Radial JX44
Radial JX-42
Tonebone Switchbone

JX-42™ Development

Soon after we launched the JX44 Air Control guitar and amp switcher, we received numerous requests to build a more affordable version that could be equally as functional in a small club gig as it would on a concert stage. The point here is simple: not all guitarists require programmability or the need to run four amps on stage at the same time.

The next rendition was the launch of the JX62. This full-size 19" rackmount switcher is able to handle a bunch of guitars, basses and with built-in DI box outputs, can pretty much handle any sort of instrument whether it be acoustic or electric. But as we added features it became clear that this was still way too complex for many. So we got to work, and began identifying what would be important for a guitar or bass tech and distilled down the feature set to really come up with a solution that could fit most setups and budgets.

During our market research we concluded that for most concert level musicians, four instruments and two amps on stage was more than sufficient. For instance, a guitarist could have a Les Paul in input-1, a Strat in input-2, a 12 string in input-3 and a Dreadnaught in input-4. Output A and B could be used for a pair of guitar amps. Since acoustic guitars may be used, we added thru-puts on each channel to allow a direct box to be connected if the need came up. For bass, one could connect output-A to a stage amp and have output-B dedicated to a direct box for an upright.

Optimizing the signal path

We also wanted the JX-42 to be adaptable to either passive (magnetic) pickups or be functional with wireless (buffered) systems. To address this, we ordered custom-made dual wafer potentiometers that could accommodate both. One wafer sets the Drag control™ load correction for magnetic pickups, while the second is used as a trim to set the signal level when using buffered sources. Years ago, while developing the Radial JD7 guitar selector, we discovered that when a magnetic pickup is properly loaded, the instrument sounds and feels much more natural. When mixing and matching instruments, the trim makes it easier to balance signal levels.

Ask any guitar tech and they will tell you that working with top artists can be a seriously challenging proposition, particularly when it comes to retaining the sound and feel of their instruments. They really do not care about the problems, the merely want everything to work perfectly all the time. Truth is, managing guitar signals is an extremely finicky task that is plagued with problems. This can be severe tone shift due to low quality (chip based) buffers, hum and buzz caused by ground loops and switching noise when connecting to high gain amps. Delivering 'perfect' is not easy.

A key component to the JX-42 is the 100% discrete class-A signal path. Unlike chips that can contain thousands of transistors and then huge amounts of phase inducing negative feedback, the JX-42 employs individual transistors at each gain stage which are carefully controlled with almost no negative feedback. Unlike the ultra miniature chips used in cell phones, large, full size parts are employed to ensure the least amount of artifact. This extra bit of magic may be over the top for some, but for tone fanatics, there is no other way.

Ultra quiet switching

During the development, we also discussed switching options. Mechanical switches such as relays are certainly viable, but given the fact that today guitar amps are often connected to PA systems, clicking and popping can pose a real problem – particularly with high gain amps in 20,000 watt PA systems! To address this, we chose to use opto-resistive couplers to do audio signal switching. Unlike relays that employ a 'hard contact' – opto-couplers can be set to ramp up and ramp down the signal for quiet, pop-free switching. And since they are not mechanical, they are less prone to failure. The Radial Switchbone – used by industry greats such as Derek Trucks, Steve Vai and Allan Holdsworth - employs the same great sounding buffers, Drag control and opto-resistive switching.

Part of the plan was to create a valuable tool that could be used for all kinds of other instruments alongside guitar and bass. Since each input is buffered, has a variable load or can be trimmed so that the all of the instruments connected will have the same output, it is easy to incorporate the JX-42 into just about any multi-instrument setup. When using similar sized instruments such as mandolins, banjos and fiddles, one can easily connect a direct box like the Radial JDI to the thru output to feed a PA system and share a single channel.

Physical attributes

The engineering department hates it when asked to cram in as many features as possible into such a small box. There are two reasons for this: 1st – it is a lot more difficult to do and 2nd – as parts are brought closer together noise has a bad habit of creeping in. But with today's high cost of transportation, smaller more compact solutions tend to play an important role. Further, as many artists travel with backup systems, being able to rack-mount two JX-42s into a single 19" space is a real bonus.

Remote Controllability

Finally, every artist or stage tech has a different perspective when it comes to stage setups. In some cases, the guitarist may want to select the active guitar or amp, in others, the stage tech is doing the switching. As there is no right or wrong setup, the JX-42 is equipped with connections for two optional remote control footswitches:

JR5 Remote

Originally designed for the Radial JX44, the JR5 has five footswitches. This is used to select the active inputs. Only the four guitar select switches are active as the fifth (mute) function is performed by the JR2. This can be positioned near the guitar tech so that he can hand off guitars to the artist while selecting the active instrument.

JR2 Remote

This remote control has two footswitches. It is used to select the active amp. It also enables the JX-42 output to be muted. As a second amp is mostly used for soloing, this is usually stationed on the artist's pedalboard. This also enables the artist to mute the amps during a break.

The JX-42 may well be the smallest, most comprehensive, best sounding and flexible switcher ever made for concert touring.