#1
Hi, i have just fitted new tubes on my laney lc15. something doesn't seem right. at first i got no sound so i made sure the valves were in fully and after that it seemed to work but the sound is odd. one of the preamp tubes is lighting up which i thought wasn't supposed to happen?

also i have been told this amp needs biasing by one person on the duncan forums but i can't find anyway to bias the tubes. please help
#2
get a professional to do the biasing, don't turn it on and play through it by the way. Unless you know your stuff when it comes to amp electronics, you will get yourself killed.

take my advice
#3
Most amps have to be biased by a tech. They do have bias meters, but few amps are able to be biased by an untrained normal person.
#4
how is an amp biased? there is supposed to be a hole in the chassis near the tubes for biasing on this amp but i cannot see it. some people say it doesn;t even need biasing but one guy told me it does.

as for just 1 of the 3 preamp tubes lighting up, whats that about?
#5
All the tubes do light up. That's the heater. The LC15 has a trim pot for bias, but it doesn't have anything to do with the pre-amp tubes. I have an LC15 and I had a problem with one tube not lighting up. I had to take it apart and bend a metal tab in the socket to get it to make contact with the tube pin. I've also got some other problems with mine. It makes bad noises when playing before it heats up. And it's hotter than a mofo when running. So I've set it aside until I can do a complete teardown and checkout.

It's a great sounding amp though. I like it better then my Fender Pro Jr when it's working.
#6
Quote by fly135
All the tubes do light up. That's the heater. The LC15 has a trim pot for bias, but it doesn't have anything to do with the pre-amp tubes. I have an LC15 and I had a problem with one tube not lighting up. I had to take it apart and bend a metal tab in the socket to get it to make contact with the tube pin. I've also got some other problems with mine. It makes bad noises when playing before it heats up. And it's hotter than a mofo when running. So I've set it aside until I can do a complete teardown and checkout.

It's a great sounding amp though. I like it better then my Fender Pro Jr when it's working.



i guess i will just take i to a tech and see what he thinks. thanks