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previous: Jim S. Hi Guys, first time poster here, bu... -- 4/7/2000 12:21 AM

Re: Plate voltage on BFD

4/7/2000 2:39 AM
Matt	Re: Plate voltage on BFD Is that plate current or cathode current. If plate, I'd say it's a bit warm. My BFD puts out about 430 V with a GZ34. I have about 118 V at the wall. I bias it rather hot at 30 mA cathode current. It hasn't blown any tubes yet and it's on at least an hour a day. Anyway I shoot for 11-12 W dissipation on the 6V6s. I'm mainly surprised that your supply is that high with a 5Y3. The caps are probably rated at 450 or 475 and are certainly seeing peeks above that at startup. Personally, mine's a bedroom amp, so I'm not too concerned about running it hot and seeing voltages close to yours, but I do plan on building one of those "vintage power" devices outlined at geofex.com for a couple of my other amps. Basically, with a 6 or 12 V transformer of sufficient current, you can knock the voltage from the wall down that many volts and be closer to what the amps originally saw in use. Cheers, Matt

4/7/2000 2:39 AM

Matt

Re: Plate voltage on BFD

Is that plate current or cathode current. If plate, I'd say it's a bit warm. My BFD puts out about 430 V with a GZ34. I have about 118 V at the wall. I bias it rather hot at 30 mA cathode current. It hasn't blown any tubes yet and it's on at least an hour a day. Anyway I shoot for 11-12 W dissipation on the 6V6s.

I'm mainly surprised that your supply is that high with a 5Y3. The caps are probably rated at 450 or 475 and are certainly seeing peeks above that at startup. Personally, mine's a bedroom amp, so I'm not too concerned about running it hot and seeing voltages close to yours, but I do plan on building one of those "vintage power" devices outlined at geofex.com for a couple of my other amps. Basically, with a 6 or 12 V transformer of sufficient current, you can knock the voltage from the wall down that many volts and be closer to what the amps originally saw in use.

Cheers,
Matt

Replies:

JCS Thanks for the reply Matt. Yes that... -- 4/7/2000 8:36 PM