I successfully tightened up the bass of my Filtertron

Discussion in 'Effects, Pedals, Strings & Things' started by Dr. Lo, Jan 14, 2015.

  1. Dr. Lo

    Dr. Lo Supporting Member

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    While the TV Classic Filtertron is often lauded for its sound, I found it too bassy/muddy in my Cabronita's neck position. I explored various capacitor values to use as a high pass filter (wired in series between pickup's hot lead and the switch). .005 uF lobbed off may too much bass, making the resulting sound quite weak sounding. However, .018 uF was, to my ears, perfect. I'm used to a Strat's single-cool nexk pickup and rhe sound I got was like that, though louder.
     
  2. Abandoned

    Abandoned Member

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    Whoa whoa whoa... Tell me more. I've been experiencing the same exact thing. I love a Strat neck pickup yet still a bit too thin and weak.
    But would really like less bass and more clarity/sparkle in the TV Jones classic neck pickup in my USA Cabronita.
    My bridge pickup is fine - does what it did just effect the neck pickup?

    Also - is your Cabronita a USA model?
     
  3. TheoDog

    TheoDog Silver Supporting Member

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    Did you settle on this solution after exploring the pole piece adjustability?
     
  4. Pedro58

    Pedro58 Supporting Member

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    Why not just use a Strat pickup?
     
  5. zzzzzzz

    zzzzzzz Supporting Member

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    Haha yup I've got an epi 355 with a tv classic bridge and a Tom Anderson tele neck pickup and it sounds perfect to me. It looks custom (or maybe mutant depending on your perception) but I really love it. I'm interested in this topic though
     
  6. Dr. Lo

    Dr. Lo Supporting Member

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    Adjusting pole pieces had no significant effect.
     
  7. Dr. Lo

    Dr. Lo Supporting Member

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    Yes, it just affects the neck pickup. My Cab is a Warmoth clone. Same specs as the custom shop model.
     
  8. Dr. Lo

    Dr. Lo Supporting Member

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    A Strat pickup does not fit in a Filtertron rout.
     
  9. strangesounds

    strangesounds Member

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    Very cool! How does it change the middle position sound?
     
  10. Dr. Lo

    Dr. Lo Supporting Member

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    Just tighter in the bass, but not annoyingly so.
     
  11. ruger9

    ruger9 Supporting Member

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    I've done this trick with humbucker neck pickups before, to make them less woofy, and it works great. I used a cap & resistor, on my PRS with DGT pickups.

    I don't recall what values I used, but I know I experimented with a few until I was happy.
     
    Last edited: Jan 15, 2015
  12. Dr. Lo

    Dr. Lo Supporting Member

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    Folks: Here's how to wire it up. The .047 uF capacitor shown in this figure is way too large, meaning that the bass cut will be barely noticeable (for me, perhaps not for you). As stated in the OP, the capacitor I preferred was rated at .018 uF. For the uninitiated, "uF" means microfarad.

    [​IMG]
     
  13. MasterEvan07

    MasterEvan07 Supporting Member

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    Forgive my obvious ignorance, but does swapping caps change the inherent characteristic with the Tone and Volume at 10 or just when rolling the knobs back?
     
  14. Dr. Lo

    Dr. Lo Supporting Member

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    Yes, when wiring a capacitor in series with the hot lead of the pickup (as shown in figure above), the sound is changed irrespective of where you've set the volume and tone controls. I think that what you are thinking of is the "treble bleed" or "treble bypass" circuit, which helps to retain treble content when you roll down the volume control, and this applies to all pickups wired to that volume control. Often, rolling down the volume control muddies the sound because too much treble is sent to ground. The treble bypass circuit reduces the degree to which treble content is sent to ground when rolling the volume control down. I have both circuits on my guitar. The bass cut (affecting only my neck pickup because the capacitor is only added to the neck pickup's circuit) knocks off a set amount of bass at all volume/tone control settings, while the treble bypass helps to retain treble when I roll down my volume control, irrespective of which pickup I'm using since I have a single volume control on the guitar.
     
  15. meowmers

    meowmers Member

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    Interesting. I always thought caps affected high end more than the low end.

    I had a sprague orange drop dropped into my tele to make it slightly less bright and a little warmer. Works on volume10 tone10 as well (or at least i think so)
     
  16. Dr. Lo

    Dr. Lo Supporting Member

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    You are referring to the capacitor that's connected between one of the tone control's lugs and its casing. In this application, the capacitor serves to roll off treble content as the tone control is turned down. You are correct that the capacitor's value can affect the treble content even with the tone control fully up. When implementing a bass cut, one wires the capacitor between the pickup's hot lead and wherever that hot lead is to be connected (i.e., to the selector switch in the case of single volume control, multiple pickup guitars, or to the volume control in the case of single pickup guitars or in that of guitars with pickups each having their own volume control). A figure is provided above.
     
  17. Pedro58

    Pedro58 Supporting Member

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    Sorry. I'm an incurable smart-ass. Your work around is actually brilliant. It's simple, easy to revert to original spec if you discover you don't like it, and---the best part--- you don't have to buy and sell a truckload of expensive neck pickups to get one that doesn't get mushy.

    I wonder if it would work on a PAF-style humbucker? I bet it would!

    Ah! I see Ruger9 said as much. Great!
     
  18. Dr. Lo

    Dr. Lo Supporting Member

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    No worries! I'm not the brilliant one since I didn't come up with it. It CERTAINLY is a heck of a lot cheaper (less than $10 for several capacitors of different capacitance values) than going through various pickups, and it's also much easier to install than having to swap pickups. Yes, it would probably do wonders for muddy sounding PAF-style neck humbuckers.
     
  19. midwayfair

    midwayfair Member

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    There's one major problem with this, and the reason you rarely if ever see this added to guitars: The bass rolloff is entirely dependent on the input impedance of the next device in line and its input capacitor, if any. An 18nF might sound fine going into your amp -- though if you're curious, the cutoff frequency in that case is only 8Hz, so the bass rolloff is less than a half decible at the lowest note on the guitar, so you're only affecting the subs, and even then nothing in the audible range is attenuated more than a decibel.

    However, if you plug into a pedal like the humble LPB-1, suddenly your 18nF divides in series with the 100nF input cap and you only have 15nF, about 1/8th of the size of the input capacitor the circuit was designed for. That 15nF then forms a low pass filter with the 100K resistor at the very least (the resistance is actually lower, but this keeps things simple), and you suddenly have a cutoff of 100Hz, which is quite a bit higher than what you were cutting going into your amp.

    This isn't horrible, but the LPB-1 was designed to pass all frequencies. Some pedals have significantly steeper input rolloffs and it's possible to get in a situation where your high-pass filter capacitor in your guitar significantly affects the sound of the pedal.

    For instance, a fuzz face was designed with an input capacitor of 2.2uF -- over one hundred times larger than the capacitor you've put in your guitar. It's meant to be an all-pass stage to produce plenty of fuzz. Even when the circuit is modified for humbuckers, that capacitor is pretty much never made smaller than 100nF, which is five times larger than yours.

    You could wire a tone control that bypasses the capacitor with a potentiometer -- the pot would just be wired with lugs 2 and 3 across the capacitor, and then the pot controls how much bass is allowed to pass -- but that's not a perfect solution, since the pot value required to actually cut bass would be larger as the input impendence of the next circuit in line goes up.

    It would probably be best to put in a switch to short the cap for situations where the capacitor is a problem.

    EDIT: Wanted to address this:

    Capacitors act as a short (like a piece of wire) for certain frequencies and block (impede) other frequencies. Resistors impede all frequencies; more resistance is blocks more signal. You can use them to direct signal. The most basic filter is an RC (resistor-capacitor) filter. Depending on how they're oriented, you will create a low-pass or high-pass filter. This filter calculator shows the two basic types at the top:
    http://sim.okawa-denshi.jp/en/Fkeisan.htm

    Capacitors aren't perfect frequency killers, though. Some signal still gets through and any signal cut for a simple single-order filter is 6dB per octave. (The next octave up or down will be half as loud.)

    The type of filter formed by the guitar's tone pot is on the left. The pickup has a resistance (it also has inductance, but let's ignore that for now), so that's R. Your tone cap is C. The tone pot then controls how much attenuation of the frequency you get, but let's pretend it's fully CCW for now. The cap "sends" signal to ground ( the little symbol below the "C" that looks like a rake). Ground = silence, so any frequencies that get sent there are cut from the signal.

    The op's filter is the high pass filter on the left. The "C" is his 18nF capacitor. The "R" is whatever the input impedance of the next device is. In this case, the cap directs certain frequencies from the output of the pickup ("Vin") and passes them on ("Vout") to the next device. The resistor (R) conducts all the signal to ground by a certain amount, and all frequencies of the capacitor by progressively larger amounts until the capacitor is acting as a perfect signal blocker. They are dependent on each other. If you had infinite resistance to ground, no frequencies would be cut by the capacitor.
     
    Last edited: Jan 15, 2015
  20. Dr. Lo

    Dr. Lo Supporting Member

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    Interesting. So, far, I'm loving the sound I get, but it's good to keep in mind. The relative cheapness of the procedure implies that very little is lost in trying. If it's too problematic when combined with the rest of someone's signal chain, then reversion back to stock wiring is a piece of cake.
     

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