valve amp problem

My amp an emille 6550 integrated, has lost sound on the left channel. I have checked the speakers and sources and it is definately the left channel of the amp. Prior to losing the channel, there was a loss of sound at low volumes.

The amp currentley has four Brimar 12at7's, four calvertron electron 6350's and four svetlana 6550c's

I checked the bias of the valves and from left to right, the first was off the scale to the left and there was a pop through the speakers when putting the bias swith to that valve. Two and four were at the end of the scale to the right. Number three was ok and could be adjusted. I tried number three valve in another socket and it could not be biased which makes me think it isn't the valves. However, I no nothing about valve amps so please bear with me.

I am right in thinking its something more serious than a valve replacement?

 

It sounds like it. Did you smell anything? Have you had a look inside (not powered!) There are some DIY diagnostic types on the tube forum at http://audiokarma.org/forums/index.php.

 

No smells and if was quite happily playing on one channel. I haven't looked inside as I wouldn't have a clue whats what. Thanks for the link.

 

You might be able to spot something like a burnt resistor, enough to make your decision whether you need technical help.

 

Have you tried swapping the pre-amp tubes over, it sounds like it could be a problem there

 

if you've not replaced the valves in the last year ....they will be about due ...you need to consider them as consumables...It wont do any harm to get a replacment set then use the used ones as drop in replacements if one dies...

 

Whilst I am happy to replace the valves, what I can't understand is why I can still bias the valve in socket three and yet even putting this valve in another socket will not allow that socket to be biased. I am assuming that it is the 6350 valves that are biased as they are closest to the screws.

 

theres no telling whats happened to the valve .....but the point I was making was that valves do die [regularly]...so you need a few spares of each type.

if you contact hotroxuk [there my local supplier] they will be able to test any dodgey valves...though you have Watford valves local to you ?

http://www.watfordvalves.com/aboutus.asp

I'd be very surprised if they could not help.