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Discussion Starter #1
I recently decided to swap out the stock humbuckers in my Korean Tokai Love Rock with some humbucker-sized P90's. I ordered a set of cream coloured Kent Armstrong (KA) Convertible P90's and a set a BG-Pups Pure 90's in Black/Chrome. I figured I'd try'em both out, and hold onto or sell the ones I didn't prefer. I received the KA's first and upon installing them was shocked at how gritty and bright the bridge pickup was. The sound was great, but where I used to have my tone set fully open (10) with the 'buckers, I was now riding it closer to closed (between 2 and 4) depending on the song. Dialling the tone control from ten down to about five made no difference to the sound - bright, bright, bright. Only under 5 did the tone control start to roll-off the high-end. I noticed that with the neck pickup the tone control behaved "normally" or as you would expect. But the sound of this bridge pickup with the tone set around 4 was everything I was looking for so I wasn't too worried about it. The only problem was that the cream of the KA pickups didn't match the yellower cream of my Tokai accoutrements. I told myself not to care about such trifles.

Then I got the BG-Pups I dropped them in. The first thing I noticed with the BG-Pups dropped in was that the tone control seemed to return to normal - that is fully open (10) was fully bright and turning it down yielded nearly immediate and gradual results - similar to how the 'buckers responded to the tone control. With the tone control fully open on the BG's bridge pickup I got a similar sound to what I was getting with the KA's bridge with the tone control set to around 4. The BG Pure 90's sound was a little less gritty and aggressive, but fuller and deeper. Frankly I think that most people would have preferred the BG Pups sound (and they look smokin' in the guitar), but for the project I'm currently working on the KA's bitier, grittier and slightly thinner sound was my choice.

Having decided to stick with the KA Convertible 90's I ordered another set in chrome since the cream ones didn't match the cream on my Tokai. I got them and dropped them in. I was surprised that the tone control remained "normal" with this chrome KA bridge pickup - that is it behaved like it had with the 'buckers and BG-Pups. Furthermore, this chrome KA bridge pickup didn't have quite the same grit and bite that the cream one had. I considered that the difference might be the chrome casing, so I popped it out of the chrome cover, and while that made a slight difference in tone, it didn't make up for the vast difference in tone between the chrome KA bridge and the cream KA bridge. I thought that perhaps I'd missed something when installing the cream KA's the first time - failed to solder a ground wire or something on the bridge pickup - so I reinstalled it and sure enough it were as it had been before - overly bright and shrill with the tone at 10, but freakin' awesome with the tone around 3 or 4.

So I now believe that there's something "wrong" with my cream KA bridge pickup and that the chrome KA, BG-Pup and the original 'bucker are "proper". The KA Convertible 90's have three wires, a white that goes to the pot, and a red and ground that both get grounded. I've triple-checked my soldering and it's right.

Because the cream pickups are sealed into the plastic cover with a black epoxy I can't easily open them up to inspect what's going on inside like I could with the chrome versions. Nevertheless, mismatching cream colour and "tone weirdness" aside I've left the cream KA's in the guitar because I love the sound I'm getting from this "improper" bridge pickup.

As I'm new to guitars and their electronics (I come from a vintage synth restoration background) I'm curious if anyone here with more knowledge than I of the inner-workings of pickup electronics might have an idea about what's going on with this cream coloured KA Convertible P90 bridge pickup that isn't happening with any of the other pickups I've purchased and installed?
 

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If you measure it while it's still soldered you'll get a different reading because you're reading the whole circuit. It may be interesting to see what it reads as you turn the tone pot.
 

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Discussion Starter #7
I say if it's the tone you want use it!
You can always put the chrome cover on it

Nathan
Well a chrome cover won't fit over the cream cover, and the cream cover can't be removed without some serious futzing because the pickup is epoxied into it. Nevertheless the color isn't a huge issue for me, I'm just curious to investigate what might be odd about this pickup that's causing it to behave differently to the others. I'm new to guitars and their electronics so I'm curious to poke around and maybe learn a thing or two in the process.

And to that end . . .
 

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Discussion Starter #8
The "weird" cream KA bridge pickup measures the same on my meter as the "normal" chrome covered KA bridge pickup.

I tried measuring it in circuit by attaching probes to the pickup wires where they connect to the volume pot (8.1K), by attaching probes to the end of a TR cable connected to the guitar (8.1K), and by completely removing the pickup from the circuit and measuring it directly (8.4K), which is also exactly what the "normal" behaving pickup measures. Altering the setting of the Tone pot didn't change resistance reading of the pickup at all (when measuring from either location), it just remained 8.1K. BTW, the pots are wired 50's style . . . not sure if I mentioned that before.

When I have time tonight I'm going to try running it through the neck circuit (with the neck volume and tone pots) just to see if it still behaves strangely. I'm guessing it will.
 
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