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In Reply to: Re: plate load-"brilliant" question posted by dave slagle on October 29, 2001 at 14:53:35:
I used an 866A under the cathode in a preamp I was fiddling with a few weeks ago. It looked really cool, but there were problems with noise. I'm not sure if it was from that or something else - it was a new design that I just sort of did for kicks and I've disassembled it since. It only dropped about 10 volts, though.
was it the same 60hz noise tom mentioned from the 5Y3???
Well, there was 60hz hum. Plenty of it. However, I was using SV572-10's as a linestage, so that could have been the cause of that. The reason I lost interest was that there was a ton of higher frequency hash. When I turned on my speakers, there was just solid noise. I don't have a scope, so I couldn't look at. I didn't really ever track down what the problem was. I just unclipped it all and moved on to other things. It looked cool, though - the bright white 572-10's and the blue 866a's (I had them in the supply too).
Reading your other posts now, I did try a hum balance pot on the 866a filament - it helped some, but not enough. I had a huge amount of voltage present on the outputs initially and tweaking the hum pot got it low enough for me to actually turn on my speakers to listen to. Well, I never actually listened to anything through it...
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