundancy when using fills (Because preset drum machine patterns aren't redundant at all... huh? Don't ask us.)
Depending on when in the bar you hit the Intro/Fill-In button, KR-55 sometimes plays the very end of the intro pattern instead of the fill pattern. Specifically, this occurs if the fill button is clicked on or after beat eight in the two-bar 4/4 patterns, on or after beat six in the 3/4 Waltz patterns, or on or after beat eleven in the 6/8 Ballad patterns. The alternate fill function doesn't work for 5/4 preset patterns, because the intro and fill patterns are the same for 5/4 patterns. We know this is exhausting...
Alternate fills "replace" part of the current preset pattern as shown in the above diagrams, but only on the very last beat, or "and" of the last beat. The diagram below illustrates exactly what happens depending on when you mash the fill-in button over the duration of a two-bar pattern:
The good news is that the LEDs to the left or right of the Intro/Fill-In panel label illuminate to let you know whether the pattern is playing back between beats 1-7 or beat 8 - this makes it easy to tell which fill will be heard.