Contents

Roland TR-505

Drum machine

TR-505
The Roland TR-505
Manufacturer	Roland Corporation
Dates	1986–1991
Price	$318 US (1986)
Technical specifications
Polyphony	8 voices
Oscillator	N/A
Synthesis type	Digital sample-based
Velocity expression	No
Storage memory	Patterns: 48 user, 48 preset. 6 Songs.
Effects	No
Hardware	Main panel features a simple LCD display, 15 buttons, 2 knobs, 16 trigger pads, 2 outputs for left and right/mono, headphone jack, and tape input/output.
Input/output
Keyboard	16 pattern keys
External control	MIDI in/out, start/stop foot pedal jack.
Audio sample	8-bit unsigned PCM data, with a 25.00 kHz sampling rate

The Roland TR-505 rhythm composer is a drum machine and MIDI sequencer released by Roland Corporation in 1986.^[1][2] It hails from the same family of drum machines as the Roland TR-909, TR-808, TR-707, TR-626 and TR-606. The drum kit includes basic rock drum sounds similar to those of the TR-707, plus a complement of Latin-style drum sounds similar to those of the TR-727 (the Latin version of the TR-707)^[3]

Samples in the TR-505 are stored as 8-bit unsigned PCM waveforms at a sample rate of 25 kHz. The TR-505 offers some major improvements over the TR-707, including 16 digitally recorded PCM drum sounds (four more than the TR-707) and five Latin percussion voices from the TR-727, reducing the need to buy a separate unit or PCM card.^[4][3]

Summary of drum voices:^[5]: 9

Although there are 16 drum samples, the TR-505 only has an 8-voice polyphony, restricting some sounds from playing simultaneously: low conga or hi conga; timbale, low tom, mid tom, or hi tom; low cowbell or hi cowbell; hand clap or rim shot; crash cymbal or ride cymbal; closed hi-hat or open hi-hat.^[5]: 9

The TR-505 offers very limited voice editing in the form of volume, velocity, MIDI channel, and MIDI note of each voice as a global parameter.^{[5]: 14,40,42}

The TR-505 contains 48 factory sequencer patterns, organized into 3 pattern groups (A, B, and C). The drum machine can also store 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:^[5]: 8

• 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.^[5]: 15

Users can copy, insert, or delete one or more steps in any given pattern, and 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, resulting in each step representing a sixteenth note. Other time signatures can be programmed by changing the Last Step (length of patterns) and the scale, allowing for shuffle and swing rhythms.^[5]: 24

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 it will only trigger the chain as a whole, not the individual pattern.^[5]: 27

Up to six tracks (songs) can be programmed using combinations of patterns.^[5]: 16 Each song can consist of up to 423 bars (patterns).^[6][5]: 18

The TR-505 consists of 16 individual instrument/ pattern pads.^[6] The pads are not velocity sensitive, but can be modified by the accent parameter.^[5]: 51

The TR-505 can transmit and receive on MIDI channels 1 through 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.^[5]: 51
• Track number message - track/song select
• Bar Number message - Song position
• Clock message - tempo synchronization, start, stop, etc..

The TR-505 can store 48 ROM patterns, 48 RAM patterns, 6 tracks, and a maximum of 423 measures.^[7]: 1

The Tape interface (in/out) allow the Tracks and Patterns in internal memory to be stored on external tape.^[4] Data can be Saved, Verified, and Loaded from the tape.^{[5]: 35,36,37}

There are companies, websites, and magazine articles documenting a DIY 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]

• Roland TR-505 Owners Manual, Osaka, Japan: Roland Corporation
• Roland TR-505 Service Manual, Osaka, Japan: Roland Corporation
• 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