Mark I Reissue: Hum noise and Effects Loop Question

[enigma]

This is my third Mark I Reissue though this is a head version. Two minor issues I'm having with it that I've never encountered with other Mark I combos:
1) There is an annoying hum when it's turned on. What could be the cause?;
2) When I use delay through the effects loop the tone sounds like somebody threw a blanket over the speakers.

Anyone have suggestions, thoughts or solutions? Thanks.

 

[Guitar GeeK]

For your first question, it sounds like it could be from the plug. If you get an Ebtech Hum X (a ground loop eliminator), you can probibly get rid of the hum. On the effects loop thing, I have no idea how an effects loop opperates, so my only advice is to plug it into the input for your guitar.

 

[enigma]

I need to add that the hum is much more pronounced on the Vol 1 knob. When the guitar is plugged into Input 2 and only Vol 2 works the hum is very low.

 

[Ultramog]

I have the same hum situation on my M1RI -- louder on input 1 also. Funny thing is it just started about a week ago. Also the Uninterruptible Power Supply its plugged into sometimes starts beeping until I go to standby or 60 watts for a few seconds. Then I can go back to 100 watts without the beep. WTF? Weirdness...

Edited to Add: Just noticed your sig; I'm in North Jersey, and you may be too. Is somebody dumping something in the power grid?

 

[Ultramog]

On #2: I've tried a good reverb and a Full-tone trem through the loop and it seems to muck up all the relative values I've staked out in 6 months of tweaking the gains & stack. A blanket thrown over them is about right. I've thought that maybe you need to crank the loop gain above unity to recapture some tone. Similar to the idea of connecting a short cable there and boosting for an added gain stage. But I finally feel like I can goose the little guy in the right direction and don't want to go there...

 

[enigma]

ultramog, my other amps don't make a hum as loud as the Mark I. Interestingly enough the added "dirt" in the loop with my delay actually produces a very nice, overdriven tone! :roll: