DSL40C hum

[MarshallDog]

But if you unplug everything, and the hum goes away, how can that be the amp?

I would be looking at the guitar, the cables, and any FX you might be using first...

Have you tried a different guitar? Different cable?

My Jubilee did the same thing when switched to channel 2 only. At a low volume it was fine but simply turn up the volume with a guitar plugged in OR nothing plugged in and it would start going into a strange hum. Changed V1 and its all better. Must have something to do with noise and the tube going microphonic or something Its worth a try.

 

[Bownse]

To address the obvious:

I can dial in/out hum by using the inverse of volume and gain. Crank up the volume and crank down the gain or there will be hum. Crank down the volume and the gain can go up more.

 

[rmlevasseur]

Even a poor tech would be able to detect a bad tube. if the amp was working fine when it left the shop, but hums now, you are likely looking at environmental factors. Sitting too close to my computer/monitor will cause noise.

Interesting he changed your jack though. I kinda doubt the DSL will be a collectors item but I wouldn't want anybody making such "improvements" absent an actual issue. Not necessarily slamming your tech, but I am wondering if the guy just found a reason to bill you.

 

[Micky]

The DSL input sits on a board, that has a jumper that connects to the motherboard.

Soldering the input board directly will eliminate loose jumper connection problems.

In my DSL5c, I had a problem with the FX loop jumper connections.

 

[Havoc]

But if you unplug everything, and the hum goes away, how can that be the amp?

I would be looking at the guitar, the cables, and any FX you might be using first...

Have you tried a different guitar? Different cable?

I have tried 2 different guitars, but not different cables, effects.

My thoughts were that if it were something out in front then the hum should be on the clean channel as well.

 

[Micky]

With the gain up on the Ultra Channel, it would be FAR more noticeable...

 

[Jethro Rocker]

To address the obvious:

I can dial in/out hum by using the inverse of volume and gain. Crank up the volume and crank down the gain or there will be hum. Crank down the volume and the gain can go up more.

Are you having the same issue as you are not the OP.? I can try turning mine up with no source and see. Again, I think it's not amp related. Plug a cord only in with no guitar, taking care not to letvthe tip touch anything. Turn up amp a bit and shake the cord. You'll hear all kinds of interesting things. The slightest thing like computer monitor, noisy AC etc will obviously be amplified greatly as gain and volume is cranked on ultra channel.

 

[MarshallDog]

To address the obvious:

I can dial in/out hum by using the inverse of volume and gain. Crank up the volume and crank down the gain or there will be hum. Crank down the volume and the gain can go up more.

It's the same thing I had with my amp as stated several times before...get some new preamp tubes, I bet you a 6 pack of your favorite beer it fixes it!

 

[Havoc]

It's the same thing I had with my amp as stated several times before...get some new preamp tubes, I bet you a 6 pack of your favorite beer it fixes it!

I'm going to try the pre amp tubes, any suggestions?

 

[Bownse]

It's the same thing I had with my amp as stated several times before...get some new preamp tubes, I bet you a 6 pack of your favorite beer it fixes it!

I'm not the OP. I was giving an example of one way to address hum (dial in gain/volume to dial out hum).

Mine just came back from a tune up with ALL tubes tested as well as a rebias and all connectors, sockets, and pots cleaned up as part of the bench fee.

 

[MarshallDog]

I'm not the OP. I was giving an example of one way to address hum (dial in gain/volume to dial out hum).

Mine just came back from a tune up with ALL tubes tested as well as a rebias and all connectors, sockets, and pots cleaned up as part of the bench fee.

Oh, I see...