New set of valves - help needed please

blueskunk

Hi folks. 

Hope you are all well. 

My my little Laney lc15r recently went dead due to valves being hammered. 

Just got a new full set of valves which arrived today. Can I just replace each one or would this have to be done by a specialist amp dude and biased etc ?

Thanks 

crunchman

From what I can see, it's fixed bias (which means the bias ought to be checked), as opposed to cathode biased, where it kind of self adjusts.

It will almost certainly work without re-biasing.  The main risk is that you could shorten the lifespan of the valves, but it may be cheaper to replace the valves a bit more often than to pay someone else to bias it if you aren't confident doing it yourself.  If it is biased too cold it might not sound great either.

There is a thread about it here:
http://www.thefretboard.co.uk/discussion/24838/replacing-power-valves-in-a-laney-lc15r

ICBM

It depends whether it just died because the valves stopped working (almost certainly only one preamp valve) or whether one power valve failed more dramatically and took out something else - probably the HT fuse, but possibly other things…

When changing preamp valve, only change one at a time. That way you will know if the old one was faulty or whether it can be kept as a spare. When changing power valves, if it's blown the fuse then change both at the same time - even though only one will have failed, the other is probably fairly worn anyway. You can find out which if you want to keep a spare, but you may need more than one fuse to find out if you don't have any other means of testing them.

Maynehead

As long as they're the correct types, it's unlikely to damage the amp if you stick them straight in yourself, unless there's an underlying fault with the amp.