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Bartolini split coil puzzle

Trying a pickup swap on a five-string bass where the stock pickups are slanted (swept backwards to complement multiscale) rather than perpendicular to the strings. MK1's are the intended replacement. Problem is that the import Barts are are soapbars containing reverse-P split coils...

Slanting these (top toward bridge, bottom toward neck) means the pickup coverage is "shorter" top-to-bottom, so the obvious choice seems to be the MK1-6 rather than the MK1-5 (the housing is the same size, but the rails are a little longer on the former). However, there is a potential problem with the A string here. Normally, the A would naturally fall into the "gap area" of a P-pickup's split configuration. But in this case, once the pickup is slanted, there's a chance the A string would fall across both rails of the split coil (or since the six string configuration of the pickup is wider, I suppose the string might miss the rails entirely... hmm). I cannot actually see the rails inside the pickups to see how they will line up with the strings, and one of the things I'm wondering here is whether the "doubled" field from the separate rails of the split-coil, should the A fall across both of them due to the angle, would *increase* the signal from just this A string alone, creating a perceived volume imbalance from string to string, or even just *cancel* out the signal from the string entirely. Since I would have to do some cutting here just to fit the pickups, I'm not sure there's a way to test it. Does anyone have any opinions on what might happen here?
 
I haven’t tried these pickups in that application so I don’t have input there but if you have the 6 string pickups in hand you could test them by making a frame to hold the pickup over the body and temporarily hook it to an output jack. You could even just hold them over the string but some type of a jig will be more steady.
 
You can dangle a paper clip over the top of the pickup to get a sense of where the magnetic field is (and isn’t).

What’s your string spacing over the pickup? Unless it’s pretty wide, I think you’ll be just fine.
 
The way I’m picturing it, the 6 string split will be right in the middle, and that’s exactly where your A string will go even if slanted. I’d take my chances with a 5 string pickup.

or, rather, I’d probably go for sidewinders or dual coils…
 
Bart has several models in the MK1 shape, as well as the P2 shape, which are the same length, just a hair narrower. Look further on the Bart website. From reading your post, you haven't seen all of what Bart has to offer. On an Ibby I used to own with Bart MK1 pickups, I upgraded them to the USA CBC Barts: big tone, humbucking, good presence in the mix, my sound man loved them. If you are so inclined, they have 4-conductor output for wiring options.
 
Thanks to all of you for your thoughtful responses.

The jig might be a good way to test, but it does require some rather precise placement to work.

String spacing at bridge is 16mm, so the string spacing over the pickups is not what I'd consider particularly wide.

Yes, having the A string glide right between the rails is exactly what I imagined here as an exercise in Murphy's Law... rather than riding over both rails, it might miss them both. But you can see why I thought the six string pickup might be a better bet-- utilizing a five-string pickup in a slanted position might leave the B and G strings just barely over the rails, or even outside the rails. I would not be able to tell visually, either.

I had actually considered the six-string MK6CBC pickups as a replacement... they have humbucking rails that would reach all five strings, even after giving up some of the coverage due to the slant. I'm aware that Bartolini makes some fine products, but I am concerned that I might not prefer the tone. That may sound entirely odd, considering that these are considered not only drop-in replacements, but an upgrade, and they're a fairly common choice for replacing this particular pickup as an upgrade (as is the Bartolini NTMB preamp for the stock preamp).

The reason I was hoping to go with the MK1 split-coils is that I've used them a lot in other basses, and really liked them, even with the noisy Ibanez preamp in a Soundgear (I've just rolled off the treble a bit to reduce the noise in that instance). I do understand that the MK1's are not USA-made, "actual" Bartolini's, but I really do like the sound of the MK1's. Perhaps a better question to ask would be which of the USA Bart's that offer "full string coverage" are most similar in tone overall? There's a split coil P pickup, the MK5P or MK6P, for example. But I think that model is even less likely than the MK1 to work for that A string in a slanted position, since it's not a reverse-P.
 
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Do you think I could get away with slanting a five string pickup? I'm sort of presuming here that the five string soapbar with rails could be expected to cover string spread of basses with up to 19mm spacing at the bridge (76mm total). Judging by my own spacing at the bridge (64mm total) this is roughly 15% more than I'd need if the pickup was straight up and down. Obviously that difference is going to be less by the time I look at the neck pickup, since the strings get closer together as they approach the fretboard. I don't know how much top-to-bottom string coverage I'm giving up by turning the pickup at an angle, and so far I haven't found much in terms of internal measurements on the MK1. They are of course not even listed as part of the Bartolini site catalog.

On the other hand, finding a set of 5-string MK1's seems to be much easier than finding the six-string variety.
 
What angle exactly?

Assuming a slant of 25 degrees, that gives cos(25) = 0.9063, meaning you still have 90% of your string coverage. In other words, you only lose 10% of coverage, which is less than the 15% you estimate.

Like I said, you’ll be fine. Go for it!
 
Your assumption was spot on.
 

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