For years, guitarists have been using AB boxes as a means to fulfill their tonal desires and switch between two different amplifiers to achieve very different tones. As many guitarists know, dual-amp set-ups are absolutely wonderful but carrying two full 4x12 stacks to a gig is not always convenient. This challenge led us to switching heads and speaker cabinets as a solution. The Headbone™ head-switcher was the first to be developed. We then looked at switching speakers. During preliminary tests, we soon realized that using the same head and switching the speaker cabinets could produce some pretty spectacular tones. Radial President Peter Janis explains: "I have this old red knob Fender® Twin from the 1980s and although it is loud, it really does not have the warmth or character of my '65 Twin reissue. But when I plugged it into a 4x12 cabinet, I was astounded. It sounded huge! This experience solidified my resolve to make a cabinet switcher and this evolved to become the Cabbone we have today."

Solving the problems

Although the concept of switching speaker cabinets seems pretty simple, one look inside the Cabbone and you will see that there is a lot more to making this work than a simple toggle switch. In fact the footswitch does not switch the signal at all; it sends a toggle command to a PIC or programmable timing chip that in turn, sets the whole switching process into action. Why not just a simple switch? Well... if it were that simple, there would be speaker switchers everywhere.

Consider the big picture first: the Cabbone requires you to connect one speaker cable from the amplifier head, and connect two more speaker cables from the Cabbone to each of the two speaker cabinets. On a big stage - it is both impractical and inefficient to run long speaker cables to and from a pedal board. This meant that we needed some type of remote control. Next problem – tube amplifiers need to see a load at all times or else they will self-destruct. If they do not have a speaker connected to them when in use, all kinds of problems can develop including blowing the output transformer and significantly reducing tube life. Final challenge – power handling and tone preservation. Switching the output of a 100W head is serious business! The power has to be 'managed' in such a way as to ensure the electrical contacts do not arc while ensuring the amp sees a speaker load even if disaster occurs. And of course messing with the tone is simply out of the question. With the Cabbone, it must sound right and the show will go on!

The inside scoop

Look inside a Cabbone and you will see that it is absolutely stuffed with components including two high power relays. When you hit the Cabbone's footswitch, it sends a change command to a PIC (Programmable Interrupt Controller) which sends a command to each of the relays, turning speaker out-2 ON and then moments later, turning speaker out-1 OFF. A carefully timed overlap ensures the amp head sees a constant load, thus protecting it from damage. Furthermore, in the unlikely event that the Cabbone's power is shut off, a default setting we call 'Safe Mode' springs into action that connects the amp to speaker output-1. This provides your amp with a safety net. (Yup – safe & smart!)

A huge benefit with using relays is that in addition to being controlled by the Cabbone footswitch, they can be remotely controlled using a contact closure or external switch. We call this function Slingshot™. Slingshot is an easy to use remote control system that is based around standard footswitches and ¼" guitar cables. With the choice of latching or pulse modes, just about any footswitch or MIDI controller can be used to remotely toggle the Cabbone's speaker outputs. The Cabbone's Slingshot circuit is equipped with both an input and an output. This lets you use a footswitch to toggle the Cabbone's speaker output, while it simultaneously changes channels on your guitar amp. With a single foot action – two completely different worlds of tone emerge.