The 4th article in the “Upgrading Your Electronics” series, we will now cover the hotly-debated topic of capacitors. In fact, the only topic that gets repeated more often in forums all across the interwebs is whether fingerboard wood has an effect on tone. Capacitors are a big deal to many guitarists in search of the perfect tone so I’ll try to tread lightly on this one.
Before we begin, if you haven’t checked the first 3 parts of the series, please do so (especially Part 1) by clicking here or any of the links to the right.
In the most simple of terms, a capacitor is an electrical component that temporarily stores energy. Capacitors are measured in Farads and made in different values, and when used in an audio circuit, the values correlate to audible frequencies. So, in a continuous circuit, the capacitor “stores” frequencies and sends them to ground via the tone pot – essentially removing them from the final output frequency spectrum. Sounds familiar? It’s a similar principle to choosing 500k pots and 250k pots. A higher value cap, such as .1uf, will store and send more high frequencies to ground than lower values, such as .01uf.
Over the years, trial-and-error has led to what we now consider to be the standard range of caps used with guitars – between .050uf (high) and .010uf (low). Single coil pickups seem to perform best with higher value caps, such as a .047uf cap, while humbuckers generally perform best with lower value caps, such as .022uf. There are exceptions, however. A very common choice of caps for a dual humbucker guitar, like a Les Paul, is to use a .022uf cap for the bridge pickup and a .010uf cap for the neck pickup. Why? Neck pickups tend to be darker sounding than bridge pickups and don’t require as many high frequencies to be removed from the signal. So a .022uf cap on the neck pickup will sound darker than a .010uf cap. It’s all personal preference but the values I mentioned above are a good starting point and you can change to other values as you see fit.
So what’s the big deal then with capacitors if the value differences are fairly straight-forward? The big debate surrounds the construction of the capacitor. Caps are made with different materials: ceramic, polypropylene, polyester film, silver mica, paper-in-oil, and so on…. Modern manufacturing allows for cheaper materials to be used to build a capacitor, to the point that caps can be made for (literally) pennies. Typically early vintage instruments used ceramic and paper-in-oil caps because that’s what was available at the time, and those materials are still used today though at a higher price point. There is a perception among guitar owners that using cheaper caps in boutique, vintage, or vintage-spec instruments is just plain wrong. As in “I’m not putting a $ .10 cap in my $3,000 guitar!” So they buy true vintage or vintage reproduction caps so as to not compromise the quality of their instrument or tone. I see arguments all over the internet about capacitors and, in my humble opinion, all sides are correct to a certain extent.
The lower the cost of the capacitor, the higher the likelihood of manufacturing inconsistencies and overall reliability. This holds true for most things, generally speaking. So I understand and support those that claim a more expensive capacitor should perform better than a less expensive capacitor. On the other hand, the sole purpose of the capacitor is to capture certain frequencies and send them to ground – nothing else. Will a paper-in-oil cap do that better than a polyester cap? Most likely not. I understand and support those who make that argument as well (although, in a vintage-spec instrument, a paper-in-oil cap just feels right!)
Remember, that a capacitor has zero effect on tone when the tone control pot is wide open (fully clockwise). If you never use your tone control, the capacitor value and material has no effect on your tone. If you turn your tone pot to 1, you will most likely hear no difference between various caps as it’ll be dark and muddy no matter which one you use. But if you spend much of your time with the tone control somewhere between 9 and 5, you are the perfect candidate to try out different caps to see what value and material works best for your ears.
So what do I use in my guitars? My main Rockville Austin (S-type) uses a real 1958 Fender ceramic .05uf cap, primarily because I’ve had this cap for a number of years and I like having that piece of history. My PRS guitars have Orange Drop caps because they are extremely consistent in tone, much like the guitars themselves. My Rockville Delta (T-type) and Gibson Les Paul Special use Russian .047uf and .033uf PIO caps because I wanted a vintage vibe for both of those guitars. I also use a Russian PIO cap in my old Fender P-bass.