Treble bleed caps(or whatever they are called)

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Laroosco!, Nov 2, 2005.

  1. Laroosco!

    Laroosco! Member

    Messages:
    2,604
    Joined:
    May 28, 2002
    Location:
    Detroit, MI
    Will they work on humbuckers??

    I have an Epi Dot that I've done some upgrades and it is just about perfect except that it gets super muddy when I use the volume knobs.

    I've used volume kits on my Strat and Tele with great success but have never heard of anyone using one on a humbucker guitar.

    Any help is appreciated

    Thanks
     
  2. big mike

    big mike Moderator - EL34 Emeritas Staff Member

    Messages:
    22,875
    Joined:
    Oct 31, 2003
    Location:
    Raider Nation
    Yup. PRS Uses the 180PF on their volume pots with the 5 way. Works for me!
     
  3. erksin

    erksin Member

    Messages:
    21,283
    Joined:
    Nov 17, 2004
    Location:
    Portland, OR
    Yep - they work great on HBs...
     
  4. Laroosco!

    Laroosco! Member

    Messages:
    2,604
    Joined:
    May 28, 2002
    Location:
    Detroit, MI
  5. pfflam

    pfflam Silver Supporting Member

    Messages:
    7,059
    Joined:
    Aug 26, 2005
    Location:
    PDX: The Rose City
    And ,might I add to that question by asking that if you wire up a 500k volume pot for a humbucker will it also work with SCoils in the same guitar if they are wired with resistors of 240+k to make the volume values proper for them?

    Does that question make sense?

    I want to have a Humbucker or like in a Tele with two other Single coils so I want to have the 500k pot work for the HB but have resistors twixt it and the SCs so that they don't distort or get too trebbly?
    Would this then work witht the 'trebble-bleed' fix?
     
  6. Clorenzo

    Clorenzo Member

    Messages:
    1,940
    Joined:
    Jun 16, 2004
    Location:
    Munich / Madrid
    Yes you can use the 680pF/220k combo with humbuckers too. In fact that keeps the frequency response fairly constant as you turn the volume down, while the single 180pF cap as used by PRS actually increases slightly the treble.

    BTW hats off to Acme for openly admitting that "There is nothing special about these components, you can buy them from Radio Shack for 50 cents or less (we're guessing)." Refreshingly honest compared to those ripping off people with components supposedly "specific for guitar" and hence 10 times their real price.

    As for pfflam's sc/hb question, you should put those 240k resistors between the hot wire of the sc's and ground, not between them and the pot. And yes, the bleed circuit on the 500k pot will still work fine.
     
  7. Richard Guy

    Richard Guy Member

    Messages:
    775
    Joined:
    Oct 19, 2005
    Location:
    Springfield, VA
    Try soldering a .001uf disc cap across the middle lead and hot lead on your volume pot. It will preserve your treble as you decrease the volume. No more mud. ;)
     
  8. Scumback Speakers

    Scumback Speakers Gold Supporting Member

    Messages:
    9,767
    Joined:
    Oct 6, 2003
    Location:
    Los Angeles, Ca
  9. erksin

    erksin Member

    Messages:
    21,283
    Joined:
    Nov 17, 2004
    Location:
    Portland, OR
    That's what I used - works great...
     
  10. Tone_Terrific

    Tone_Terrific Member

    Messages:
    24,602
    Joined:
    Dec 26, 2004
    Location:
    Canada-GTA
    Kinman pups has a decent explanation and solution at the site.
    Adjust the values to taste. I prefer this sort of series arrangement myself and have used it for a long time, hb or sc's.
     
  11. Clorenzo

    Clorenzo Member

    Messages:
    1,940
    Joined:
    Jun 16, 2004
    Location:
    Munich / Madrid
    If you guys want to see what each combination of R and C values does to the frequency response of the pickup, download this Excel spreadsheet (warning: for it to work you have to go into Tools -> Add-Ins... and activate "Analysis TookPak" and "Analysis ToolPak VBA"):

    www.harryj.net/voltone.xls

    adjust the pot values, the pickup parameters (the default ones are for a PAF, for a typical single-coil try R = 6k, L = 2.8H, C = 60pF) and play with the "Bleed R" and "Bleed C" values (to simulate no resistor, give it a very large value like 100000000). For those who don't want to bother, as you turn the volume down:

    - 220k / 680pF basically preserves the frequency response of the pickup:

    [​IMG]

    - 150k / 0.001uF is very similar, with the peak slightly higher:

    [​IMG]

    - 180pF moves the resonant peak up in frequency and increases slightly its amplitude, so the sound changes to more of a single-coil character:

    [​IMG]

    - 0.001uF keeps the resonant peak roughly where it is, but increases its amplitude a lot, so if with the volume at 10 the peak is about 5 dB, with the volume at 4 it's about 18 dB:

    [​IMG]

    - For completeness, here's the response without the bleed circuit:

    [​IMG]
     
  12. Jon Silberman

    Jon Silberman 10Q Jerry & Dickey Gold Supporting Member

    Messages:
    36,145
    Joined:
    Jan 3, 2002
    Location:
    Northern VA
    Interestingly, as an experiment, I recently upped the cap on my '86 Custom to 1000 pf. The experiment was successful - rolling down the volume on the humbucker settings produces very single-coilish tones (rolling down the volume on the single coil settings, on the other hand, sounds awful but I've never found much of a need to do that so it doesn't bother me).
     
  13. KaBudokan

    KaBudokan Supporting Member

    Messages:
    230
    Joined:
    Mar 18, 2003
    Just wanted to say "Thanks!" to Clorenzo for this app. I was having trouble finding certain capacitor values, so using the app you linked to I was able to come up with something that works very well using stuff I had here in the house. Here's the frequency chart:

    Values: 270k resistor with a 470pf cap

    [​IMG]
     
  14. John Phillips

    John Phillips Member

    Messages:
    13,080
    Joined:
    Mar 17, 2002
    Location:
    Scotland
    So far no-one has mentioned the single most important factor - the cable.

    It's the capacitance of the cable that causes the roll-off in the first place by effectively being a cap in parallel with the lower part of the volume pot track.

    Changing cable type and/or length can drastically change the cap and/or resistor values you need, so there can be no universal answer even for known pickup types and pot values.

    Amp voicing can also make a difference too.

    FWIW I use a 680pF cap (no resistor) on my humbucker PRSs, with a 20' Horizon Vintage II cable - yes, I know that is not the most transparent cable but it's the one that sounds the best to me when the volume is up full; even an otherwise identical 10' one has a slight shrill top-end that I don't like. So I picked my cap value to fit the cable. With my P90 guitar the right value is 330pF. Both of these give (to my ear) an almost perfectly even tone most of the way down, or perhaps very slightly brighter at low volumes, which I find more useful than the other way round; if it's too much you can always roll off the tone slightly.

    If I used a shorter or lower-capacitance cable I would certainly have to use smaller cap values or fit resistors - even with a 10' Horizon, the extra brightness is much more noticeable even if I turn down the treble on the amp a bit to compensate for the cable.
     
  15. rpavich

    rpavich Member

    Messages:
    256
    Joined:
    Apr 11, 2005
    Location:
    West Virginia
    The only thing I can add to this discussion (trust me, from practical "bad" experience of fishing things in and out of a humbucker equipped ES335) is solder one end two leads to a pair of alligator clips and the other end to the volume pot wipers and let them hang out of the guitar....plug it into your amp at stage volume, play with the cap attached by the clips and keep putting in caps until it sounds just like you want it to..then solder in permanently.

    bob
     
  16. jzguitar

    jzguitar Member

    Messages:
    246
    Joined:
    Jun 23, 2005
    Location:
    Nashville, TN
    I've got a couple of questions-

    1. I'm using a .001 cap on my volume pot. If I add the 150k resistor, what difference will it make? Is it just the taper of the pot that is affected or will there be a tone difference?

    2. Will different types (but same values) of caps have an impact on the tone in the treble bleed circuit? I have a Mallory in there now - it sounds fine but you know how it goes - "if it ain't broke, fix it anyway." :rolleyes:

    Thanks!

    jz
     
  17. John Phillips

    John Phillips Member

    Messages:
    13,080
    Joined:
    Mar 17, 2002
    Location:
    Scotland
    Laroosco! - just a thought, since I was working on one today and it reminded me that it hasn't been asked yet - as this is an Epi, are the volume pots wired up properly, or backwards like many Korean ones including most Epis?

    Not in the sense that they turn in the wrong direction, but that the input and output wires are reversed (pickup to wiper, output to top tag) - you can easily tell if you put the switch in the middle position and turn one volume right down. If you hear the other pickup, the pots are wired backwards (you should get silence if they're wired correctly). When they're wired backwards like this, turning down the volume also reduces the effective pot resistance as seen by the pickup, and adds resistance in series with the output - these things drastically muffle the tone as you turn the volume down.

    Check this before you try cap values.
     
  18. SpanishCastle

    SpanishCastle Member

    Messages:
    8
    Joined:
    Jul 23, 2006
    What about series connection of the components? any knowledge on humbucker guitars?
    the parrallel connection changes the taper of the pot.

    also using the spreadsheat:
    what about the LP arrangement option? if i click that on the 680/220 combo doesn't work anymore. does that mean that this circuit isn't right for a LP?
     
  19. PanamaCZ

    PanamaCZ Member

    Messages:
    191
    Joined:
    Jun 15, 2003
    Location:
    Chicago
    I really appreciate Clorenzo for making this available and his helpful comments! I used this tool lately to troubleshoot tone issues. And while I'm at it, a heartfelt thanks to John Philips for consistently offering helpful advice.

    SpanishCastle,

    I tried the values you mention, selecting and deselecting the LP option, and I observe frequency response changes. Are you enabling the macros when opening the spreadsheet and have you added the tools mentioned?

    As to series connection of components, I'm guessing you're asking about series connected pickup windings prior to the volume/tone circuit? If so, the pickup R values would add, but the pickup C values would react like a parallel resistance circuit. For example, if the pickup C values are the same and the pickup windings are in series, the series pickup C circuit would be half that of each pickup alone. Here’s the formula:

    (C1 X C2)/(C1+C2)=C total

    If your question on series connections is something else, you need to consider the description on the "Main" sheet of the spreadsheet that describes the circuit under “SOME TECHNICAL DETAILS”. Depending on your comfort level with the equations shown on the "Calc" sheet and your familiarity with series/parallel circuits, you might consider editing these equations to achieve the circuit you are questioning.

    Mike
     
  20. SpanishCastle

    SpanishCastle Member

    Messages:
    8
    Joined:
    Jul 23, 2006
    hi there,
    thanks for your reply
    i was mentioning putting the condensator and resistor in series. another modification that gets used. i enabled the macros and the two analysis tools.

    about that popular combination:
    enabling the LP arrangement will totally screw it up right?
    at least here it shows

    after all i've been reading around. the most important thing is to know your cable capacitance as i understand to get to know the best capacitor value. i think that's the primary issue to solve. and then play around with the resistor values. correct me if i'm wrong.

    now i have an even more complicated question.

    what about if you have this setup:

    guitar - cable - pedalboard - cable - amp.

    we assume that there is a pedal with a buffer in the pedalboard.
    now what cable do i have to conclude for the capacitance measurment.
    only the cable from guitar to pedalboard? or both?
    greetings and any help will be appreciated. im no technician on this field so please :) no formulas :).
     

Share This Page