What the heck am I looking at here? Ibanez SR885 content

[MarTONEbass]

This is an Ibanez SR885, made in Japan in 1991 from what I am reading. The party I bought it from stated that the preamp was fried and after reading up on the bass a bit, some people said it lacked output, so I knew I was going to replace at least the preamp when I bought it.

I set to disassembling the bass and I came across the strangest thing: underneath the jazz pickups are what appear to be another pair of single coil pickups. There are wires and everything. They were hooked up inside the control cavity, but I snipped the wires to remove the preamp, so I don't know how it was wired.

In 25+ years of playing bass, I have never seen or heard of such a thing. Does anyone have any info on what is going on here?

 

[Solarmist]

That's a new one on me, and I've been an Ibby SR guy from early on. Waiting for more responses.

 

[Doctor J]

Dummy coils for hum cancelling.

 

[josiah goldfish]

Exactly that. I made a ramp for an ibby fretless in place of the neck pup (no visible screws, just slots into the pup rout) and was surprised to see the extra pickup too.

 

[vxjoe]

I have the same bass. No need for hum cancelling on mine. I think the OEM pickups were proprietary. Search for the Ibanez forum, there was info on the bass last time I looked.

 

[MarTONEbass]

Well, you learn something new everyday, never heard of that. Thanks.

 

[PortlandBass77]

Holy shithead! I have never seen or heard of anything like that! Do they actually work at hum cancelling, or are they just a novelty?

 

[Doctor J]

Some pickup manufacturers have the dummy coil attached to the bottom of the pickup itself. It's actually quite a common technique. They dummy coil isn't magnetised so you can get real single coil sound without the noise. Very simple but very clever. If you think of Alembics, that black piece between the two pickups is their dummy coil. They have the best explanation of how it works too.

The coil with the magnet "hears" the string, and the air coil only hears EM which it will cancel out of the other signal. This is what the Series bass is doing. The pickups are true single coils; the hum canceller (shared by both pickups) is a coil with no magnet which only serves to remove the hum when summed with the pickups. The EM/hum radiation is basically going to read identically anywhere on the instrument, so, with proper matching, you should be able to perfectly cancel the hum with minimal effect on the single coil sound.

 

[MarTONEbass]

Thank you for the info, it's fascinating!

 

[Standalone]

Is this what they mean by AFR pickups -- "Active Full Range" ? The copy on the 1992 catalog talks about how they are noise-free. They're not my absolute favorite pickups, but now I'm thinking it might be worth playing with the preamp a bit and changing things out on my 885.

Ibanez Rules 1992 US Ibanez Catalog