The world of guitar is, like most things in life, full of strange buzzwords and mis-information. In this article we’ll focus on one of the most controversial of these terms: true bypass. By the end, you should understand exactly what it is, what it does, and why you do (or do not) want it in your pedals.
Let’s start by breaking the concept down:
What Bypass Means
Pedals, by definition, all have a big stomp-able switch that turns the effect on and off. When the switch is on, we hear the effect that the pedal creates on our guitar signal. When the switch is off, we hear what the signal would sound like if the pedal weren’t there. In this state, the pedal is said to be bypassed. The guitar signal is not flowing through the part of the pedal that creates the effect. The effect circuit is being bypassed inside the pedal, hence the name.
If bypass were entirely that simple, we wouldn’t need this article. In truth, there are several ways to bypass a pedal.
Types of Pedal Bypass
In general, there are three ways to bypass a pedal. I’ve made a handy (albeit ugly) diagram to illustrate them.
The first, most basic, and oldest is called (for the purposes of this article) simple bypass. This uses a single switch that either sends the guitar input to the effect, or directly to the output, where it joins up with the effect output. This switching circuit is the cheapest and simplest to make, which is why nearly every pedal up until the late 70’s did it this way (and why some still do). The big drawback, as you can see from the diagram, is that the effect circuit is always connected to the output. This has the side effect of “loading” the output of the pedal, symptoms of which include high frequency loss and reduced dynamic range. Depending on the effect circuit in question, and the other things in your signal path, these problems will either be barely noticeable, or quite obvious. Another more prominent drawback is that this design is prone to sending pops or clicks to the amp when the switch is engaged. You can actually hear Keith Richards’ Maestro Fuzz Tone making switch pop noises if you listen carefully to “Satisfaction”!
In the late 1970s, a few Japanese companies like Roland (Boss’s … er, boss) and Ibanez looked at the state of guitar effects and said “there must be a better way.” Their idea was to produce a transistor-based switch that cut the effect out of the circuit completely, and did so without pops or clicks. The “logic bypass” accomplishes these goals, and over time became the de facto standard for effects switching. However, certain guitarists were not happy with this arrangement, and rightly pointed out that their precious signal has to pass through all that switching logic even when the effect is bypassed. The pedal makers had traded one form of tone-coloring bypass for another (though the true effect a logic bypass has on tone is open for debate).
True bypass was invented as a “best of both worlds” solution. There are two switches working in parallel: one at the input and one at the output. When the pedal is in bypass mode, it truly, completely bypasses the effect. There is no effect circuit dangling off the bypass to load it down, and no complex switching logic to travel through – just a straight, unimpeded path from input to output. There are mechanical true bypass switches that are basically a “double” version of the simple bypass switch, or the pedal can employ relays instead of mechanical switches. Either way, the bypass tone is kept as true as possible.
“So Matt,” you ask, “if true bypass is so great, does that mean I should only use true bypass pedals from now on?” Well …
The Effect of Buffering
Here’s the thing: true bypass is, on paper at least, a great idea. That said, there’s a little fact that I haven’t revealed yet: a direct, unimpeded bypass is not necessarily the best thing for your tone. The reason, in a word, is “buffering.”
If you have read my article about buffers, you know that they are very useful for keeping your signal intact over long cable runs. The thing you may not yet know is that some of those supposedly bad logic bypass pedals have buffers built into the switching circuit. The people who designed those pedals knew that your tone might need a little help getting to the amp intact, which is why they buffered their switching circuits. Those buffers are always on, even when the pedal is bypassed. You bought a pedal, and got a buffer thrown in for free!
With a true bypass pedal, you get no buffer help when the effect is off. If you have nothing but true bypass pedals, your wee little guitar signal has to travel through quite a lot of cable plus the pedals themselves to get to the amp. The end result is very similar to the tone loss caused by bad bypass circuits. This is why many guitarists are confused by the weaker bypass tone when they trade their old Boss Metal Zone in for a super pricey boutique true bypass pedal.
Is it possible to build a pedal with true bypass switching and a buffer that’s always on? Yep, but then it wouldn’t officially be “true bypass” now, would it? This is the decision that pedal manufacturers have to wrestle with. They know that a certain segment of the guitar community insists on true bypass pedals, even though it may not be what’s best for them in the end.
So, What Do We Do?
You could do what I do: use true bypass pedals, and build (or buy) a dedicated buffer to run in front of them. That way you get the strength of the buffer to drive your signal home to the amp, and you can rest assured that your bypass tone will be untouched by tone goblins.
Or you could just … ignore the whole problem, and use whatever you want. There’s absolutely nothing wrong with that. If you are happy with your tone, do you really care that the pedals are true bypass or not? There is no objective “best” solution when it comes to this stuff, so you may as well trust your instincts and use the pedals that make you happy.
Questions? Concerns? That’s what the comments are for. I’ll respond to whatever I can.