Top mounted pickup info

[LARRY KLOSE]

I'm considering replacing a top mounted pickup on my archtop and am wondering where  are diagrams or illustrations on what I will encounter when I get in there--and whether it needs professional attention.  No tap on the coil or other complications I'm aware of.  I was an assembler at a major amp manufacturer long ago so I'm quite familiar with soldering and I've messed with minor repairs from time to time.

Larry

[Thomas James]

Do you have photos? What model/brand? The hardest part can be fishing the harness out, and more importantly, back into the guitar.

[LARRY KLOSE]

It's a Steve Andersen Vanguard from about 2003.  Full archtop body with the pickup mounted on the top in neck position and two pots on the lower treble bout.  To get pix I'll have to open it up.  I did that once but I've re-assembled it and have been playing it since.  It appears that it was originally equipped with a Kent Armstrong top mount PAF--I found an archived dealer page with the same ax (same serial no.) that shows the KA pickup and it's consistent with what he was using at the time--black KA with two rows of adjustable pole screws.

When open,the wiring looked like two wires to the Pup and it appears that the original pots are intact--volume and tone. Both are functional.  It doesn't appear that there's a lead for a coil tap.

Some time later it was changed out to a Seymour Duncan Humbucker, single offset row of pole screws with gold cover.  No model number indicated anywhere I can find (and if anyone knows how to ID these, please let me know the secret place it's shown)-just a stamped Duncan logo on the bottom.  Looking at the SD site, it would be a difficult task to ID without a model number--there are dozens.   Also stuffed inside the body was a great deal of acoustic foam surrounding the pickup--stuffed tightly into the body.  That really helped the acoustic tone of the guitar.<G>  I'm guessing that the purpose was to use to suppress feedback with loud picking.  The guitar wasn't used much, however--codition is very clean and there's minimal fret wear.

Would measuring the impedance across the Pup leads with a multi-meter and comparing that with those on Duncan's list give me an idea of what I'm dealing with?

I think the Pup is too bright for jazz, which is what I want to use the guitar for.  I'm looking for a more sweet and mellow, classic sound.  I'm thinking about a Lollar Imperial which Andersen has used a lot in recent times. 

Thanks,

Larry

[Andrew]

Duncan pickups come with a sticker on the bottom that indicates the particular model, at at least they do currently. I wouldn't be surprised if many of those stickers end up coming off eventually. Measuring the impedance against their product info would be a good start - you should at least be able to narrow the list down significantly. Its also possible the pickup was a custom order from them. Their customer service/tech department was very helpful for me once in diagnosing a defective pickup, friendly and easy to talk to. Itd be worth it to give them a call.

As Thomas pointed out, the main challenge will be getting the components out and back into place.

[LARRY KLOSE]

Thanks.  I will take a look inside again and see what's in there when I have a chance.  Is the pickup itself generally just a two wire hookup to leads that go to the remainder of the harness or is it more complex than that?

Larry

[Joshua Levin-Epstein]

Hi Larry,

Some humbuckers come with single conductor and shield, others with 4 conductor plus ground. Just follow the instructions (no post graduate degree required).

What you want to do is not a big deal. I would start at the SD site and get a copy of the appropriate diagram (LP jr, single pick-up volume & tone). That's your back up plan. The easiest  way to do this is to leave the current harness intact, pull it out and use it as an example. You're going to replace the most expensive part (the pick up) so just buy a couple of new pots, a cap and a jack (and some wire, maybe). Get a piece of cardboard and copy the pattern of holes from your guitar. This will hold everything while you make the connections. You should make yourself a tool like this :http://www.stewmac.com/Luthier_Tools/Tools_by_Job/Tools_for_Electro...

and go to town. I fish the pots through using heat shrink tubing. I fit one end of a long piece through the appropriate hole onto the shaft of one of the pots. The pots are connected together so you pull one into place and the other follows. While I envisioned your guitar like a ES 175, it is possible you have a endpin jack . The process is the same and perhaps a little easier, as the end pin jack will ground the strings when it is tightened against the tailpiece. Otherwise you'll need to run a ground  from under the tailpiece to the output jack (which occasionally gets forgotten...).

The benefit of getting all new parts is they are easier to work with compared to de soldering etc. It will also be easier to swap back if you change your mind.

As an aside, you might want to (or not) add a High Pass network across the in and out of the volume control. This is typically a .001 mfd cap and 150k ohm resistor in parallel across the two lugs. In theory, this keeps the highs in and evens the taper as you turn down. Lots of examples online.

Without being flip, it has probably taken me longer to type out these "instructions" (leaving time for my index fingers to cool) than it will for you to do the swap.

[LARRY KLOSE]

This is an archtop, laid out like an ES 175, with the jack on the rim of the lower treble bout and one neck pickup.  Andersen is a custom builder so I would like to assume he used high quality stuff and that the pots and the harness can be retained for the new pickup.  The volume control works fine, so I suspect it has a high pass network already.  The tone control is also very linear.   I'll find out for sure how it's riggedwhen I get my endoscope (see other thread).

I'm assuming that the Lollar pickup comes with wiring diagrams as well.

Pics of the guitar with the original Armstrong pickup here: http://www.myjazzhome.com/03_Vanguard.shtml

Larry

PS re Andrew's comment: there's no model sticker on the back of the SD Pup.  It's either flown the coop (maybe it stuck to the acoustic foam that was packed inside) or was never there.