blew a power tube, can i still use amp

[fourmations]

hi all

had a jam today and smelled burning...

low and behold, one of my power tubes was gone
(the other was glowing big time but not red or anything)
i knocked it off and used another amp

can i still run the amp on one for bedroom volumes?
(there is two power (6L6) and 5 preamp tubes (12ax7)

I will be getting tubes for it, Do you have to bias 6L6's?

cheers

4

[chrisjedijane]

I don't think it'd be such a good idea to use it with one of the power tubes missing - that's if you get any sound out of it at all. I don't know that much about amps, but I can't imagine it'd be good for the amp.

[fourmations]

hi chris (and all)

the amp was still working fine, I was messing around with the settings for different tunes
so I can't say for sure but i think there was a volume drop all right

I didnt actually notice that one blew until i smelled something
and had a look, i turned it off in case the other blew

Im new to valve amps, but i think that the losing one of the power (output) tubes
will result is a lower output but will still work??

Regards

4

[zhivago]

I'd just replace the tubes, to be honest.

valve amps can be very picky sometimes.

I have heard of people taking output tubes out to lower the volume, but that involved amps with 4 output tubes, and they'd take two out (and not any two, there are specific ones they'd take out)

since you're new to tube amps I'd say play it safe...they are not as sturdy as transistor ones are, and sometimes when they break down, the tech bills can be pretty high.

just change the tubes, it doesn't cost nearly as much as what a visit to the tech would cost in the event of the amp breaking down.


better safe than sorry etc.

[chrisjedijane]

yeah, +1 on what zhivago said - for all it would cost you to replace the power tubes it's worth it.

[fourmations]

ok

who's the thicko!!  ME! 

i plugged the amp back in earlier
and the tube is not blown!

I dont know why i thought it was,
perhaps it wasnt glowing as strong as the other one, (Bad bias?)
and i though that it was picking up light off the one beside it
I really dont know, trick of the eye or something?!

The burning smell was probably 25 yrs of dust around the tubes (gotta get the hoover out!)

the thing is that the amp is seriously loud and doesnt get driven at home
so i have never seen the power tubes glow like that before, (under decent load)

I need to get it serviced as there are lots of crackly pots, the fx loop cuts out
and other niggles, i just dont have the cash at the mo,

i want to get tubes, but no-one knows anything about the amp
it was only made for 2 years from 1980-1982

cheers

4

[zhivago]

hey these things happen.....

any tech will be able to tell you what tubes to use...just get a bit of cash together and you wn't be sorry

[blacktiger]

If your tubes were glowing brightly, you may have problems.  There is a phenonenon called "red plating" when the whole tube glows red, which is usually followed by the tube blowing and sometimes taking the output transformer with it.  Get the amp to a tech.  Any amp that's 25 years old will need some service.

[fourmations]

they were orange and didnt seem to be red-plating
it does need a service tough all right,

love the slayer cat! 

4

[RumorsOFsurF]

Aren't tubes supposed to glow orange?

[fourmations]

yep, thats what i meant that they were orange which is okay,

blacktiger was talking about red-plating where the base is overheating
and will glow in a a strong cherry red colour
(never seen it happen but have done a bit of reading!)


Regards

4

[Taylorplayer]

The filiments at the base of the tube should be orange... the plate inside shouldn't have color..

Where in dublin are you fourmations?

[fourmations]

im in rathfarnham

where you?

rgds

4

[Taylorplayer]

just over in lucan... going to check out Damien Rice tomorrow in your neck of the woods.