A3 has a very weak magnetic field, so a softer response but also a greatly reduced output.
For a long time the prevailing opinion was that A3 was not strong enough to handle a heavier wind.
However, it seems to do quite well in the Custom wind. Yields a crisp tone with a vintagey attack.
Forum member
orpheo once described it as a PAFish tone yet with hotter-than-vintage output.
Substantially less output than the SH5 Custom of course.
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Hex poles do generally tighten up the bass response in humbuckers and add come extra clarity to the highs.
IMO the difference might not be enough to entirely compensate for the loose feel of a soft magnet.
But for modding an existing pickup it might help a lot. IMO definitely worth trying as the easiest option by far.
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A more significant change might be to address the magnetic issue directly.
I see two basic possibilities, though probably there are others that haven't occurred to me.
First possibility, changing the magnet.
I love the UA5 in bridge pickups: fairly vintagey mids combined with tight lows and strong highs.
Quite a bit more output than A3, but it doesn't have the same kind of low-mid hump.
Neither does A6, which is fat and loud, almost like A8 only with much mellower highs.
Switching to a different alnico might alter the voicing more than you want in this case, anyway.
Double thick bar magnets are another viable option here.
There's a forum member who has made custom doublethick bars in various combinations for a few of us.
Not sure he's still doing it currently, but if you're interested in getting one I could reach out to him and ask.
Double A3 gives more output and bigger lows, but probably wouldn't deliver the extra highs you want. I have one of those.
Perhaps a double magnet made from A3 layered with A4 or A5 could be an option?
An A5 layer would boost the power, tighten & enhance the lows, and make the highs more modern and cutting.
It might also impose a more aggressive character, emphasizing the upper mids as well as the highs.
An A4 layer would keep the midrange voicing pretty even, while tightening the lows and keeping the vintagey sparkle up top.
It would also give some extra output, just not as bright in the highs or as deep in the bass as A5.
I have a double thick hybrid made from A3 and UA5; it's got more upper-mids than A3 but is definitely stronger and brighter.
But there's a reason why the majority of humbuckers are still made using A5.
Second possibility, magnetic spacers - boosting the primary magnet while adding a different flavor.
One A4 or A5 spacer would likely tighten up the lows and give you brighter highs without revoicing your mids too much.
A single ceramic spacer could be an option too, but its strong field might overpower the personality of the much weaker A3.
Haven't done that so I can't offer an opinion.
If using just one auxiliary mag, I'd place it next to the screw coil for enhanced treble at the bridge.
Using two magnetic spacers is an option too, of course, but would alter the voicing more.
Not sure whether you want to experiment with the neck pickup too - IMO for neck position a plain swap might be preferable.
A4 or UA5: both have fairly vintagey mids and bright, open highs.
But adding magnetic spacers is also an option here.
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As a more elaborate alternative, if you're ambitious and experienced you might think about changing out the slugs.
Not something you'd want to do to a vintage Ibanez pickup of course.
But an option for pickups that aren't collectible.
Replacing the steel slugs with rod magnets yields a more singlecoily voice even when in series, but especially so when split to the slug coil.
Adds immediacy to the pick attack thanks to their tight focus and proximity to the strings.
It's a more modern feel - still, I think using A2 rods should preserve much of the vintagey midrange character.
A2 rods are rich and plenty bright, but don't have the loose lows as when A2 bars are under the coils.
