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EKO Ritmo 20

With the recent developments in drum machine technology bringing rhythm programming within the reach of any musician, you might imagine that we had seen the last of stand alone preset machines; EKO obviously do not agree and present us with their Ritmo 20.

This rhythm box has, as the name suggests, a selection of 20 preset rhythms to choose from. Three of these are in 3/4 time while the rest are in 4/4. This may sound fairly limiting but the machine also offers Intro and Fill-in breaks for each of the 20 rhythms.

Nine sound generators are built in, these are: Bass Drum, Snare, Conga, Tom-Tom, Hi-Hat, Cymbal, Rimshot, Claves and Cowbell. To adjust the overall sound balance a six channel mixer is provided. This is where the machine comes into its own, the percussion simulation is excellent, but more of that later.

The circuitry comes packaged in a very smart pressed steel case finished in matt black. All the rhythm controls are neatly arranged on a sloping front panel while the Mains input, Fuse, Headphone level and Output socket, Audio outputs and Foot-switch connector are on the back.

Control panel

An internal view showing neat construction.

The rhythms are selected by 12 black switches arranged in a 10 x 2 format, ie each of the 10 selects one of two rhythm banks dictated by the other two switches. All of the switches have built in red LED's to indicate the rhythm selected. The rhythms encoded in memory are; Bank 1: Beguine, Samba, Jazz Rock, Rock 1, Rock 2, Rock 3, Disco 1, Disco 2, Funky and Pop Rock, and Bank 2: Waltz, Jazz Waltz, Tango, March, Swing 1, Swing 2, Shuffle, Ballad, Bossa Nova and Cha Cha. Above the selection switches are the voice balance controls, these allow six channels to be mixed; Bass Drum, Snare, Conga/Tom-Tom, Hi-Hat, Cymbal and Rim Shot/Claves/Cowbell. The sustain of the Conga/Tom-Tom voices can also be changed for any rhythm with a Sustain switch. Two other switches are provided, duplicated on the dual footswitch supplied, one for, Intro or Fill in, depending whether the rhythm is running or not, and one for Start or Stop. The last two controls are Tempo and Volume (with power on/off at minimum setting). The Down-beat, or first beat in the bar is indicated by an LED situated by the Tempo knob.


The first thing you notice about the unit when it is switched on is how quiet it is! The output circuitry has a noise gate built in to prevent any voice breakthrough. The only disadvantage with this type of circuit is that when you stop the rhythm the gate mutes the sound immediately which is quite noticeable if you stop on an open Hi-Hat or Cymbal beat.

To start a selected rhythm you can either press Start/Stop, which will run the selection as normal, or the Intro/Fill-in switch, which will start the rhythm with an introductory break before getting into the normal beat. When the rhythm is running, hitting Intro/Fill-in again brings in another break, this time as a 'frill' which returns to the normal selection on the Down Beat. The Intro's and Fill-ins are all different, arranged to complement the selected rhythm.

The sound quality of the voicing is very good, especially the Snare, Hi-Hat, Cymbal and Cowbell! The option to mix the sound balance is also very valuable and fading in different channels during a rhythm introduces some interesting possibilities.

Although the rhythms cannot be mixed you can jump between selections while the unit is running. This again increases the versatility of the machine.


The circuitry with the top board removed.

Internally, the layout is very impressive, being packed with electronics as can be seen from the photographs. The top circuit board contains most of the voicing and output circuitry. The board underneath holds the control circuitry, two EPROM's with encoded rhythm patterns, metallic voicing, Headphone amplifier and power supply regulation.

No less than 8 oscillators and 4 ring modulator type circuits are used to produce the metallic voicing! These circuits are mixed in different proportions to synthesise the Hi-Hat, Cymbal and Cowbell voices.

Each EPROM contains the data for one bank of rhythms, including Intro and Fill-in. The 4/4 rhythms are 32 steps long whereas the ones in 3/4 time are 24 steps long. Both the Intro and Fill-in's are 16 or 12 steps long. Since each EPROM can hold a total of 1024 bytes, it seems strange that the designers have not used this full capability as a total of 32 rhythms could be stored. This could be accessed with the same number of switches on the panel but arranged in 8x4 format with 8 rhythms in each of 4 banks.


It is difficult to fault the construction of this unit. Removable connectors are used extensively throughout to allow easy servicing and adjustment. All the wiring is neatly arranged in looms and all the IC's are in sockets. The voicing PCB's are even separated with an aluminium screen to prevent interference.


Although this machine is preset it does offer an interesting range of rhythms especially with the Intro/Fill options. The voices are excellent proving that a lot of time has been taken to develop what is probably the closest simulation possible with analogue circuits.

The foot switches are also a useful addition to break up the rhythm while your hands are otherwise engaged!

It would have been nice to see a programmable front end linked to such a good range of voices but this would obviously push up the final price. The Ritmo 20 complete with dual footswitch and signal lead retails at £189 inc VAT. A smaller version, The Ritmo 12, is also available, presumably with the same voicing but with only 12 rhythms and no Intro feature. This is priced at £125 inc. VAT.

Both the Ritmo 20 and Ritmo 12 are distributed by John Hornby Skewes & Co. Ltd. They can be contacted at (Contact Details). Please mention E&MM when doing so.

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Guide to Electronic Music Techniques

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New Products

Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - Nov 1982

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Drum Machine > Eko > Ritmo 20

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Analog Drums

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