Firing up old tube amps. Should I worry?

4 x EL-34 per channel, driven by a 6AU6 and a 5687.

Just take the equipment out in the driveway, put it up on cinder blocks, connect to the oldest and funkiest speakers you have, wear safety glasses, and have a non-liquid CO2 fire extinguisher ready to hand. No worries...

If you wait until the 4th of July to do this, you get extra credit for any sparks which may be produced during the process.

For a bit of a preview, go to YouTube and run a search for *4000W Tesla coil test" or "Vanguard (Flopnik)."

They just may not work...

Best advice is to inspect them for bulges or leaks, then use a variac to raise the voltage slowly and give the capacitors time to re-form.

They won't have bulges if they've been sitting.

The traditional means for reforming/testing the filter caps is to remove all the tubes, and then put an incandescent light bulb of about 40-50 watts in series with the power plug. If the caps want to draw current (and thus in time overheat, which is Bad) they'll light up the bulb. This prevents the caps being damaged. When the bulb does not light, you're all set to go.

Otherwise you do run the risk of the caps failing, and they can take out the power transformer with them.


So don't run the amps unless you've done something about this!