Happy New Year!
Just found the manual and although there is only a block diagram it does have a tech description of its operation.The VCA uses switching devices operating at 250khz which are pulse width modulated to control gain..The pwm is proportional to the control voltage.As the input signal level increases the control voltage willalso increase proportionally. this causes the pulse width to decrease and reduces the gain of the vca.
quickly switching the FET from "off" to "more-on" by varying the pulse-width
Quotequickly switching the FET from "off" to "more-on" by varying the pulse-widthI thought the FET is actually switched on or off. The pulse width just determines how long it on & how long its off. There is no grey area the FET is completely chopping bits out of the signal, but at a much higher than audio frequency. This is why with a bit of heavy filtering you can`t hear it.
the quotes are by clicking on the quote button up top in the post window, typing or pasting what you want quoted, and then clicking on the quote button again.once you see what it puts in when you click the quote button (open and close), you can just type that in yourself, if you'd like =)ju
Zmix said - PULSE WIDTH MODULATOR Using Pulse-Width Modulation (PWM) to control an FET is what Crane Song uses in both the STC-8 and Trakker. The technology has been around for about 20 years, having been used by several companies, including EMT. The Pye compressor works the same way, I believe, and they are at least 30 years old . . . . MXR's ROCK! Especially drum/percussion sub-grps . . . . but Sssh! Don't tell everyone, or they will become outragiously expensive like everything else! Andy P