The delay between a control being turned or a key being pressed and hearing the result in the output. Hardware synths have almost zero latency - but many software synths have a lag....
Matrix-6
This synthesizer was based on the popular Matrix line. The Matrix-6 is basically a
stripped down Xpander with a 5-octave, 31-note (C-C) keyboard, which features on and
off velocity, as well as channel aftertouch. It features 6-note polyphony and pitch and
modulation levers (not wheels) to the left of the keyboard. Each voice has two DCOs (as
opposed to the Xpander's VCO), a VCF, three envelope generators (5 stage: Delay,
Attack, Decay, Sustain, Release), two ramp generators (simple envelopes), tracking
(not just for the keyboard but for remapping any modulation source), portamento and
FM controls, three LFOs, and two VCAs. Along with other "Matrix" products from
Oberheim, the Matrix-6 features what Oberheim called, "Matix Modulation System",
which makes for very flexible and powerful modulation programming. With this much
programmability it is unfortunate that the only user interface is a single slider and a
keypad.