P90 Wiring Question.

Discussion in 'Tele Home Depot' started by wadeeinkauf, May 16, 2021.

  1. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    We know that if you have two pickups selected and one is reverse-wound, reverse-polarity you have essentially created a humbucker and have a low noise output(noise free).

    Say you really just wanted the neck pickup to be selected but wanted it to be noise free.

    Here is the question. If you had volume controls on each pickup and have your selector set to both pickups on, could you turn down the bridge pickup volume all the way…..to the point you could not hear it at all……and still have noise cancelling output from the neck pickup with its volume all the way up.

    It must not work or we would see this setup everywhere. You really would not need two volume controls. Just a 500K or 250K resister wired to the bridge PU from the neck position of the 3 way pickup selector switch.
     
    Last edited: May 16, 2021
  2. Wally

    Wally Telefied Ad Free Member

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    Hmmmmm... It seems to me that when you take that one pickup to zero, you have taken it out of the circuit and therefore would in effect negate the relationship that created that widely spaced humbucker, correct?
    There are P90 sized/style humbuckers. Gibson calls theirs the P100. Seymour Duncan builds a very good humbucking version, imho.
     
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  3. kbold

    kbold Friend of Leo's

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    Hmmmmmmm ... you seem to be running the same post in 2 different forums??? o_Oo_Oo_O
     
  4. NoTeleBob

    NoTeleBob Tele-Afflicted

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    In a two volume setup, if you turn one pickup down all the way you will generally be shutting off both pickups.

    You can turn one down to something like 2, but it's NOT going to be the same sound as if you had only one of those pickups on. It's going to be strongly colored and in a way that I don't think you'll be able to get back to the one pickup sound by tweaking.

    That's per my testing... certainly other wiring schemes would change the equation. But, I don't think you can get to where you want to be.
     
    Last edited: May 16, 2021
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  5. jvin248

    jvin248 Doctor of Teleocity

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    .

    The hum cancellation happens by having one signal 'positive' and the other signal 'negative' where the exact hum hits both coils where they cancel each other. The string is more dynamic and thus creates a different signal on each coil where one does not cancel the other. If you turn one pickup down you are weakening the 'negative' signal and thus more 'positive' signal gets through making the hum.

    As an alternative ... look up the 'Illitch' hum canceling system.

    .
     
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  6. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    That's right I am. Many builders here do not follow what is going on in the Pickup forums.
     
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  7. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    This is exactly my concern. I have this question over on the Just Pickup forum. Trev333 said that just keeping the volume up a little will give you reduction in 60 cycle hum. This makes sense.

    I have just ordered a set of Seymour Duncan Phat Cat SPH90. I use humbucker size pickups in my builds and could not find a good quality stacked P90 in a humbucker size. Which got me wondering about this.
     
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  8. Wally

    Wally Telefied Ad Free Member

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    Monterey....I was at the Defense Language Institute 1971-1972. Good memories there.....
     
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  9. NoTeleBob

    NoTeleBob Tele-Afflicted

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    My testing shows that that's not actually true... it doesn't matter what the volume setting is on the two pickups - or even if they are producing output. As soon as you go in to "humbucking" mode, the guitar goes quiet and stays that way no matter what the volume setting are.

    My electronic theory is weak, but I assume it's because the noise isn't actually sound related, it's 60 cycle hum. The hum is the same in both pickups regardless of volume. It is unaffected by the volume control.
     
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  10. boredguy6060

    boredguy6060 Poster Extraordinaire

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    Gibson and Epiphone both made a solid body guitar that had a P90 and a humbucker , I believe the name was a Blues Hawk. That guitar used a dummy load to add noise canceling to the P90.
    You’re gonna have to research the name and use of a dummy load. It’s been out of production for several years and all I can recall is the use of a dummy load. I think it was an interesting way to handle the hum.
    I don’t know if that’s the answer to your question or not but that’s all I have.
    Good luck,
     
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  11. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    Thanks for the input. Yes I am familiar with this. It was another coil located away from the strings. It only picked up the hum and was fed into the output of the P90 or any single coil which canceled out the hum.
     
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  12. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    Yes I do understand this. The hum is caused by a 60 cycle sine wave created by “house current” the electrical power company. The appliance/lights that use it if not well shielded act as an antenna and transmit this signal which is picked up by the pickups. A RWRP pickup will generate the sine wave 180 degrees out of phase with a pickup that is not RWRP. The two signals then cancel out each other…thus no more hum. I am wondering if there is more going on because of the induced fields…inductance is too complicated for my level of education in electronics. I will do testing when I get my P90s in and see.
     
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  13. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    Thanks for sharing your observations. I will do some testing when I get my P90s in. I am thinking that a little signal reduction caused by RWRP pickup may be knocking the hum down to where it is not noticeable. If I could have found a good quality stacked P90 in a humbucker size I would have gotten it. If anyone knows of one please let me know.
     
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  14. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    I think you’re right. I am going to crawl back out of the rabbit hole.
     
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  15. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    I have a reason for wanting a noise free P90 in a humbucker size. For my current build I want to make my Seymour Duncan Phat Cats noise free in all positions. After climbing out of this wiring rabbit hole I am going down this new rabbit hole.

    I will make two dummy coils one for each pickup. On the 3 way pickup selector switch I will wire the dummy coils so they are in the circuit in the neck only or bridge only positions. Think of this like a humbucker wired in parallel mode. When in the both position the dummies are not in the circuit. This middle (both) position will use the built in RWRP bridge pickup for noise free operation. No additional switches will be needed. Thinking about it I think I will only need one dummy coil. Wire the same coil to both the bridge only and neck only position.

    How to make the dummy coils. Came across this technique. Make an air coil….(no magnets or pole pieces). Put them anywhere in the body you can find. They are there only to pickup the 60 cycle hum to be mixed in with the single coils P90 but at a 180 degree phase inversion. That’s it. I pulled apart a cheap humbucker. It will make the two single coil dummy coils. I expect the output of the hum signal to be close enough to equal that of the P90s eliminating the hum. I plan on making the bridge pickup cavity deep enough to but these dummies under the bridge pickup. Think there is enough room.

    I will post how it turns out when my new build is completed.

    1.jpg 2.jpg 3.jpg 4.jpg
     
    Last edited: May 17, 2021
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  16. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    Thanks for your input...As you see that is the conclusion I have come to.
     
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  17. Gris

    Gris Tele-Meister

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    There is another issue to consider. When you go to the middle position on my P90 Goldtop and then turn one PU down a bit, there is a volume drop even if the other PU is all the way up.
     
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  18. wadeeinkauf

    wadeeinkauf Tele-Afflicted

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    Yes, I have abandoned that approach as not optimal. This stacked coil/dummy coil is the way most manufacturers are achieving a noise free closer single coil tone.
     
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  19. Freeman Keller

    Freeman Keller Poster Extraordinaire

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    Several people have mentioned the fact that with normal 2V2T controls with the switch after the pots that if you are in the middle position and turn one V all the way down it kills both pups. There is a remedy for this shown on the StewMac site and I wire all my guitars that way. Don't know what it does for your problem, just wanted to mention it.
     
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  20. Gris

    Gris Tele-Meister

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    Interesting, with this different wearing does turning one way down still bring the volume down on the one that’s all the way up?
     
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