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PostPosted: Mon Nov 22, 2004 2:36 am 
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Enter the patient: an '85 Westone Spectrum DX. In immaculate condition- the late 85's and 86's got this really durable super high-gloss finish. Gloss black shows every flaw, and this guitar was perfect. Bright chrome bridge and tuners with a nice tremolo and locking nut.

Only trouble was, some pirate had stolen the electronics out entirely- no pickups, controls, nothing. Even the strings were still in place.

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The Spectrum DX was a mid to high-line successor to the Electra Phoenix. It offered twin humbuckers, but had a premium tremolo bridge, graphite nut, and locking nut. It offered premium performance at a mid-line price.Check out the Spectrum DX in the Guitar Gallery's Westone catalog section.

Ever since I played Matthew's P-90 equipped MPC, I'd been thinking about installing P-90's in something. It was just about the only sound short of a Dobro that wasn't represented among my guitar family.

I picked up a pair of Mighty Mite P90 clones, and found the DX on ebay. It really looked like the routed cavity for the twin humbuckers was jsut about wide enough for a pair of P-90's about perfectly, if you carved out the corners where the pickup covers screwed on.

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I began by scoring the finish with a sharp razor blade, to prevent the really hard finish from chipping as I chiseled it out.

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Using a very sharp woodcarving chisel, I carved away the corners to the depth of the pickup cavity. It didn't take very long, and the maple was wonderful to carve- firm and reilient, yet yielding to the blade without difficulty.

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It really didn't take very long.

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From my lurking on the reranch forum I know that leather dye is recommended for staining fingerboards dark... and from the bad old days when I used leather dye I know what that stuff is- it's the ink in permanent magic markers. So I felt no remorse in using a black sharpie to color the exposed wood black that was revealed by chiseling. stained it nice and flat black. and it's not ever coming off, no sir.

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Enter the instruments, with covers removed: overwound single-coils, nice and fat.

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They're mounted by a very simple yet effective method: a pair of adhesive-backed foam pads stick into the cavity, the pickups sit on top of them and long sharp wood screws pull them downwards- the foam is much more solid and reliable than hanging on spring trapezes. I'm tempted to do this with the next humbuckers I install.

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A perfect fit! Well, almost. I actually had to take a half millimeter of width out of the pup cavities. But not bad, it really does fit without much difficulty.

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Tah dah! both pickups installed, and it looks bone stock. Now for some wiring!

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I hooked up some jumper wires to a cord, and has the satisfying BARAAANNGGGG of a guitar coming to life! Happy day! I'll tell you what though, a guitar with single-coils and wiring completely unshielded has a lotta hum, lotta hum, I'm tellin ya.

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I set to work planning the guitar's wiring. I'd been looking forward to doing some full-bore modding on a guitar, and this was clearly the one. For sure I wanted an MPC-style rotary switch instead of a 3-way selector switch. I started out by testing different combinations to decide on what order made most sense tonally.

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Then I tested some blend pots I ordered from Stew-mac. A pair of piggybacked control posts, they allow blending or fading from one pickup to the other. I played one of these on a Greco bass recently and realized how wonderful it was.

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I've spent the better part of a week playing around with different circuits and switching arrangements. I can tell you for sure that none of these work:

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...but I've found something that does. I'm still tearing out the last wiring setup to rewire and test, and I expect to have positive result in a few days. I'll keep you posted.

In the meantime, the P-90 DX has besome just a fabulous guitar! The P-90's sound very vintage, very twangy and jangly and wonderful- it's really odd to have such an old-fashioned sound on a guitar that's shiny perfect, excellent action & neck, perfect intonation... and it's pretty...

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The controls are odd, yep. That's a stacked pot for master volume & tone, and the chicken head twists a 4P6T rotary that dials in some whoppin' combinations. The flat black tele barrel knob is the blend, and I've got a lot to say about that but it'll have to wait till I can get the latest version wired and tested- but I promise it'll be worth the wait.


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1985 Westone Spectrum DX X140- custom pickups & wiring.

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Last edited by X189player on Sun Nov 28, 2004 4:51 am, edited 2 times in total.

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PostPosted: Mon Nov 22, 2004 9:19 am 
That is very cool! Did you really expand the cavities and mount the new pickups without ever removing the strings. Awesome :up:

I recognice the heap of non-working diagrams. Looks a lot like my own attempts. A couple of tries are always needed before one works properly. :)


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PostPosted: Fri Nov 26, 2004 3:34 am 
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yep! I was just too lazy to take off the strings, which were in good shape anyhow.

the scribblings all amounted to something- the first version didn't work right, because the blend pots didn't work the way I expected. After some voltmeter tests, I did pull out the wiring and re-wire it a second time with a new plan, which works like a charm! I'll fill you in on the details below.

BTW, playing these P-90's makes me recognize- duh! the middle single coil on a H-S-H Phoenix or Westone. It's very overwound and got that hot twang.


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PostPosted: Fri Nov 26, 2004 5:46 am 
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Since this was going to be a hot rod guitar, I wanted to drop in some kickass wiring mods to really get the most out of the P-90 clones. Having played Matthew's MPC's, including one refit with P-90's, I was a big fan of the MPC-style 'Tone Spectrum Circuit'- a big rotary chickenhead selector switch that offered series, parallel, and out-of-phase options.

But like all hot rods, things get out of hand. I'd just played a Greco bass that had a standard blend switch instead of a selector switch, and I loved the tone shaping control it offered. I installed one in the Telerez, which suffers from a way-too-hot neck humbucker that overpowers the alnico bridge single, and the blend pot actually let me dial that into a usable range.

Of course, It had to be a sleeper, dead stock to all outward appearances. The Spectrum DX only had two knobs, a selector switch, and an output jack, and I didn't want to drill any new ones, nor fit clunky toggle switches.

In place of the standard 3-way toggle, I mounted a 4P6T rotary switch that offered six positions via a nice black chickenhead that blended into the black guitar. The volume position gave way to a stacked pair of chrome barrels for master volume and tone. That left a second knob position free for the blend pot, a faded flat black tele barrel. In three knobs I'd have all the wiring permutations I could dream of. I really like the odd three-control configuration, too. To me it screams HOT ROD!

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Figuring out how to wire it was the really fun part. For those interested the diagrams are at the bottom, so scroll down. For those like me who like wiring mods, I'm going to go off for a little while on how i got to the present design and how it works.

I started by picking up the blend pots from Stew-Mac (they aren't expensive- under 6$), and studied the wiring diagrams that showed a simple replacement for a three-way switch for combining two pickups wired parallel.
You can see these diagrams on the Stew-Mac site here.
Find blend pots in Stew-Mac's online catalog here.
By the way, I've got no connection, they're just one standard source of parts and information, there are others.

So I started out by deciding what I wanted in the mod. All combinations of series, parallel, in phase and out of phase. Plus I like having a position for each of the pickups by themselves, and I wanted to arrange them in an order that made sense tone-wise. Different opinons varied on what that order should be, so I hooked up the pickups with jumper wires and tried them out myself.

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I decided on:

1: N
2: NB series
3: NB parallel
4: NB series, out of phase
5: NB parallel, out of phase
6: B

You could argue this, but I knew I wanted the single pickups at each end and that order made sense to me. You could change the order if you wanted.

Next I began to experiment with blend pots. They did work as described, but that meant wiring the pickups in parallel. What I needed to figure out was how to wire them for series and parallel.

I started one of the best places you can start for something like this, John Atcheley's excellent articles and diagrams on the Guitarnuts page. I pored through them, figured out how all the mods worked, how the switches were being wired, how to read the diagrams. Hats off to John for starters! But there was precious little info anywhere on blend pots, so I figured I'd have to work it out for myself.

In order to undersatand blend pots I could see that there's one most common form of volume control, in which the pot, a variable resistor, is wired in parallel with the pickup. I'm going to call this a bypass volume control, because what it does is reduce volume by bypassing the signal source.

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The pickup is producing this AC current, and it's trying to push it in both directions. If you bypass the pickup with a wire, when it pushes one way, the signal loops around on itself- no matter how hard it pushes, it just spins the current around in the loop and nothing goes toward plus or minus. In fact, other signals can go past without being affected at all. Then, as the resistance increases, the bypass is shut down and the pickup is able to send out signal. So the higher the resistance, the louder the signal.

I always learned to think of this volume controls as 'grounding out the signal', and that's true in a way, but it makes more sense I think to consider it a way of bypassing a signal source. That also makes more sense when you look at multiple pickups.


There is another kind of volume control, though, I'm going to call it a inhibit volume control, because it limits volume by limiting it directly, by placing resistance in its way. The higher the resistance, the quieter the signal, just the opposite of the bypass kind.


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this kind of volume control is used in 'Gibson-style' guitars with seperate volume controls, because each parallel pickup can be limited seperately without affecting the other. You can't use bypass-type volume controls for parallel wiring, because what bypasses one pickup effectively bypasses the other, so it automatically becomes a master, not individual volume.

This is also, as John recently pointed out- why we use 500K pots, not because of humbuckers, but because humbuckers were early on always associated with wiring in parallel.

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Note that it actually doesn't make any difference which side of the pickup the resisistance is on. The signal from the pickup is primarily AC, remember.

Now, with pickups wired in series, if you want to have separate volume controls you've got to use the bypass volume control type, because a direct resistance type is going to affect all the other sources in the chain. Bypass volume control lets you bypass each individual source without interfering with the others.

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So... to wire pickups in series, you have to put them in parallel with their volume pots, and in order to wire them in parallel, you've got to put the volume pots in series with them. And you can take either combination and bypass the whole thing and call it a master volume (as I believe was done on some Gretsches)



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Got all that? Good! Now for the blend pots!

When I first started playing with blend pots, I misunderstood how they work- I thought that at center position, they were about halfway throught heir travel, and would allow roughly 50% of total resistance on each side. In fact, I spent a long time wiring the guitar for this behaviour, which it turns out isn't how they work. At center detent, both sides are supposed to be 100% on! Back to the drawing board, rip out the wiring, and try again.

After spending some time with a voltmeter, I determined that at center detent, both sides are at 100%, which means that the entire working range of each pot is on one side or the other of that center detent. In the old days pots were made with a coil of wire, and this meant that on one side ther was a coil, but on the other half it was a solid wire, no additional resistance at all.

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That also means that depending whether you're using them as bypass or inhibit style volume controls (for series or parallel pickups), you'd need to use one side or the other of them!


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So here's where the Aha! happened for me. I had gone through countless pages of drawings and diagrams trying to figure out how to wire the thing in series and parallel, all with nothing more than a 4-pole switch. (I even considered bigger switches, but they get too physically large to fit into a guitar). I came up with a lot of things that didn't work.

It occured to me that it didn't matter which order you placed the pickup and pot. That meant you could run a connection halfway across, and effectively short-circuit the parallel circuit into series, and still have a pot for each pickup. Sure, it was crazy, sure it meant switching which pot affected which pickup... but if I was using a blend pot, they were all on one knob anyway... waitaminute... the light started to go on....


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For those truly looking for cheap reckless thrills, I offer the above as a cheap and dirty way to wire a series switch in their Gibson-style guitar (yeah, you have to reverse one set of leads, selector to ground). Realize that not only will this fire your gitar into series, it will invert the volume controls- not only will they control the opposite pickups, but 10 will be quiet and 0 will be loud loud loud! How useless is that? Well, it's a pretty good ricky racer hot rod trick, with nothing but a single SPST switch. But back to our story...

This new configuration opened the door to how I could combine series and parallel with a blend knob. To switch from parallel to series mode, a switch would connect A with N1 (or N2 in phase reverse mode). Likewise it was easy to just switch which side of the blend pot to use, making the center position either zero resistance (for series) or max 500K resistance (for parallel). Bypass the blend pot entirely for Neck or Bridge pickup alone.

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I wired it up and it works, it works like a charm, it's awesome, I love it! I get a wonderful range of tones in every register, and it feels like such a hot rod...

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For those who want to try it, here's diagrams:

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Next guitar I wire this in, I might consider using only a 4-position switch, and opting out of the neck-only and bridge-only positions, since I can get them with the blender in every position anyway:

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Finally, here's a deluxe version with coil tap (which you could adapt to the 4-position as well). I'll be installing this in my next Explorer project:

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All comments and corrections most welcome. Try this one, it's pretty cool!

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PostPosted: Sat Nov 27, 2004 1:24 am 
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What a great looking machine and now with the mods, Oh boy, its just to much.
This has got to be up there with the top ten threads with so much useful info.

I think the blend pot is a great idea to give us another option not often discussed.
I'd like to try it in a H/S/H guitar to tweak the middle p/up between the neck and bridge.

Normally the center p/up is on 100% or off. I'd like to use the blend pot to turn it on then
dial it in from 0 to 100% with the neck and bridge together then N and B separately.

That means I'll have to find a push-pull blender wired to feed the 2 different settings.
Sounds simple but probably more complicated in application.

What program did you use to make those excellent diagrams?


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PostPosted: Sat Nov 27, 2004 3:23 am 
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I used Visio for the diagrams. Glad you liked the info! I've been beside myself with excitement getting blend pots working the past couple weeks, but i wanted to wait to say anything about it until I got it wired and working for sure!

Blend pot for the center pup would be a natural- good idea! The only problem is that blend pots don't come in push-pull varieties, so you'd have to lose a knob- but you could sacrifice one of the tone pots (i like a master tone anyway myself). Make the center knob a blend- hmm, great idea! I've got a couple of project bodies routed for H-S-H, sounds like a great option for one of them!

here's a diagram- note that the two signal feeds to the blender are coming from the center pup and from the selector switch. I converted the bridge pup to a master tone, but in keeping with the original H-S-H scheme I didn't have it affect the center pup. you could turn it into a true master tone by connecting it to the volume pot (at the center lead) instead of to the selector switch.

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PostPosted: Sun Nov 28, 2004 8:15 pm 
What fun :) ! I too like to experiment with different PUs permutations , both my cardinal 250 & 350 has modifications added to widen their tonal possibility , though I limit myself to use DIP switches mounted at the back cavity for added switching , not very practical , more as a preset option .Fun non the less . .
x189player , I'm curious to know that in your wiring experiment process have U come across wiring plans similar to those VCC controls that's on current W***B*** guitars (Single pot to vary between Series & Parallel connection on a Humbucker) ? Been wanting to try it out myself . .


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PostPosted: Sun Nov 28, 2004 9:21 pm 
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I've heard of them but haven't seen the circuits, I'd sure like to. Call me dumb, I can't recall the manufacturer you're alluding to...


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PostPosted: Sun Nov 28, 2004 10:21 pm 
It's Washburn Idol series , will let U know if I can find it .
Oh . . Great post btw !


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PostPosted: Tue Nov 30, 2004 2:12 am 
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That is great. Now I have no excuse not to do this mod.
All the work is done.

1 master tone is a good idea. Why bother dilly dallying with 2 of them.

Thanks a ton for the diagrams.


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PostPosted: Tue Nov 30, 2004 10:20 am 
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That looks and sounds like a fantastic guitar. I'm glad my P-90 swap inspired you to try them out in a Phoenix. Good work!

Matthew


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PostPosted: Fri Dec 10, 2004 9:31 am 
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I got a chance to play the P-90 Hot Rod last night when Paul came by to pick up the X-199 he lent me a while back. Very, very cool guitar. The Mighty Mites sound great and the blend knob really lets you hone in on any combination of chime and growl you might want. I'm not really a fan of strat-style guitars, but I have a feeling this one would get played a lot if I had it around. I don't need any more guitars right now, but I have to admit I'm considering attempting a similar project on my own in the future...

Matthew


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