Sequential Circuits introduced the TOM as a fully programmable digital drum machine, positioning it as an accessible entry into high-technology rhythm generation for musicians. Priced at a suggested retail of $799.00, the instrument featured eight digitally recorded instrument sounds, including bass, snare, two toms, open and closed hi-hats, a crash cymbal, and hand claps. The design emphasised ease of use and expandability, allowing users to add entirely new sounds through plug-in cartridges from Sequential. Each cartridge could introduce up to seven additional sounds, significantly broadening the sonic palette available to the performer.
The core functionality of the Sequential Circuits TOM revolved around its extensive programmability. Users could record rhythm patterns in real time or enter parts one beat at a time using the Single-Step mode. The machine provided 99 pattern locations, numbered 00 to 98, with each pattern capable of ranging from one to 99 measures in length. The total memory capacity was 2,300 notes, a figure that could be expanded to over 5,000 or 10,000 notes through a factory update. Users defined the measure and time signature, offering flexibility in compositional structure. Patterns could be appended together to form longer sequences, and individual patterns could be copied to new locations.
Song construction allowed for the linking of up to 99 different patterns to create complete musical pieces. There were 99 song locations available, and songs could be edited, copied, and appended in the same manner as patterns. Song programming included the ability to specify patterns, other songs, tempo changes, and volume changes. The initial tempo for each song could be programmed, and the song length could extend up to 256 events. This hierarchical structure enabled complex arrangements while maintaining user control over the overall flow of the music.
To retain data when the power was disconnected, the Sequential Circuits TOM utilised a non-volatile memory system backed by a battery with a five-year life. For permanent storage and reprogramming, a cassette interface was provided. The cassette input and output were AC-coupled, allowing drum data to be stored onto tape. This feature ensured that users could back up their work and transfer data between units or to other systems, providing a reliable method for long-term preservation of compositions.
The instrument incorporated several features designed to add a “human touch” to the mechanical precision of digital drumming. The “Improv Factor” allowed users to program a series of fills that were automatically added to the basic rhythm, creating minor variations in the drum patterns. Additionally, the “Human Factor” mode enabled the programming of minor variances in tuning and volume within patterns. A “reframe” function was also included, which allowed users to redefine the first beat of any pattern if the starting position was not ideal. These features aimed to mitigate the rigid, quantised feel often associated with early digital drum machines.
Interfacing capabilities were a significant aspect of the Sequential Circuits TOM’s design, facilitating integration with other musical equipment. The machine featured a multi-mode clock input and output, allowing it to sync with almost any basic sequencer system. It also included MIDI (Musical Instrument Digital Interface) connectivity, which enabled the Sequential Circuits TOM to connect directly with any MIDI-equipped instrument or computer-based music system. Through MIDI, users could program all drum parts, including volume and tuning, in real time from any velocity-sensitive keyboard instrument, such as the Sequential Multi-Trak or Prophet-T8.
The MIDI implementation supported specific functions including Note On, Mode Control, Song Select, Timing Clock, Start, Stop, and Continue. The machine operated in MIDI modes 1, 3, and 4. The MIDI output provided a clock signal of 24 pulses per quarter note via a five-pin DIN connector. The MIDI input, also on a five-pin DIN connector, allowed the reception of MIDI data. This connectivity made the Sequential Circuits TOM a versatile component in a broader studio setup, capable of both triggering and being triggered by external devices.
Audio output was provided through two individual ¼-inch phone jack outputs. These could be configured for stereo output, mono output, or headphones. The standard clock output offered selectable clock rates of 1, 2, 4, 6, 8, 12, 16, 24, 48, or 96 pulses per quarter note, with a 5Vpp clock amplitude. A programmable trigger output allowed 0 to 5V trigger pulses to be programmed as events within a pattern. The external clock input accepted 24, 48, 96, or MIDI as a clock source, while the dedicated clock input was DC-coupled for syncing to other devices, accepting a 24 PPQN square wave or 48 PPQN pulse at 5 Vpp.
Control over individual sounds was detailed and precise. Each of the eight base sounds, as well as any cartridge-added sounds, could be programmed to different tunings, volumes, and pans within any measure. There were 32 different levels of tuning and 16 different levels of volume available for each instrument. Panning offered three positions: left, right, and centre. This level of control allowed for nuanced arrangement and mixing directly within the drum machine. Erase functions were available for selective deletion of instrument events, patterns, and songs.
The tempo of the Sequential Circuits TOM could be selected and varied to any value between 40 and 250 beats per minute. A programmable metronome was included to assist with timing. Error correction features allowed for timing adjustments to values of ½ notes, ¼ notes, ¼ note triplets, ⅛ notes, ⅛ note triplets, ¹⁄₁₆ notes, ¹⁄₁₆ note triplets, ¹⁄₃₂ notes, and ¹⁄₃₂ note triplets. Instrument events could be recorded as “improv events,” and the same sound could be stacked on top of itself up to four times. A run/stop footswitch jack was provided for hands-free control. The unit was powered by a 15 VAC adaptor.
Features
- 8 digitally recorded instrument sounds including bass, snare, toms, hi-hats, crash, and hand claps
- Sound expandability via plug-in cartridges adding up to 7 extra sounds each
- 99 pattern locations with patterns up to 99 measures long
- 99 song locations with up to 256 events per song
- Programmable tuning, volume, and stereo pan for each sound
- Improv Factor and Human Factor modes for adding rhythmic and dynamic variations
- MIDI input and output for real-time programming and synchronisation
- Multi-mode clock input and output for interfacing with sequencers
- Non-volatile memory with 5-year back-up battery life
- Cassette interface for data storage and transfer