DSL50 Hum HELP

[Rbardell]

Hey guys, new to this website but have learned alot. I have a DSL50 that I just retubed becuase there was a hum in the clean channel that starts out fairly quiet, if it's even there at all, to a loud "ground" hum that sounds like my guitar cable is laying on the floor..grounded. It takes about 10 - 15 minutes to peak out really noticably. The High Gain channel, it is non-existent. If I unplug the cord from the front of the amp...hum is GONE!!!, plug just the cable in, not touching anything with the other end...Hum back. I just replaced the Tubes with JJ EL84L and biased both tubes to 43.7. I was told that between 40 and 45 was right for the DSL 50.

Any suggestions about the hum?

[bnwitt]

Did you change the preamp tubes as well as the power tubes? If not, did you try switching V1 and V2 to see if the hum changes channels?

[Rbardell]

Yes I changed all the tubes. The hum was there before I changed tubes as well. I guess it, "just sounds better" through the new tubes. Changed V1, V2 no change.

[Fragger]

Are you using a speaker cable or a instrument cable?

Is there fluorescent lighting in the room directly below the cable?

[Rbardell]

A real speaker cable and I've had in various rooms with all different types of lighting, the hum is there as long as something is plugged in to the input jack.

Thanks everyone for the replies!!

[Fragger]

Speaker cables aren`t shielded and can be a source of hum.

Do you have an instrument cable to try in the input jack?

[Fragger]

Here is a thread addressing the problem I`m trying to eliminate.

http://www.thegearpage.net/board/archive/index.php/t-9431.html