Starfire Wiring

Recently I read over some posts discussing the various pros and cons of the typical wiring schematics used by Guild. This got me curious about what inside of my 1967 Starfire IV. For those of you who haven't seen, here's the Starfire wiring layout from the Guild website:



Here's the wiring layout from my 1967 (from a redraw I did in Photoshop):



The major difference is the pickups are wired to the outer lugs instead of the middle lugs. The ground is also wired up differently. All pots are CTS, dated from 1966 to early 1967. The .01mf is a mustard cap. The .047mf is an MKS film - obviously a recent replacement prior to my purchasing the guitar. Also of note, all the pots are 500K, except for the neck tone pot, which is 200k. I didn't actually measure all the 500Ks, but I took a measurement from the bridge tone pot and got 420K and I noted that the other two pots had the exact same part #s...

So, why do the pots have three lugs (ground plus ?) and what is the sound/tone difference of using one log or the other? I can come up with good guesses but it's easier just to ask and know.

Thanks.

The top one is more of a Gibson style wiring in my experience, the bottom one (your guitar) is what people sometimes refer to as "decoupled", because when both pickups are selected, you can turn down either pickup without it influencing the other. I think Rickenbackers are wired that way too.

My own Guilds are wired that way, and most of the ones I've played - but my experience is really pretty limited to late fifties to mid sixties Hoboken built electrics.

Hans could probably tell you when Guild stopped doing that wiring scheme.

FWIW, my '71 JS II also uses the middle lugs the same way the '67 SF as built does. Is it possible that there is no electrical significance to which lug is used?

fronobulax said:

FWIW, my '71 JS II also uses the middle lugs the same way the '67 SF as built does. Is it possible that there is no electrical significance to which lug is used?

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Walter Broes said:

the bottom one (your guitar) is what people sometimes refer to as "decoupled", because when both pickups are selected, you can turn down either pickup without it influencing the other.

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I think this is the difference, not? This leads me to ask a question of my own. In the "decoupled" setup, are the volume controls completely independent? Can you turn one all the way down without cutting altogether?

Walter Broes said:

the bottom one (your guitar) is what people sometimes refer to as "decoupled", because when both pickups are selected, you can turn down either pickup without it influencing the other.

Click to expand...

I think this is the difference, not? This leads me to ask a question of my own. In the "decoupled" setup, are the volume controls completely independent? Can you turn one all the way down without cutting altogether?

Click to expand...

No, my volume controls are not independent. I cannot turn one control all the way down, with the switch in the middle position. Maybe I'm completely out to lunch here, but I thought that the first layout is a common variation on the modern Gibson that does have independent volume controls.

I'm more interested in trying a design that isolates the capacitor from the pot input -- similar to the so-called Gibson 50s wiring. My biggest complaint about my guitar is that the tone turns to mud as soon as I roll off the volume, regardless of switch position...

Well, I probably misread the wiring schemes posted, sorry.

In the typical Hoboken "Guild" wiring scheme I was talking about, the volume controls *are* independent, and you can turn one pickup down entirely in the middle switch position without it affecting the other one.

The drawback of the "decoupled" scheme is that things turn to mud even faster when turning down, and that when everything's turned down, it tends to hum.

I'm only talking from experience and messing around with what I have, I couldn't give you the technical explanation as to why a certain wiring scheme behaves a certain way.

I do know that for pots with a value higher than 250K, the taper gets pretty lousy, 500K pots don't have that great a taper, and 1 Meg pots are even worse. But a 250K is not an end-all solution either, because it eats a lot of treble compared to the higher values.(and that's with everything turned all the way up)

There's a pretty widely published modification that involves a cap and a resistor that helps retain highs when turning down, the "treble bleed mod" - I've never tried it because I actually like the effect of a pickup losing highs when turning down.

And there's a schematic of "old style Gibson wiring" on the Les Paul forum's home site, if you're looking for that one.

Walter Broes said:

There's a pretty widely published modification that involves a cap and a resistor that helps retain highs when turning down, the "treble bleed mod" - I've never tried it because I actually like the effect of a pickup losing highs when turning down.

And there's a schematic of "old style Gibson wiring" on the Les Paul forum's home site, if you're looking for that one.

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Right on. I'm going to be trying one of those schematics soon. Only nuisance is digging out those darn pots from the Starfire body... :x

I agree about the volume pot values... 500k seems to be a good compromise for many applications. Seems like tone pot value is of far less importance.

lautmaschine said:

Only nuisance is digging out those darn pots from the Starfire body... :x

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FWIW, my experience is that the Starfire has been the easiest archtop to work on in this respect.

So, I tried the following wiring tonight. This has decoupled or independent volume controls in the middle position. It also features the so-called Gibson 50s or brightness mod that supposed retain pickup brightness as you roll off the volume. I've heard through the grapevine that combining these two mods reduces the effectiveness of the brightness mod.

My take is the difference in brightness is subtle but noticeable. The independent volumes is very cool though and is not as noisy as I was expecting. In fact, I don't really notice a noise increase -- but perhaps my ears are tired.

If I try any other variations, I'll report back...

Walter Broes said:

The drawback of the "decoupled" scheme is that things turn to mud even faster when turning down, and that when everything's turned down, it tends to hum.

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Definitely so.
I started here a few of those 'wiring approach' threads mentioned by lautmaschine.
Decoupled volume pots gave me a very noticeable hum when both pots were turned down.
Now I have "coupled pots" (that is, turning a pot down in the middle position affects both pots and lowers the overall volume) and use the master volume to adjust the general output (mine is a SF V though).
I love the 'treble bleed' mod, but I've found that not all guitars need it. Further you have to experiment quite a bit before finding the right capacitor (or capacitor + resistor in parallel) value to have a smooth, good effect that does not thin the tone.
Re: pot value. I don't remember what value are the pots in my SF V now. But after all I believe that we all love the somewhat trebly tone that our Guilds deliver, right :wink: ? So maybe 250k pots would tame the treble a bit too much. Trying 250k or 300k pots as tone pots might yield fine results though.

slidincharlie said:

Walter Broes said:

The drawback of the "decoupled" scheme is that things turn to mud even faster when turning down, and that when everything's turned down, it tends to hum.

Click to expand...

Definitely so.
I started here a few of those 'wiring approach' threads mentioned by lautmaschine.
Decoupled volume pots gave me a very noticeable hum when both pots were turned down.

Click to expand...

There is some hum on my guitar with the decoupled volume pots, but I did not find it to be terribly noticeable. What I gained overall was significant, however. The pickup blending possibilities were much better. With the coupled scheme, for example, my bridge pickup disappears almost entirely from the mix after rolling down below 8 or 9.

Here's another layout I tried tonight. This is a coupled scheme that simply wires the cap to the switch instead of the pickup.

Without a master volume I actually hate the two-volume configuration, because it makes difficult to adjust for the wanted volume when I play in the central position (both p.u. engaged).
I do prefer to wire a 2-pickup guitar with just one volume pot and two tone pots, so I can control the overall volume much better. Of course in this way I lose any chance to blend the pickups, but I retain the possibility to adjust the tone of each pickup.

I don't mind the two pickup volumes too much, I had to get used to it with my first Guild, coming from a Gretsch with master volume, but now I like it. You can almost keep the guitar in the middle position all the time and work the volumes to get the pickup you want.

Strange how some guitars with the decoupled wiring hum like crazy when you turn them all the way down, and some don't - two of my Guilds do, two don't. Couldn't tell you why though...

Walter Broes said:

I don't mind the two pickup volumes too much, I had to get used to it with my first Guild, coming from a Gretsch with master volume, but now I like it. You can almost keep the guitar in the middle position all the time and work the volumes to get the pickup you want.

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Ok, but if you are in the middle position and want to decrease the *overall* volume you have to adjust TWO knobs (unless I'm missing something here...). This drives me crazy :x

Yep, for overall volume, you would have to adjust both knobs, but it's something I don't find myself doing, and if I have to, I'll just go to a pickup by itself.

to decrease the *overall* volume you have to adjust TWO knobs

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Or use a volume pedal, which is what I do even with single volume control guitars like a Tele.

A 220 pf cap between the lug the pickup attaches to and the wiper (center lug) allows highs to pass through unimpeded by the volume pot (treble bleed mod). But I kind of agree with Walter:

I actually like the effect of a pickup losing highs when turning down.

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And I like the sound of my SF III coupled with one volume turned down slightly. I don't particularly care for the sound of one or the other pup only.