Easy Mods: Guitar Tone Caps

We’re going to have a little discussion this week on a simple mod anyone with a soldering iron and 5 minutes can perform on their guitar, the tone capacitor. Now this topic has been beaten to death all over the intrawebz and there is a lot of conflicting information, opinions, and “facts” floating around out there that can easily confuse those looking for some actual information. So I’m going to give you the lowdown from my experience as a technician as well as some cool info and shootouts that I found online. Hopefully this can be a solid guideline for those of you wanting to experiment with some different aspects of your guitar.

First of all the capacitor (which shall henceforth be known as “cap” for ease of typing) itself. What does it do? The signal from the volume pot of the guitar is connected to the tone pot as well. The tone cap is connected on one end to a lug of the tone pot and on the other end to ground. This effectively acts as a low-pass filter with the setting of the tone pot deciding how much of the high frequency goes to ground (out of the signal). The tone pot and cap are always in the guitar signal so the pot value has some effect on tone as well. A 250k pot tends to leak a tiny bit more high frequencies to ground than a 500k or 1M but has a more even taper than the higher value pots. If you don’t want any of the signal going through the tone pot, they make pots that are “no load” meaning that when set to 10, the pot is completely bypassed and out of the signal. If you doubt that the pot still affects the signal when on 10, just check out the difference between positions 1 and 2 on an Esquire. Position 1 is the pickup with the tone pot completely bypassed while position 2 has the tone pot engaged. This is a great comparison of the effects of the tone pot on the signal.

Now that we know what the tone pot does, let’s talk values. Capacitor values are measured in Farads but the ones we use in our guitars are measured in very small numbers called microfarads, the symbol for which is µf. The two most commonly found values in modern production guitars are 0.022µf and 0.047µf. The higher the value of the cap, the more high frequencies it rolls off, therefore it’s common to find a 0.047µf cap on a guitar loaded with single coils and a 0.022µf cap used in a guitar with humbuckers. Just because this is the “industry standard” for off the shelf guitars in no way means that this is the necessary values that must be used with these pickups. Experiment! Enjoy! This stuff is fun! Depending on the style of music you play, a higher or lower value may be exactly what you’re looking for. You’ll most likely want to stay below 0.1µf though; anything above this will pretty much give you mud. A 0.1µf cap will yield a very warm, dark jazzy tone when the pot is rolled off. This may be too dark for some but I’ve found my Tele-style guitar loves this value with the tone pot set around 4 or 5 for jazz and mellow accompaniment. Your standard vintage Strat from the 50’s and perhaps the 60’s as well, used a 0.05µf (now replaced by 0.047 mostly) tone cap to tame the bright single coils. Again, some people find this too dark and switch to a 0.022µf or 0.033µf. The 0.047µf will also produce warm, jazzy tones with a bit more clarity than the very dark 0.1µf while the 0.022µf and 0.033µf values will retain more high end with a bit of (what I find to be very charming) nasal quality to it depending on the pickups. Your standard LP type guitar with humbuckers will usually be found with a 0.022µf cap that won’t kill all of the highs from your humbuckers. This value is perfect for getting that “woman tone” and I’ve found works very well with any pickups that are overdriven, single coil or humbuckers. Feel free to experiment with any value of cap under 0.1µf in your guitar. There is no way you’re going to damage the instrument with changing this part out (unless you’re just horrible at soldering, in that case check out this video) and the results can be quite interesting. A good way to A/B is to attach alligator clips to your tone pot and just swap caps out with the clips to find the tone you are looking for. Also, P-90’s and other more specialized pickups may benefit from different, more oddball values. I’ve found that a 0.033µf compliments my P-90’s quite well.

Now we need to discuss capacitor types. Different capacitor types do actually yield different tones. Now, this is a subject that I see a lot of debate and argument over. There are believers and non-believers so we’re going to discuss the types without getting too into the tones they provide. Then I’ll provide a link to a video shootout that I’ve found to be extremely well done and provides a good reference for the sound of different capacitor types.

The most common cap found in production line guitars is ceramic. These are small disc-shaped capacitors that are extremely cost effective and considered by most tone connoisseurs to need immediate replacement. There is nothing wrong with these capacitors, they do the job they were intended to do which is shunt high frequencies to ground. From what I’ve heard on these guys is they have a bit of a grainy aspect to the highs and really have no definitive character when rolled down, they just sound kind of flat to me. Ceramic disc caps are super cheap (usually a couple of cents each) and easy to find. If you’re not too concerned with the minutiae of tone, these work just fine. If you’re picky like me, you may want to try something else.

One of the most popular capacitor upgrades I’ve seen and been asked to do for people is to install an “Orange Drop”. These are made by Sprague/Vishay and are pretty easily identified by their orange casing and rectangular shape. The 715P and 716P series are made from Polypropylene film and foil and have a slightly aggressive top end that I’ve heard described as “harsh” before but I prefer the term aggressive as they lend themselves well to more aggressive styles of music like rock and rockabilly and even country where a dominant top end is desired a lot of the time. I’ve also found these to have a very “clear” sound when used with hotter humbuckers.

Another popular capacitor for a vintage tone is paper-in-oil caps. These can be found in new manufacture from Angela Instruments (in both aluminum and copper foil), Allparts (Vitamin Q) and Luxe Repros. I love these for Tele’s and Strats. They have just the right amount of treble bleed when bypassed (tone on 10) and roll off highs smoothly with a rich sound. They’re hard to describe but I’ve found them to be the most “vintage” tonally and the most pleasing to me on single coils. Paper-in-oil capacitors tend to be on the expensive side due to not being widely manufactured. There are also lots of vintage paper-in-oil capacitors out there to be had but they command a premium price and are getting harder and harder to come by.

Polyester film capacitors are another cap upgrade I’ve used with great results. The most sought after of these being the vintage Mullard “Tropical Fish” capacitors that are getting pretty hard to track down and quite expensive. I’ve used some before and found them to be punchy and big sounding with single coils, fattening up otherwise thin sounding guitars. Some great alternatives to the vintage Mullards are the Orange Drop 225P series. Unlike the 715P and 716P series, the 225P is made from Mylar film and has a very smooth quality to it. I hear it as having a similar “fattening” quality to the Mullards but I also hear a slightly more present top end and wonderfully clear midrange with these. Another one I liked for customers looking to upgrade on the less expensive side are metalized polyester film caps that can be had fairly cheap. While they don’t sound like the Mullards or Orange Drop they do have a “fattening” quality to them with what I’ve found to be an almost “hi-fi” top end and very even mids.

Mallory capacitors are also very popular. These metalized film caps have been compared to the famous “Bumblebee” capacitors found in vintage Gibsons. I personally have not heard the vintage “Bumblebee” caps so I cannot comment on this but I’ve found the Mallory caps to be transparent and gorgeous with a “sweetness” to the sound that I cannot describe. Maybe it’s in the overtones but I just hear something in there that my ears really enjoy.

[Black Beauty] One of the most requested capacitors I had was the Sprague “Black Beauties”. These are very sought after vintage capacitors that have a warm tone Les Paul fans adore. I have never even come across them in my work but I know they can be found if you look hard enough. You will more than likely pay a premium for them but if you do have or find them, please comment below as to how you would describe them, we’d love to hear. Luxe does make a nice replica but I’ve been told they actually don’t sound quite the same.

A little quick note on vintage capacitors. As capacitors age, the materials used to make them tend to dry out and become ineffective. Some vintage capacitors were made for military use and have the internals protectively encased in other materials that keep them from drying out. The point is, as with anything you are purchasing online, do your research. Only purchase vintage capacitors from a reputable seller that specializes in them. You might pay more than from the guy on eBay with the colorful auction, but you’ll be guaranteed a quality product that hasn’t dried up and gone past its useful specifications.

I’ve hit on the most commonly found and asked for guitar tone caps that I came across when I was a tech and my opinion of their sound. Here’s a couple of links you absolutely should check out if this is an interesting subject to you. This is a test with visual spectrum analysis results that I found fascinating. Also check this video out:

Guitar Tone Capacitors, Part 1: Evaluating Material Types

This guy A/B’s a bunch of different capacitors and values in his Epiphone. I found this fascinating as well and have watched it about 20 times now.

Thanks for reading folks. Hope you enjoyed the article. Please feel free to add your own opinion of what various tone caps have done for you and your guitar. We’ll see you next time, in The Corner.

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