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Q. How do sequencers work?

By Tom Flint
Published July 2001

I would like to know how sequencers actually work. I am considering buying one, but am not sure which to go for. Initially I was thinking of buying the Yamaha QY70 (my budget is a bit restricted and I also don't have much space). After trying it out in a shop, I was happy that it offered the functionality but was not too impressed with the sounds. I do, however, like the sounds Roland synths have to offer (they sound warmer and more realistic).

My question is: can the QY70 be used as a sequencer for an external sound module (or a synth keyboard such as the Roland RS5)? If so, does that mean that the sounds coming from the module are recorded/sampled by the sequencer, or does the sequencer simply trigger them from the sound module? My concern is that if the sequencer samples the sounds, they may lose sound quality.

George Tsikos

Assistant Editor Tom Flint replies: A sequencer in its most basic form is a memory bank which stores note information as MIDI data. It's a bit like a multitrack recorder, in that it is usually used to record music as separate tracks, except that a multitrack recorder will record audio rather than MIDI data.

Older hardware sequencers like the Roland MC50, which I still use to this day, have no internal sound module or preset rhythm patterns. They simply remember the note information sent to them from a connected keyboard or MIDI control device. This MIDI information will usually be note pitch, length, velocity, and any other controller information delivered from a modulation wheel or real‑time controller knob. When the sequence is replayed, the sequencer sends the recorded note data back out to the keyboard or sound module and will, in effect, play back the performance. The beauty of MIDI is that you can always change the sounds, shift the note data, and perform all manner of edits to your music in a way that is not possible with recorded audio.

The QY70 certainly functions as a sequencer that can control other devices, but it also has its own internal sound‑generating module and rhythm generator. You should be able to plug any other sound module, regardless of make, into the QY70 and control that device's sounds over MIDI. The audio of that device will still come from its own audio outputs, because only note information is stored in the QY, so you will need to route the sound module's audio outs to your amp and mixer before you can hear the result. This is how you would use the Roland module.

Concerning the QY's own sound set, it's worth making the point that XG sounds are extremely editable and can be controlled and modulated in a great number of ways using MIDI control data. Bearing this in mind, you might find that the sound generator on the QY offers you much more than its preset sounds first suggest.

Although storing MIDI information requires only a fraction of the memory that would be needed to record audio, sooner or later you'll fill up the memory of the QY70. To relieve this problem, Yamaha have provided Mac/PC storage utility software so you can move QY MIDI data to a computer's hard drive. For hooking up to a computer, the QY has a 'To Host' output connector, which should connect to the computer's modem or printer port. If you don't have a computer in your studio to do this, you might find the QY a little restrictive, and it might, in that case, be worth looking for a sequencer with a floppy drive or other removable storage medium.

Yamaha have a manual library on their web site, where you should be able to access the PDF manual for the QY70: