Marshall JCM2000 DSL50 hum

[titan7]

Just wondering what causes the slight hum and vibration if you put you hand on top of the head when it's on? It does not come throught the speakers. I just noticed it was more pronounced on the DSL 50 compared to the DSL 100.


thanks!

[Enzo]

The power transformer is a large hunk of iron with wires wrapped around it - more or less - inside the thing. While it is designed to transform power from one level to another, it can't help but to act like a large electromagnet to some extent. The 60Hz current flowing through it causes this vibration.

One amp might vibrate more than another just from natural variations. How tight the layers of iron are compressed, how solid is the chassis it is bolted to, etc. I wouldn't say that one model is more likely to vibrate than another. FInd another 100 and 50 and it might be the other way around.

[titan7]

Ok, some people were telling me that if there is a hum or vibration that there is a grounding issue and I should have a tech look at it?

[Enzo]

I'd say it is perfectly normal for some vibration in a power transformer. Unless this is affecting the operation of the amp, I'd say it is not a problem.

[titan7]

Thanks, I call my tech also, he said normal and not to worry so much!

[titan7]

Okay, I turned it on again and in a quiet room you can hear it hum from 5 feet away. Both my DSL 50s do this, one is a little quieter than the other. Do you think I should make sure the tranny screws are tight? Again the fuction of th amp is perfect. I am assuming it's not a grounding issue??

Perhaps I will just pick up some mercury trannys,

[Jasonp]

I've owned a couple DSL's and they all do that. Actually most all tubes amps do this that I've owned. Some are quieter the others.

[Rbardell]

DSL 50 Hum

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?