As a reference resource, I have collected the treble bleed capacitor and resistor combinations recommended by the the major guitar pickup manufacturers (and some guitar makers too). I am reproducing that list here. Below the list I have also included notes and additional information based on my research and experience. I hope you find it useful. Feel free to contact me with any questions or suggestions.
The Treble Bleed Modification List
(listed in order of increasing capacitor value, for no other reason than I have to choose something)
NB: Resistors are IN PARALLEL with their capacitor unless stated otherwise
PRS – 180 pF cap (500 kΩ volume pot, no parallel/series resistor).
Bill Lawrence – 330 pF capacitor & 80 kΩ resistor
Mojo Tone – 471 pF capacitor & 220 kΩ resistor
DiMarzio – 560 pF capacitor & 300 kΩ resistor
John Suhr – 680 pF capacitor & 150kΩ resistor
TV Jones – 1 nF capacitor & 150 kΩ resistor (2 nF cap suggested for 500 kΩ pot, humbucker)
Seymour Duncan – 1 nF capacitor & 100 kΩ resistor
Chris Kinman – 1.2 nF capacitor with 130 kΩ resistor in series!
Lindy Fralin – 2.5 nF capacitor & 200kΩ resistor
If anyone has any other recommendations from other manufacturers to add, feel free to drop me a line and I’ll add it to the list!
1: For capacitor value conversions, 1000 pF (picofarads) = 1 nF (nanofarad) = 0.001 µF (microfarad). For treble bleed mods, very small value caps are used, usually 1000 pF (1 nF) or less. For comparison, the most common capacitors used for tone controls are significantly larger; 0.022 µF and 0.047 µF. (i.e. 22 nF and 47 nF).
And yes, it would be much easier if we all just worked in nanofarads.
2: Treble bleed mod can have NO effect on your guitar tone when the volume pot is on 10 as the capacitor (and its resistor if present) are short circuited.
3: Guitars with active pickups or a buffer preamp onboard the guitar do not usually require a treble bleed mod.
4: The simplest treble bleed mod is to use a low value capacitor on it’s own. For many people this may not be particularly satisfactory – the tone of your guitar may become noticeably brighter as you roll down the volume (the opposite of the original problem). However, an advantage of the lone capacitor option is that the taper of the volume pot does not change (i.e. the change in volume across the sweep of the volume pot is unchanged from the stock un-bypassed state).
PRS guitars actually choose this approach, and install a 180 pF bypass cap as standard on many of their guitars (usually with humbuckers and 500 kΩ volume and tone pots).
The Gibson “50’s wiring” can have a similar effect to a lone capacitor (some suggest even more neutral) BUT the effect of the guitars volume and tone controls are now interactive (e.g. the tone control can produce changes in volume) which some people find to be a drawback.
5: Adding a resistor in parallel with a larger value capacitor helps to keep the guitar tone more balanced as the volume pot is decreased and corrects the issue of too much treble from a lone capacitor. The lower the value of this bypass resistor, the less the capacitor passes treble at low volume settings. Conversely, the higher the value of the resistor, the more treble is passed by the capacitor.
However, a parallel resistor affects the taper of the volume pot. This results in a more gradual change of volume across the range of the volume knob (i.e. it will give you less volume change between 10 and 7 and a faster volume change between 1 and 3). Personally, I am long used to this and find un-altered circuits change volume too drastically without it. Volume swells can be less smooth at the lowest numbers on the volume knob, particularly for high gain players. No such thing as a free lunch, eh? Everything is a compromise, all the time.
For those of you who don’t like how the parallel mod affects the volume pot taper, and the volume changes too slowly for your liking, a capacitor and resistor in series (e.g Chris Kinman’s mod) gives a less drastic change in volume taper but the tone of the guitar may change in other ways as the volume pot is turned down. In fact Kinman is the only well known manufacturer recommending a series cap/resistor combination. You may or my not notice much of tonal difference between parallel and series resistors so feel free to experiment and let your ears tell you what works best for you.
6: The capacitor/resistor values that work best for you will depend on your total cable capacitance, which is related to the input impedance of the first non-true bypass pedal buffer circuit or amplifier input stage and the total length of the cable connecting them to the guitar. You may have to experiment to achieve what your ears will regard as the perfect combination for your setup.
The good news is that most people who are bothered by the loss of treble at lower volume pot settings will be happy with many of the above choices. You don’t have spend too long trying to figure out what the perfect choice might be before trying, just dive in. In fact the values are not critical at all and anything in the ballpark of the middle of the list will be fine.
The TV Jones values (1 nF & 150 kΩ) are recommended by many sources as a good choice for maintaining a consistent resonant peak as volume decreases: e.g. John Hewitt (in his simulation work here); and recommended by the excellent people at Ann Arbor Guitars in their video here. (Incidentally Ann Arbor Guitars have some great videos on their YouTube channel, including this great explanation of treble bleed circuits).
Incidentally these values (1 nF & 150 kΩ) are sold by Stew Mac as a their “Golden Age Treble Bleed Circuit”. Fender have recently marketed a “Tone Saver” that they claim is not a simple treble bleed circuit but when cut open features, can you guess? Yep, a 1 nF cap and a 130 kΩ resistor in a fancy package that costs 10 times more than the practically identical Stew Mac product. *rolleyes*
Personally, I currently like the DiMarzio values (560 pF & 300 kΩ). With a Planet Waves 10ft cable, depending on which effects pedals I am connected to it is either tonally neutral to my ears or introduces a slight but pleasant increase in brightness at low volume pot settings. In my circuit simulations, this combination also produced the smallest change in volume pot taper of any of the parallel resistor/capacitor combinations (though it is still a very noticeable change).
7: Pickup maker Jason Lollar recommends no treble bleed at all but suggests a smaller value tone cap or even Gibson 50’s tone pot wiring. He has stated that even with the volume knob on 10 the treble bypass circuit will affect your tone. But his statements are completely contrary to basic electronics knowledge. True, some people prefer the Gibson/50’s tone pot mod. But a smaller value cap on the tone pot has no bearing on treble loss at low volume pot settings if you use standard wiring, and, as the cap/resistor are completely short circuited when the volume pot is on 10 they cannot have any effect on the circuit or your tone. I am perplexed by these statements and suggest you ignore them.
8: The construction of capacitor or resistor you use in passive audio frequency circuit can have NO bearing on the sound of your guitar. Let me repeat that another way – the type of capacitors and resistors you choose will have NO effect on the tone of your guitar. None, Zero, Zip, Nada, Zilch! The only thing that matters is the VALUE of the capacitor or resistor. If the values are identical, your PIOs/Polys/Bumblebees/orange drops etc. will all sound exactly the same. I am not going to argue this point with any one. The basic physics of capacitors, i.e. how we know they work, makes it clear that at audio frequencies this is the only way things can be. This will be the subject a future blog post!
You may have your personal favourites, for whatever reason, and that’s fine, but I assure you that if your brain tells you that you can hear a difference, it’s all down to expectation bias. Blinded A-B testing, e.g. from before-and-after recordings, will convince most people of this quite easily. i.e. when people don’t know what type of capacitor is being used, and are asked to pick which one is which, they are unable to tell the difference between different types (i.e. they get the answer right, and wrong, as often as randomly picking an answer without listening would produce).
It’s high time we stopped allowing vendors to sell horribly overpriced components on the basis of mythical characteristics that don’t actually exist. (Yes, Gibson, I’m looking at you, with your $100+ for a pair of fake bumble bee capacitors. Shameful!)
By all means, buy whatever components you like and are willing to spend money on if they will inspire you to play your guitar more often and get greater enjoyment from your music. Don’t let anyone tell you otherwise! But don’t believe that you’ll achieve vintage tonal nirvana because you allow yourself to be horrifically overcharged on what are the most basic and cheapest electronic components possible.
9: Guitar signals are tiny, the voltages are very small. This means that the voltage rating of the capacitors is of no importance. You can use whatever voltage rating you like but while higher voltage rating components are physically larger and little easier to handle, lower voltage rating caps are a better fit in tight spaces such as guitar control cavities.
This post was updated in July 20, 2017. Small edits and additions. Many thanks to all of you who emailed with comments!