True Bypass Pedals and Buffers

True bypass (often referred to when discussing effects pedals) can be thought of as a straight wire connected from the input to the output of a pedal. With a true bypass pedal, when the pedal is in bypass mode (off), the guitar signal is routed directly to the guitar amplifier without any of the interference, loading, or noise that are often caused by the pedals that are in-between. The concept is simple: true bypass pedals connect the instrument directly to the amp, so the original tone of the instrument is retained and you enjoy a more natural tone with better feel and response. True bypass pedals are great, but they are notorious for switching noise (this is most audible when playing with high gain or distorted amp tones).

What is a buffer?

A buffer is in fact a preamplifier. Buffers are used EVERYWHERE in audio where a signal is driven with a power source. The battery-powered built-in preamp in your acoustic guitar is a buffer. Your active bass is driven with a buffer. The input to your mixer or tape recorder is buffered. And all effects pedals from wahs to fuzzes employ buffers to make them work. Turning these pedals on or off usually introduces a popping transient when the circuit is charged that can be very loud. So the way around the problem is to never turn the buffer off. The pedals are buffered and therefore not true bypass.

Buffers have several advantages: You can drive longer cables with less noise, have a tuner connected with less interaction, and loading no longer becomes a problem as you chain a bunch of effect pedals together. So clearly, buffers are great, right? No, not necessarily. Buffers introduce another problem: you no longer are connected to your amp. Your signal is now "active" and invariably the buffer alters the tone of your guitar. The quality of the buffer becomes a major issue.

So what is the solution?

It comes down to making choices. If you are a tone freak and want true bypass performance as if you are connected directly to your amp, then you need to make sure that ALL of the pedals you are using are true bypass. Be prepared to live with some switching noise. When you connect devices like a tuner to the circuit, the tuner will immediately load your pickup and thin out the tone.

A good option would be to connect an effects loop selector to your pedalboard. This simple device lets you connect a group of pedals into separate loops and bring them into your guitar signal path only when you need them. This way, tone-robbing pedals - or those old vintage devices that sound great but are noisy - can be used and completely taken out of the circuit when not needed.

But what about long cables, noise, and driving more than one amp?

Well, this is where buffers come back into the picture. Without a buffer, each time you introduce another pedal or cable, more noise gets into your system. This is because guitar pickups are high-impedance devices that are particularly susceptible to noise from power transformers, power cables, stage lighting and radio frequencies. Furthermore, if you extend a high-impedance cable more than 20', the tone of the instrument will change due to the capacitance of the cable and more noise will enter the circuit. Then there is the strength of the guitar signal itself. If the guitar signal is divided in two to drive two amps or in three when you add a tuner, the tone will be severely altered. The ONLY solution to circumvent these problems is to introduce a buffer.

But wait a minute...buffers sound bad, do they not?

Actually, it depends on the quality of the buffer and this, once again, comes down to making choices. Most pedal manufacturers employ pre-packaged ICs (integrated circuit chips) to buffer their signals. These class-B chips are wonderful because they are designed to be extremely efficient, quiet, and very compact making them perfect for pedals that employ 9V batteries that would otherwise quickly run dead. These chips are also inexpensive. This reduces manufacturing costs and best of all, anyone with basic electronic knowledge can use them.

Only one problem…they can sound bad.

Why? Well - guitars are not buffered sources. Guitars are musical instruments. They breathe. They react and respond. They are alive. As soon as you connect anything in between the pickup and the amp, the instrument becomes detached. It is just not the same. It is the way that the guitar reacts to the circuit that completes the instrument.

As any tonesmith or audiophile knows, the preferred method is to use a single amplifying device to do the job. This is known as a Class A buffering circuit. Unfortunately, because Class A circuits never shut off, they are very inefficient and draw a lot of power. This makes them impractical for 9V batteries as they draw more power to achieve sufficient headroom. Furthermore, unless they are designed very carefully, they are much more prone to noise, which is a major concern with high-impedance guitar circuits. That said, the good news is that because we are dealing with guitar signals, we do not care about being "efficient." Our only goal is great sound.

With a high-quality Class A buffering circuit that has been optimized for guitar, you get the benefit of less noise; you can use longer cables; you can drive multiple effects, and you can drive multiple amps without the level dropping…and your tone always remains your tone.

That's all for now – keep on rockin'!