A bad case Of Bias,or a hot time in the old amp last night

[haikublues]

Last night I made a stupid mistake in changing the (2) Chinese 6L6 output tubes for some RCA metal ones, without 1st biasing the amp. 1st I smelled burning then I saw a trace of smoke, I quickly unplugged the amp and put the old tubes back in. At this point neither of the fuses are blown,the light comes on for the front panel and all the tubes are functioning normally (there are (4) 12AX7's in addition to the 6L6's. But there is no sound, I checked the speakers by themselves and they work fine. When I went into the amp the only parts that appeared burn't were (1) 2.2K resistor on each output socket which I replaced with new ones but still no sound. Any ideas where to look next? Any information anybody can provide is gratly appreciated.
Thanks,
haikublues

[MWJB]

Which pin were the 2.2K's connected to?

Are there any resistors feeding pin 4, if so, how are these measuring up?

[52 Bill]

Which pin were the 2.2K's connected to?

Are there any resistors feeding pin 4, if so, how are these measuring up?

Yes, as MWJB asks, how do the screen grid resistors measure? Anything may look fine, but metering them is the only real test.

What about the voltages on the output tubes?

[Enzo]

And you might look up the specs on the old metal 6L6. They are plain old 6L6, no 6L6G or any other added letters. The metal ones look cool, but are not well thought of for audio. The original metal 6L6 has a much lower voltage and power rating than the glass ones.

[Gtr_tech]

Right....the original metal 6L6 had like a 19w plate IIRC. Thats between a 6V6 and a modern 6L6. You can't see through the metal envelope to tell when they're screaming for help either.

[Diablo]

I've got a pile of 6L6 tubes, so I'm wondering why you can't use them for audio or a guitar amp if you can bias them down below the 19 watt rating? I assume the metal jacket over the tube acts like an insulator and makes the tube run hotter than one without the metal jacket. Does all this have any sonic effect?

[Enzo]

They were designed as radar tubes if I recall correctly - always doubtful. They tend to be more microphonic than the more modern versions. Use them within their specs and there is no reason they shouldn;t work, but like the man says, you can't see inside them.

19w 360v I think

The metal jacket will radiate heat as well as a glass jacket.

[Steve Conner]

The metal 6L6 is probably better suited to a 6V6 amp nowadays. I've only ever seen two of them, and they were unusable because of really bad grid current, which made me think they had gas.

[haikublues]

Thank you all for your comments, I would have responded sooner but I just picked up 2 art commissions (although irrelevant to the discussion,they pay the bills). The 2.2 resistors are on pins 5 and 6. there is is also a 470 ohm on pins 1 and 4. I'm attaching a copy of the schematic as well.
Thanks again,
haikublues

[MWJB]

So how do the 470s measure up, what's your voltage at pin 4?