G&L Wiring- Need help building.

Discussion in 'Luthier's Corner: Guitar & Bass Technical Discussi' started by Jujo, Mar 31, 2011.

  1. Jujo

    Jujo Supporting Member

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    Guys,
    For those unfamiliar this setup has vol, treb, and bass controls. I think it's totally brilliant and I must have it.

    I want to put the PTB system in my strat. Can you guys answer a couple questions based on these diagrams:

    - what is the "201" on the back of the volume pot here?
    - what is TWB2a and TWB2? shown at the bottom left
    - why are they showing the tabs on the 5 way being connected to each other?
    http://www.glguitars.com/schematics/Legacy_Special_Schematic_drawing.pdf

    - 1 MEG C pot? I've read that means reverse taper, but I called up G&L and they said it's a normal taper. Why would they put a C on the diagram?
    http://www.glguitars.com/schematics/Legacy_schematic_blockdiagram.pdf
    http://www.glguitars.com/schematics/Legacy_schematic_drawing.pdf

    Thanks for any insight!!

    -
     
  2. RussB

    RussB low rent hobbyist Silver Supporting Member

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    the 201 is a 200pf treble bleed cap

    TWB2a & TWB2 are the model numbers of those particular pups
     
  3. Jujo

    Jujo Supporting Member

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    Anyone else have some input on this?

    Thanks Russ. That makes sense about those being pickup model numbers. If it's a 200pf, why would the diagram show 201? Strange...
     
  4. fumbler

    fumbler Member

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    Hmmm . . a bass-cut control. To tell you the truth, I've never said to myself "gee, I wish my guitar sounded thinner." But maybe it'd be interesting to try . . .


    On to the circuit:

    Those jumpers on the 5-way switch are completely pointless. You could wire it using only one side of the switch and it would function identically. Maybe the person who drew that diagram meant to do something else but never got around to it.

    The "treble" control is wired like any standard tone pot in any guitar - it bleeds treble away to ground on a parallel path (yes, technically wrong but useful). It is treble-cut only and cannot add any treble.

    The "bass" control is also cut only. Interesting. It's wired in series and uses the cap to bypass treble to the output while the pot rolls off bass. Personally I would NOT use the same value cap on both. I would make the "bass" cap a higher value (0.047 at least) so that you preserve some mid-range if both tone pots are rolled down.

    And I agree that a standard audio-taper pot is what you want. Maybe linear even. You'd want it to work like the volume pot (which is wired the same way). A reverse taper would have very little noticeable effect between, say, 6 and 10.
     
  5. Jujo

    Jujo Supporting Member

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    Fumbler- thanks for your input. I thought those 5 way jumpers are wrong to- I'm thinking "aren't those connections already wired into the switch by default?"

    I had this system on a G&L I once owned. I loved the tones I could get. I'll stick with the stock values to start. I realize I may need to tweak it before I'm fully satisfied. The caps are different on the treble (.022) and bass (.0022).
     
    Last edited: Apr 1, 2011
  6. cc9cii

    cc9cii Member

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    Those connections are just redundant. i.e. not necessary. Probably just a left over from previous variation of the wiring scheme.

    You might find that bass cut works better with a reverse taper. The customer service person may not know (or maybe he/she knows but likes them different, much like some preferring linear taper volume while others prefer audio taper).
    That's just the way the cap values are indicated. The last digit denotes how many "0" to add, the resulting value in pico farads. i.e. in this case 1.
    Because they serve different functions.
     
  7. fumbler

    fumbler Member

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    You're right, I should look more carefully next time.

    How would you describe the effect of the bass control? I might try this some day.
     
  8. Jujo

    Jujo Supporting Member

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    I hear about like this:

    - bass cut allows you to remove any low end boom, and it can tighten up the low end.
    - gives more eq control from the guitar so you can tailor you tone in real time, instead of making adjustments on amps or pedals.
    - balancing the treble and bass, you can make the mids poke out in different ways, it all add all kinds of new tonal characters to the guitar.
    - treble and volume controls work as you'd expect
     
  9. Jujo

    Jujo Supporting Member

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    UPDATE:

    I have installed the bass roll off. So I have volume, treble and bass controls. I bought a ton of cap values so I could find the optimum values for my guitar.

    It is working. Works pretty well. But it ain't perfect. I'm finding that the bass roll off cuts too much of the volume when I cut the bass way down. Of course, that makes sense, but IIRC my G&L didn't cut that much volume when I rolled off the bass.

    So any suggestions? I will probably try re-routing the signal from the 5way switch. Right now the 5way is connected to the volume pot 1st. I may try wiring the 5way to the bass control 1st. The info on this setup from G&L is confusing. I've seen conflicting diagrams.
     
  10. Jef Bardsley

    Jef Bardsley Member

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    If the bass control cuts too much volume, try a larger cap value. This will move the roll-off down so it cuts less midrange. You could also use a smaller pot to just have less cut, but try the cap first.

    Putting the bass control "before" the volume pot (closer to the pickups) should reduce the interaction with the cable capacitance when the volume is rolled down.
     
  11. GeorgeSunset

    GeorgeSunset Member

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    Take a look here


    http://www.metalguitarist.org/forum...73-tight-control-simple-passive-bass-cut.html



    It’s from 2008, but he did quite a lot of stuff. Look at all those graphs. Very nice and understandable I think. he talks about different cap values too!


    If it cuts to much, can a 500k pot be the answer, because it will cut less bass (look at the second graph I think it was).

    Thinking of trying that thing out. May guitar can get pretty dark, and a bass cut may be the ticket (thin 2 humbucker in series – it can be a bit muddy). Thinking master volume, neck and bridge treble cut (normal tone control) and a bass cut for the neck only (bridge is almost to bright, so no bass cut needed at all) and some other sorcery as well :)
     
  12. Jujo

    Jujo Supporting Member

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    Thanks guys! I will be poking around with it some more. Gonna let it ride for right now as I have it all strung and tuned up. Next string change I'll be doing some more experimenting.
     

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