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PostPosted: Wed Apr 01, 2015 11:20 pm 
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Mark IV

Joined: Thu Aug 15, 2013 12:20 am
Posts: 646
Location: Tucson, AZ
https://warpedmusician.wordpress.com/20 ... r-sh-4-jb/

I've been messing around again. This is better than having a tone knob.

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2007 3 Channel Dual Recto w/loop mod

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PostPosted: Thu Apr 02, 2015 1:28 pm 
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Single Recto

Joined: Thu Jul 21, 2005 2:56 pm
Posts: 1691
Location: Pacific Coast
Thanks for the link!

Yeah, Seymour Duncan JB SH-4 is somewhat a peculiar pickup. It has a lot of windings, yet its a fairly mild pickup. And the way the article describes this mod, seems like this mod is NOT for any humbucker pickups.

Cool that you used a 25k ohm pot (for low impedance pickups or active pickups e.g. EMG) 'cause I want to tried that on my LP build and I could obtain long shaft 25k pots (I think).


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PostPosted: Thu Apr 02, 2015 3:16 pm 
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Mark IV

Joined: Thu Aug 15, 2013 12:20 am
Posts: 646
Location: Tucson, AZ
Yeah, the 25k was more about having a good linear pot, but it worked out really well. The pot I used was from a Marshall amp clone that is kaput.

I think the only change I might make is to put a 15k or 22k resistor to ground, but 100k pot would also be groovy and could be approximated with a 250k pot with a 180k resistor across it or a 500k long shaft pot and a 120k resistor. Guitar pots and resistors are easier to get than digging through a parts supply place for the right pot. Those changes would keep the tapped coil from becoming so weak as to not transfer the vibrations and give a person the ability to jack the power back up to near the original output, but retain the offset.

It's my opinion that this mod puts a JB into the general neighborhood of a Duncan Custom. It's a little different, since the offset between coils is more exaggerated. This mod is meant for any well balanced pickup that has a definite mid spike from that lack of phase cancellation. My JB became very smooth with a tight bass. If performed on a PAF style pup, the pot would need to be large (500k to 1M) to make as little impact on the pickup when the pot is on.

BTW, that's my blog. When I'm not sick, I do some small projects or decode schematics. I used to build pedals and work on amps, but sh!t happens.....

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PostPosted: Fri Apr 03, 2015 1:02 pm 
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Single Recto

Joined: Thu Jul 21, 2005 2:56 pm
Posts: 1691
Location: Pacific Coast
... I really appreciate your blog then! :wink:

Yeah, as much as like PAF pickups, (I am a weekend warrior luthier), I find that sometimes you have to match the guitar bodies with PAFs. As you stated and my experience, PAF do sound sound "thin in the midrange" kind of a hollowness. This hollowness could be exaggerated with different guitar bodies. Maybe to ones liking, maybe not.

But that's pretty cool you sweep through impedances with the pot with the SH-4. Now I'm bummed out because I did sell one of my JB model. Its that I got from a friend who traded for my SD (don't recall the model). But then in another forum a member wanted to buy a JB model pickup. So I sold it to that member.


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PostPosted: Fri Apr 03, 2015 2:46 pm 
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Mark IV

Joined: Thu Aug 15, 2013 12:20 am
Posts: 646
Location: Tucson, AZ
I like the hollowness, honestly. Sometimes I want "in-your-face" tone, but the affect on the bass and the overall bright, punchy tone is nice. I actually did this on a LTD AX-2E, which looks like a classy BC Rich. The maple neck-through with mahogany wings and ebony board make the strings seem snappier than other guitars I've played. I've had three or four pups in it and they all end up sounding different than my alder or sapele guitars. I know that solid body guitars don't have the same sound contribution from the woods as other types, but the strings must vibrate a little differently depending on the density of the wood and the bridge.

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2007 3 Channel Dual Recto w/loop mod

My Humble Music Tech Blog:
Dual Rectifier Index


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