What's causing this low hum?

[jmbjandfam]

I have a 2013 Fender MIJ 75 Limited Edition PJ. I bought it used and for the most part have just played it at home at bedroom levels. It sounds great but recently I took it to play at church. At church I play direct through an Eden WTDI. As soon as I plugged it in, I noticed a loud, low pitched hum. I turned down the bridge (jazz) pickup some and turned down the tone knob and was able to tame it enough to play.

At first I thought it was possiblly the old wiring in the church or possibly my DI but after doing some testing with other basses, I realized it's the bass.

I have tested it at home now and when the amp is turn up to gigging volume, sure enough, there is a loud low hum. I can turn down the bridge pickup and it goes away. Turning down the neck pickup (precision) has no effect. Turning down the tone does help but as soon as I turn down the bridge pickup, it's gone.

Let me quailify that the hum is not the typical grounding buzz that goes away when you touch the strings. Touching the strings has no effect on this hum. Only way to cure it is to cut off the bridge pickup. P pickup only is dead quiet.

Any ideas on what might be causing this and what I can look for to eliminate this?

 

[sissy kathy]

Perhaps your bridge pickup is a normal j pickup and is picking up RF from something (amp?) only thing I can suggest is getting a humbucker for the bridge pickup and/or shielding. You ARE talking about the same results w/two different amps, right?

 

[jmbjandfam]

Perhaps your bridge pickup is a normal j pickup and is picking up RF from something (amp?) only thing I can suggest is getting a humbucker for the bridge pickup and/or shielding. You ARE talking about the same results w/two different amps, right?

Yes same hum playing direct to PA through Eden WTDI as well as playing through my home amp which is a TC Electronic BG250 without the Eden WTDI.

 

[jmbjandfam]

This is the bass I have:

 

[megafiddle]

Try reorienting the position of the bass. Is there a position where the hum disappears or is greatly reduced?

If so, it is single coil hum and the source is a magnetic noise source, like an amplifier power transformer.

-

 

[sissy kathy]

Keep in mind that a great many electric items put out RF even CFLs, normal florescent lights, and consider where is the transformer for the church? At my church the transformer is right outside the nave.

 

[Zooberwerx]

When I hear the term "hum", then first thing that comes to mind is a ground compromise or conflict. When dealing with audio components, a ground loop is frequently the culprit and lifting the ground on one component is usually adequate to resolve the problem. I do not have enough expertise in dealing with passive bass harnesses to offer a solid suggestion but a decent tech should be able to locate the source and correct it.

Riis

 

[jmbjandfam]

Yeah it's definitely a low pitch hum, not the typical buzz. It doesn't change or waiver at all when I move the bass around, hold the strings, touch the bridge etc. The hum remains constant until I turn the bridge pickup down and then it disappears. I thought maybe there could be a bad wiring connection to the bridge pickup?

 

[Zooberwerx]

Yeah it's definitely a low pitch hum, not the typical buzz. It doesn't change or waiver at all when I move the bass around, hold the strings, touch the bridge etc. The hum remains constant until I turn the bridge pickup down and then it disappears. I thought maybe there could be a bad wiring connection to the bridge pickup?

Buzz is more typical IME when dealing with single coils, RF interference, and so on. You could very well have an improper wiring connection amongst the pots, switches, jack, shielding (if any) and pickups. I guess even a bad pickup could be suspect. I'm a terrible diagnostician when it comes to things like this. Any decent techs within driving distance; I believe you're in Moore Co, correct?

Riis

 

[iiipopes]

This is the entire reason Seth Lover invented the humbucking pickup. The OP's hum is definitely because the J-bridge pickup is a single coil. Welcome to the world of single-coil pickups. If you want to get rid of the hum, I suggest you get something like a new Fender N3, or a Fralin Split-Coil J pickup to replace the bridge pickup. These two models are both split-coil humbuckers in a Jazz configuration and are direct drop in's so you don't have to change your controls - just solder the leads in the same places as your current bridge pickup. They will also be the best match to your stock P-pickup and very similar to the stock bridge pickup. If you go with Fralin, email Lindy and tell him what you have, and he will wind the replacement to match.

 

[jmbjandfam]

Buzz is more typical IME when dealing with single coils, RF interference, and so on. You could very well have an improper wiring connection amongst the pots, switches, jack, shielding (if any) and pickups. I guess even a bad pickup could be suspect. I'm a terrible diagnostician when it comes to things like this. Any decent techs within driving distance; I believe you're in Moore Co, correct?

Riis

Yes I'm in Moore County. The only tech I know of is at the Guitar Center in Greensboro. I've talked with him before (not about this subject) and he seems like a great guy but I haven't had any work done there.

 

[jmbjandfam]

This is the entire reason Seth Lover invented the humbucking pickup. The OP's hum is definitely because the J-bridge pickup is a single coil. Welcome to the world of single-coil pickups. If you want to get rid of the hum, I suggest you get something like a new Fender N3, or a Fralin Split-Coil J pickup to replace the bridge pickup. These two models are both split-coil humbuckers in a Jazz configuration and are direct drop in's so you don't have to change your controls - just solder the leads in the same places as your current bridge pickup. They will also be the best match to your stock P-pickup and very similar to the stock bridge pickup. If you go with Fralin, email Lindy and tell him what you have, and he will wind the replacement to match.

You may be right but this particular noise is very different from the standard single coil buzz that I have experienced in the past and is completely independent of the extremely minimal single coil buzz that exists in this same bass. I am a little stumped by this at the moment since I have no wiring experience and don't really know what to look for.

 

[DiabolusInMusic]

You may be right but this particular noise is very different from the standard single coil buzz that I have experienced in the past and is completely independent of the extremely minimal single coil buzz that exists in this same bass. I am a little stumped by this at the moment since I have no wiring experience and don't really know what to look for.

The fact it is only present on the single-coil pickup and is not affected by touching metal is a pretty good indicator of 60hz. It might be something else, but my money says 60hz.

Can you test the bass out in some different environments? If it happens in some places but not all, it is 60hz.

 

[jmbjandfam]

The fact it is only present on the single-coil pickup and is not affected by touching metal is a pretty good indicator of 60hz. It might be something else, but my money says 60hz.

Can you test the bass out in some different environments? If it happens in some places but not all, it is 60hz.

So far I've tested it at both the church and at home (really the only 2 places I'm playing now). It is much more audible at the church but even at home, once the amps are turned up, it is present on both my TC combo and my son's Orange TB 500. At bedroom volumes at home is is not noticeable.

 

[iiipopes]

You may be right but this particular noise is very different from the standard single coil buzz that I have experienced in the past and is completely independent of the extremely minimal single coil buzz that exists in this same bass. I am a little stumped by this at the moment since I have no wiring experience and don't really know what to look for.

Exactly. The electrostatic noise a player hears when not touching the strings, which sounds more like a buzz, is often mistaken for hum. What the OP has is true hum - 60 Hz bleed through. Listen very carefully to the tone with nothing else going on. If the pitch of the perceived hum is between Bb and B, 1st & 2nd frets on the A string, then it is most definitely hum, and purchasing a end-to-end bridge humbucker is in order.

 

[jmbjandfam]

Exactly. The electrostatic noise a player hears when not touching the strings, which sounds more like a buzz, is often mistaken for hum. What the OP has is true hum - 60 Hz bleed through. Listen very carefully to the tone with nothing else going on. If the pitch of the perceived hum is between Bb and B, 1st & 2nd frets on the A string, then it is most definitely hum, and purchasing a end-to-end bridge humbucker is in order.

Wow, great information, just tested it and the hum matches the pitch of Bb just like you suggested. Looks like we have a winner!
Thanks again!

and now the pickup hunt begins......

 

[eriky4003]

jmbjandfam,
I've used the Electroharmonix Hum Debugger to good effect for the 60Hz hum. You can always try that rather than switching pickups on the bass. I'd recommend ordering from a place you can return this 'effect' in case it does not work for you.
Good luck.

 

[paulears]

Whenever strange noises come from single coil pickups in venues rather than pubs and clubs and home, I always check there isn't a loop system for people with hearing difficulties - single coil pickups seem to really hate them. Churches may well have one of these systems turned on and not even know it, as they're often install and forget devices.

 

[Dogghouse]

Seymour Duncan makes a great "Stacked" single coil Jazz Bass bridge pickup which is dead quiet and a good match to stock Fender P pickups. "STK-J1b".

 

[iiipopes]

Whenever strange noises come from single coil pickups in venues rather than pubs and clubs and home, I always check there isn't a loop system for people with hearing difficulties - single coil pickups seem to really hate them. Churches may well have one of these systems turned on and not even know it, as they're often install and forget devices.

He does have a point. I have a Korg rack tuner I got about twenty years ago. It used to be my main gigging tuner, slotted in between the bass and the amp. I always had hum in the system, in spite of having humbucking pickups in my bass, until I put a plug adaptor on the tuner mains plug that eliminated the chassis ground, in the same manner as having a ground lift in a microphone circuit. Now, because the entire system was properly grounded with a three-point plug, there was no shock hazard, and the hum was eliminated. More recently, I went to tapewounds, and since the black tape isolated my fingers from the strings and from the bridge ground, I had to go to EMG actives on stage to eliminate the hum, since EMG actives do not use a bridge ground. But usually, it is simply the single coil demons that are the reason most of us use humbucking pickups on stage.

Seymour Duncan makes a great "Stacked" single coil Jazz Bass bridge pickup which is dead quiet and a good match to stock Fender P pickups. "STK-J1b".

I tried them. To me, a stacked pickup loses bottom end. I like stack designs for the neck pickup in electric guitars, especially Kinman pickups, but I prefer side-to-side or end-to-end humbucking designs for bass because I'd rather trade just a little bit of top end to make sure the bottom end is retained.

The bottom line: start with the instrument using good humbucking pickups and shielding and work the signal chain up from there to keep hum and noise as low as possible.