August 20, 2023 Buffers, Impedance, and Myths
Ever wondered about buffers and impedance? You’re not alone.
Many swear by buffers on their pedalboards, especially before and after fuzz pedals, to maintain signal strength. But why? Let’s dive into the world of buffers and impedance.
A guitar buffer is typically a high input impedance, low output impedance, unity gain amplifier. It’s designed to preserve your guitar’s signal strength and prevent loading of the pickups. But what’s impedance?
Impedance, symbolized as “Z”, is like resistance but for alternating current (AC). Guitar pickups produce AC, so we care about input impedance, which is the input’s resistance to AC. Contrary to intuition, we want high resistance on the input. Why? High input impedance ensures the full signal is captured without any loss.
Imagine a hose (your guitar cable) with changing pressure (your signal). If connected to a container with low pressure, the hose’s pressure drops rapidly. This is the “loading effect” we aim to avoid with buffers.
On the flip side, output impedance is the resistance to current at the circuit’s end. High output impedance limits the current, while low output impedance allows for a strong current output, which is ideal.
Buffers, in essence, are impedance transformers. They boost signal strength without affecting voltage. But there’s a limit to how strong a signal should be. Excessive current draw can strain the power supply and produce unwanted heat.
When choosing a buffer, consider these specs:
- Input Impedance: 500KΩ – 1MΩ
- Output Impedance: 1KΩ – 10KΩ
Beware of buffers boasting “Super High Input Impedance.” While it might sound appealing, ultra-high input impedance can introduce noise.
Buffers play a crucial role in preserving the tone quality of a guitar or any instrument signal, especially in setups with long cable runs or multiple pedals.
Here’s how buffers can affect tone quality:
Without a buffer, long cable runs can result in a loss of high frequencies due to the capacitance of the cable. This can make the tone sound dull or “muffled.” A buffer helps maintain the strength and clarity of the original signal, ensuring that the high frequencies are retained.
Impedance Matching: Buffers present a high impedance to your guitar and a low impedance to your pedals or amplifier. This is beneficial because guitar pickups prefer to see a high impedance, while most pedals and amps prefer a low impedance source. Proper impedance matching ensures that the signal is transferred without any loss or alteration.
When multiple pedals are chained together, especially those that are true bypass, the cumulative effect can lead to “tone suck.” This is a loss of signal strength and clarity. A buffer placed at the beginning of the chain can prevent this by driving the signal through the subsequent pedals.
If you use different guitars or swap out pedals, a buffer can help maintain a consistent tone by ensuring that the signal always sees the same load impedance.
Some vintage fuzz pedals, like the Fuzz Face, are known to interact directly with the guitar’s volume and tone controls. Placing a buffer before such a pedal can change this interaction, which might be perceived as a change in tone quality. In such cases, it’s often recommended to place the fuzz pedal first in the chain.
Not all buffers are created equal. While many are designed to be transparent, some might impart a slight coloration to the tone. It’s essential to choose a high-quality buffer to ensure minimal tone alteration.
When used correctly, buffers can greatly enhance tone quality by preserving signal strength, ensuring proper impedance matching, and preventing tone degradation due to long cable runs or multiple pedals. However, it’s essential to be aware of the specific needs of your setup and choose buffers accordingly.
