Audibly Fast Optoisolators?

[varialbender]

I'm working on a phaser, and I'm hoping to get it going pretty fast. Are there any optoisolators out there that can get going really really fast? Anything in the audio range? How much more expensive are they?

Thanks

[Paul Perry (Frostwave)]

Maybe you could do something wiht the H11F1 or H11F2. they have a led and a fet, the fet works as a resistor. It will certainly be FAST enough..

[Mark Hammer]

The other option is to use transconductance amps, such as found in the Ross and Small Stone.  They have no effective limits on sweep speed.