Treble bleed cap/Burstbuckers/ why such tepid tone function on VC?

Started by petemoore, August 06, 2008, 09:18:47 AM

Previous topic - Next topic

petemoore

  Why is it so different ?
  Guitar 1: Paf and Hot HB in bridge..
  Guitar 2: Burstbuckers.
  Both have 500k volume/tone pots.
  #2 Les Paul I can't get much treble bleed sound, and have advanced to a .1uf capacitor, barely tell there's any treble bleed and I want it to treble 'Boost' like..
  #2 Les Paul, smaller bleed capacitors turn the pots into 'treble / bass switch'..full on is too bassy, volume at 8 is a treble boost [with some boost help down the line]/
  I bought #2 so to have two guitars to wear out at 1 time...but one reason I go back to the more fretworn and worn #1 is because the volume controls are tone controls the way I like them.
  I want #2 to behave in the same way, but have hit a wall after trying to find out any differences in values / wiring that would help me along and/or account for the differences in function.
  ...secretly hoping someone won't say what I'm hoping it isn't...that BBuckers have HF rolloff in them and therefore just don't output the Frequencies that a PAF will...going to see if I can find info to compare on the two.
Convention creates following, following creates convention.

Ace


DougH

From what you have described I would guess it may be your pots. Cheap pots (even Alphas) have poor log tapers for volume rolling on a guitar, IMO. Alphas are okay for pedals but for guitars I would go with PEC's or something. (Check Stew Mac and see what they carry- I can't remember the brand names typically used for guitars.) I'm even thinking of upgrading at least the volume pots I use on amps, the Alpha log tapers really suck sometimes...
"I can explain it to you, but I can't understand it for you."

petemoore

  Seems like even cheep pots would have a R/L resistance that'd 'activate' a treble bleed cap though.
  Kind of tight, but it looks to me that the #2's pickups are connected to the pot wipers, and the #1 pickups are like a 'regular' volume control, signal input opposite the Gnd.
  And even that i don't understand as being all that different when the pot is between say 6 and 8...you have a resistor to ground on one side and an R/C as the other side of the pot [treble bleed cap]...which'd be about [if not exactly] the same as with the signal input on an outside lug.
  ie...500k pots [which is what the guitars have in there], I should be getting a treble bleed across the signal path lugs if there's a resistnace enough to make the HF's have the 'easy route' through the cap...at least somewhere...
  The thing that makes #2 less desirable/usable than #1 is that treble 'clank' I can get #1 to do.
  I don't think reversing the signal direction through the signal lugs of the volume pots would make any difference...something I 'could' do...I can't think of much else to try, and I don't really want to change the pots..[
  I know you know more about pot quality because I use mostly alpha's and Epiphone' pots...but still...set somewhere in the middle should make treble bleed I think since the pot will introduce resistance on either side of the wiper...and the signal side resistance having the treble bleed across it.
  I kind of expected to see 250k pots which would seem a possible feasable explanation.
Convention creates following, following creates convention.

DougH

Quote#2's pickups are connected to the pot wipers, and the #1 pickups are like a 'regular' volume control, signal input opposite the Gnd.

Ahh, I think that's it Pete. If the pickup is connected to the wiper, you are shunting more of the current to ground as you turn the volume down. With the pickup connected to the "hot" lug, the load presented by the pot stays constant. I would swap the wiper and hot lug of the VC on that guitar and give it a try. I bet that's it.
"I can explain it to you, but I can't understand it for you."

petemoore

Ahh, I think that's it Pete. If the pickup is connected to the wiper, you are shunting more of the current to ground as you turn the volume down. With the pickup connected to the "hot" lug, the load presented by the pot stays constant. I would swap the wiper and hot lug of the VC on that guitar and give it a try. I bet that's it.
  At least part of it...
  And I think you are right about the taper, also, before much attenuation occurs the pot must be below ... well much lower setting than #1. With a steeper taper [like #1 has], a smaller amount of loading via R to ground / larger resistance for the HF's to bypass is possible.
  #1 had it's volume pots replaced as a matter of maintenance with some really good old stock 500k's..note to self, new pots are newer than old pots, I like the taper, they need replaced again..
  The other thing is these Burstbuckers have a different frequency response in general, more low mids to begin with.
  For now a 472 cap treble bleeds, and I stuck a .068uf between the jack lug and wire.
  It may not be the ideal design but it's a darn sight better play than with lows and low mids swamping things out so much.
  I still don't get the hot treble at any setting like #1, but I think that'll have to wait until I have sufficient gumption to aquire pots of desired taper and quality / dig out the old pots from their knobs and the cavity..ughh.
Convention creates following, following creates convention.