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.
8-bit unsigned PCM data, with a 25.00 kHz sampling rate
The Roland TR-505 rhythm composer is a drum machine and MIDIsequencer 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 the TR-727.[3][4]
Voice synthesis
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.[5][3]
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.[6]: 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.[6]: 14,40,42
Sequencer
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:[6]: 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.[6]: 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.[6]: 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.[6]: 27
Up to six tracks (songs) can be programmed using combinations of patterns.[6]: 16 Each song can consist of up to 423 bars (patterns).[7][6]: 18
Keyboard and external control
The TR-505 consists of 16 individual instrument/ pattern pads.[7] The pads are not velocity sensitive, but can be modified by the accent parameter.[6]: 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.[6]: 51
Track number message - track/song select
Bar Number message - Song position
Clock message - tempo synchronization, start, stop, etc..
Storage
The TR-505 can store 48 ROM patterns, 48 RAM patterns, 6 tracks, and a maximum of 423 measures.[8]: 1
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 the tape.[6]: 35,36,37
Modifications
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,[9] voice circuit bending,[10] adding individual audio outputs,[11] adding CV outputs,[12] adding pitch change to each voice,[10] and adding circuits to randomize sequences.[10]
