arc vt150se

Wonderful amps.

You should try to isolate the problem. Remove the Pre amp to make sure it's not that. Then cables and finally tubes. It could be a dry joint or anything. I wouldn't poke around inside though. Death awaits you if you don't know what you are doing. A lot of stored power in the power supply.

If this fails to find the problem send it back to ARC. It could probably do with a service anyway. Some new coupling caps would bring huge sonic joy I am sure after many years of hot use. One of my favourite amps of all time. Epic on a Magnepan or ML CLS

What about when there is no preamp connected to it?
Will it still emit that crackling noise ?
There might be a faint hum when nothing's connected but it will be a safe thing to try

>> Not a good idea to poke around inside,the voltage can be lethal. <<

High voltage will not hurt you, high amperage will drop you dead...

-RW-

Have you tried switching the tubes yet[one set at a time]?Could simply be a bad tube or dirty tube socket.You can clean the sockets with Deoxit and a pipe cleaner,be sure to unplug them the night before so they can discharge.Also you can try wiggling the speaker cables and interconnects to check for a bad connection.If there is an internal part beginning to fail,these remedies of course won't work and it's time for the repair shop.Not a good idea to poke around inside,the voltage can be lethal.