Why you are thinking about Pot Value wrong
By Sean Arbow
When I was a beginner learning about guitar wiring, I was often misled by common generalizations like "humbuckers need 500K pots, and single coils need 250K pots," or the recent "you must use 1meg pots with CuNiFe wide-range pickups!" trend. Like many new to the craft, I mistakenly believed that specific pickup types required specific potentiometer values to sound "right." However, as my understanding grew, I realized how inaccurate and limiting this mindset is for guitarists. Now, I believe we need to move away from simply repeating this "rule" and, more importantly, from the idea that there is only one correct way to approach wiring. This notion of a single "right" way is more subjective than objective, though changing this ingrained perspective is challenging.
Two things before we start.
Understanding Pot Value as Audio Compression
A pot's function is similar to a basic audio compressor. Audio compression involves setting limits on the frequencies present in a raw audio signal. In recording, this technique balances the volume levels of multiple signals or evens out the peaks and troughs within a single track. This balancing act allows lower-end frequencies to be more audible instead of being overshadowed by overpowering high frequencies. Essentially, for musical instruments, think of the pickup as the "Signal" or "Track" being compressed.
Focusing on Function Over Pickup Type
To better understand pot and pickup pairings, let's temporarily disregard standard music industry pickup names like Humbucker, P90, and Single coil. This mental separation encourages a focus on the pickup's function rather than its label. Instead, consider using terms like "Single transformer" or "hum-free transformer" to describe the pickup. Not a one for one. But VERY similar in design.
G.U.N.: A Model for Pairing Pot Values with Transformers
This thought model, G.U.N., provides a new and improved approach to selecting potentiometer values for use with transformers. It focuses on achieving the desired sound by considering the transformer's inherent EQ and the desired tonal outcome.
1. Gauge the Sound: Begin by clearly defining the desired sound. Consider the existing EQ characteristics of your transformer(s) and how they compare to your sonic vision. This initial understanding is crucial for the subsequent steps.
2. Utilize Compression: With a clear understanding of both the transformer's EQ and your target EQ, the next step involves considering the compression applied by the potentiometer. A general range for musical instrument applications is 50k to 1000k, although deviations are possible. Higher values (e.g., 1meg) result in less signal compression (aka more frequencies), while lower values (e.g., 50k) introduce more compression (Limiting frequencies)
The core of this stage is balancing the transformer's EQ with your desired EQ using appropriate pot values. This may require experimentation.
3. Neutral Responses: Even when making careful adjustments to compression, incorporating subsequent components like filter circuits can still unintentionally modify the desired equalization (EQ). This section examines the use of combined potentiometer values to influence the instrument's tonal and dynamic response.
For example, pairing a 1meg volume pot with a 500K tone pot will result in less compression at maximum volume (aka more highs and complexity) compared to using two 500K pots. Simultaneously, this combination will not be as bright in the high frequencies as using two 1Meg pots in the volume and tone. Adding the 500K tone pot effectively makes the tone control function as if it starts at a '5' setting, relative to an original 1Meg tone pot combo.
Historically, this technique has been employed in instruments such as the Jazzmaster (which uses a 1M volume pot and a 50K tone pot in its rhythm circuit) and the 1950s Original Les Paul Junior (which pairs a 500K volume pot with a 250K tone pot). These strategic combinations offer nuanced control over the instrument's tonal characteristics and dynamic performance.
Here are some scenarios:
Transformer with Low end Range that i want to get highs out of: This is super common with overwound Hum free transformers. In the scenario you want to gauge the amount of compression to match your ear.
First try. knowing that the first thing that goes with compression is high end. I would start with 1meg. If i didn't like that then i would try 500k. If that is too much compression i would try the in-between with a 1meg Volume and a 500k Tone.
Transformer with High end Range that i want to tame a little: This Is common with transformers that are underwound. Just like before understanding compression we want to start with 250k to cut more high end range out. How does it sound? If you dont like it, go down a step, now we have 100k pots, is that too much? lets do a mismatch combo, 250k in the volume and 100k in the tone.
To summarize. If you are someone who believes that pickups needs certain values, You are limiting yourself and your sound. Compression and the values you choose create a sound uniquely yourself. so just try things.
About the Author: Sean Arbow
Sean has been obsessed with circuit designing for 20+ years, He was our custom shop builder and has made tens of thousands of kits for people, including some very high-profile musicians. He's the style of nerd your favorite local tech fanboys about
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