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previous: Chris Harden Ray,I've checked ou... -- 7/9/2000 2:49 PM View Thread

Re: Power Drive

7/9/2000 8:45 PM
Ray Ivers
Re: Power Drive
The MOSFET source follower should work fine. Any follower has 100 percent AC and DC feedback, which should result in plenty of DC bias stability. I don't know if you subscribe to Glass Audio magazine , but the latest issue has an old Norman Crowhurst article with a grid-current curve (5881?) that goes up to 30 mA at +50 volts grid drive (1.5 watts grid drive - no 12AX7's here).  
My amp design has one op-amp, and a few FET's, too. The op-amp is there because absolutely nothing else will achieve what I want, and the high-voltage FET's are there because they are quiet with headroom equivalent to a tube stage. The only problem I have with op-amps is when they're used for any old gain-stage application; it's easy to forget that when an op-amp is used, you've just added 15 to 50 components to your signal chain.  

Chris Harden When I started building the amp, I ... -- 7/9/2000 9:36 PM