Music Machines http://www.hyperreal.com/machines/ ftp://hyperreal.com/machines/ --------------------------------------------------------------------------- The Clock/Sync/Trigger FAQ by: Mike Perkowitz (tint@hyperreal.com) original draft: 7/7/95 Contents: - Introduction - MIDI - Roland DIN Sync - Trigger and Gate - Tape sync - SMPTE - Oddities Introduction. Various kinds of musical equipment use SYNCHRONIZATION. Most sequencers (whether hardware or software) have an internal clock which they can transmit or can be slaved to an external clock signal. Similarly with drum machines. Synthesizers with built-in arpeggiators and sequencers can often synchronize to an external signal. Older analogue synthesizers can be triggered with gate and control voltage signals. This mini-FAQ attempts to explain the workings of several different kinds of sync information. MIDI Among the messages defined by the MIDI spec are realtime clocks. The MIDI clock has a resolution of 96 pulses per quarter note (ppqn), and most MIDI sequencers, drum machines, and synthesizers can synchronize to it and send it. Roland DIN Sync Before MIDI came into existence, Roland used a standard of its own to communicate sync information between drum machines and sequencers. DIN Sync is so called because it uses the same 5-pin DIN connectors as MIDI. DIN Sync has a resolution of 24 ppqn. Many Roland classics use DIN Sync for clock information: MC-202, TB-303, TR-606, TR-808, CR-8000. (sequencers?) Except for the TB-303, all of these can send and receive clock signals (though not all at the same time). In addition, the TR-909 can sync to DIN Sync *or* MIDI (but cannot convert) and the TR-707 can broadcast both clocks, but cannot be synced to an external signal. The Roland SBX-10 and SBX-80 use both MIDI and DIN Sync. The MSQ-100 and MSQ-700, both intended to be sequencers, are primarily used to convert between MIDI and Sync as well. Korg also used DIN Sync, with a slight difference: Korg sync ran at 48 ppqn. Otherwise, the two standards are completely compatible. The Korg DDM-110 and DDM-220 are both DIN Sync machines, and Korg's KMS-30 can convert between MIDI and Sync, at both 24 ppqn and 48 ppqn rates. With the continued popularity of analogue drum machines and sequencers, particularly Roland ones, there are a number of older and newer tools to convert from MIDI to Sync. The Garfield Dr. Click (?) and Masterbeat will both do it. The Kenton Pro-2 and Pro-4 will both convert MIDI clocks to Sync (among many other features). There also exist retrofits for a number of Sync instruments of varying kinds. Plans for a simple MIDI-Sync convertor can be found at hyperreal.com/machines/categories/do-it-yourself/schematics/mididin.* Trigger and Gate Before the advent of MIDI to convey note information, synthesizers generally used CV/Gate to control each other. The CV (control voltage) was a continuous value to convey pitch (or other information), and the gate was a trigger to communicate when a key is pressed and released. Synthesizers with arpeggiators, and some simple sequencers, often have a simple trigger input. A pulse received would tell the arpeggiator or sequencer to advance one step, playing the next note. Gate and trigger standards from one manufacturer tended to be identical (i.e. a Roland gate signal could also be used to trigger a Roland arpeggiator), but the standards varied from manufacturer to manufacturer. Generally, Roland, Arp, Sequential, and later Korg units were all compatible. Moog instruments used a different kind of trigger altogether. ***[Explain s-trig and v-trig. do old korg and yamaha use diff trigger/gate?] Roland and compatible triggers were simply a positive-going voltage pulse. This effect can sometimes be emulated closely enough by a percussive sound being sent to the trigger input, allowing a vintage arpeggiator or sequencer to be synced to MIDI through the medium of audio. Tape Sync ***[what are the standards anyway?] Some instruments that have tape sync and MIDI, allowing some kind of MIDI sync to tape (i.e. a multitrack recording): TR-909, MSQ-100(?), SBX-10, SBX-80, KMS-30. SMPTE ***[i know very little about smpte] Oddities The Moog Source has both CV/Gate inputs and a DIN Sync input. Apparently, both have to be properly driven to sync the Source. ***[more details please?] The Korg Wavestation has an unusual enough "sync" feature: complex voices can be built out of "wavesequences" -- sequences of internal wavestation sounds. Wavesequences can be synced to MIDI, allowing some sequencer-like uses.