# bass single coil hum



## tiki16 (Sep 18, 2011)

HI I just updated a MIJ Fender jazz bass knock off with a new single coil pickup. There is a lot of hum. I shielded the cavity with aluminum tape and the electronics are grounded with a wire running from under the bridge to the volume pot. The shielding has helped with some of the hum. If i touch the pickup and the bridge the hum subsides so I know the grounding is working

If I try to ground the shielding to the grounding wire, the electronics and pickup go silent. 

Any help appreciated.


----------



## fraser (Feb 24, 2007)

do you still have 2 pickups in it?
what happens if you turn the volume knobs up full on both pickups?

a jazz bass is supposed to be hum cancelling when both pickups are cranked-
maybe its a wind/polarity mismatch with the new pickup.
you could try reversing the wires on one or the other pickup.

mine is fully shielded and all that- but unless both pickups are dimed, there is hum anyway-
thats single coils for you.


----------



## tiki16 (Sep 18, 2011)

It's just a single pickup in the bridge.


----------



## fraser (Feb 24, 2007)

well-
you can try twisting the wires going to the output jack-
or use shielded wires there.
or play with dummy coils.
but if this is just regular single coil hum- then thats the way it is.
you can reduce it is about all.
can you angle the guitar away from the amp to reduce the noise?
if so, then you know its not a bad wiring/component thing- its just single coils bieng single coils.

how come your jazz bass only has one pickup?


----------



## tiki16 (Sep 18, 2011)

Yes if I angle it the noise subsides. It's much louder than the previous pickup. It's an old MIJ jazz bass knock off. It's not an actual fender. I think the shielding tape helped but it is still noisy. Never heard of dummy coils?thx


----------



## fraser (Feb 24, 2007)

well some pickups are just inherently noisier than others-
could be that the one you installed is hotter as well- thatll increase the noise.
since it seems you just swapped the pickups, that may be the case here.
without actually hearing the guitar its hard to say.

make sure the shielding is properly grounded, and if there are more than one connections to ground, cut it down to one if possible.

a dummy coil can be made with any spare pickup-
basically you take a pickup, if its magnetic polarity (north-south) is the same as the pickup you are using, you remove the magnets or recharge the existing magnets so its polarity is the opposite.

you take that pickup and wire it 'backwards' into the circuit.
so it is reverse or neutral polarity- and wiring the hot lead to ground, ground lead to the switch effectively makes it reverse wound.
this creates the same arrangement as a humbucking pickup-
but since only the original coil is operating- it doesnt really affect the sound, other than the noise reduction.

in my experience, just like shielding etc- it wont eliminate the noise, itll just cut it down.
im a dyed in the wool single coil guy- and i like to play loud and with a bit of gain.
ive kinda become immune to the noise, but its nice to reduce it when possible.


----------



## tiki16 (Sep 18, 2011)

I tried to ground the shielding but it knocked out my electronics. How do you ground shielding?


----------



## fraser (Feb 24, 2007)

run a wire from a ground point- like the back of a pot- that needs to connect to the shielding.
if the shielding isnt grounded out, then all you have is a bigger antenna for noise.
there should be a ground wire from the pots already, as well as one contacting the bridge and output jack.


----------



## tiki16 (Sep 18, 2011)

Well i just tested my tele at same vol and it hums just as loud as the bass so I guess i'll leave it as is.
thx.


----------



## marauder (Oct 19, 2009)

tiki16 said:


> I tried to ground the shielding but it knocked out my electronics. How do you ground shielding?


If grounding your shield knocked out your signal, then you have a wiring issue. The shield is somehow coming into contact with the "hot" from your pickup. This is probably the source of the "extra" noise as well.


----------

