BC Audio
Member
- Joined
- Feb 16, 2010
- Messages
- 119
Can't figure out Gibson "split-coil" P90s
This is the guitar I'm talking about: http://www2.gibson.com/Products/Ele...es-Paul-Traditional-Pro-Split-Coil-P-90s.aspx A special run for GC, apparently. I've had two of these now.
I thought these guitars were wired incorrectly based on my measurements of the resistance of the pickups. But based on listening to them, it seems as though the "tap" in the P90 is not just a tap at some point along a single winding, but that there are two coils, one of which is wound in the opposite direction - or something. I can't find any specs on these pickups.
The DC resistance measurements don't match the specs on Gibson's web site (the link above):
Specs:
Bridge 8.6k, 6.4k tapped
Neck 7.0k, 5.0k tapped
My measurements (taken w/ pickups in the guitar):
Bridge 5.0k, 1.3k tapped
Neck 6.2k, 1.8k tapped
Ok, so the first thing is that the bridge and neck pu's seem to be reversed. But more strange are the super-low resistance numbers. It seemed obvious to me - something was wired wrong.
Here's how each pickup is wired in the guitar. There are three wires from each pickup: bare ground wire, white and black. WHT is connected to the top of the Volume pot, and BLK is connected to the pull switch that shorts to ground when pulled. From this I would surmise that WHT is the full coil and BLK is the tap.
Here's where it gets weird. On the bridge pickup, I measure 5.0k between WHT and GND, 6.8k between BLK and GND, and 1.8k between BLK and WHT. Like this:
GND --- 5.0k --- WHT --- 1.8k --- BLK
Naturally, this lead me to believe that BLK is the top of the winding and WHT is the tap. So I wired it that way. And it sounded awful. The 6.8k "full" winding sounded thin, almost out-of-phase. The 5.0k portion of the winding sounded fuller, with much more low end. So I put it back to stock wiring and commenced head-scratching.
With the pot in the normal position, BLK is not connected to anything. The output of the pickup is WHT.
With the pot pulled up, BLK shorts to GND. So you effectively have GND --- 5.0k --- WHT --- 1.8k --- GND, which is two coils (or portions of the same coil) in parallel. My measurements confirm this, as 5.0k and 1.8k in parallel = 1.3k which is what I measured in the up position.
Anybody have any more info on these pickups? I might just dump 'em and get some good replacements, but I'd really like to know what's going on with these.
Thanks.
This is the guitar I'm talking about: http://www2.gibson.com/Products/Ele...es-Paul-Traditional-Pro-Split-Coil-P-90s.aspx A special run for GC, apparently. I've had two of these now.
I thought these guitars were wired incorrectly based on my measurements of the resistance of the pickups. But based on listening to them, it seems as though the "tap" in the P90 is not just a tap at some point along a single winding, but that there are two coils, one of which is wound in the opposite direction - or something. I can't find any specs on these pickups.
The DC resistance measurements don't match the specs on Gibson's web site (the link above):
Specs:
Bridge 8.6k, 6.4k tapped
Neck 7.0k, 5.0k tapped
My measurements (taken w/ pickups in the guitar):
Bridge 5.0k, 1.3k tapped
Neck 6.2k, 1.8k tapped
Ok, so the first thing is that the bridge and neck pu's seem to be reversed. But more strange are the super-low resistance numbers. It seemed obvious to me - something was wired wrong.
Here's how each pickup is wired in the guitar. There are three wires from each pickup: bare ground wire, white and black. WHT is connected to the top of the Volume pot, and BLK is connected to the pull switch that shorts to ground when pulled. From this I would surmise that WHT is the full coil and BLK is the tap.
Here's where it gets weird. On the bridge pickup, I measure 5.0k between WHT and GND, 6.8k between BLK and GND, and 1.8k between BLK and WHT. Like this:
GND --- 5.0k --- WHT --- 1.8k --- BLK
Naturally, this lead me to believe that BLK is the top of the winding and WHT is the tap. So I wired it that way. And it sounded awful. The 6.8k "full" winding sounded thin, almost out-of-phase. The 5.0k portion of the winding sounded fuller, with much more low end. So I put it back to stock wiring and commenced head-scratching.
With the pot in the normal position, BLK is not connected to anything. The output of the pickup is WHT.
With the pot pulled up, BLK shorts to GND. So you effectively have GND --- 5.0k --- WHT --- 1.8k --- GND, which is two coils (or portions of the same coil) in parallel. My measurements confirm this, as 5.0k and 1.8k in parallel = 1.3k which is what I measured in the up position.
Anybody have any more info on these pickups? I might just dump 'em and get some good replacements, but I'd really like to know what's going on with these.
Thanks.
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