Double-checking + sharing a weird wiring scheme

Discussion in 'Tele-Technical' started by pould, Jan 8, 2021.

  1. pould

    pould TDPRI Member

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    As suggested by the title, I've been working on a custom wiring scheme for my Squier Affinity Tele and I've come up with something pretty unorthodox but hopefully pretty cool as well. There are 3 knobs and no blade switch, with pickup blend, tone (with 50s wiring), and volume controls with a kill switch and a bass cut switch integrated as push/pull pots. Both capacitor values are 0.0022uf, there was some conflicting information on how to wire a bass cut switch but it seems like that value will work for wiring the cap in series with the hot lead. I'm still relatively new to electronics in general, so I want to be sure that I'm not making some grave mistake in this wiring before I order parts.

    37016CE8-0A52-4CBF-9BF6-5943150AE421.jpeg

    [​IMG]
     
    Last edited by a moderator: Jan 8, 2021
  2. moosie

    moosie Doctor of Teleocity Silver Supporter

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    Second image is broken, not showing. First image I can't see the values, but if you say the tone cap is .002uf... well, that's an order of magnitude too small. You likely want a .02 uf in that position.

    Bass cut, remember smaller cuts MORE bass. I'm not sure how you'll like a .002 there. Usually it's a .001, on a POT, to dial the cut and allow some bass to pass untouched.

    What's that upper pot doing? Can't read the writing.
     
  3. pould

    pould TDPRI Member

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    Thanks for the input on cap values, the top pot is blending between the 2 pickups in lieu of a pickup selector switch. I'm a bass player first and my Schecter Stiletto is wired this way, so I figured it would be worth trying out. Plus, a blend pot has all the functionality of a blade switch in that it can output full neck, full bridge, and neck+bridge in parallel.

    https://www.amazon.com/gp/product/B01KWIX18C/?tag=tdpri-20
     
  4. moosie

    moosie Doctor of Teleocity Silver Supporter

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    Cap values

    I wasn't thinking last night. Both of your cap values (.002 uf) are probably an order of magnitude too small. If your bass cut were on a pot, with the ability to dial in some cut, yet still retain some dry signal, you want a deeper cut (smaller cap), or you'll always have the pot fully rotated to max cut. Since it's on a switch, all of your signal is affected by the cap. If you cut deeply, it'll be way too much, resulting in a very thin sound.

    Treble cut cap values:
    With a pot to retain some dry signal: .01 uf thru .05 uf. Early Fenders even used .1 uf.
    With no pot, so all signal is affected, good values are in the range .0005 uf (500 pf) thru .005 uf.


    Bass cut values:
    With a pot to retain some dry signal: .0005 uf thru .005 uf.
    Wired so the entire signal is affected: .01 thru .05 uf.

    See the pattern? It's the exact opposite for bass vs treble cut. I'd start with .02 uf treble cut on a pot, and .02 uf bass cut wired on a switch. But, I strongly recommend ordering a selection, so you can try them, and let your ears decide. You may want to solder in some long leads with alligator clips on the ends, for testing.
     
  5. moosie

    moosie Doctor of Teleocity Silver Supporter

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    Blend vs Pan pot

    Be careful with this. Check out this guitarnutz thread.

    Nearly all sellers list 'blend' pots, when they really mean 'pan'.

    A pan pot is essentially an A (log) pot, and a C (anti-log) pot on the same shaft, with a center detent. This means that only at the extremes of rotation is any pickup fully ON. In the center, both pickups are heavily loaded by resistance, like having separate vol pots, with each dialed to '5'.

    What you probably want is a true BLEND pot, where at center both pickups are FULL ON. Turn one way, pickup A remains full, while pickup B reduces in volume. Turn the other, B remains full, A reduces. It acts like separate vol pots where both are on 10, and you choose to dial ONE of them back a bit.

    Note that in either case, you're still going to have some of the 'off' pickup bleeding into the circuit. It's a resistor, not a switch.

    Assuming you can find a true blend, you might be able to modify it, by disassembling, scraping the track, and putting it back together, so that the pickup being turned down goes 'open' at the end of the rotation. That would in effect be your switch.


    Here's another link, where reply #3 discusses a possible way to use a pan pot:

    "I read a piece by Craig Anderton once, think it might have been in Guitar Player, where he discussed using dual gang pots as pickup blend pots on guitars. Basically, each gang is wired as a volume pot for one pickup, only one will be wired backwards so that as one pickup is turned up, the other is turned down. This works, but has a downside, as mentioned, of cutting the level in half when the pot is in the "middle" position (both pickups on equally). Craig's solution to this was to add a resistor from each gang's wiper to its "hot"end, the resistor's value being about 20% of the pot's value."

    From what I can tell, he was using a straight dual gang, but it applies to a pan pot as well.


    I think historically we only see the kind of circuit you seek in basses. Maybe because it's only the higher frequencies of guitar where we notice the loading, and the bleeding through of the other pickup. Gretsch uses a switch, dual volumes, and master vol. On Fenders, we see the DIY blend circuit (often the repurposed second tone knob on a Strat), but it's a no-load pot, which is essentially a pot and a switch combined.
     
  6. pould

    pould TDPRI Member

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    Yeah, writing 0.0022 instead of 0.022 was just a mistake on my end, I'm planning on using that value for both caps to start.

    Regarding what you said about the blend pot, I have a couple of different areas in my current setup where I can adjust for the loss in volume at the middle pot position, so I think I'll just settle for a pan pot. At middle position, is the full output of the guitar reduced or does 50% from neck plus 50% from bridge sum to the output level of any one of the pickups on its own?
     
  7. pould

    pould TDPRI Member

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    Ah, never mind on that last question. Reading that link now, useful stuff in there
     
  8. moosie

    moosie Doctor of Teleocity Silver Supporter

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    OK. But no, it's not additive.
     
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