Epiphone LP with SD Jazz - mains noise

[mcentee2]

I swapped out my Probuckers for SD Jazz pickups recently, and truth be told I cannot remember if I had this problem with the probuckers.

So:

Epi Plus top Pro - decent guitar, un-shielded cavity and routing, SD Jazz Bridge and Neck pickups, 4 wires (plus bare), no cover.

Red/White are twisted and taped, green/bare are grounded at the pot, black goes to hot.

The Jazz pickup bobbins are equally wound so there should be little if any imbalance picking up hum to the level I have.

The pickups have the magnets the right way around - screws=south, slugs=north, and I have them oriented with neck screw nearest the neck, bridge screw nearest the bridge.

The loom is fully replaced with a quality one with braided wire to the switch and back to the output.

All joints and grounding paths from pickups bare, base and bridge/strings/winders check out via visual and multimeter continuity checks so far


I get mains hum, definitely mains hum as it is directional, with either bridge or neck pickups active. The usual ef "noise" goes quiet when I touch strings etc as I am then grounded, all as normal there.

But - With both pickups selected in the middle position the guitar is silent, so there is some "bucking" going on between the pickups, just not for each pickup.


Any ideas ?

 

[Mincer]

Re: Epiphone LP with SD Jazz - mains noise

Are you getting this in other rooms or buildings, too? These pickups aren't noisy at all, so they shouldn't be the source of the noise.

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

Are you getting this in other rooms or buildings, too? These pickups aren't noisy at all, so they shouldn't be the source of the noise.

Indeed, that is what I am hoping to confirm somehow, so thankyou I haven't done other test in other rooms.

Suffice to say my Strat with SD stacks is completely silent!

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

Quick update.

This isn't as directional as I thought. It seems to be fairly constant on rotation of the guitar.

If I split the coils then I get a recognisable and louder hum that is directional the same as my strat (when not in noise cancelling mode).

When I bring the LP close to my body it quietens down a fair bit but some hum remains.

I have wired the neck pickup direct to the output Jack and the hum is still there.

This is probably "normal" after all maybe, but am puzzled why it is dead silent in the middle position.....

 

[Chistopher]

Re: Epiphone LP with SD Jazz - mains noise

I'd say a a noisy piece of wire or soldering joint might be the culprit. Shielding the control cavity and shielded wire to the pickup selector might considerably cut back on noise. Pickup covers will help as well, but even with a quality cover it'll dampen the high end a tad bit.

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

Thanks, all 3 wires to the switch are braided and grounded, the pickup wires are grounded on the pots, the output is grounded to the switch itself and output jack lug.

Still puzzled as why it is dead silent when both pups are on, but both pups have the noise when on individually.

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

Ok, did a lot of searching forums for this and some people back in the day seem to have had similar experiences with noisy humbuckers (balanced) that are quiet when both on in the middle position.

I weeded out countless threads about checking the bridge grounding

So whatever is causing the noise it is effectively being cancelled by both pups being parallel, opposite winds etc. But is inherent to each pickup itself, given they are both SD Jazz and both are noisy this makes sense.

So, these are SD Jazz pickups, 4 way plus bare, it isn't clear but does anyone know if the 4 way is shielded along its length at all?

If not that could be one possibility for each pickup having some individual noise from RF/em, but again I am struggling to see how the two pickup's wire runs can be seen as parallel and *opposite*.

The 3 switch wires are all braided and grounded at both switch end and to pots/jack, so these are shielded.

The pots and wiring in the cavity aren't shielded, so I could look at that, but that is in no way "parallel and opposite" at all so I can't equate that with being silent in the middle position.

Wired directly to output the neck pickup and wiring picks up the noise.

I keep having to come back to the pickups themselves being unbalanced, but that also doesn't seem right either.

What am I missing?

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

One more update, with some new findings, but no answers yet:

I did some more directional testing, and have now heard something unexpected!

Imagine me standing in front of and facing my amp with my guitar held as normal across my front, therefore parallel to the amp.

The bridge pickup is silent.

Rotate 90 degrees until it's loudest hum point, another 90 until quietest again etc back full circle.

I do the same with the neck pickup , but....it is not at its quietest/loudest at the same points as the bridge, it is 45 degrees out as I turn around!

Quietest neck is 45 degrees turn away from amp, nosiest is 135 degrees.

Weird, weird, weird.

 

[BRHGM]

Re: Epiphone LP with SD Jazz - mains noise

Check the bridge ground. On an Epiphone, it is under the pole of the bridge and is not usually soldered. This could explain that your hand

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

Bridge ground is good, no issues at all.

I did some.more testing, and figured one of the differences between neck and bridge pickups was their orientation in respect of screw and slugs, or neck screw is towards the neck, and bridge screws are towards the bridge.

I turned the bridge around in the cavity so that both neck and bridge screws are positioned towards the neck, and now the directional noise for both pickups matches direction.

Hurrah, so I can discount anything really odd going on.


I will do more tomorrow with the pickups in this same orientation and see what they do when parallel etc.


Still need to get to the bottom of which bit needs shielding as something does somewhere!

 

[Mincer]

Re: Epiphone LP with SD Jazz - mains noise

Hmm, I wonder what you would discover if you took the guitar to a friend's house or store...it might have something to do with RF interference at your place.

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

Agreed, re rf.

However, possibly me learning something but I thought humbuckers bucked hum ? Especially balanced coil ones should be almost silent, and I mean more silent than you could easily hear.

Direct pickup to output, hums.

Maybe my expectations are too high, and would welcome any "sounds normal to me" advice too.

 

[Mincer]

Re: Epiphone LP with SD Jazz - mains noise

Well, generally they do...but anyone who plugs into a circuit that has neon, or dimmer switches, or dirty power can hear hum in humbuckers. It doesn't really sound like single coil hum to me...but it is annoying at gigs, and would be intolerable at home. I've heard hum from cell towers and wifi signals too- humbuckers don't really block that out, either.

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

Just a final update for this one for future reference.

I (again) took the bridge pickup out from the guitar and hardwired it to a jack, same noise.

I removed the screws and slugs so just had the coils - same noise.

I wrapped it all in grounded foil - still the same noise.

Back to measuring the DC of the coils, and it showed Slug: 3.86K, screw 4.17K

So, even though I know that DC isn't everything, these are two coils on the same pickup with supposedly the same wire so this disparity has to do with the number of winds.

@LtKojak has been kindly helping me offline and has suggested, probably correctly that the bridge actaully has the slug coil from a Neck Jazz.

This would explain everything.

Now, on the one hand I am sure someone at SD would like to know this for their QC checks - on the other hand, I think I am actually quite happy now that I know the source of the noise, I happen to have a Hybrid JazzN/JazzB with all the "nice" things that brings.

With an A2 from @LtKojak - poss degaussed at some point - I have a "unique APH-1" and good sounding pickup

Thanks all for input during this.

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

Update:

I returned this Jazz bridge and just received its replacement, another Jazz bridge.

This one measures:

Slug: 4.0K
Screw: 4.2K

Is this one incorrectly wound as well?

I haven't installed this yet pending views from all.

I have sent a direct email to SD support as well.

 

[Mincer]

Re: Epiphone LP with SD Jazz - mains noise

I'd think that is within tolerance, but I'd love to know what SD support says.

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

I'd think that is within tolerance, but I'd love to know what SD support says.

I will report back when I have a response, thanks.

 

[mcentee2]

Re: Epiphone LP with SD Jazz - mains noise

SD support have now confirmed this is within spec and expected, nothing untoward.