Metropoulos Forum

Playing on my 100 watt tonight, had a noticeable volume drop and the tone started sucking in a big way. Took a look inside and v6 &7 are cherry red. I'm not taking apart tonight, too tired. Have not had any problems w/ it since finishing it last Nov or so. Play it dimed a lot, into a hotplate. Amp has sat for about 3 weeks though, been out of town and stuff. Tubes are those "Mullard" reissue el34's. I'm thinking the tubes just shot craps, need a new set and a rebias, but could something have detached and fried these? Amp is NOT gigged, but I have played it quite loud at band practice. Fuse is not blown, shut it down pretty quick. Tomorrow I'll pull it and check voltages. Any advice? clark

Like I figured, it was thte tubes, the "mullard" reissues. These are total crap. No way these should have gone this fast, at least that one pair. I put hte original e34l's from the kit, though they don't sound as good, at least they work and aren't fried from when I was having arcing in the original tube sockets. eh, screw it, i'm calling tube tramp and getting NOS. Ya get what yoou pay for I guess.

These high plate voltages can be a pain sometimes. After battling with red plating for a while, I ended up just getting a variac to drop B+ to 450 VDC.

The Shuguang EL34 is a nice low cost alternative but NOS is always the way to go IMHO. Tube tramp will sought you out.

So far my Shuguangs are taking the 500v... and liking it.

wdelaney72 wrote:So far my Shuguangs are taking the 500v... and liking it.

Did you try other production tubes at 500 VDC and get red plating? If so, which ones?

Nevermind, I re-read what you posted in the other thread. Sorry.

You ended up biasing your Shugs at 65%? I've had to keep my JJs at about 50% to keep them out of the danger zone (though they only red plate with the volume on 5. Any other setting is fine).

I went w/ NOS Siemens rft. No red nothing and sounds better. clark