Roland TR-707 Circuitbent/Expanded (727 808 909 + 4 Soundgas Banks)

In stock now. Modified to allow switching between eight different sets of voices, and if that isn't enough, circuitbent with tuning pots and various patch points and toggle switches which transforms this into a complete monster.

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Modified to allow switching between eight different sets of voices including 707, 727, 808 and 909, plus four of our own custom banks. Circuitbent with tuning/decay pots, patch points, DAC distortion switches and audio input (using hihat circuit for rhythmic gating) transforming this into a total monster.

UPDATE: Just back from the tech. Ready to ship!


Modified and expanded Roland TR-707 Rhythm Composer for sale with exclusive Soundgas HKA mod and Circuitbenders mods with tuning pots, patch points and toggle switches (more info below). This is a BEAST.

Supplied freshly serviced and modified with extra voice EPROM expansion from HKA Design, but for this one we’ve added four banks (of the eight) with our own sounds – an idiosyncratic selection culled from some of our favourite drum machines by our wizard synth tech, Chris. This non-invasive, reversible mod allows switching between eight banks of sounds (it still operates exactly as a stock 707 at power up). Featuring new drum sounds in each kit. The last two sounds  (707 crash + ride or 727 quijada + chime) remain the same across all banks, as they are stored on their own ROMs. The banks included are:

  1. TR-707
  2. TR-727
  3. TR-808
  4. TR-909
  5. Soundgas Roland CR/TR (CR-78 & TR-66) – hear the first demo of this bank
  6. Soundgas Korg favourites (KR-55 & Mini Pops 7)
  7. Soundgas Elka/Maestro (Drummer One meets Rhythm King)
  8. Soundgas Toy Box (Mattell + Casio)

Note that we will add more detailed info soon. All sounds are extracted from our own machines. Note that the limitations of the EPROM storage mean samples must be short and punchy (hence the cymbals having their own EPROM). This affects the choice of sounds to include, and also means you won’t get a deep booming 808 kick.

Bank switching is done by holding down one of the first 8 step keys while turning the machine on. The setting is remembered and will be recalled the next time it’s turned on. There are no modifications to the outside of the machine, and the installation is easily reversible.

Covered by our usual warranty.

Requires a 9-12V power supply (not supplied). Find them on the Roland website here.


CAUTION : As far as we are aware we have checked every patchbay connection but it may be possible that some connections may cause the 707 / 727 to either reset itself, crash, or clear the user memory. This is very unlikely but if the machine ever locks up just turn off the power and wait for a few seconds before restarting.

18 way 3.5mm jack patchbay: Connections made between the sockets on the patchbay cause all kinds of distortion, ring modulation, sound swapping, modulation and general alien effects to be applied to the sounds. Multiple connections can be made at any one time offering thousands of different percussion grinding options. Slightly different sounds and effects seem to be available when using the separate sound outputs.

2 x 3 Way patchbay multiples: These are the 2 sets of 3 sockets to the left of the cartridge port. They further multiplies your creative possibilities by allowing you to connect more than one plug to the same patchbay source. Each group of three sockets are internally connected to each other as shown by the black lines.

2 x 3 way DAC distortion switches. These switches on the top right of the machine offer four types of distortion from all out electro grinding to mild overdriven crunch. Each switch also has an effect off setting in the centre. We can take no responsibility for damage caused to your ears or your equipment from using these switches.

2 x Patchable switches. These are the four plugs and two switches on the top left of the machine. By routing a plug from the patchbay to one of the sockets and then from the adjacent socket back to the patchbay the switch can be inserted in line with any of the patchbay connections. Essentially this allows you to find two effects you like on the patchbay and then turn them on and off at the flick of a switch instead of having to repatch the cables.

TR-707 Hi-Hat Decay Knobs. The top knob controls the decay of the closed hat and the bottom controls the decay of the open hat. Due to the fact that both sounds use the same sample source you will find that the open hat decay knob acts as a kind of ‘master’ decay over both controls with the top knob setting the decay of the closed hat relative to the setting of the open hat decay.

TR-707 Crash & Decay Decay Knobs. The top knob controls the decay of the crash sound and the second knob down sets the decay of the ride. These knobs can only shorten the standard sounds, so the sounds are set to standard TR707 decay when at maximum and the decay is shortened as the knobs are turned down.

TR-707 audio input. This jack socket on the right of the machine feeds an audio input to the Hi-Hat sound bus. When a plug is inserted the Hi-Hat sound is removed from the mix and replaced with the audio input controlled by the Hi-Hat decay knobs and hats level slider.

Pitch Controls: The individual pitch controls are the knobs at the bottom of the front panel. The knobs control the pitches of the instruments in the same sound groupings as assigned to the volume faders. The exception to this are the ride/crash on the 707 and the star chime/qujada on the 727, which have separate volume faders, but a shared pitch control.


Photos are of a similar unit. The current one is in very good cosmetic condition with minor signs of age, and circuitbent with many new switches, pots, sockets. Please get in touch if you require more information on condition.

Voltage Information

See description for more information.


For sales in UK the price will include 20% VAT. Buyers elsewhere may incur VAT or other local taxes on import.


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