#1
I made a thread recently trying to answer one question and ended up with a big problem. I have a Vox AC15C1 amp. My questions are:

1.) Are amps in general supposed to hum?

2.) How do I determine if it is a ground loop hum?

Turning down the volume on my guitar gets rid of the hum. Responses appreciated.

EDIT:

I obviously don't know much (read as anything) about ground loop hum or amplifier hum in general, but I'm desperately trying to eliminate it. I'm trying to establish whether a noise gate will solve my problem (I don't think it will as I don't have an effects loop) and if not what I need. I was directed to this:

http://www.musiciansfriend.com/guitars/ebtech-hum-x-hum-exterminator/150452000000000

Should this get rid of the constant hum of my amp?
Last edited by Born Headless at Feb 5, 2012,
#2
If you are playing like a lead channel with gain then yea, the amp is going to hum a little and thats fine. When you turn the amp up thats just what it does. As for the second one i'm not sure how you determine if it is ground loop hum but the Hum X or whatever that thing is called is supposed to eliminate it. I've never tried one myself so I wouldn't know if it works or not..
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#3
Hmm, I'm just trying to get a blunt answer from someone knowledgeable on such things before I make a purchase. I don't care what the hum is. I know it's not the guitar as it hums on all guitars and the louder the amp is the louder the hum is. I don't have an effects loop so I can't put in a noise gate. So I was considering buying this Hum X which is supposed to eliminate ground loop hum. I know my humming isn't due to tubes or my guitar so does that narrow it down to ground loop hum? Are all humming issues with new amps due to ground loop hum? I'd like to know before I buy this thing.

EDIT: It's not feedback and it's not obnoxiously loud humming, just a constant low hum. Are amps supposed to hum a little just from being on and so loud? And either way will the Hum X ground loop thing fix it?
Last edited by Born Headless at Feb 6, 2012,
#5
Yes, almost all amps have a bit of background hum.
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#6
You will get hum on that amp regardless but it shouldnt be annoyingly loud. If its really loud try to move the amp to a different outlet in your house. make sure there are no other electrical devices connected to the same circuit. if you notice any change in the hum when doing this you may benifit from a HumX
#7
Thank you for the responses! Well here is the deal: The hum is not that bad. It's not like feedback, it's not obnoxiously loud. It's just a constant low buzz, really not that bad. That being said, it's kind of annoying to have it anyways. I'd prefer to sound more professional and have it dead silent in between notes/songs/anything. Unfortunately, I don't know how to fix this. I've figured out a noise gate won't work as I have no effects loop and putting it between the guitar and amp will only quiet my guitar, not the amp. And the HumX won't work as apparently the hum I hear is normal and not a ground loop hum. Any alternatives?
#8
Most amps tend to be a bit light on the power supply filtering. I often end up increasing it a bit. You are talking about modding the amp though, not exactly a "user serviceable" endeavour.

Ground loops are normally due to plugging things into different mains outlets separated by some distance - say the amp and an effects unit/power supply. Plug everything into the same power point and it normally stops it.
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#9
Meh... Well I just have my guitar going straight into my amp which is going straight into an outlet, no effects or anything, very plain jane rig. So, I guess my next question is, what causes the amp to hum in the first place (the "normal" hum all amps have)? Is it STILL due to 60 cycle hum or anything like that? I'm trying to figure out if the HumX will still help me out.
#10
Are you serious? You said rolling down the guitar volume gets rid of the hum. Doesn't take a ****ing genius to figure out where the hum is coming from.
#11
Quote by phoenix_crush
Are you serious? You said rolling down the guitar volume gets rid of the hum. Doesn't take a ****ing genius to figure out where the hum is coming from.


Please just bear with my ignorance and help me out man. So does that 100% narrow it down to a guitar issue and NOT an amp issue? The hum is coming from my guitar meaning it's 60 cycle hum and a simple noise gate will resolve all this? I wasn't sure, I thought turning down the guitar volume just turned everything down and that the amp hum might go down with the guitar volume.
#12
HumX will do squat.
Sounds like your guitar is picking up something in the room - possibly the amp itself? Try walking around the room and facing different directions - does it change?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#13
What type of guitar do you have? Does it have single coil pickups or humbuckers?
#14
HSS, hums on all pickups...old beat up washburn, got a standard MIM tele on the way (single coils)
#15
Have you tried turning down the guitar volume yet? I thought i asked this in your other thread but i cant seam to find it now. Anyways, report back if the volume knob makes the noise go away or not. That will answer alot..
#16
Yes, turning down the volume on the guitar eliminates all the hum even if the amp is cranked up. So, does this mean it is a guitar problem instead of an amp and that a noise gate in between will solve it (at least most likely)?
Last edited by Born Headless at Feb 6, 2012,
#17
^ If someone could answer this question for me it would potentially solve my problem /shameless bump....
#18
You sure do want to buy that noise gate dont you! lol

So, little more troubleshooting you can do as far as this subject goes.

What this tells us is that there is noise being introduced to the signal from the guitar to the input of the amp. So Whats in this chain?

Sounds like you have Guitar > Cable > Amp.

That makes it easy.

1.) use a different cable of good quality

Still have noise?

2.) Could be your grounding on your guitar

with the gain up fairly high to make the test easy place your hand on the strings. When you remove your hand from the strings completely meaning no part of your hand is touching the strings does the noise get louder?

If yes, its a grounding issue

if not next test

Last area is your pickups. If they are crappy pickups they will be alot noiser than normal pickups. Single Coil pickups are going to be alot noiser than humbuckers by design.
#19
I told you how to check if the guitar is picking up noise from something in the room - walk around.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#21
okay, if these tests check out fine, then it's a guitar issue and the noies gate will work?
#24
Then your guitar is acting like an antenna and picking up some form of radiation in the room, possibly the amp itself. You can use the guitar as a signal detector to find the source of that interference.
The main reason I have never been too keen on single coil pickups is because a lot of venues are EMR factories. Lighting rigs in some pubs can make a sc guitar practically unusable.

Also, is the noise louder when you aren't touching the strings?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band