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Hey guys,
I've been at this for days and it's been driving me nuts, so I'm pulling a last resort here asking for help, from people who might actually know what the deal is.
Basically, I'm getting a lot of hum out of my amp (Blues Jr, tubes) in a way that I haven't seen described as I've been looking it up. I've tried plugging in with both my Strat and my brand new Tele (which has humbuckers) - in both cases, the hum is the same, and it's very prominent at not that high a volume. And I'm playing jazz, so this is happening clean.
I actually think there might be two kinds of hum going on here, one of which I'm more concerned about than the other. First, there's the hum that goes away when I touch the strings or a metal part of the guitar, which is very very loud but goes down to almost nothing on contact. That isn't really an issue - the problem is that there's a slightly lower volume but still very pronounced hum that's there even when I'm touching the strings. It seems like that hum changes as I move the guitar around - I tested this with my Tele, which again has humbuckers so I figure this should not be a problem (and all of the appliances in my room were turned off when I did this). The amp doesn't hum when no cable is plugged in.
Part of me thinks it's the wiring in my house, because I don't remember getting this bad of hum when I used the amp elsewhere, but I'm not sure if those symptoms describe what that would be like... and I sincerely hope it isn't, because I'm living in a rental and there might not be that much I could do about it, haha.
Does this sound familiar to anyone? Any suggestions on how to reduce it? Thanks guys.
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06-19-2015 03:09 PM
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If the amp has a 3-prong plug, plug it into a 3 to 2 prong adapter (leave the ground unconnected) and see if that fixes the problem. If it does, buy a Hum-X to plug the amp into (instead of the possibly unsafe 2 prong adapter).
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Hey, thanks for the reply.
Just tried - doesn't sound like it changed anything.
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my old house has horrible wiring.
fluorescent lights are a noise source, and the microwave is the worst.
do I know any solutions? no
but this is why I don't use single coils much anymore . . .
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- Try different cable. there could be a short on the cable.
- After amp cool down, pull out and reinsert the tubes. Just to ensure good contact.
- Sometime, if tubes are old, noise or hum level increase. That is what happen to my Mesa.
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I tried a different cable, had the same problem. I was really hoping that was the issue too, would've been such an easy fix, haha.
I haven't touched the tubes yet - I was seeing that as a last resort, but it looks like that's the next step. I don't think they're old, but I dunno much about tube life spans - I got this amp probably around November last year.
Thanks for the reply!
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Try taking the amp to a friend or relatives house and see if you still get the hum, if not then it's probably your house wiring if it does then you probably have a fault with the amp.
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It's your house or something nearby. Sorry it can be very difficult to track down.
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Do you have lighting dimmers fitted anywhere in the house ?
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If when removing your hands from the guitar the hum gets "very very loud" it is likely your guitar's bridge is not wired to ground.
When you rotate your body and get different levels of hum you are listening to your guitar as an antenna picking up EMF 'radiation' from the surrounding AC and everything connected to it. This is probably from the wiring in your guitar and perhaps exacerbated by the steel that is not grounded. You say it's not that loud so I wouldn't worry about it too much. You could shield all the cavities if you want to reduce the symptom. You may have cheap pots, cold solder joints and dodgy wiring which can also be part of the problem.
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Could be a bad tube,power or preamp.
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Originally Posted by BigToe
I have to respectfully disagree with this post. The fact that when he touches the strings, the noise goes away indicates he has a string/bridge ground. Also, while less than stellar wiring in the guitar can exacerbate the problem, It would be better to identify the actual cause of the problem. However, these problems can be extremely difficult to track down, so having your instruments completely shielded may be the practical solution.
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Again I respectfully disagree. If the amp is not making noise with the instrument not plugged in (or in some cases plugged in but the volume on the guitar rolled off) indicates the amp is not a problem. Originally Posted by jads57
Im even going to go out on a limb and say it's not the power as the amp at idle is not a problem. Most likely cause is EMF as stated above.
The best way to diagnose is use a battery powered amp, cut the power to the house in the electrical box. If the noise disappears, start turning on breakers one by one until the noise comes back, after that, you have some detective work to do. If the noise is present with all the breakers off...... Good luck.
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My son's ipod did this to me when he plugged his charger into the same circuit as my amp. It was a horrendous hum. It wasnt until several times did I notice the correlation and moved him along to another location. Strange that it was the worst when the ipod was plugged into the charger and when my strat was plugged into the amp.
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I've spent an aggravating amount of time trying to sleuth the source of guitar & recording noise. There are so many variables and possibilities. Looked at cables, house wiring, everything in signal chain, PC (when recording), guitar shielding, other devices on circuit, etc. Replaced a noisy outlet. Shielded a guitar. Got a Hum-X. All of these solved a specific problem. Still have an unresolved horrible noise issue if I route my signal chain simultaneously to both an amp and a USB audio interface, but not one or the other.
Do what vintagelove suggested, trying different house circuits and turning of others at the breaker. Compare noise with a SS amp or a battery amp. Take the amp someplace else to test. Avoid single coil noise when testing so try things with a clean audio source (e.g., plug in an MP3 player rather than a guitar.)
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There's a lot of disinformation and disagreement about electric guitar noise and how to solve it.
For a simple amp guitar setup always start with an amp powered up but no cable inserted. No noise? Then it's not the amp.
I have a shorted jack socket that I plug the guitar cable into. I then plug the other end into the amp. No noise? It's not the cable.
I then take off the shorted jack and plug into the guitar with the guitar volume at zero. I regularly find this is the first point noise starts and it relates to poor contact on the earth side of the guitar jack. I clean the jack plug and the guitar jack socket with a cotton ear bud dipped in Servisol. Even visually it can be surprising what gunk comes off on the ear bud. I blame traffic fumes. This is most often the cause of humbucker guitars being noisy.
In my experience, noise that goes away on touching the strings is related to improper grounding of the strings. Unscrew the guitar jack socket so you have access to the wires and use a wire with small alligator clips on each end. Attach one end to the earth of the jack socket (with the guitar cable still plugged in to the guitar and amp) and clip the other end to the bridge or strings. Less noise? Use a multimeter continuity tester to check strings to bridge, bridge to earth continuity.
Having checked string earthing then you are able to assess noise from RFI sources. This is the noise that changes when the position or orientation of the guitar changes. If you have an issue and unlimited funds then perfect the household electrics, and the electrics at anywhere you gig.....or go noiseless single coil, single coil and cavity shielding or humbucker. An electrically sorted guitar is far cheaper and more flexible than fiddling with the mains.
Screening the cavities of an electric is very easy with water based graphite paint. The only essential is to maintain the isolation of your live signal from pickup to jack socket. I've screened telecasters and combined the string earthing down the drill holes for the wiring (cotton buds as pain brushes). I screen the pickup cavity and control cavity and paint up to the recess for the switch plate. I wire an additional wire from the jack socket earth lug through to a small wood screw attached to the cavity floor and graphite paint over it.
There might be a little high frequency loss with this but not enough to worry a jazz guitarist.
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Originally Posted by Chimera1to1
Don't we always strive for that elusive velvety dark tone? Velvet fog like Mel Tor-may.
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Chimera1to1 has the best advice. When you have a problem with a signal chain, check each link in the chain to isolate the point where the noise is coming in.
Definitely try your rig in a different location with no other changes to see if your house is the problem (e.g., a strong EM noise source nearby or poor grounding).
Don't mess with your tubes since the noise isn't there with the guitar inplugged..
Don't mess the guitar's shielding or wiring until you've stepped through the signal chain and found them to be the problem.
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What is the logic behind your theory? Originally Posted by vintagelove
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Actually the OP is a bit confusing. It seems like Jalopes is talking about both amp-related noise & guitar/grounding noise. Important to separate the two when troubleshooting. Originally Posted by BigToe
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Doesn't sound like an amp problem to me. Originally Posted by Jalopes
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That's not enough of a diagnostic to eliminate the amp; really need to test it with something plugged in. That's why I suggested plugging in an MP3 player to the amp. Originally Posted by BigToe
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"I've tried plugging in with both my Strat and my brand new Tele (which has humbuckers) - in both cases, the hum is the same, and it's very prominent at not that high a volume. And I'm playing jazz, so this is happening clean."
Highly unlikely both guitars would have an earthing or shielding problem.
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How long have you been in the rental?
The first thing i would do is check the A.C. outlet is wired correctly and grounded.
This can be easily diagnosed with an electrical outlet checker, usually $5.00 at the hardware store.Last edited by Treading Water; 06-23-2015 at 02:59 PM. Reason: clarity
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If you touch the strings in the hum goes away your guitar is properly grounded but it is lacking in the shielding department.
Next, if the noise goes away when you pull the cable out of the amp , If the problem is in the amp it is before the first preamp tube. If you look at the schematic there's not a lot that can go wrong before the first preamp tube. There's a shorting Jack and a 1 M and 68K resistor and that's it. The chances of the problem being with those components is pretty slim so rule out the Amp completely by trying a known good new preamp tube and move on.
There's a lot of verbiage in this thread and I'm not going to read all of it but those are two points that popped up from the original post.
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