Re: Taming the Bass in a C5?
The C4 is my favorite Custom. I have them in my 57 reissue LP Custom, my Explorer and my Jackson DK1.
A4's have a very balanced EQ. No brittleness of a ceramic. No boomy low end and sometimes peaky highs of an A5 (polished). No loose, syrupy bottom and mid heaviness of an A2. For me, the C4 just works. I use A4's in other winds (Brobucker, '59 neck) with similar results. My experience with them has been the bottom stays tight and the highs are never grating. In the Explorer and DK1 there is a certain creaminess not present with the other mags.
I have not tried a UOA5 yet but I wasn't impressed with a rough cast A5 either. Give it a try and see what happens.
+1. A4's have more uses than most people realize. Being unoriented, they have some complexity in their sound. Having a relatively flat EQ is a virtue to some players, but certainly not all. If you're used to a big EQ push, an A4 can seem rather bland.
But, that does let more of the PU and wood's natural sound come thru (which may or may not be a good thing). Lindy Fralin is a big proponent of A4's; I had a long conversion with him a few years ago, and he's sold on their virtues. Another of his strongly-held beliefs is that thick necks are an important part of tone quality.
A5's in the neck slot have a often-desirable sharp high end. But with that comes a low end that's sometimes overbearing. I've used A4's in place of A5's in bridge PU's to tame the high end, but want use them in the neck too, to cut out the occasional A5 bassiness (I went a different route and used spin-a-split and hybrid coils to thin out neck HB's).
RC A5's have a slightly different in tone, mainly taking off a little high end harshness, and sometimes that's all you need. I would have never believed that an UOA5 is at all related to an A5, had I not tried some right after Addition FX showed up here as the forum magnet supplier. First PU I put one in was a C5, and I was amazed at the warmth and rich texture. Everything I didn't like about the C5 disappeared, and without the drawbacks of an A2.