"50's" les paul wiring debunked?

Discussion in 'Luthier's Corner: Guitar & Bass Technical Discussi' started by walterw, Mar 9, 2007.

  1. walterw

    walterw Gold Supporting Member

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    the received wisdom on this and other gear-type forums is that gibsons wired so-called "50's" style, with the tone pot wired to the volume through the volume pot's middle lug, will clean up better when the volume is rolled down than guitars wired "modern" style, with the tone wired in through the "input" lug, the one opposite the grounded lug, supposedly due to less loading from the tone pot. this has not been my experience, so in the tradition of esteemed poster John Phillips, i wired up a "debunker" switch to test what really happens.

    i put the output of the 500k tone pot to the middle lug of a two-way mini toggle, and the two output poles of the mini-toggle went to the input (far) lug and the output (middle) lug of the 500k volume pot. this way, i could instantly switch between "50's" and "modern" setups.

    i then turned the tone pot about halfway down to make it's effect obvious, and tested as follows:

    with the volume all the way up, i could tell no difference, which was to be expected, since the two live lugs of the vol pot are shorted together at this point.

    with the volume turned about halfway down, the difference between the two options was clear and dramatic: one way was far brighter than the other. and the kicker? once i traced the wires back to the connections, it turns out the modern wiring option was the clearer setting!

    the lower the volume was turned, the more obvious the difference, as the 50's setting got dull much sooner than the modern setting. turning the tone knob all the way down also exaggerated the effect, again darkening the 50's setting much more than the modern setting.

    the hard test was to hear a difference between the two settings with the tone all the way up. i thought that the modern setting was still a tiny bit brighter, but i couldn't positively rule out placebo effect at that point.

    my theory is that with the tone circuit tied to the input lug modern style, when the volume is turned down, the guitar output is panned away from the pickup and from the tone pot, lessening it's effect. with the 50's circuit, however, as you pan away from the pickup with the volume pot, the tone pot is still fully connected to the output.

    i tried this test with two different guitars, with the same results both times. (i didn't test the different tone pot configurations, but supposedly they don't matter since they just use two lugs of the tone pot as a variable resistor, rather than the three-lug divider network of the volume pot. maybe i'll do another test of this aspect later.)
     
  2. Jef Bardsley

    Jef Bardsley Member

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    The switch you used - if you push the toggle to the right, does it energise the right or the left outer lugs?
     
  3. John Phillips

    John Phillips Member

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    This is what I find too. Actually what happens is that the two controls become much more interactive with the 50s scheme... which is probably why it was changed (from a purely technical point of view, that's a bad thing).

    With the tone control up full, you do get a slightly brighter tone as you turn down the volume. This is because the resistance of the tone pot is fixed at 500K, and as you turn down the volume, the lower part of the volume pot track quickly becomes far less than this, which means that the tone pot is then seen as less of a load, proportionately.

    But when the tone control is down a bit - and remember that '5' on a Log pot is one tenth of the resistance, not half, ie 50K on a 500K pot - now the tone control behaves more like an extra cap in parallel with the capacitance of the cable... which is what causes the treble loss as you turn down the volume in the first place.

    At some point in between 10 and 5 on the two controls - and depending on the exact capacitance of the cable, which is almost always overlooked but is extremely important - the two effects more or less balance, but adjusting either control will change the tone.

    So, if you usually leave your tone controls up full and dislike treble loss as you roll the volume down, you'll most likely want 50s wiring. If you use your tone control a lot, and want more independent operation of the two functions, you most likely want modern wiring.
     
  4. GuitarsFromMars

    GuitarsFromMars Member

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    Nicely stated,John-I prefer the 50's wiring...;) call me old fashioned.
    One thing I forgot,50's wiring also makes for better 'woman' tone.
     
  5. Scumback Speakers

    Scumback Speakers Gold Supporting Member

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    Sounds to me like the original poster's pots, switch, caps, hearing or wiring was suspect.

    I've gone round and round with this over 35 years of playing. I've had a 68 LP Custom since 74, which qualified for the modern wiring scheme. It got bassy as you turned down the volume below 8, regardless of the tone control setting.

    Then I got the "volume control" kits put in, various cap/resistor, just resistor, etc, networks on the volume pot. They offered crystal clear tones when turned down, but sounded a bit thin, hi-fi like and sterile below 6-7.

    When I finally went with the 50's style wiring, that's when the most pleasing, organic and natural guitar tone happened when I turned my guitar volume down.

    Which two guitars did you try this with, walterw? What type of pots, caps, and what pickups?
     
  6. walterw

    walterw Gold Supporting Member

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    ok, this is where the fun starts, because the whole point of my post was my results were the opposite of what john describes! i'm going to have to try again and do it seriously, with resistance measurements and so on, to see if i missed something. i will also pay attention to what i'm plugged into, i.e., tube/solid state, buffered/unbuffered, etc., to see if that's a relevant factor.
     
  7. Jef Bardsley

    Jef Bardsley Member

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    I tried this briefly last night, and while my first impressions matched Walter's, I noticed a surprising degree of change in the taper of the volume pot with the tone turned done. The 50's wiring produced a more immediate change when turning the volume down, as well as a more gradual slope, while the modern wiring maintained it's level for quite a while before suddenly dropping. Thus, comparing the tones was not possible due to the volume differences.

    I, also, have to try this again. ;)
     
  8. K-man

    K-man Supporting Member

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    That's a good point. Most switches will connect the opposite and middle lugs from the position the switch is in.
     
  9. Mike9

    Mike9 Gold Supporting Member

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    I use the '50s wiring as well as 500k audio taper volume pots and it works well for me.
     
  10. John Phillips

    John Phillips Member

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    Exactly. That's why the 50s wiring is 'wrong' from an electronics point of view, because it makes the two controls interactive - when both are below full, changing either affects the setting of the other.

    You forgot to ask what cables :).

    This is extremely important, but for some reason it always seems to be ignored for discussions like this... presumably because the cable is not physically part of the guitar. But electrically, it is - every bit as much as much as the pickups, control pots and tone caps are.

    The capacitance of the cable (its only really important property, tonally) is a load on the pickups and pots, exactly like another small tone control which is permanently turned down. It's this capacitance which is the cause of the treble loss as you turn down the volume control, since it's in parallel with the lower part of the potential divider.

    It's in the same position circuit-wise as the tone control in the 50s wiring, but without the series resistance of the tone pot. When you turn down the volume control, the tone control becomes progressively less important because of its series resistance (which quickly becomes much higher than that of the lower part of the volume pot) - hence why highs are retained better - but the capacitance of the cable remains the same. Consequently, how effective the 50s wiring is at retaining highs better depends on the cable. A really high-capacitance cable might actually reverse the effect, compared to a low-capacitance one.
     
  11. walterw

    walterw Gold Supporting Member

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    there's an old saying, "the truth will set you free, but first it will piss you off!"

    upon further testing, it appears that i fell into the trap that Glass Snuff adroitly avoided, namely, letting volume color my perception of tone.

    with both vol and tone down somewhat, the modern setting was louder, i.e., less volume attenuation, so i leaped to the conclusion "less loss=better". unfortunately, i failed to note that this louder sound was darker, not brighter. the 50's setting made the volume pot taper drop off faster from "10", but the sound was a bit brighter on the way down.

    this appeared to be true on a 70's lp deluxe i'm currently fixing with its old, awful pots (250k audio vol, 250k lin tone), with the new cts 500k audio's i replaced them with, thru 10ft of george L cable into a buffered pedal input and through to my bench amp, and thru 3ft of generic instrument cable straight into the clean input of that same amp, a peavy bravo (20 watt tube amp).

    i'm the type of player who uses the guitar vol constantly to clean up my sound, and usually only uses the tone knob when the vol is all the way up. i've been happy with the behavior of my modern-wired guitars, but i will convert to the 50's style for my gigs this weekend and submit a battlefield report afterwards.

    now if you will excuse me, its dinnertime, and my teriyaki crow wings with humble pie dipping sauce is ready.
     
  12. fakeox

    fakeox Member

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    Great thread! Would the Kinman bypass thing work with the 50s wiring?
     
  13. Pearly Gator

    Pearly Gator Member

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    My guitars all have the tone circuit modified to be wired to the volume pot wiper lug. I find many more "voices" to be available by blending the controls. Electronically incorrect? Okay. However I dig the sonic mojo.

    Yeah, what he said. :dude
     
  14. skylabfilmpop

    skylabfilmpop Member

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    How significant are the tone pot lugs in all this? 50's and 60's wiring seem to have different schemes for this as I have seen. 50's having the output of the tone pot (middle lug) grounded and the tone cap connected to the wiper wheras the 60's and modern employ a grounded wiper aand connect the tone cap to the output. Has anyone ever consideded the switch to be the result of streamlining production. In the modern scheme the volume and tone pots are prepped identically with the wiper (third lug) grounded. Seems to me the existence of two seperate grounding scenarios renders these parts non-interchangeable and creates a production slow down if they run out of say 50's style tone pots.
     
  15. GuitslingerTim

    GuitslingerTim Member

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    Your questions were answered in a previous response.
     
  16. Jef Bardsley

    Jef Bardsley Member

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    It will still work, though you might want to change the values. Most proponents of 50's wiring consider it unnecessary, however, and offer the 50's schematic as an alternative to 'treble bypass' circuits.

    Skylab, the tone lugs make no difference, and you might be right - the change is the result of production engineering. However, there also concurrent changes in pot values to consider. In the 70's Gibson started using 300K pots.

    I have more to say about this, after I do a few more tests, but right now I have to go run a Marshall/Vox clinic.
     
  17. Jarick

    Jarick Member

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    So in short, if I almost never touch the tone control, and don't want my tone to get too dark when rolling down the volume, I'd prefer 50's wiring?
     
  18. Lex Luthier

    Lex Luthier Member

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    I posted about 50's style wiring over a decade ago on the old Gibson forum, I think some people at the time thought I was smoking crack when I said it actually made an audible difference.
     
  19. Jef Bardsley

    Jef Bardsley Member

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    Well, as those of you who are also on the Les Paul Forum will understand, I'm about to commit heresy. I may as well get it over with.

    The '50s wiring sucks!!

    I've spent a total of about 9 hours, 3 amps, three guitars, 7 pots, uncounted capacitors, several pedals, and 5 cords testing this over the last several days and in my not so humble opinion, the much revered '50s wiring is a big tone suck. Yes, it has more highs. But it does so at the expense of the mids and bass, and that's not a good trade-off. It also screws up the volume pot taper and causes the pots to be interactive.

    To be clear, there often isn't any difference between the old and the new configurations. With either pot on 10, they are the same. And, you have to turn the tone down, way down below 5, before any difference appears. So, given the number of players that leave things on 10, I suspect many, many proponents of the '50s wiring have never actually heard a difference at all. They're just "hearing" what they were told they would hear.

    When the difference does appear, the most noticeable thing is, as soon as you roll back the volume there's a sudden drop in level. Through a clean amp, if you were cutting through before, you're suddenly lost in the mix. And, as you roll the volume further down, the sound gets weaker and weaker. It has no body. If you're playing a Les Paul, the tone approaches that of a Telecaster. A Tele starts sounding like a mosquito. The effect is so dramatic that, at cutoff, when the sound almost goes away, the tone control has practically no effect at all.

    Now, as I posted several days ago, there is the consideration that 'louder is better', and I did consider that. It's possible to equalize the outputs when comparing them, and my comments above about tone reflect some of those tests. However, standing there on stage, you have no such EQ. With '50s wiring you're losing a lot of volume and tone compared to the modern wiring scheme. Unless you leave either control on 10. In that case, it's just cosmetic. ;)
     
  20. GuitarsFromMars

    GuitarsFromMars Member

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    I would venture that you might just not be hearin' too well-several thousand vintage and not so vintage Les Paul owners can't ALL be wrong,son...

    :jo
     

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