Carverfest Amp Tube Supernova

It was part of a matched quad....doh!

Martin, I'd get my money back for those tubes, they clearly weren't matched very well since you didn't light all of them up at the same time

Seriously, it could be a problem in your amp or more realistically cheap tubes. I'm betting the latter. I'll probably spend a month with mine, if they last that long, before I try swapping them out.

One of these days I am going to get into some serious tube swapping, just not yet.

I had one blow last week in the same far right position. That's where the DC Restorer circuit is located...coincidence?

Maybe only coincidence. Has anyone else blown a tube in that position?

Maybe only coincidence. Has anyone else blown a tube in that position?

119.8 volts on the input gives me 358 volts DC at the tube circuit. I think I had the MM set to AC the other day when I got 470~

It's a shitty little Craftsman MM....

After a reflow and reseating the tube sockets, it seems to be working fine (for now).

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I'm tempted to buy better sockets and get rid of these.
The tube that went off is running 40 degrees cooler than the other three.
Not sure if that's relevant.

Gary: 120AC vs 440VDC B+

"Has anyone else blown a tube in that position?'

That's what she said!


Sorry; but this problem seems to need a LOT of comic relief......

Gary: 120AC vs 440VDC B+

Then how come I have 358 volts on mine?

I measured it with the tubes in.
Playing music on the DQ-8s, moderate level.

I think Mike got 20V less than me FWIW.

Did you measure tubes out?
Or at a different point?

So I will ask bob in Florida next month for maybe a new / update design using a transformer that is more to the tubes 300 plus volts that they are designEd for. How much of a change could that be in the parts list?

I measured it with the tubes in.
Playing music on the DQ-8s, moderate level.

I think Mike got 20V less than me FWIW.

Did you measure tubes out?
Or at a different point?

Tubes in playing music. 458 at the big cap, 348 at the orange wire point on the tube pin.

118ac
425dc cap
353dc pin 9
411dc pin 7
13 pin 3
6.1 ac heaters

Hooked to amazing ribbons playing moderate level stereo 20WPC mode.

Mullard NOS and new versions are the ONLY 6BQ5's I know of that will handle 550v.....
Martin- if you check that tube on a tube tester- I bet it is still good- it was an over voltage condition that caused it to glow.

Cheers!~

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voltages on mine.

line 117v ac
B+= 410v

output tube
pin7= 407v
pin 9/orange= 355v
pin 2 both in spec

input tube
pin 6= 262v
pin 7 83v
pin 8 85v
pin 3 .349v

bias 13.25


both amps check about the same.
the B+ and a the 3.9K drop resistor check out at the same voltages

martin & gary, I blew that same tube before leaving carverfest & just shut it down & unhooked everything & packed it up! when I got home found out my ct-23 was dead!! victim of that tube!! so there was no way I was gonna fire it up till I got new tubes!! mark suggested that I try some TAD tubes!! they are working & sounding great but only have about 20 hours on them so will give them some time to settle in. I also bought some cryoed mullards that I have yet to try!! I would never run that amp until you get new ones!! just my 02!!