Hello and welcome back to Mod Garage! This month, we will take a deeper look into a problem that occurs when using a treble-bleed network on a volume pot. We’ve talked about treble-bleed networks in detail before. A lot of players, including myself, can’t live without one, while other players don’t like the effect a treble-bleed network will have on their tone when rolling back the volume. When using a treble-bleed network together with an old-school fuzz or booster, you can get into some trouble. Same for using such a device with an active guitar circuit or after an active buffer device. The tone will start to sound harsh and not desirable at all. So why is this and what can be done about it?
To put the problem as simply as possible: The input impedance of a classic fuzz or booster design is very low, usually lower than 20kohms. Together with the pickup inductance (usually 2.5 H up to 8 H) it creates a low-pass filter, a happy accident with an ear-friendly result. When a fuzz pedal, for instance, receives a kind of neutral carrier signal, it results in good, harmonic-sounding overtone content. But this balance is very fragile, so if the fuzz receives an input signal containing a lot of high end (caused by a treble-bleed network, buffer, active guitar signal, etc.), that balance is disturbed. A lot of intermodulation distortion will be generated between the overtones of the input signal and the generated overtones of the distorted signal. Sum tones and difference tones will be present, which sound dissonant and not very pleasant. So, we can say that the natural filtering of the guitar signal at the input of the pedal is essential for the typical, well-known fuzz tone.
“A treble-bleed network can help you to cut through the mix when you play with reduced volume, so this is definitely a mod to consider.”
I’ve tried to simplify this complex subject wherever possible, hoping that it’s not too much theory. But I think you get the problem. So, what can be done to get rid of it? Don’t worry, you don’t need to remove your beloved treble-bleed network; we will simply make it switchable. This way, you can have both options in your guitar: treble-bleed network engaged and treble-bleed network completely shut off. This mod is not very complicated. All you need is a push-pull or push-push pot with a DPDT switch of your choice or a stand-alone DPDT switch. We will break down the mod into two possibilities:
Fig. 1
1. Replacing the volume pot. The easiest way to make the treble-bleed network switchable is by replacing your standard volume pot with a push-pull or push-push pot of your choice. The benefit of this method is that all connections are made on the new volume pot, so you will have no extra wires running through the circuit. A downside in a passive circuit can be that it’s hard to find a new pot with a good working taper as a volume pot. Usually, manufacturers only stock one version in 250k, 500k, and sometimes 1M, but only with one given taper.
Start to remove the treble-bleed network from your volume pot; we will reuse it with the new pot. Disconnect the wires from the pot and remove it. I prefer to solder all possible connections on a push-pull or push-push pot outside the guitar, which can make things much easier. Here is the wiring diagram for this operation (Fig. 1).
After installing the treble-bleed network to the switch and soldering the two wires from the switch to the pot, you can install the new pot and reconnect the wires. In the diagram, the treble-bleed network is engaged when the pot is pushed down and in its normal position, assuming that this is the standard operation, and you only want to shut down the treble-bleed network when using a fuzz or booster. If for any reason you want the treble-bleed network to be engaged when the pot is pulled up, this is easy to do. Solder the wire on A1 to C1 and the wire from A2 to C2 and you are done.
Fig. 2
2. Adding the treble-bleed network function to a tone pot or using an additional switch. If you want to add the mod to one of the tone pots rather than to the volume pot, the basic operation stays the same: Replace the pot with a push-pull or push-push pot of your choice. But now you can’t do all connections on this pot; the wires from A1 and A2 will have to go to the volume pot. This is also the way to go if you want to add an additional DPDT switch to the guitar, so you don’t need to replace a pot. Here is the wiring diagram for this option (Fig. 2), showing a DPDT switch. If you want to replace one of the tone pots, you naturally have to reconnect the wires and the tone cap from the pot to the new one.
All the rest stays the same. If you want the treble-bleed network to be engaged when the switch is up, simply solder A1 to C1 and A2 to C2.
This mod is also for all players who want to have both options but do not plan on using a fuzz or booster. Without a treble-bleed network, the tone gets noticeably warmer when rolling back the volume and a lot of players regard this as a kind of second tone you can have from your guitar. But in some cases, a treble-bleed network can help you to cut through the mix when you play with reduced volume, so this is definitely a mod to consider.
That’s it! Next month we will have a closer look into the PRS sweet switch and how to substitute it, so stay tuned! Until then ... keep on modding.
Phat Machine
The Phat Machine
The Phat Machine is designed to deliver the tone and responsiveness of a vintage germanium fuzz with improved temperature stability with no weird powering issues. Loaded with both a germanium and a silicon transistor, the Phat Machine offers the warmth and cleanup of a germanium fuzz but with the bite of a silicon pedal. It utilizes classic Volume and Fuzz control knobs, as well as a four-position Thickness control to dial-in any guitar and amp combo. Also included is a Bias trim pot and a Kill switch that allows battery lovers to shut off the battery without pulling the input cord.
Silk Worm Deluxe Overdrive
The Silk Worm Deluxe -- along with its standard Volume/Gain/Tone controls -- has a Bottom trim pot to dial in "just the right amount of thud with no mud at all: it’s felt more than heard." It also offers a Studio/Stage diode switch that allows you to select three levels of compression.
Both pedals offer the following features:
- 9-volt operation via standard DC external supply or internal battery compartment
- True bypass switching with LED indicator
- Pedalboard-friendly top mount jacks
- Rugged, tour-ready construction and super durable powder coated finish
- Made in the USA
Static Effectors’ Street Series pedals carry a street price of $149 each. They are available at select retailers and can also be purchased directly from the Static Effectors online store at www.staticeffectors.com.
Galloup’s Plek tech Adam Winarski preps a Yamaha acoustic for the machine.
Presently, many certified guitar-repair specialists possess the expertise required to deliver an instrument that both sounds and plays wonderfully. The standards set by manufacturers and distributors have significantly risen, safeguarded by rigorous quality protocols to guarantee the best possible acoustic experience for customers. Additionally, lutherie training has raised the bar for critical processes, and one of the most tricky is fretwork.
Traditional fretwork once involved manual labor, with technicians utilizing sandbags or similar supports to steady the neck as they straightened it with a truss rod during the filing process. A notable advancement in this field came in the mid 1970s when Don Teeter, an author and repair expert, imposed a new method: fixing the guitar body to the bench and using blocks to maintain the neck in a playing position. This refinement was one of many in the continued quest to produce superior instruments by standardized methods.
An example of the Plek’s readings from an acoustic guitar.
Photo courtesy of Galloup Guitars
In the late 1970s, another pivotal innovation was introduced by Dan Erlewine. He created an advanced fret jig with a specialized body-holding system and neck supports, adding another layer of precision to the repair process. During my collaboration with Dan in 1985, we developed a rotating neck jig that counterbalanced the forces of gravity, keeping the instrument in its playing orientation while adjusting the neck supports. This step represented a significant leap in establishing control and standardization of fretwork procedures in our industry. By 1986, our approach had evolved into a freestanding workstation coupled with a sophisticated hold-down mechanism and enhanced neck supports, culminating in increased accuracy, efficiency, and consistency. Over the decades, the Erlewine/Galloup rotating neck jig has become a benchmark in numerous shops, enhancing fretwork performance.
"This step represented a significant leap in establishing control and standardization of fretwork procedures in our industry."
By the 1990s, automated and computerized technologies permeated the guitar manufacturing and repair sectors. Initially applied by import companies in the mass production of guitars, the technology, although expediting processes, did not immediately achieve high execution standards. However, the tech dramatically improved over time, with computer-driven systems eventually transforming the industry. Contemporary automated production utilizing such advancements meets exceedingly high standards of precision. Some bespoke guitar manufacturers, such as Steve Andersen, were pioneers in adopting these methods, but it was companies like Taylor that established them in the modern era.
Inevitably, the progression of technology extended beyond the mere production of parts. Around 1995, German engineer Gerd Anke envisioned the integration of computer-assisted technology into enhancing instrument playability, giving rise to Plek technology, which uses computers to precisely measure and analyze the various components of a guitar, like neck relief, fret height, nut and bridge specs, and more. Nashville guitar-repair tech Joe Glaser was among the first to recognize the machine’s value, followed by San Francisco luthier Gary Brawer. When Heritage Guitar Inc. invested in a Plek machine, the guitar industry could no longer disregard the significance of this innovation.
“The machine’s scanning data confirmed that there was one nature of an ideal fret plane, done by hand or machine, and unsurprisingly, it conformed exactly to what physics predicts, not personal mojo.”
In the spring of 2022, Galloup Guitars obtained its first Plek machine. Promptly, our technician Adam Winarski paved the way for the Plek’s integration in our shop. Now, it’s a rarity for an instrument to leave our shop without having undergone Plek analysis and machining. Impressed by the results of our integration, we created “Intro to Plek” as a course for all students enrolled at the Galloup School of Lutherie, offering our students a practical introduction to this technology. We furthered this educational initiative with a comprehensive one-week intensive “Plek Certification Training Course” for both students and the public. This advanced Plek course serves those seeking to boost their knowledge base and employability in this high-precision field.
Plek is rapidly becoming an industry standard for major manufacturers and smaller shops alike. However, this does not mean that those without access to this technology cannot execute proficient fretwork. Personally, I continue to use my Erlewine/Galloup neck jig—not only out of nostalgia, but also because it remains an excellent method for delivering accurate and reliable guitars. Still, it’s undeniable that the process of fretting, fret dressing, and analytics of fretted instruments has undergone significant transformation, resulting in better sounding—and playing—guitars. And ultimately, that’s what it’s all about.