Asymmetrical Humbuckers

[big_teee]

So what do you experts think is the point, In Turns, & DCR, do you start to really notice AC Hum? You can get scientific, or general, if you like? I've made several Very mismatched bridge Humbuckers and they still cancel Hum, but maybe not as much.
I have split capability in my test guitar, and Humbucker mode is always much quieter than split.
Later,
Terry

[Mark Hammer]

Well, I think one first has to recognize that audibility of hum-rejection is largely a function of hum-attraction. I have single coils that get far more hum than others, even when the "others" use unshielded wires. So, take dual-coil pickup A and a 98% hum-cancellation in that one might still result in more audible hum than 94% hum cancellation in dual-coil pickup B, simply because the individual coils in A attract more hum to begin with.

Many years ago, Jeff "Skunk" Baxter had a column in Guitar Player, and one of the installments concerned precision-matching of coils for better hum-rejection. Like a good little boy, I believed him and followed up, under the naive assumption that a 3-1/2 digit ohmmeter, and a profound belief in the equivalence of DCR and #turns, would take me to hum-free performance.

It worked. But, as things like John Suhr's Strat backplate dummy coil so amply illustrate, you can get hum cancellation even when the coils are not at all matched for DCR, #turns, etc.

Kinda makes me wonder what would happen if a "split-able" dual coil pickup had one relatively shielded coil, and an unshielded coil, such that cancelling the unshielded coil would get you a different inductance/output, but not quite as much hum as if you cancelled the shielded coil.

[David Schwab]

I have an old Bartolini Hi-A pickup from 1977. The two coils are very mismatched. One reads 4.62K, and the other is 3.4K.

The 4.62 coil is closer to the bridge. It's a very quiet pickup and doesn't hum at all.

[Mark Hammer]

Do those use different wire gauges for each coil?

[Rick Turner]

Mark, what do unshielded wires have to do with humbucking?

Answer...very little.

Buzz prevention, maybe, but not the classic 60 cycle alternating polarity radiated magnetic field induced hum.

Bill Lawrence tried to convince me that unshielded humbuckers were quiet. I thought he was deaf.

[Mark Hammer]

Actually, I meant "shielding" in a more general sense. If course, that's the sense that all too often seems to erode tone, but be that as it may, the intent was to inquire whether there was some other means of altering humbucker inductance and tonal quality (just for an option in the tonal palette, NOT for a "single coil sound") that did not have to incur quite so much of a "hum penalty".

And just to concur with both you and Bill (how could I disagree with him? talk about hubris, eh?), yep, completely unshielded dual-coil arrangements can be dead quiet.

[salvarsan]

Joe Gwinn did some plausible estimates a few years back in this post.

Using simple Ohm's Law calculations and knowing that coil voltage output is proportional to windings, you can figure out the math.

His worked example showed that even with a 30% mismatch in windings count, you got a very audible 18dB hum cancellation.

[big_teee]

Joe Gwinn did some plausible estimates a few years back in this post.

Using simple Ohm's Law calculations and knowing that coil voltage output is proportional to windings, you can figure out the math.

His worked example showed that even with a 30% mismatch in windings count, you got a very audible 18dB hum cancellation.

I have such a pickup and it is not bad on hum.
It's my blade hybrid.
I have a blade bobbin wound to 8k with 43ga PE, and a traditional Screw bobbin with 42 ga SPN wound to 4.5k
It works great. Not sure what the turn count is on each bobbin.
I may be imagining things, but the pickups seem much quieter once I pot them.
It seems to help on the hiss and fry sounds.
Terry

[David Schwab]

Do those use different wire gauges for each coil?

No, uses the same gauge.

[Zhangliqun]

I make nothing but fairly heavily mismatched buckers. I have no charts or technical info to offer but I don't notice any more hum from these than from humbuckers matched to the turn.

[David Schwab]

I make nothing but fairly heavily mismatched buckers. I have no charts or technical info to offer but I don't notice any more hum from these than from humbuckers matched to the turn.

Just curious, but why do you mismatch all your humbuckers? For more high end?

I wind all mine matched to a few turns.

[big_teee]

Just curious, but why do you mismatch all your humbuckers? For more high end?

I wind all mine matched to a few turns.

I do it to put emphasis for more or less treble.
Usually more turns Farthest from the bridge, is less Tinny IMO!
Also makes a stouter Coil for Split Mode.
I only do this on the Bridge Pickup.
I like the Neck P/U Symmetrical.
T

[David Schwab]

I do it to put emphasis for more or less treble.
Usually more turns Farthest from the bridge, is less Tinny IMO!
Also makes a stouter Coil for Split Mode.
I only do this on the Bridge Pickup.
I like the Neck P/U Symmetrical.
T

Well besides emphasizing one coil or another, if you mismatch the coils you get less treble cancelation, so the pickup is brighter.

[Ward]

Just curious, but why do you mismatch all your humbuckers? For more high end?

I wind all mine matched to a few turns.

I made a hummer with 2.5k of heavy insulated 42 poly on each bobbin with an A5 mag, it balances real well volume wise with two 7.5k singles in a HSS configuration (with 500k pots of course) and has a real good tone as well. This has nothing to do with anything except to say under wound humbuckers me like.

[David Schwab]

I made a hummer with 2.5k of heavy insulated 42 poly on each bobbin with an A5 mag, it balances real well volume wise with two 7.5k singles in a HSS configuration (with 500k pots of course) and has a real good tone as well. This has nothing to do with anything except to say under wound humbuckers me like.

They do sound nice and clear.