Roland TR-505

8-bit unsigned PCM data, with a 25.00 kHz sampling rate (non-linear DAC circuitry to simulate 12-bit resolution)[4]^(p5). The TR-505 is not a cut-down baby brother of the TR-707. Instead offers some major improvements including 16 digitally recorded PCM drum sounds (four more than the TR-7070).[5] Also including five Latin percussion voices, eliminating the need to but a 'latin version'[3] or PCM card down the road.

Summary of Drum Voices:[6]^(p9):

Although there are 16 samples the TR-505 only 8 voice polyphonic. This means some samples are restricted from played simultaneously: Low Conga or Hi Conga; Timbale, Low Tom, Mid Tom, or Hi Tom; Low Cowbell or Hi Cowell; Hand Clap or Rim Shot; Crash Cymbal or Ride Cymbal; Closed Hi-Hat or Open Hi-Hat.[6]^(p9)

There is almost no voice editing in the TR-505. The user is limited to setting the Volume, Velocity, MIDI Channel, and MIDI Note of each voice as a global parameter.[6]^(p14,40,42)

The TR-505 contains 48 factory sequencer patterns, organized into 3 pattern groups (A, B, and C). The drum machine also contains 48 user created sequencer patterns, organized into 3 pattern groups (D, E, and F).[3]

The TR-505 features five basic modes, including the following[6]^(p8):

• Track Play - plays whole tracks (arrangements of patterns to form songs).
• Track Write - sequence patterns into tracks.
• Step Write - sequence patterns by stepping through each position in the pattern.
• Tap Write - sequence patterns by tapping drums sounds in real time.
• Real time - play patterns in real time by tapping the pads.

An accent can be applied to any position in a pattern and will affect all instruments triggered at that position by increasing output volume.[6]^(p15)

You can Copy, Insert, or Delete one or more steps in any given pattern.You can also Copy, Insert, or Delete patterns anywhere in a track (song)[1].

Each individual pattern is a single measure long, The default time signature is 4/4 consisting of 16 steps and quarter note scale. This results in each step representing a sixteenth note. Other time signatures can be programmed by changing the Last Step (length of patterns) and the scale. This can also result in shuffle and swing rhythms.[6]^(p24)

Two or more Patterns can be combined, using Pattern Chaining, to play as a single pattern. Each pattern in the chain occupies a pad, but will only trigger the whole chain, not the individual pattern.[6]^(p27)

Up to six tracks (songs) can be programmed using combinations of patterns[6]^(p16). Each song can consist of up to 423 bars (patterns).[7][6]^(p18)

The TR-505 consists of 16 individual instrument/ pattern pads.[7] The pads are not velocity sensitive (pad velocity is fixed, except when modified by Accent parameter)[6]^(p51).

The TR-505 can transmit and receive on MIDI channels 1 -16 and Notes numbers 25 to 99. It also contains a MIDI Omni mode allowing it to receive all MIDI data. The TR-505 responds to the following MIDI messages[3]:

• Key message - trigger signal for the individual voice.
• Velocity message - Note-on velocity is both transmitted and received allowing more expressive.[6]^(p51)
• Track Number message - track/song select
• Bar Number message - Song position
• Clock message - tempo synchronization, start, stop, etc..

Storing 48 ROM patterns, 48 RAM patterns, 6 tracks, and a maximum of 423 measures.[4]^(p1)

The Tape interface (in/out) allow the Tracks and Patterns in internal memory to be stored on external tape.[5] Data can be Saved, Verified, and Loaded from tape.[6]^(p35,36,37)

There are companies, websites, and magazine articles documenting a DYI process for circuit bending and modifying the factory setting of the Roland TR-505. An example of a few modifications include: changing audio samples[8], voice circuit bending[9], adding individual audio outputs[10], adding CV outputs[11], adding pitch change to each voice[9], and adding circuits to randomize sequences[9].

• Vince Clark[12]

• Roland TR-505 Owners Manual, Osaka, Japan: Roland Corporation
• Roland TR-505 Service Manual, Osaka, Japan: Roland Corporation
• Gilby, Ian. "Beat Box". Sound On Sound. April 1986. p. 24. ISSN 0951-6816. OCLC 925234032.
• Gilchrist, Trevor. "Drumatix Goes Digital". Electronics & Music Maker. May 1986. p. 38-39.
• Reed, Tony. "Roland TR 505 Rhythm Composer". International Musician. May 1986. p. 102-103
• "Roland TR505". Making Music. April 1986. p. 27-28
• Alex Grahm. Rhythm Machines 2. self-published. 2018. ISBN 978-1983552588.

• Roland TR-505 Rhythm Composer | Encyclotronic - Review, Tech Specs, Images, Media, and Purchase Links
• Roland TR-505 ROM Expansion | HKA Design - Sample modification kit for TR-505
• Roland TR-505 | Burnkit2600 - Circuit bending and modding the TR-505
• Roland TR-505 | Polynominal - Review, mp3 demos, and manual
• Roland TR-505 | Vintage Synth Explorer - Review and media