Noise cancellation on pickups with base plates

[Chipotle]

I installed the Ernie Ball/Music Man silent circuit in one of my strats. What I've noticed, is that I get the least cancellation on the bridge pickup, which has a baseplate installed. I'm wondering if that baseplate has an effect on the noise. I'm using a Squier strat pickup with the pole pieces and magnet removed for the dummy coil. I get about 14 db of reduction on the neck and about 8 on the bridge.

[mr fab]

it suspect that your bridge pickup is much hotter than the dummy(ie as more turns of wire) and hence less reduction in noise as the noise picked up in the bridge pickup is much more than the dummy

[Lollar Jason]

pickups with a reflector plate- steel- or inductance plate is going to have a little more noise- Fender Wide Range, Firebirds, Thunderbirds, travis bean, doesnt make any difference if its grounded. Seems to be noticeably worse if you are using wiring with no shielding.

[Chipotle]

Thanks for the help. The circuit adjusts for gain and I did my best to find the spot on the trim pot with the most cancellation for the bridge. It just seemed like perhaps the noise was a bit too different to cancel. So, I was wondering if the baseplate might make that pickup's noise a bit too different than the dummy coil's. I don't have shielded wire on that pickup, just regular cloth strat pickup leads. Maybe I will try shielding those leads.

Much appreciation for the tips!

[ScottA]

Base plates are buzz antennas.

Shielding will help.

Also good grounding is key to minimize the noise, but they'll still make some. I find that grounding through the screws and the bridge plate (on Teles) works best. Redundant grounds seem to make things worse.

[Mark Hammer]

Base plates are buzz antennas.

So does that imply that, with respect to their individual hum levels, the base plate disturbs the "balance" between two otherwise reasonably-matched pickups?

[ScottA]

So does that imply that, with respect to their individual hum levels, the base plate disturbs the "balance" between two otherwise reasonably-matched pickups?

I reserve "hum" for the 60 cycle magnetic noise that is cancelled by opposed windings and "buzz" as a catch-all for other EMI that is non-magnetic in origin.

Baseplates add "buzz", so combining two identical but RWRP pickups, one with a baseplate and one without, you will have good "hum" cancellation but you will still get "buzz" from the baseplate.

[Mike Sulzer]

I reserve "hum" for the 60 cycle magnetic noise that is cancelled by opposed windings and "buzz" as a catch-all for other EMI that is non-magnetic in origin.

Baseplates add "buzz", so combining two identical but RWRP pickups, one with a baseplate and one without, you will have good "hum" cancellation but you will still get "buzz" from the baseplate.

I think your terminology here is very confusing. "Hum" normally refers to 60 Hz and harmonics: the annoying noise made by using an ac power system. Hum thus defined comes in two types:

1. From magnetic fields, produced by currents: this is the kind canceled by opposed windings and is most noticeable when ferromagnetic material is involved since there can be very large microscopic currents resulting from applied macroscopic currents, that is, leaky transformers, etc.

2. From electric fields: charge changing in time produces oscillating electric fields which are picked up by wires, etc., when proper shielding is not used. In this case the oscillating charge is not necessarily associated with enough current to make significant magnetic fields. For example, suppose you plug a single wire into the hot side of an electric outlet and put it near an unshielded strat. You will hear a lot of hum, even though there is no significant current flowing in this "open" circuit.

I do not see how a base plate can be much of a buzz antenna if it is grounded. Grounding it pretty much zeros out the electric fields. I suppose there could be some effect on the higher harmonics of magnetic hum since the induced current increases with frequency. Maybe this is the effect that was described in the original post.

[Lollar Jason]

"I do not see how a base plate can be much of a buzz antenna if it is grounded. Grounding it pretty much zeros out the electric fields"
One would think so- first time I experienced it I made sure the inductance plate was grounded. Anyone have a solution im all ears. Were not talking one or two examples either- hundreds of them. Its typically a low level of noise that you have to try to hear but its there none the less and more noticeable when you have identical pickups - one pickup with the plate and another without in the same guitar.

[big_teee]

I experienced a similar deal with soapbar bass pickups.
using ceramic magnets, and no metal parts they were quiet.
I installed a grounded base plate, and instantly had some noise.
I took the plate off and it was quiet again.
It must be a conductor for the noise to travel through.
Pickguard shielding if you have one seems to help some.
T

[ScottA]

I think your terminology here is very confusing. "Hum" normally refers to 60 Hz and harmonics: the annoying noise made by using an ac power system. Hum thus defined comes in two types:

1. From magnetic fields, produced by currents: this is the kind canceled by opposed windings and is most noticeable when ferromagnetic material is involved since there can be very large microscopic currents resulting from applied macroscopic currents, that is, leaky transformers, etc.

2. From electric fields: charge changing in time produces oscillating electric fields which are picked up by wires, etc., when proper shielding is not used. In this case the oscillating charge is not necessarily associated with enough current to make significant magnetic fields. For example, suppose you plug a single wire into the hot side of an electric outlet and put it near an unshielded strat. You will hear a lot of hum, even though there is no significant current flowing in this "open" circuit.

I don't think it's confusing at all.

Your type 1 I reserve for "hum".

Your type 2 I reserve for "buzz".

They are two different, distinguishable types of noise. They arise from different physical phenomena and they are also cancelled or reduced in different ways. Opposed windings don't get rid of "buzz" and copper shielding doesn't get rid of "hum". "Buzz" doesn't go through peaks and troughs when you reorient yourself in the field the way "hum" does.

You can call them whatever you like, but they are two differentiated types of noise and they have to be dealt with differently.

[ScottA]

I do not see how a base plate can be much of a buzz antenna if it is grounded. Grounding it pretty much zeros out the electric fields. I suppose there could be some effect on the higher harmonics of magnetic hum since the induced current increases with frequency. Maybe this is the effect that was described in the original post.

As the other pickup builders have corroborated, it's a real effect.

[Mike Sulzer]

Hum and buzz do not separate into different physical phenomena. Hum is the lower harmonics, and buzz is the higher harmonics, but both can result from either electric or magnetic field interference.

It is interference from electric and magnetic fields that have to be treated differently, not "hum" and "buzz".

I don't think it's confusing at all.

Your type 1 I reserve for "hum".

Your type 2 I reserve for "buzz".

They are two different, distinguishable types of noise. They arise from different physical phenomena and they are also cancelled or reduced in different ways. Opposed windings don't get rid of "buzz" and copper shielding doesn't get rid of "hum". "Buzz" doesn't go through peaks and troughs when you reorient yourself in the field the way "hum" does.

You can call them whatever you like, but they are two differentiated types of noise and they have to be dealt with differently.

[Mike Sulzer]

As the other pickup builders have corroborated, it's a real effect.

So the first thing to determine is this: is it the result of electric fields or magnetic fields? As I said earlier, the magnetic field cause seems more likely since you can induce currents in a metal baseplate, but there must be a way to determine what the cause actually is.

[ScottA]

So the first thing to determine is this: is it the result of electric fields or magnetic fields? As I said earlier, the magnetic field cause seems more likely since you can induce currents in a metal baseplate, but there must be a way to determine what the cause actually is.

This is a reasonable statement.