Hum on Custom 50

[runr53]

I just received a PRS Custom 50 amp with matching Stealth 2x12 cab. I unboxed it, set it up and was met with a pretty consistent hum. It hummed with both Masters down to 0 and on both channels. When I did play through it I couldn't get either channel to go into a drive sound. Whether I dimed the masters or dimed the channel volumes or somewhere in between. The sound sounded pretty clean. I made sure I added guitar volume and it got loud, but no crunch.

I am hoping it is an easy fix, but any suggestions? I have contacted the dealer I got it from, but it was mail-order. BTW, I've dealt with these guys for years and they are great.

Also, I don't want to do anything that will void the warranty.

The PRS website is not very helpful as far as tech notes or manuals for the amplifiers and no manual came with this amp. There is a tube chart on the inside of the head and that is about all.

Thanks, in advance, jlg

 

[Bluesboy998]

Sounds like a bad preamp tube,It happens.The preamp tubes are 12 ax7 there are three in a row, take off the covers and with the amp on and plugged into speaker ,Take the amp off standby and tap each tube with a pencil,if it's a bad tube it will make noise .Also check power tubes they sometimes come loose in shipping , I hope this helps .

 

[runr53]

Thanks. Yeah. I started to figure that might be it. In the morning I'm going to go through them with some new JJ's I just got for my Marshall. One thing I noticed, if I plug a cable in only one side of the loop it quiets down quite a bit. So I am going to check that one too. Although I don't have a 12dw7 in my little stash of preamp tubes.