DrKev wrote a great page about Treble Bleed. DrKev is a musician, guitar teacher, guitar tech, and ex-physicist, living in Paris, France. He is currntly keeping his page up to date — > Here’s his contact e-form – contact DrKev
The rest of the article is a merge of his original page and editing and additions by Bruce Gombrelli
Last Update: 20203.07.30
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Do you need a treble bleed??
Answer: MAYBE – Some pickup arrangements work excellent without one, some not so much. Some players like a treble boost when turning down the volume, others don’t. It boils down to personal preference. However, I played for years, happy with my sound, not knowing what a treble bleed was, only to open up my 2002 American Deluxe Strat and find out, low and behold, it has a bleed circuit in it!! But yet, my other strats I love so much don’t…but now I’m informed and can recognize when it is a good thing, or when it is not needed.
What type of pickups
Higher Output single coils, Humbuckers work great with treble bleed. Vintage output and lower output, high resonance pickups don’t need it (ie:57/62, 59’s)
The Treble Bleed Modification List
List of Builders and Manufacturers values: (assuming all are in parallel unless noted)
- PRS – 180 pF cap (500 kΩ volume pot, no parallel/series resistor)
- G&L – 200 pF (no 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
- Bruce Gombrelli — 680 pf Capacitor & 220K resistor with 500K Linear Pot for HSS guitars. (different for single coil) – The Linear pot helps with the taper. – Bruce doesn’t recommend using Treble Bleed for Vintage Bright Pickups (like 57/62, etc)
- TV Jones – 1 nF capacitor & 150 kΩ resistor (2 nF cap suggested for 500 kΩ pot, humbucker)
- Fender – 1.2 nF capacitor & 150 kΩ resistor in parallel, plus a 20 kΩ resistor in series
- 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 & 200 kΩ resistor
Guitar Cable length Rule of thumb: If you use a 10 ft cable from your guitar, choose the Mojo, DiMarzio, or Suhr values. If you use a 30 ft cable choose the TV Jones, Fender, or Seymour Duncan values. See note 6 below.
Conversions
For capacitor value conversions, 0.001 µF = 1nF = 1000 pF(microfarad) (picofarads)(nanofarad) 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).
When does it affect the guitar sound?
Treble bleed mod will not change your guitar tone when the volume pot is on 10. The reason is that the wiper of the pot is effectively shorting out the treble bleed circuit.
The more you reduce the volume (increase the resistance across the middle and top wiper) the more it comes into play. The high frequencies by pass that resistance through the capacitor so that makes the value of the cap important for how it shunts high frequencies to the middle wiper (your output).
There’s another interesting effect is that without the parallel cap it tends to change the taper of the pot (hence why I often use a Linear Pot with it) and is also why a parallel resistance works well across that wiper, but that’s a bigger conversation.
Another interesting effect is how the cap value affect the resonance of the pickup.
Passive Only
Guitars with active pickups or a buffer preamp onboard the guitar do not require or employ a treble bleed mod.
Version 1 – Basic Version – Single Cap
The simplest, easiest treble bleed mod is to use a low value capacitor by itself. Although simple, it tends to be very bright.
PRS guitars installs a 180 pF bypass cap as standard on many of their guitars (usually with humbuckers and 500 kΩ volume and tone pots).
DrKev: “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.”
Version 2 – Single Cap and Parallel Resistor
When there is only a capacitor what you’ll notice is that the bass is filtered but the treble is not. If a resistor is put in parallel with a capacitor it helps to keep the guitar tone more balanced as the volume pot is decreased and corrects loss of bass/”too much treble” problem of a capacitor only circuit. It allow some of the treble to drain off around the cap making it less bring..
In general; The lower the value of this bypass resistor, more bass sneaks by at lower volume settings. Conversely, the higher the value of the resistor, the more bass is blocked. Another way to view this is the higher the resistor, the more treble and less bass.
Taper Effects: The added 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).
“I’m in the process of experimenting with a Linear pot instead of an Audio pot to I can use this effect to my advantage. (A linear pot shows a marked decrease on volume very quickly which to the ear sound like a very fast reduction and loss of fine control but this effect would reduce how quickly the volume decreases at higher settings like 6-9” – Bruce Gombrelli
Volume swells can be less smooth at the lowest numbers on the volume knob, particularly for high gain players. Some of this change can addressed with the Fender mod of adding an additional series resistor in the 20 kΩ to 50kΩ range.
A popular 250K pot value set is a 560 pf and 150K parallel resistor used by Dimarzio.and Bruce Gombrelli 660pf cap with a 220K resistor.
How it works in a nut shell
Think of it this way. Full on the circuit doesn’t affect anything (except the pot itself is in parallel with the pickup(s) select. As you reduce the volume, the resistance of the pot increases between the pickup and output (effective adding series resistance) plus lowering the resistance to ground, effectively shunting more signal to ground
Version 3 – Cap with resistor in series
“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 changes in a different way as the volume pot is turned down. This series combination passes a little more midrange than the equivalent parallel circuit. It feels a little like dialing back the bass and treble a touch. You may or may not notice this tonal difference between parallel and series resistors, you may prefer one over the other, and may prefer the taper change of one over the other, so feel free to experiment and let your ears tell you what works best for you.”
Version 4 – Lets get more complicated again Treble Bleed
Interestingly though, in Fender‘s current American professional series guitars they have a new combination, which is a 1.2nF cap, 130kΩ parallel resistor, and a 20kΩ series resistor. The extra little series resistor is interesting. Without we can already maintain the resonant frequency and peak height with standard parallel bypass components. This extra series resistor doesn’t make much difference tonally (because most of the above noted values already do a good job without it and the ear won’t be very sensitive to the differences). But it does restore some of the change in the taper of the volume pot closer to it’s stock characteristics.
Cable Capacitance
The capacitor/resistor values that work best for you will generally depend on your total cable capacitance, which is related to the total length of cable your guitar. That in mind, and based on my circuit modelling, my current rule of thumb is as follows:
“If you use a 10 ft cable from your guitar, choose the Mojo Tone, DiMarzio, or Suhr values. If you use a 30 ft cable choose one of the versions with 1 nF or 1.2 nf capacitor.” DrKev
Ears, it’s all about ears
You ears and someone elses are not the same. Some players are more sensitive to high frequencies so it you are very fussy, you may not like something that sounds perfectly good the masses.
Golden Age Treble Bleed
1nf and a 150K resistor parallel used to be the defacto standard. Fender “Tone Save” is nothing more than a treble bleed using a 1.2nf cap and a130K resistor.
Does the construction make a difference?
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. The only thing that matters is the VALUE of the capacitor or resistor. If the values are identical, your ceramic/PIOs/Polys/Bumblebees/orange drops etc. will all sound exactly the same. Your ear and subjective appraisal will make more difference than the type of cap. The one operation difference is that some caps tend to last longer (by LOTS of years so you might not even be alive at that point).
The physics of capacitors is where to go if you want to learn about the affects of different cap material, Google searchs, blogs and chat group opinions will NOT give you the correct answer for this. Research this in DETAIL yourself if you doubt it but it may require a few courses in physics to prove it to yourself if you have confirmation bias.
Overpriced caps: It’s high time we stopped allowing vendors to sell horribly overpriced components on the basis of mythical characteristics that don’t actually exist.
NOTE: If you LIKE the way a capacitor looks or like that can handle 1KV or more (guitar pickups are mv), then buy anything you want, art knows no scientific logic.
Do Capacitor voltage rating matter on a guitar?
Speaking of voltages. Guitar signals are tiny, REALLY tiny, the voltages involved 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. Why would a capacitor need to be 100V when the max it ever sees is in the millivolts? (1000’s of times smaller)
As another note, Fender currently uses 50V caps on their Stratocasters.