The AMDEK Rhythm Machine Rmk-100
The AMDEK Rhythm Machine Rmk-100 is a rare programmable drum synthesizer that was produced by (Analogue Music Digital Electronics Kits) in 1981-83. AMDEK Corporation was established in Osaka Taiwan by Ikutaro Kakehashi in 1981. Kakehashi the owner of the Roland Corporation created AMDEK to produce computer monitors for the emerging personal computer market, and small do it your self electronic kits for musicians. For a few years from 1981-83 the company had some success producing some of the earliest Super VGA computer monitors, along with the small analog effects unit kits for musicians, and rhythm synthesizers such as the RMK-100 rhythm machine. However, in only two short years by 1983 the company backed out of the computer monitor market due to mounting completion, and along with the discontinuation of AMDEK’s production of computer monitors came the end to AMDEK’s production of small synthesizers and effect unit kits as well. Although, AMDEK discontinued making the small effects unit kits, and computer monitors, the company did not entirely disappear. In 1983 Ikutaro Kakehashi renamed AMDEK to what is now known as the (Roland DG Corporation), and then used the renamed company as a vehicle to release a range of the company's own computer and music peripherals.
In terms electronic drum machines the AMDEK Rhythm Machine Rmk-100 is arguably one of the rarest drum machines produced in its era, because of its limited production and that it was only offered in a kit form. As a kit, the RMK-100 was also one of the larger and more complex do it your self electronic projects produced by AMDEK, and somewhat of an oddity. The majority of do it yourself kits produced by AMDEK consisted of guitar related effects boxes such as the: (CHK100 chorus, DSK100 distortion), and the (PCK-100 Percussion Synthesizer.) However, as a do it your self kit the AMDEK RMK-100 was unique in the aspect that it is far more than a percussive tone generator. It was a completely programmable electronic drum machine with 8 banks of 16 step pattern creation capability, which made for a bit more of a complex build. And when completed the result was a quite an impressive little machine for its time.
The AMDEK Rhythm Machine Rmk-100 is a truly analog drum machine which utilizes transistor based tone generators that produced Bass drum, Snare drum, and Hi Hat sounds. A few other pre-built commercially available analog drum machines of same era have been compared to the Rmk-100 in regards to the quality of synthesized drum sounds produced. Most notably the Roland TR-606 Drumatix, and the Boss Doctor Rhythm DR-55. Although, the Boss Dr-55 drum machine is frequently used when making a comparison to the Rmk-100 the overall design in respects to the tone generating circuitry more closely resemble that of the Roland TR-606, rather than the Dr-55. However, in terms of sequencer programming, and overall similarity in operation the Rmk-100 is much closer to the Boss DR-55.
The functionality of the AMDEK Rhythm Machine Rmk-100 is rather simplistic. The Rmk-100’s synthesized drums are selected by a 4 way slid switch labeled “Sounds” located on the top left of the control panel. The method used to input the selected sounds into the Rmk-100’s 16 step sequencer is performed by two buttons on the lower portion of the control panel. The Rmk-100 uses these two buttons labeled “Start” and “Stop & Reset” at the bottom of the control panel to play and stop user programmed sequences. However, these two buttons are also used to enter new drum sound data into the 16 step sequence.The programming function of the “Start” and “Stop & Reset” buttons are selected by the mode selector switch, which is located directly above the “Start” button on the Rmk-100’s control panel. When the mode selector switch is set to write the “Start” button enters selected drum sound data into the sequence, and the “Stop & Reset” button is used to progresses through the 16 sequencer steps as well as resets/clears the currently selected drum sound in a created sequence. One of the sound sequencing limitations of the machine was the auto Hi Hat function. Unlike the Open Hi Hat which is user programmable the Closed Hi Hat is not. A user has only three options when it comes to Hi Hats, off, 8th note, or 16th note. This does somewhat limit some functionality of the Rmk-100 but, there is an overall Hi Hat Volume control knob located at the top of the control panel to offer a bit more flexibility. Although, other machines with more features and intuitive functions were commercially available during the early days of programmable drum machine technology the Rmk-100 kit was a fraction of the cost of these other machines and also quite powerful.
Being that the AMDEK Rhythm Machine Rmk-100 was designed as a do it your self kit the possibility of modification was considered by the manufacture. In many ways the more modern idea of “open Source” hardware is represented quite well in the Rmk-100. On the main PCB board populated by the oscillators used to create the machines synthesized drum sounds, AMDEK left an open block for modifications, and a pre-drilled hole labeled “USER” at the top of the machines casement. Many builders of the Rmk-100’s modified their machines to utilize the “user” port as a gate input or output trigger to send or receive analog control voltage signals to clock sync outboard sequencers or to control other drum machines. Another, popular modification to the RmK-100 was output splitting. However, this modification required the builder to drill into the casement of the Rmk-100 and add output jacks for each of the synthesized drum sounds, but for the studio recording artist this added a great deal of mixing flexibility. More modern modifications to the Rmk-100 have included the implementation of microcontrollers in order to send general midi data to the Rmk-100 enabling it to be sequenced by computer software or other general midi instrument sequencers.
As the years have passed obtaining original functioning analog synthesizers and drum sequencers is becoming harder and harder, some have fallen into disrepair or have been modified by circuit benders, and others like the Rmk-100 were subject to being limited in production. Although the digital age has brought about the advent of software emulation of many the rare machines produced in the past, the sterility of digital emulation is driving many to return to a warmer analog sound. This drive towards analog machines such as the AMDEK Rmk-100 has increased. However, for those who collect these machines it has become an ever increasing costly proposition to acquire them.