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Thread: Question in regards to treble bleed resistor

  1. #1
    daz
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    Question in regards to treble bleed resistor

    This could apply to amp or guitar, but i didn't see a guitar forum so i'll post it here. In a guitar i have tried several different scenarios and i'm finally decided on my choice of cap value for treble bleed. But i have tried a 220k resistor and the pickups i'm using get too muddy like that. Without the resistor it's too bright. And yes, i tried a lot of caps but the one i chose gives me brightness without cutting off at a nasally sounding range. So i really want this value, but it's too trebly by itself and the lows get too muddy with a 220k resistor in parallel with it. So i was thinking of changing the resistor so that it has less affect. but before i tear the damn guitar apart yet again i wanted to ask this in hopes i get it right this time and don't have to do it again twice. So here goes....i can't visualize the way the 220k works, but i want to know 1)-am i correct in assuming if i RAISE the resistor value it's effect will be lessened? 2)-how will raising it (or lowering if u say thats how to lessen it's effect) effect the taper of the pot for cleaning up with a distorted amp? 3)-would changing the value by 2 (IE: doubling it or halving it) change the effect linearly, or in other words make it retian 1/2 as much low end?

  2. #2
    Senior Member kleuck's Avatar
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    It's a somewhat difficult point, as it depends mostly on your tastes and gear, PU sound is highly interactive with the pots, treble bleed,cable, impedance of the first pedal or amp.
    Using a resistor in // has two effects : gives a "maximum" efficiency to the treble bleed cap, and soften a little the curve of the volume pot.
    I prefer to choose the resistor first, between 100% and 50% of the pot's resistance, i like this curve, then i choose the cap.
    If you use a higher resistor, you will make the treble bleed "more efficient" actually, ie giving more highs, and subjectively when setting the volume pot low, less lows.
    I use this trick to have an added control on the lows (similar to Reverend guitars low-cut)
    Example : 3359569056_294a00289c_b.jpg
    On the schematic the resistor is 25% of the pot, but i used a higher one later (470K)

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    Also, I think it's important to note that the resistor value in this circuit will affect the knee frequency of the cap. Since Daz has already chosen a cap value, he needs to understand that changing the resistor in the circuit changes that caps pass frequency. So, with a different value resistor, the cap value would also need to be changed to achieve the same pass frequencies.

    I'm not great with all the math anyway, and it's just as well because it doesn't really help here. The reason is that the pickup/s Z and resonant peaks, volume pot taper, amplifier responses to changes, and probably some other stuff I missed all affect what your ears percieve at different guitar volume settings. Experimentation is the best way to get a good sounding result. "MY" frankenstrat uses a 500k 25% taper pot with a 220p cap IN SERIES with a 220k resistor. This just happens to work with this guitar and the amp I usually play it through. I can go from clean with a little mid cut perception to grindy/reedy single coil to fat saturated leads with my guitars volume knob and pickup selector. But this may not work for your guitar and amp.

    Most guitars employ the cap in parallel with a resistor. The roughly 25% rule seems fine. So, 220k for a 1M pot, 120k for a 500 ohm pot and 68k for a 250k pot. You still need to use an audio pot for the best adjustment. The typical value for the cap would be 180p to 220p for a 500k pot. So, I'll use that value as a starting point. If we assume a 25% audio taper and a volume adjustment of 50% then we'll work with 25% pot value parallel with resistor in the circuit to determine the pass frequency of the cap, and therefor determine what a good value cap would be for a 250k and 1M pots. I'm going to use a calculator for this to save time... I'll be determining a cap value that is close to the same response as a 200p cap with a 500k pot. Incidentally, this value range is used on many custom guitars and PRS guitars. You can ask Carlos if the guitars volume knob control is acceptible! So... It looks like a 100p cap for a 1M pot and a 470p cap for a 250k pot. There you have it. But wait!!! The pot value also affect the resonant peaks of the pickups!!! Oh crap! Now we're back to sheer experimentation again.

    I probably went through ten string changes with a different circuit each time until I settled on one I liked. If you don't need to remove your strings to access the circuit you've got no room complaining. Be patient and just make changes until it's acceptible. And, as per my point above, know that your "chosen" cap value is moot if you change the resistor value. A bigger value resistor needs to be combined with a smaller value cap to affect the same frequencies at any given volume pot setting. And don't be afraid to try a series resistor with the cap also. It greatly reduces the extreme brightness at very low volume pot settings. Sooo many circuits to experiment with. So little time!
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  4. #4
    daz
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    Thanks guys. Chuck, as usual you're a bottomless pit of info. I will go ahead and try a 120k with a 250pf on my 500k pot. I tried 250pf with a 220k but it was too much low end. So maybe the 120k will do the trick. I guess i should just extend some wires outside the guitar so i can experiment. I always mean to do that but i just kepp telling myself this is the one. Stupid.....i know better ! My other guitars required i try about 3-5 different scenarios before i found the right combo. But this one is much harder to nail because the pickups are so weird in the way they sound in different settings. Telling you what it is will probably make you say "ahhhh, no wonder". It's a '72 tele thinline RI with the reissue wide range buckers. I know a lot of people hate them saying the originals are worlds better. But i really like these after i figured out how to tweak them. But it's the cleanup tone thats hard to dial in. The sound on 10 i like a lot just as it is.

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    The only guy I know that plays a thinline with buckers is probably going to die with it. So it must have something to offer for the right player.

    You'll want to INCREASE the resistor size to reduce the effect of the mud. Infinite resistance = too bright. 220k resistance = too dark. In between would be a higher value resistor. That is, somewhere between 220k and infinite resistance. So you could try a 470k resistor parallel to the 220p cap. To avoid getting it too bright on really low settings and too dark on the higher settings you could try:


    A 220p cap in series with a 100k to 470k resistor (start with 220k)

    A 220p cap in series with a 47k to 150k resistor and those parallel to a 470k resistor.

    I also thought about running wires outside my guitar for refining the circuit, but never did. In retrospect I think it's a good idea.
    "I should have been born sooner. Of course, if I had been, I might be dead now." trem

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    daz
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    Thats what i first thought, (higher R=less lows) but w/o going back and looking i thought one of u said the opposite. Anyways i will try this today and give a 470k a shot.

    As to the guitar, your friend may have a original. Those pickups are loved by many. The stock reissue wide range buckers are liked by some but many find them muddy, and they are to some degree. But it's all about how you use them and wire the guitar etc etc. I happen to love the basic tone they have, but they do have some sonic flaws you have to dial out. They sound about 30% humbucker and 70% single coil, but the dynamics seem 100% sc which is what makes them so good. I doubt anyone prefers HB to SC as dynamics go, and with these you get a sc like sound and dynamics but with the fullness of a HB. It's a great combo.

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    Quote Originally Posted by daz View Post
    and with these you get a sc like sound and dynamics but with the fullness of a HB. It's a great combo.
    I thought tha's what P-90's were for!?!

    This guy had a reissue. When HE played it, it sounded great. When I played it it sounded all wrong. But he had blonde hair and I have brown. He was a vegetarian and I'm ardently omnivorous.
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    Senior Member kleuck's Avatar
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    Wanted to reply a few hours ago, but the forum wasn't responding ?
    I wanted to say that if cap+series resistor gives the more even response in brightness, the resistor kills too much of the presence peak imoh with Teles, P90, and high value pots like i use.
    But for a Humbucker -i do not use these anymore, except a Mini, not a real HB- it's perhaps the best combo.
    I don't know the Wide Range well, so no true advice here, except that it can be an option to try.

  9. #9
    daz
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    Quote Originally Posted by Chuck H View Post
    I thought tha's what P-90's were for!?!

    This guy had a reissue. When HE played it, it sounded great. When I played it it sounded all wrong. But he had blonde hair and I have brown. He was a vegetarian and I'm ardently omnivorous.
    Well, they DO need tweaking which is why i'm looking for the perfect TB setup. But also i swapped magnets and adjusted them a lot of different ways. Theres a A2 in the neck and A5 in the bridge, and if you swap them they both just seems to sound better. Also, while you see 3 adjustable poles on each coil, there are 3 more under the cover that must be adjusted from underneath so you have to remove the guard. I tried several ways and arrived at a way that along with the mag swap makes them worlds better.
    P90's to me don't sound like this, but then i have had very few. Plus while these are noisy for a HB, not near as much as a SC.

  10. #10
    daz
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    Quote Originally Posted by kleuck View Post
    I wanted to say that if cap+series resistor gives the more even response in brightness, the resistor kills too much of the presence peak imoh with Teles, P90, and high value pots like i use.
    But for a Humbucker -i do not use these anymore, except a Mini, not a real HB- it's perhaps the best combo.
    I don't know the Wide Range well, so no true advice here, except that it can be an option to try.
    Thing is, i don't like tone controls and always disconnect them, so i am using the tone pot in series with the TB. That way i can dial in as much or little of it's overall effect as i want. The reason i posted this is i'm not trying to dail in the perfect amount, but trying to balance the amount of high end with the amount of lows. With cap alone it's too shrill and turning the series pot down relieves some brightness but the lows are still missing. With resistor the lows were too much, so i just need the right value. I'll try a 470k tonite and if that doesn't do it i'll hand some wires out and put a 1M pot in place of the parallel R and see where it sounds best.

  11. #11
    Senior Member kleuck's Avatar
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    Good option.
    But perhaps should you try to improve your tone rather than bypassing it or leaving it dimed all the time : i did not like them in the past, just because most of them are stupid indeed.
    Using a Log pot (where often they are linear) a lower value for the cap (15 nf instead of 47 for example) and a PIO cap instead of the crap usually used can (and in my experience always) turn a useless feature in something you can't live without
    My 2€

  12. #12
    daz
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    Quote Originally Posted by kleuck View Post
    Good option.
    But perhaps should you try to improve your tone rather than bypassing it or leaving it dimed all the time : i did not like them in the past, just because most of them are stupid indeed.
    Using a Log pot (where often they are linear) a lower value for the cap (15 nf instead of 47 for example) and a PIO cap instead of the crap usually used can (and in my experience always) turn a useless feature in something you can't live without
    My 2
    Many reasons actually, but mainly i just don't like them in any way shape or form. And i also, because i never would turn them down i would also never know when they were accidentally moved and there were times i did as much as 2 or 3 sets with a sound i was hating and thinking my rig was screwed or something only to realize my friggin tone knob got turned by accident ! No, i really hate tone knobs, but for many reasons besides that.

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    I've adjusted gear for a few pros. As part of the work, two of them had me disconnect the tone control on a couple of their guitars. I never use tone controls either. A long time ago I had a guitar on which I replaced the tone control with a midrange control. I used the hell out of that. Very good for thinning out humbuckers for clean tones or changing a thick, saturated lead tone to a crunchy rhythm tone. Funny I haven't put one in any of my current guitars. Especially since I've really taken to amp control from the guitar instead of pedals. I think it may be because I use to love extra pickup option switches and didn't mind a more complicated setup. I guess I like it as simple as possible now. If the right bright circuit can get me from clean to lead with just the volume control then any extra controls are just novelties.

    I've been meaning to make myself another guitar (not like some here, But from parts). Just meat and potatoes. Humbucker in the bridge, single in the neck, a three way switch (that also splits the coils on the bridge for a single/single middle position) and a volume control. And thats it. Maple neck, rosewood fingerboard, light alder body, recessed Floyd with a bridge lock doohicky on it. I'd probably do an oil finish for feel and to make it an obvious diy. I havent settled on a body style yet. Which is just as well since I don't have the funds right now.
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  14. #14
    daz
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    Last nite I tried several scenarios and i don't think i can achieve exactly what i want with these pickups. I finally settled for a 1000pf and a 220k. The overall balance is good and the tone seems more correct like what it should be....turned down and cleaner with little tonal change. There is one change tho and it's a big one for me. When using a 250 pf you get that sizzle on top because the the majority of the frequencies that are passed with that value are upper trebles. But the problem i have with 250 is no matter what values resistor i use I can't get a present sound. Theres not enough brightness with a 220k, and using more it gets too dark and doesn't cut. And theres no in between. The 1000pf gets me the presence and all, it all good except theres no sizzle on to which makes it have a bit harder and clunkier attack, for a lack of a better description. It's ok, but I'm not sure if i will be happy as it is. I just don't thing theres a answer with all the scenarios i tried. Actually, i DID think of one idea i may try when i get around to it. Di it just as it is now but usa a 250PF or even smaller and go straght from lug to lug bypassing the series pot. Of course it will only work to do what i'm thinking with the pot under 10 and and maybe not enough to matter till all the way at which time it may be too little of the 1000pf. Just thinking out loud

  15. #15
    Noodle of Reality Steve Conner's Avatar
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    I've seen people replace the tone pot with a rotary switch that selected a bunch of different capacitors, or RC networks or whatever.

    Mark Hammer likes a double-ended tone pot arrangement where the wiper is grounded and a different-sized capacitor is hooked up to each end. The middle becomes "10" and turning it either way darkens the sound.
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    Senior Member kleuck's Avatar
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    Quote Originally Posted by Steve Conner View Post
    I've seen people replace the tone pot with a rotary switch that selected a bunch of different capacitors, or RC networks or whatever.
    I do the same with push-pull pots to lower the resonance frequency, turns a P90 in a decent Humbucker (except for the hum cancellation)

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    There's no rule about how complex the circuit can be. You could use a 1000pf in series with a 220k, then parallel a 330pf across that 220k, then parallel that curcuit to another 220k resistor. Now you have a smaller effect from the 1000pf cap and all the effect of a 250pf (1000pf in series with a 330pf = 248pf). If that's too much 250pf you could add another, say, 100k resistor in series with the 330pf cap in the circuit. It can start getting silly, I know. But it depends on how far your willing to go. Different results CAN be had.
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    The method that Kinman puts forward seems to be to match the bleed cap to the capacitance of the cable being used (eg ~1n2F), then add a series resistor of about half the pot value (eg 130k).
    I find that a low capacitance cable (eg George L) makes this type of thing unnecessary though.
    Pete

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    Senior Member kleuck's Avatar
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    I do not agree, i use low capacitance cables (ie : Sommer Spirit, 78 pf/meter, and i measured the same) and the effect of a treble bleed is still here.
    At least with Teles, P90 and mini-humbuckers.

    Edit : i use 4 to 6 meters, so it would turn in 13 to 20 feet.

  20. #20
    daz
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    Quote Originally Posted by Chuck H View Post
    There's no rule about how complex the circuit can be. You could use a 1000pf in series with a 220k, then parallel a 330pf across that 220k, then parallel that curcuit to another 220k resistor. Now you have a smaller effect from the 1000pf cap and all the effect of a 250pf (1000pf in series with a 330pf = 248pf). If that's too much 250pf you could add another, say, 100k resistor in series with the 330pf cap in the circuit. It can start getting silly, I know. But it depends on how far your willing to go. Different results CAN be had.
    Thats basically the kind of thing i was thinking of. But i'm burned out for now and will try it when i feel up to more of this PITA. Next time however i'm doing the hang the wires out thing. Might rig up a 220p and the 1000p with trim pots in parallel with each and a trim in series with each ! That should end this fiasco once and for all !

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    Well, capacitence wise that works out a little better than my George L (~390pF, 15ft).
    I've got 250k volume pots in all my guitars, except for the Les Paul, which has 300k pots on the Burstbuckers.
    I think the combination of low capacitence cable and 250k volume controls helps to keep mid setting treble loss to a acceptable level, for me at least.
    Pete

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