Fender’s Greasebucket system is part of Cory Wong’s sonic strategy.
Tone pot with Fender Greasebucket tone system:
This 250k tone pot is a standard CTS pot with a 90/10 audio taper found in all U.S.-built Fender guitars. The Cory Wong guitar uses the Fender Greasebucket system, which is added to the pot as a ready-to-solder PCB. The Greasebucket PCB is also available individually from Fender (part #7713546000), though you can use conventional electronic parts for this.
Fender introduced this feature in 2005 on some of the Highway One models and some assorted Custom Shop Strats. The Greasebucket name (which is a registered Fender trademark, by the way) is my favorite of Fender’s marketing names, but don’t let it fool you: Your tone will get cleaner with this modification, not greasy and dirty.
According to Fender, the Greasebucket tone circuit reduces high frequencies without adding bass as the tone knob is turned down. Don’t let that description confuse you. A standard Strat tone control does not add any bass frequencies! As you already know, with a passive system you can’t add anything that isn’t already there. You can reshape the tone by deemphasizing certain frequencies and making others more prominent. Removing highs makes lows more apparent and vice versa. In addition, the use of inductors (which is how a passive pickup behaves in a guitar circuit) and capacitors can create resonant peaks and valleys (band-passes and notches), further coloring the overall tone.
Cory Wong bringing the funk onstage.
This type of band-pass filter only allows certain frequencies to pass through, while others are blocked. The standard tone circuit in a Strat is called a variable low-pass filter (or a treble-cut filter), which only allows the low frequencies to pass through while the high frequencies get sent to ground via the tone cap.
The Greasebucket’s band-pass filter is a combination of a high-pass and a low-pass filter. This is supposed to cut high frequencies without “adding” bass, which has mostly to do with the resistor in series with the pot. That resistor means the control will never get to zero. You can get a similar effect by simply not turning the Strat’s standard tone control all the way down. (The additional cap on the wiper of the Greasebucket circuit complicates things a bit, though; together with the pickups it forms an RLC circuit, but I really don’t want to get into that here.)
The standard Fender Greasebucket tone system is used in the Cory Wong Strat, which includes a 0.1 μF cap and a 0.022 uF cap, along with a 4.7k-ohm resistor in series. These are the values used on the PCB, and without the PCB it looks like the illustration at the top of this column.
Push-push tone pot with preset overwriting function:
The lower tone pot assigned to the bridge pickup is a 250k audio push-push pot with a DPDT switch. The switch is used to engage a preset sound by overwriting the 5-way pickup-selector switch, no matter what switching position it is in. The preset functionality has a very long tradition in the house of Fender, dating back to the early ’50s, when Leo Fender designed a preset bass sound on position 3 (where the typical neck position is on a modern guitar) of the Broadcaster (and later the Telecaster) circuit. Wong loves the middle-and-neck-in-parallel pickup combination, so that’s the preset sound his push-push tone pot is wired for.
The neck pickup has a dedicated tone control while the middle pickup doesn’t, which is also another interesting feature. This means that when you hit the push-push switch, you will engage the neck and middle pickup together in parallel, no matter what you have dialed in on the 5-way switch. Hit the push-push switch again, and the 5-way switch is back to its normal functionality. Instead of a push-push pot, you can naturally use a push-pull pot or a DPDT toggle switch in combination with a normal 250k audio pot.
Here we go for the wiring. For a much clearer visualization, I used the international symbol for ground wherever possible instead of drawing another black wire, because we already have a ton of crossing wires in this drawing. I also simplified the treble-bleed circuit to keep things clearer; you’ll find the architecture of it with the correct values in the previous column.
Cory Wong Strat wiring
Courtesy of singlecoil.com
Wow, this really is a personalized signature guitar down to the bone, and Wong used his opportunity to create a unique instrument. Often, signature instruments deliver custom colors or very small aesthetic or functional details, so the Cory Wong Stratocaster really stands out.
That’s it! In our next column, we will continue our Stratocaster journey in the 70th year of this guitar by having a look at the famous Rory Gallagher Stratocaster, so stay tuned!
Until then ... keep on modding!
Ripple (specifically ripple voltage) in electronics is the residual periodic variation of the DC, or direct current voltage, within a power supply using an AC, or alternating current, source, like the electrical outlets in your home or studio. If you're curious, you can read all about DC versus AC current at electrical4u.com/dc-current.
Ripple is wasted power, and has many undesirable effects. It heats components, causes noise and distortion, and may cause digital circuits to operate improperly. Ripple can be reduced by adding the aforementioned electronic filter into the circuitry, to ensure that the pedal is getting the proper juice. There are parts called electrolytic capacitors that do a lot of the heavy lifting in this section of a circuit. You can learn more about capacitors at a variety of websites, including Wise-Geek.com, Techcircuit.org, Beavisaudio.com, and coda-effects.com, and you can see what they look like above.
Ripple is wasted power, and has many undesirable effects.
Those of us who love and cherish old amps know all about capacitors. The first thing I do when I acquire a gem from yesteryear is take it to a qualified amplifier technician to have it thoroughly inspected, and to have the power filter capacitors replaced with new ones. The reason for this is that over time these capacitors can dry out and cause the amp to not function properly, or to just simply stop working. In a worst case scenario, it can even cause electric shock.
When an electrolytic capacitor is going bad, it can appear to be deformed, sometimes bulging out at the ends. If the power filter capacitors—or really any of the electrolytics—look like this, it's a sure sign that it's time to take the amp to a tech for them to be replaced. In some cases, there might not be any visual indication at all when a cap goes bad. Most amp technicians I have dealt with say that a good rule of thumb is to replace these capacitors every seven years or so.
For reference, here's what caps can look like when they're blown:
The electrolytic capacitors in effects pedals also wear out over time. As in amps, caps in pedals are used for multiple purposes. Coupling capacitors let AC pass through them, but not DC. And RC (resistor-capacitor) filter caps cut off frequencies above or below a certain threshold. But the classic role is the one we're discussing here: smoothing out ripples in the power supply. Capacitors have what is known as an "end of life cycle." This means that the manufacturer only guarantees them to remain fully functional for a certain amount of time. That time frame can typically range anywhere from 1,000 to 5,000 hours.
There have been a few occasions when I have purchased a vintage pedal I had been trying to find for ages, only to get it plugged in and find it unusably noisy and/or dull-sounding. I usually re-cap these old circuits before I do anything else to them. This usually brings the pedal's power back to its former glory, ensuring that the unit will behave as it was intended to for another decade or so. I would say nine times out of 10, replacing these capacitors creates a massive difference in clarity and sound. Take a look at one of my recapped circuit boards:
Keeping your pedals healthy internally is a great way to ensure that they will last lifetimes. Having them re-capped is one way to help maintain the integrity of the circuits inside. I am so glad I discovered this when I was early in my career as a pedal user and builder. It has certainly given a few of my formerly fallen soldiers a new lease on life.