Friday, August 13, 2004

DIY Amp decision -- at last!

I'm going to build a version of the John Linsley Hood class A amplifier. I've kicked around the idea of building one of Nelson Pass's Zen amps. But the glowing descriptions of the JLH amp over at Geoff Moss's Class A Amplifier Site, I'm going with the updated, 2-rail version. (See figure 3 here.

I'm going to build it point to point, or at least try to. I still remember which end of the soldering iron is hot, but I haven't tried building anything without so much as a piece of vector board in a long while.

Using the Duncan Amp Tools PSU Designer I've settled on using a single raw supply which should provide a bit over +/- 19 volts DC. A 750VA transformer should do the job for both channels. After the rectifier bridges (one each for positive and negative rails), I'm going to use an LC-RC filter.

According to the sim, I can expect around 20mV of hum, buzz and general nastiness. Therefore, I'll use a capacitance multiplier circuit to further quiet down the rails. There will be a pair of these (+/-) per channel to give a modicum of inter-channel isolation.

Now... where do I get some big, honkin' heatsinks?

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