GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Melquiades Amplifier
In the Thread: A different breed of 6C33C amplifier.

Post Subject: Fuses on the tubes save the day.Posted by KOTriode on: 10/5/2011

Last weekend, just for fun, I brought the amp and preamp to the 2011 Burning Amp in San Francisco. On the first speakers, the Audio Kinesis, I let the heater warmup for about 15 min, and then switched on the power, the amp was fine, we played for about 1/2 hour and stopped. About couple hours later we wanted to try on the Field Coil Lowther, I plugged the amp and warmed up the heater, a friend was so excited and ask me to skip the heating period and turn on the power. So I did, the heater was probably warmed up less than 2 minutes. It start to play fine for about 5 minutes, and the tube was biased at 180ma, about 3 minutes later, the left channel pop the 250ma fused I installed at the plate, then 2 minutes later, the right amp fuse blown. I thought, Romy was right about heating this tube for an hour before playing. But 60W after 2 min, I probably wont try that!
When I got home, I installed new fuses, the amp worked fine. Later in the evening, I turned on the amp again and listen to music. When I reached to grab the volume pot on the 6C33C preamp, my right hand sleeve got caught wit the tube and knock the preamp tube out of the socket (while music was playing), the right speaker make a not so loud noise as someone would expect when pulling a preamp output tube. What happened was that the 250ma fuse in the pamp was blown when the preamp tube jumped out of the socket.
The 250ma fuse probably did save the tubes and speaker on those two occasions.

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