Tipping Your Cap: Simple Mods for More Capacitance in Your Signal Chain

Let’s begin with some typical additional capacitance values that certain lengths of cable (or capacitors) can bring to your system:

• 10’ vintage coiled cable (approx. 3 meters) -> 1 nF

• 15’ vintage coiled cable (approx. 4.5 meters) -> 1.5 nF

• 20’ vintage coiled cable (approx. 6 meters) -> 2.2 nF

• 30’ vintage coiled cable (approx. 9 meters) -> 3.3 nF

• Ritchie Blackmore-style, ultra-long vintage coiled cable -> 4.7 nF

I listed standard values here, so you should have no problem getting caps to match them in any local electronics store or online; the type of cap doesn’t really matter and will mostly be dominated by size, but I’ll share more about this in a minute.

Let’s quickly summarize the first installment of this column from last month’s issue: From a technical point of view, added capacitance shifts down the resonance frequency of the pickups, so they sound fatter, especially when using overdrive. This is exactly the reason why a lot of distortion and fuzz boxes with a vintage voicing use an additional cap at the input section; the resulting overdriven tone is fat and warm.

This month’s mod, which involves adding a capacitor to your signal, works best with vintage-flavored single-coil pickups (approximately 2.4 H inductance) or a typical old-school PAF-style pickup (approximately 3.8 H inductance). Modern high-output pickups are often sporting inductances of 6 H to 8 H, and don’t sound very good with this mod—when adding more cable capacitance to such pickups, the result is a dull and wooly tone without any clearness and definition. If you want to make your single-coil guitar sound more Les Paul-ish, you should try a 4.7n capacitor. It will shift the resonance frequency of your single-coil pickups down to the typical PAF ballpark, making for a very cool and usable old-fashioned guitar tone. It might feel a little muffled when playing clean, but ultra fat and punchy when using overdrive! In general, values higher than 4.7n are not recommended.

We have two options for where to install our cap.

On the Guitar Cable

This is the easiest location to add additional capacitance to your system, with several mod options:

1. The lightest mod ever isn’t a mod at all—it’s to simply buy a vintage guitar cable and plug it in whenever you need it! I don’t know of any company that offers modern guitar cables with intentionally high capacitance.

2. The Neutrik company offers a special angled plug, called the Timbre Plug, that you can solder to any guitar cable of your choice. The plug has a 4-way rotary knob on top to toggle between different capacitors. In addition to a bypass setting, the plug offers capacitances of 1nF, 2.2nF, and 3.3nF, letting you simulate different cable lengths on the fly.

3. You can add an additional capacitor to any guitar cable of your choice to convert it into a “longer-sounding” cable. You simply open one of the plugs to solder the cap between the hot and ground—that’s it. Small, 2.5 mm contact spacing ceramic caps are easy to put into a standard plug and are your weapon of choice here. It’s essential to only add the additional cap to one of the two plugs, but it doesn’t matter if you plug this side into your guitar, an effect, or your amp. This method allows you to build yourself some cables that simulate their older, longer relatives.

Inside the Guitar

You can also add a cap (or several) inside your guitar if you only need this mod for one instrument. If you’re looking for added capacitance with all your guitars, you’d be better off choosing one of the techniques mentioned above.

1. The easiest way is to solder your additional capacitor directly to your volume pot; this way it has a fixed value that can’t be changed and is always engaged. This operation is very simple to do, and you can use regular-sized caps for this.

2. If you want to make the cap switchable, such that you can run it either bypassed or engaged, you can install a SPST mini toggle switch or use half of a push-pull or push-push pot, which usually sport a DPDT switch underneath.

3. If you want to use more than one cap to simulate different cable lengths, your weapon of choice is a rotary switch, setting up a kind of Gibson Varitone wiring without the inductor. Because we are switching capacitances, it is essential to run an additional 10 meg resistor in parallel to each of the caps, and to use a make-before-break, not a break-before-make, rotary switch to prevent loud popping noises when using the switch while your guitar is plugged into an amp. Leave the first lug of the rotary switch open for the bypass position without an additional cap.

4. If you want to make this mod even more flexible, you can add an additional “cable simulator pot” to your system. The pot should have the same resistance as your volume pot, and should be wired to your volume pot. This way, for example, you can add a 3.3nF or 4.7nF cap to the extra pot, and dial in as much cable capacitance as you like.

On the Pedalboard

The idea of putting a rotary switch or cable-simulator-pot solution into an external unit to create a kind of extra-capacitance stompbox to use with all of your instruments is just around the corner, and yes, it’s possible! However, I don’t recommend this, because it’s physically located after the volume pot in the guitar, which means less volume (no unity gain) and less high end. But don’t worry: If you are looking for a pedalboard solution to simulate different cable lengths (which, as we defined earlier, means to shift the resonance frequency of the pickups), there are some active solutions on the market offering such a feature, usually in combination with a boost or buffer functionality. To name just a few, you should look into the Seymour Duncan Pickup Booster, Stellartone Micro Pedal, or the i2e Audio AG1.0 The PURR. Along with some other brands, these pedals will do the trick, and they’re not difficult to build if you are looking for a DIY solution.

So far, I’ve received several emails from readers asking for some more DIY guitar tools, so next month, we will look into some sustainable and environmentally friendly DIY guitar helpers—all of which you can build yourself easily by upcycling things you already have at home. Stay tuned!

Until then... keep on modding!