Original Gibson 'Mudbuckers' and noise rejection

[AdmiralB]

I recently acquired an original 'mudbucker'. It's ostensibly proper; two AlNiCo bars, about 31K DCR, sounds like it should. No performance problems.

Except...it's pretty noisy. Not as bad as something like a P90, but enough to notice, and the fact that it's apparent in a bass setting (I'm not playing 'in the style of Lemmy') is rather surprising.

Is this normal? I can't think of any reason why this design should have any less rejection than any other humbucker.

[Mike Sulzer]

If this is a sidewinder as I think it is, then it no surprise. Sidewinders, due to their geometry, do not have as good rejection of magnetic noise as a standard humbucker.

I recently acquired an original 'mudbucker'. It's ostensibly proper; two AlNiCo bars, about 31K DCR, sounds like it should. No performance problems.

Except...it's pretty noisy. Not as bad as something like a P90, but enough to notice, and the fact that it's apparent in a bass setting (I'm not playing 'in the style of Lemmy') is rather surprising.

Is this normal? I can't think of any reason why this design should have any less rejection than any other humbucker.

[AdmiralB]

Yeah, it is. This is really the first long-term experience I've had with a sidewinder.

Thanks! I feel better about it now; thought something must be wrong, but since it works perfectly otherwise, I couldn't figure out what.

[AdmiralB]

It's the pickup.

The bass is a recent (2005, I think) "SG" - essentially a modern-day EB-3 - and was quiet before the swap.

The stock neck pickup was a recent T-bird coil set arranged on a mudbucker-sized baseplate with a fake set of pole screws. I found an original for cheap, because it was missing its cover; the current cover is a perfect fit, so that worked out just fine.

I put the T-bird coils into a guitar minibucker cover and have that in the bridge position now; it's a closer match, volume-wise.

What I discovered - and wouldn't have thought about, without owning one - is that the huge mismatch in DCR causes the mudbucker to essentially disappear if both pickups are on full-up. I would have expected the opposite, that the big output would drown the bridge, but the ~6K of the bridge pickup loads the mudbucker down so much it pretty much ceases to function.

I put in 1M volumes with a 33K resistor in series with each pot's output to the tone control. The result is volume that's on '~9.7' instead of '10', full-up, but now you can hear both well.

I tried using an EMG buffered mixer, but there's not enough room in the cavity for batteries...and I didn't want to carry a power pack on my strap. It did sound good, though.

[AdmiralB]

It is far stronger, compared singly. But when both are on, the bridge pickup loads it down.

Consider two pickups, identical. Say, 6K DCR, with 500K pots. When both are 'on', the load they see is the combination, in parallel, of their two pots (each 500K, assuming full up), whatever the input impedance of the device to which they're connected...and each other. So, handwaving away, for the sake of argument, the reactive portion of the impedance of each coil, the load is 6K reduced by the parallel combinations of the pots and output load.

That works fine when the pickups are fairly similar. But the 31K mudbucker can't handle getting loaded down by the 6K bridge pickup. Before I added the resistors, when both pots were full-up, all you heard was bridge pickup...but if you rolled both back to about 8.5, the neck came back.

[big_teee]

That still doesn't answer if it is a sidebucker, or sidewinder?
What is the gauss at the screws in the middle.
I like my sidewinders to read a gauss of 300+ North.
If it is near nothing, it is probably oriented sidebucker?
T
** Also did you check that both pickups, when selected are in phase?

[AdmiralB]

That still doesn't answer if it is a sidebucker, or sidewinder?
What is the gauss at the screws in the middle.
I like my sidewinders to read a gauss of 300+ North.
T
** Also did you check that both pickups, when selected are in phase?

It's an original Gibson EB pickup, I think from an EB-2 (whatever was the hollowbody model), because it came with the bracket with the four mounting screw holes on the ends. I assume you can derive whatever terminology you want from that.

I have no way to measure gauss, but I don't see that it's terribly important - as I said, it's plenty loud, and - back to the reason I posted in the first place - I don't how that would impact noise rejection since that's not a magnetic function at all.

If they weren't "in phase" - I reckon "of like polarity" would be more correct - then the output would be expected to be low whenever both were at the same volume setting. It would 'come and go' as you swept around. It doesn't. Overall output is strong everywhere, the neck just fades out tonally when it's exposed to the full load of the bridge.

[AdmiralB]

If any of the magnets got moved or changed, or if it isn't wired right that would effect the configuration.
That was what I was going to try to help you prove.
If the pickup got taken out of an original EB bass, there is probably a reason for it.
Like it didn't work right!
GL,
T

I do appreciate that. In this case, it seems that there's not much that could be wrong, though. It reads a proper DCR, the magnets are apparently strong, and they're properly oriented. And it sounds right - it's just noisy, but from Mike's response it seems as though that's to be expected.

These pickups don't seem to be hard to find - I'm guessing that's because, in the '70s, everybody probably replaced them with DiMarzio Model 1s/Model Gs. Just like Fender "wide range" humbuckers, before they became trendy.

Anyway, thanks!