Tubes for BAT VK60. Need help

You can get those 6c33 tubes from Parts Connexion for $27, or from tubestore.com for a bit more. I believe they all come from the same Ulyanov factory regardless of distributor. As remarked by jfrech, in the BAT they lose their punch after about 1200 hours (1800 hours with Pearl Tube Coolers). About 25% of them eventually ARC out (loud popping sound followed by hum), so buy a spare or two. After sanding the pins, try Walker SST silver paste. I use EH 6SN7s in my VK75SE and they hold up well and sound fine.

Chris at Parts Connexion stated to me that upon request he will test each 6C33C and offer a 90-day warranty.

After many retubings of 6C33Cs in the VK75SE without Pearl Tube coolers, I noted (subjectively) about a 50% extension in tube life with the Coolers. I now use them everywhere, particularly with hot-running & valuable 6H30-DR input tubes. However I don't think the Pearl Coolers extend tube life 2x-5x as claimed.

BTW I've found that when retubing 6C33Cs the occasional new output tube fails to bias up. This is usually remedied by swapping output tubes around. I've become superstitious since the time I had two output tubes on one channel arc out simultaneously during first time start-up. Since then I replace output tubes one at a time and turn up the unit for a couple of minutes before powering down and moving to the next tube. BAT recommended to me that output tubes should be discarded after two arcs-- and power output is reduced each time a tube arcs. Apparently the default operation mode of these tubes after arcing was engineered for those MIGs...

Parts Connexion has the Pearl Coolers or you can get them directly from Pearl. For the hot power tubes, make sure you get the 3" tall Coolers with the red silicone O-rings. The black rubber rings dry out and break after awhile.

The Pearl Coolers do help with microphonics. The ones designed for small signal tubes include a carbon fiber mesh that slips between the tube & the vaned metal cooler.

Regarding choice of taps, with the VK60 or VK75 you can try using different taps for t & w. I found my 8R Merlins had a sweeter treble and better bass control with t on the mid tap & w on the high tap. Just couldn't get the best of both worlds without splitting the taps.