Can't find the hum

D

dwyatt

New member
Hi folks,

I have a problem with hum in my guitar that I've been trying to fix off-and-on for weeks without success. So I am coming to y'all to see if you have any ideas / beg for help.

The guitar is an Ibanez AG75 and my goal was to do my first electronics rebuild by replacing the pickups and all the electronics. Mostly just a learning exercise, and I've watched a lot of Youtube tutorials and read a lot of posts to get to where I am... my main take away so far is that I shouldn't be mucking with my "good" guitar any time soon :)

I want to wire it up similar to my Taylor T3B. Taylor uses a 5 pin molex connector on its pickups, allowing for the 4 connectors and the ground and a push/pull pot on the volume allowing for a coil split. This way I could easily swap pickups later, either into my Taylor or into my Ibanez for easy experimentation.

I swapped out the pots with CTS 500k DPDT push/pull pots for both the volume and tone controls. The volume pots are hooked up so I can split the pickups from humbucking to single coil and the tone pots are hooked up so that I can experiment with different caps.

The pickups were standard two conductor so I had to mod them into four conductor, and I believe that's been done well (swapped them into my Taylor to test).

However, there's a significant hum in the system so I've ripped it down to the absolute bare essentials (ignoring pots, caps, the switch and the output jack) to try and figure it out and now it's so very simple that I can't guess where the hum is coming from.

Here are some details:

  • The pickup wiring (colors are a bit odd because the cabling came from twisted pair ethernet) for the molex connector is:
    • Blue - North Start
    • Green - South Start
    • White - North Finish
    • Orange - South Finish
    • Brown - Drain
  • My amp is a Fender Mustang III with the latest firmware.
  • My Taylor T3B works perfectly through this amp.
  • I've checked the molex wiring with a multimeter and all of the connections are sound.
  • I'm only working with the bridge pickup at the moment.
  • South Coil - 4.06 Ohms
  • North Coil - 3.97 Ohms
  • Coils in Series - 8.00 Ohms
  • All of the molex wires were tested to ensure that nothing is inadvertently connected to anything it shouldn't be.
  • I've put the bridge pickup into my Taylor and there is absolutely no hum. It's clean and it splits correctly.
  • I did have a hum caused by a dimmer switch in my basement, which I have replaced with a standard switch.
  • I've also unplugged half the house in order to try and eliminate the hum I'm seeing in this setup.
  • You can see how I've connected the pickup to the amp cable. This simplistic setup creates a hum.
  • I have also put a volume pot into the mix and the hum reacts to the volume; max volume = max hum, no volume = no hum.

Pickup.jpg -- Here's the pickup
MolexPotEnd.jpg -- The Molex end for the pot
MolexPickupEnd.jpg -- The Molex end for the pickup
NorthEndResistance.jpg -- The resistance reading on the north end of the pickup
SouthEndResistance.jpg -- The resistance reading for the south end of the pickup
SeriesResistance.jpg -- The resistance reading for the pickup in series
TestSetup.jpg -- The setup for the hum test

Now, I'm clearly a novice so it's probably an idiotic move on my part. My expectation is that the given wiring of pickup, coils in series (i.e. humbucking) straight to the amp should have no hum. Perhaps that's wrong? If that was the case I was going to start building in more components and checking for hum as I went. However, I can't get to the "no hum" state.

I'm stumped! I've tried diagnosing everything I can and I'm left with nothing else to try. I keep coming back to the idea that the Taylor plugs in to this amp, in the same room, all other things being equal, and it's quiet as a mouse.

Can someone please point me in the right direction?
 
Re: Can't find the hum

Just stabbing at it here:
Is the Taylor shielded (shielding paint, foil, whatever)?
Is the Ibanez shielded?
Was the original pickup wiring 2 conductor as in just a braided (or spiral) shield and a center conductor?
Did the Ibanez hum before you re-wired the pickups?
 
Re: Can't find the hum

All great questions... thanks for responding.

  • The Taylor is not shielded.
  • The Ibanez is not shielded.
  • It was two conductor bare wire braided with a center conductor.
  • It's been quite a while since I had it in that configuration (and I can't put it back that way with any ease) but I'm pretty darn sure that the Ibanez did not have a hum.
 
Re: Can't find the hum

If the pickups were installed in the unshielded Taylor and the hum was not present. Yet, the hum is present in the Ibanez. And, assuming your wiring, including grounding, is fine. Then, regrettably, I don't have an answer other than strange stuff happens and you could try shielding the Ibby. Oops , scratch that, just dawned on me that the Ibby is a semi-hollow too. Sorry.
 
Last edited:
Re: Can't find the hum

Fair enough... On the upside I feel less stupid, on the downside, well.... buzzzzzzzzz :)

Thank you.
 
Re: Can't find the hum

dwyatt said:
Fair enough... On the upside I feel less stupid, on the downside, well.... buzzzzzzzzz :)

Thank you.
Click to expand...

You know, I have to wonder if the more pots, the more connections, the more hum. Two worst humbucker guitars for hum/buzz that I have are both 4 pot deals. Neither was shielded. I cured the noise by shielding both of them. Those are both North American made guitars. The Asian imports I have are all shielded with paint and they are quiet. There is another North American made guitar that I have with dual buckers. It's a semi hollow and is not shielded. But that guitar is quiet. It has one volume, one tone, no coil tap. Just thinking out loud here but maybe there is something to it.

Thinking about your Ibanez, you said that you cant remember if there was any noise before you re-wired the pups to 4 wire. But, they were shielded before you rewired them, which should help, at least some, with noise. The Ibby also has two volume and two tones. Your Taylor is single volume and single tone, yes? So, maybe there is something to the more controls more potential for noise thing. Maybe there was some hum when the pickups had the stock, shielded wiring, but not enough to bother you?

I know that doesn't help solve the problem. Just thinking out loud, so to speak.
 
Re: Can't find the hum

Does the hum go away when you touch the strings?


Sent from my iPhone using Tapatalk
 
Re: Can't find the hum

I tried another permutation that I hadn't tried before; I put one of my Taylor pickups into this configuration and it has a hum. It does not have a hum in the Taylor but outside of it, it does. I did say that the Taylor had no shielding but it does connect the pickups to a PCB, which could easily have some interesting circuitry in it that does something interesting with respect to hum.

As well, there was something I wasn't clear about earlier. The Seth Lovers have never been connected to anything before; I converted them from 2 conductor to 4 conductor before hooking them up to anything. The lack of hum in the Ibanez before was with the stock pickups.

Perhaps I need to add in a volume and tone pot and see what happens. Maybe I can add a sheath the wiring of the Seth Lovers and see if that improves things.

The Ibanez is a full hollow body so shielding it in the usual way simply isn't an option.
 
Re: Can't find the hum

Wait so the Taylor has moved connector pots, I wonder if I can buy those somewhere fir quick pickup changes. I don't mind so e sodering, but if I want to freely swappickups pack and forth without a bolt down terminal.

Sent from my SGP511 using Tapatalk
 
Re: Can't find the hum

RandomToneGuy said:
Wait so the Taylor has moved connector pots, I wonder if I can buy those somewhere fir quick pickup changes. I don't mind so e sodering, but if I want to freely swappickups pack and forth without a bolt down terminal.
Click to expand...

Yeah it's a pretty sweet setup. They've got three different pickup sets and they're all wired for easy plug and play. Mimicking it seems a bit tough, but... :)
 
Re: Can't find the hum

dwyatt said:
I haven't had strings connected to it in quite a while but I might hazard a guess that the hum goes down but does not disappear entirely.
Click to expand...

I was wondering whether the bridge ground might have disconnected when you were rewiring? Quick continuity test from bridge to ground of output jack will confirm/deny.


Sent from my iPhone using Tapatalk
 
Re: Can't find the hum

I hooked up the volume pot and the hum is certainly controlled by volume. Turn the volume off and the hum goes away. Turn it up and it gets louder.

If I touch a ground then the higher hum goes away (there are two distinct frequencies at least) but the lower hum remains.

I'm starting to wonder if I'm wasting everyone's time. As diligent as I'm trying to be with ruling things out, it still seems like the problem is all over the place.

Sent from my SM-G930W8 using Tapatalk
 
Re: Can't find the hum

VinceT said:
I was wondering whether the bridge ground might have disconnected when you were rewiring? Quick continuity test from bridge to ground of output jack will confirm/deny.


Sent from my iPhone using Tapatalk
Click to expand...
Can't be. It's just a pickup to the output at the moment.

Sent from my SM-G930W8 using Tapatalk
 
Re: Can't find the hum

So I soldered everything back together yesterday, plugged in the pickups in order to get it into a good state to go in for repair and found that the problem was resolved.

I'm not sure why... It's connected up the same way as before, but obviously not somehow.

At any rate, I'm a happy guy :)

Thanks for answering my questions and putting up with the vagueness. I'm sure it helped me in the end. This is a very forgiving forum :)

Sent from my SM-G930W8 using Tapatalk
 
Last edited:
Re: Can't find the hum

Great tone. The neck is nice and round that responds well when having the tone rolled off about half way. If you push it a bit the mids sparkle nicely. I don't use the bridge much but it actually mixes with the neck pretty well. I find it can add a bit of an edge. I lowered the bridge pickup slightly so it doesn't overpower the bridge but is just there to add colour.

All in all... I'm a kid at Christmas. Fun stuff ;)

Sent from my SM-G930W8 using Tapatalk
 
You must log in or register to reply here.

Similar threads

C
How bad is the hum in the '59/custom hybrid?
Replies
7
Views
112
Mincer
Mincer
idsnowdog
Introducing the Garbagecaster
Replies
6
Views
140
JamesPaul
JamesPaul
W
Squier Mustang Vintage Modified squeal and feedbackck
Replies
9
Views
76
idsnowdog
idsnowdog
S
Noiseless P90
2
Replies
20
Views
203
Aaron Cheney
Aaron Cheney
Mincer
The Seymour Duncan Ryan “Fluff” Bruce FLF Signature Pickup!
2 3 4
Replies
61
Views
631
Seashore
S
Back
Top