The first generation Switchbone ABY™
(click to enlarge)
"The Switchbone sounds better than any other ABY box I've ever heard."
Lyle Workman
(Beck, Sting, Todd Rundgren)
The inner workings of the Switchbone – No ICs!
The JD7, featuring the first ever
Drag™ control load correction circuit.


It is hard to believe that the first generation Switchbone actually appeared in 2001. Over the years, it has gained international acclaim with artists as diverse as The Derek Trucks Band, Mark Ribot, G.E. Smith, Allan Holdsworth, Audley Freed and Luther Dickinson. We have even seen pictures of Eric Clapton's pedalboard with a Switchbone controlling his amps. Now how cool is that? (No Eric Clapton does not endorse Radial, although you can usually find several pieces of Radial gear on the Clapton stage with bassist Nathan East among others.)

The question here is simple: What makes a great guitar amp switcher and what sets the Switchbone V2 apart from the crowd? In the end, the answer is a culmination of many different attributes that together make up what is likely the best sounding and most powerful ABY pedal ever.

100% discrete electronics

Most guitarists prefer the sound of passive 'true-bypass' switchers, even though they are fraught with challenges. Truth is, they do not so much prefer the sound of a passive switcher, but more that they likely have never tried a properly designed active one. The same 'tone-robbing' refrains also ring true for those that have tried wireless systems. The problem with most active switchers is that they employ integrated circuits (ICs) to buffer or amplify the signal. ICs stack hundreds or even thousands of transistors into a single device. ICs are amazing in that they can produce all kinds of gain in a very small package. Cell phones are full of them. But with all of this gain, absurdly high levels of negative feedback must be applied in order to keep the circuit under control. When you combine a positive signal with a negative one, you get phase and second harmonics cancellation. Inside the Switchbone, individual transistors are used so that minimal negative feedback can be applied. No ICs! The result is a much more natural and open sound.

Class-A signal buffer

Just as guitarists prefer tube amps, audiophiles prefer the sound of Class-A circuits. These single ended circuit designs amplify the signal (full wave) using a single device. ICs (as discussed previously) usually employ Class-AB circuits to do the work. These circuits divide the wave into two components whereby each half wave is amplified separately and then brought back together. Although this is very efficient, it produces an effect called zero-cross distortion that manifests itself when attempting to bring the two half-waves back together. With guitars, tone is king. Efficiency is nowhere near as important as tone. The Switchbone V2 employs the same award winning Class-A circuit that is in the Radial JD7 Injector™. The buffer is used to stabilize the signal, lower the impedance and drive long cables without noise. And with users such as Carlos Santana, Steve Vai, Steve Lukather and Neal Schon, you can rest assured the buffering is as good as it gets.

Drag™ control load correction

Another aspect to achieving great tone is understanding how changing the electrical load on the pickup will affect the tone. During the JD7™ development, we discovered that a 1 meg-Ohm input impedance can make a guitar sound glassy and overly bright. Leo Fender used this impedance on his very first tube amplifiers and everyone in the industry has followed suit. ABY switchers like the Switchbone are not tube based, they are solid-state! During our tests, we noticed that adjusting the load to suit the pickup made a tremendous difference. It smoothed the tone and seemed to accentuate the feel. In fact, the effect was so convincing that we have been adding Drag™ control load correction to as many products as we can!

Baseline level adjustment

In 2013, we developed a power booster called the Elevator™. The concept came from guitarists asking us to replicate the power booster that was in the original Switchbone with a few more features. One of the unique features in the Elevator was the ability to set the Class-A buffer slightly hotter in order to give the guitar amp more sizzle or have your single coil pickup as loud as your humbucker. We called it the Baseline™ setting. This is particularly effective with small tube amps or vintage amps that do not have a hot enough front end. You can of course still push the signal harder for solos using the power booster.

Silent optical switching

The most common type of guitar amp switcher is the 'true-bypass' type as is found in the Tonebone BigShot ABY™. These employ a simple mechanical footswitch making them very affordable. Tone purists love true-bypass switchers as they do not alter the tone of the guitar. (Keep in mind that adding non-true-bypass pedals in front of a true-bypass switcher actually negates the benefits as the effect pedal's buffer is now effectively rendering the circuit active.) Lengthening the cable will also introduce a capacitive effect which will dull the high-end response. The problem with true-bypass switchers is that they can produce loud pops when switching, particularly when using high-gain amps. The Switchbone V2 employs opto-couplers that can be set to ramp up and ramp down the audio signal to eliminate the pop. High quality opto-couplers are expensive, but they do a marvelous job at transferring the signal without introducing artefact.

Transformer isolation, ground lift and phase

If you have ever tried connecting two amps together, you have likely experienced a loud uncontrollable hum and buzz. This is caused by what is commonly known as a ground loop. The electrical ground or third prong on your amp is tied together at the electrical box. When you connect the two amps together with guitar cables, you are adding a ground lift. A ground lift breaks this connection, while transformer isolation further separates the two outputs, mitigating buzz and hum caused by ground loops.

ABY or ABC stage setups

The original Switchbone ABY was designed to work with two amps. Over the years, we received numerous requests to make a switcher that would allow the user to select between three different amps. We put the challenge to our engineering department and they came up with a solution: Allow the tuner out to be assigned either for quiet onstage tuning, or as a third output using the Both footswitch. So depending on your setup needs, you can have two amps playing separately or in tandem, or have three amps lined up at the ready. When in ABY mode, the tuner output is always on. When in ABC mode, the tuner becomes a third amp output. Bright full size LED indicators provide instant visual feedback for greater on-stage efficiency.

Power booster options

One of the unique attributes with the Switchbone V2 is the built-in +18dB power booster. It is 100% discrete Class-A and can be set as a clean boost that, when activated, increases the output to all the amps for soloing. You can take things a step further by also increasing the mid-range content by 12dB to add sustain. This is particularly useful when using single coil pickups. It is important to note that the guitar lives in the mid-range. So if you intend to have your solos cut through the rest of the noise on stage, make sure you have plenty of mid-range content coming out of your Marshall®! For gigs where you may be playing rhythm guitar, you can also set the Boost footswitch to mute for silent on-stage tuning.

Slingshot remote control

Guitarists hate MIDI. It is not that they do not appreciate it, but for most of us players, we just want to plug in and rule the stage. But as our needs and demands change, ideas emerge and next thing you know you want to switch from one amp to the other and activate a digital effects device at the same time. Radial invented the Slingshot™ remote control for this reason. Slingshot is, in its simplest form, a basic contact closure just like a footswitch. And just as a footswitch can switch channels on an amp or turn on a reverb, the Slingshot output can perform the same function. The advantage here is that you can have the Slingshot jump into action at the same time as you hit the power booster or switch from amp-A to amp-B. The Slingshot interface is found on many Tonebone products including the Headbone™ head switcher, the Cabbone™ cabinet selector and the Twinline™ effects loop router. It is as easy to use as connecting a guitar cable and can elevate your performance forever!

Radial-Tough construction

As with all Radial products, these are proudly made in Canada from 14-gauge steel to withstand the abuse of professional touring. This means that when you stomp on the Switchbone, the metal will not bend under stress which means that the sensitive printed circuit board inside will not torque. Those in the know are aware that 95% of all product failures are due to connector failure and cold solder joints. These manifest themselves when the PC board twists. We also employ the very best quality switches we can find along with steel shaft potentiometers that are encased in steel for maximum durability. As our customers are among the most demanding on the planet, we pride ourselves in building the very best product possible.