Getting a loud buzz from my rack

Terry Sneed · From: Arkansas,

I have a Black Box and an MPX 1 in my 4 space
rack. Didn't have this buzz until I put the mpx 1
in the rack. I've tried it through my Session 400
and my LTD 400 . Either amp I get the loud buzz/hum
I didn't see a place for a ground on the mpx 1 ,
but could have overlooked it. I love the mpx 1
settings, but this buzz/ hum is just too loud for
our Church singings. Can someone give me an
idea on what the problem might be please?
Thanks

Jack Stoner · From: Kansas City, MO

Its most likely a "ground loop" hum from your description. A device's metal mounting touching the metal rack rails can cause this. Isolate (insulate) the MPX 1 from the metal rack rails and see if that takes care of it.

I had a Black Box preamp and it caused ground loop hum no matter what amp it was connected to. I had to lift the AC power ground to eliminate the hum.

George Kimery · From: Limestone, TN, USA

I agree with Jack, sounds like a ground loop. Is the Black Box and the MPX-1 both connected to the metal rack mount rails? You might try putting a three prong to two prong adapter on the MPX-1. Also, isolate one, or both from the metal rack with rubber washers and nylon screws. If all else fails, get an Electro Harmonix Hum De-Bugger. About $120.00 from Musicians Friend but it will make it as quiet as a mouse peeing on a cotton ball.

Terry Sneed · From: Arkansas,

Thanks guys, yes both units are mounted right
on the rack rails. I'll put some rubber washers
between the two. ðŸ‘ðŸ‘

George Kimery · From: Limestone, TN, USA

Just to cover all bases, use nylon bolts too. (10/32). Even if you put rubber washers on both sides, a metal bolt will be touching the edges of the holes in your rack gear and could transfer a ground loop to the rack rails. I don't recall the name, but they make isolation strips to mount your rack gear that isolates the effects from each other. The Hum DeBugger is a last resort, but it is a miracle device for these kinds of problems. I rarely play places that cause a hum problem with my single coil pickups, but the Hum-DeBugger takes care of it. Wouldn't leave home without it.

Terry Sneed · From: Arkansas,

Ok thanks George .

Jim Sliff · From: Lawndale California, USA

One caution about "ground lifts". Disconnecting the ground of one unit is often done indiscriminately. A "ground lift" disconnects ONE grounding source in a unit, because grounds through multiple sources are what cause "loops" and noise.

But you must verify the piece of equipment is still grounded, which is usually through the power cord. If the piece of equipment has NO ground, when you touch it you are providing the path to ground through your body.

I've been seriously shocked a couple of times by stage personnel installing a ground lift on part of my gear without telling me.

Ground lift switches should be used as temporary solutions only, and the wiring, cables or wall plug that's causing the loop corrected permanently.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional

Michael Hartz · From: Decorah, Iowa, USA

I used these humfrees for years, work great

Pete Burak · From: Portland, OR USA

I use a product called "HumX" for ground-loop based noise.
Ken Fox reccomended it many years back.
It works VERY well for most electronic buzz issues.
Here is the company link (sold at most music stores):
http://www.ebtechaudio.com/humxdes.html

Terry Sneed · From: Arkansas,

Pete, I have a Hum X but I've tried it on hums
not as loud as the one I'm getting now, and it
just never worked for me. Michael I may try
those, thanks.

Ken Metcalf · From: San Antonio Texas USA

I had this problem with a rack and ended up having to connect the power amp with Low Z mic cables or TRS type.
I did not have much luck running a rack to a combo amp.
Ended up after trying a number of things getting a more powerful rack amp. Stewart 1.2 to 2-15" speakers.

_________________
MSA 12 String E9th/B6th Universal.
Little Walter PF-89.
Bunch of stomp boxes

Jerald Walthall · From: Arkansas,USA

terry ihave never had a hum you can come get this ss amp. and try it see if it hums but I have sold the spearkers if you have one speaker you could check it. hope things work for you
.

Terry Sneed · From: Arkansas,

Pete, I know for a fact it didn't hum when
you had it in your rack. Because I was there
with you when you was lookin for the settings,
and there was no hum at all. I'm just going to
try the different suggestions above. Thanks
Pete.

Ken, I've used a black box and a mpx 110 in
my rack case for years and never had a problem
with this much hum. Maybe it's because the mpx
1 is a larger unit, don't know.

Jack Stoner · From: Kansas City, MO

Could also be a bad cable. Replace the cables with new/known good cables to see if that helps.

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

Jack Stoner · From: Kansas City, MO

I used a HumX and it took care of the ground loop hum I had with a Black Box.

George Kimery · From: Limestone, TN, USA

The Hum-X just deals with ground loops, rigbt? I have 3 places that I play that I get a bad hum. I assumed it was my single coil pickup not liking the fluorescent light ballasts and/or the light dimmers.

I set-up next to a Crate PA and the hum was so bad, I had to move to the other side of the stage. I got the Electro-Harmonix Hum De-bugger and no more hum at these venues.Should the Hum-Debugger also take care of ground loop hum?

Jack Stoner · From: Kansas City, MO

From what I "think" their web says about the Hum Debugger its not for Ground Loop Hums, although it may also fix that. It sounds more like non-ground loop hum/noise problems is what its designed for. For example hum from a single coil pickup. I may be wrong but what I "think" they are saying on the web site.

Terry Sneed · From: Arkansas,

Well thanks guys for yalls suggestions , I finally
found something that worked. I think few of y'all
mentioned the ground, I went to Walmart and
bought a 2 prong to 3 prong adapter, and it done
the trick. Almost quiet as a mouse. Thanks again
guys !!ðŸ‘ðŸ‘

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