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The Radial J48 is a pleasure to use. It is ‘plug & play’ easy and is perfectly adept for studio as well as live concert sound. The following describes the basic approach to using the J48. For full details, please view the full J48 user’s manual.

Using the 80Hz roll-off filter is generally recommended for acoustic guitars as this will reduce the boxy sound that is often associated. It will also lessen run-away resonant feedback that can creep up, especially when the PA system is played loud.

Another innovative function on the J48 is the merge switch. This resistive mixer allows a stereo source such as a stereo keyboard to me merged or mixed mono at the XLR output. This handy feature makes life easy for the engineer when confronted with more instruments than available channels. For the keyboard player, reprogramming stereo-panned outputs is not required. Just plug the stereo source in, hit the merge and you are ready to go.

As an added bonus, up to eight Radial J48’s can be mounted into a 19” rack device called the Radial J-Rak. This can be helpful when taking your DIs’ out of the studio for a road trip. Another helpful device is the J-Clamp. This can be used to mount a Radial DI inside a rack or to the back of a speaker cabinet.

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Applications:

Using the J48 with acoustic guitar
One of the most common applications for the Radial J48 is with an acoustic guitar on stage. The J48 is designed to be used alone, with the PA and monitoring system, or in combination with the PA system and on-stage instrument amplifier.

On large professional concert stages, the monitors or sound on the stage is typically controlled by a monitor engineer or the front-of-house (FOH) engineer working double duty. In this case, the J48 is basically invisible whereby the guitar connects to the J48 and the rest is handled much in the same way as a microphone would be.

The single biggest challenge with acoustic instruments is obtaining sufficient level on stage before feedback. This is one of the reasons so many players now use in-ear monitors. This eliminates stage monitors from causing feedback. The downside to in-ears is that some musicians find that it disconnects them from the stage and therefore takes some getting used to. To help eliminate feedback, the J48 is equipped with a low-cut (high pass filter) that gently rolls off bass below 80Hz. This greatly assists by eliminating resonance.

Once on stage, if you find that you get more feedback in some areas, and less in others, try flipping the polarity switch. This will change the way the PA system and wedge monitors interact which can improve the sound and eliminate resonant feedback hotspots.

Some players enjoy having their own instrument amp on stage. This lets them set up a sound that they may enjoy. This may however be counterproductive to good sound in the room. For instance, adding reverb on stage may sound good, but when playing in an echo filled arena, more reverb in the hall could completely loose the acoustic guitar. The same applies to EQ. Cutting mid range on stage may sound good to you, but when mixed through the PA, you will want to send a flat signal to FOH so that the engineer can mix the sound so that it can be heard above the drums and other instruments.

Using the Radial J48 with bass guitar
As described above, just like an acoustic guitar, a bass guitar can either be used ‘direct’ or be used along with a bass amplifier. This applies to both recording in the studio and playing live. The advantage of a direct set-up is simplicity. No amps to carry around, no phase issues… just plug and play. For some, such as hired gun Ric Fierabracci, this approach can really work well.

“On the last Tom Jones Tour, I plugged my bass direct into the J48 and from there, had my in ear monitors set up to sound good for me and let the FOH engineer handle the sound up front. This is not about me or bass solos. This is the type of gig where all of the focus is on backing up the artist. I found this set up to be very effective. The Radial J48 quietly goes about doing its job so that I can concentrate on cues and making the artist sound great each and every night.” Ric F.

Combining the direct feed from the Radial J48 with the sound of a mic’d amplifier is a more common approach, particularly in a live event. Here, the bass player can create the sound and feel he wants on stage which is extremely important when laying down grooves with the drummer. But the same applies when it comes to EQ… what may sound great on stage, may not necessarily sound good in the hall. This is why most players take a direct feed from the bass before it goes to the amp, thus allowing the FOH engineer to work with an unprocessed sound and optimize the EQ for the room. Reversing the polarity on the bas can sometimes help time-align the low frequencies to reduce resonance and make mixing easier.

Using the Radial J48 with keyboards
Because the Radial J48 is able to handle higher levels than other active DI's, it is well suited to handle keyboards and is particularly good with older vintage keyboards that have a limited output such a vintage Rhodes Piano. When using the J48 with highly dynamic instruments such as digital pianos, samplers and drum machines, it is advisable to introduce the -20dB pad into the circuit. This will reduce the opportunity for overload distortion.

A cool feature on the J48 is the merge function. This is specifically designed to help manage huge keyboard rigs when there are more left & right outputs from keyboards than available channels on the mixer. Depressing the merge switch changes the input and throughput to two inputs and allows you to passively mix the left & right signals to a mono output. This can save valuable time during setup and eliminate the need of reprogramming all of the sounds to mono.

Using the Radial J48 in the studio
Do not be put-off by the J48's relative small size compared to large flashy studio direct boxes. We have tested most of these expensive devices and the J48 will usually outperform them when it comes to delivering great audio. This does not mean that some of these studio DIs are not valuable. It can be fun to add personality to an instrument by introducing effects such as tube distortion or radical EQ curves. The J48 was however not designed to do this. Its job is to send the most accurate signal possible to the recording system and then allow the engineer to make artistic decisions from that point.

With the advent of digital recording, ‘extra tracks’ open up the door to creative options like never before. As such, whether you are recording bass, acoustic or electric guitars, it is a good idea to always take a direct feed from the instrument and save it t a track. By doing this, you can capture a magical performance that may never be recreated and then fix it in the mix later.

The Radial J48 is perfectly suited for this. All you do is connect the instrument to the J48, and the thru-put to the instrument amplifier. The XLR out feeds your recorder where you ca quietly capture the takes and save them for future use.

Re-amping using the Radial J48 and Radial X-Amp
Re-amping or re-recording is a process that involves recording a clean track and then playing the clean track back through a re-recording device like the Radial X-Amp using effects pedals and amplifiers. This is most often used with electric guitars but is now finding more use with bass, keyboards, percussion and even vocals!

For guitar, you would start by setting up the guitar and amp as usual except you would connect the guitar to the Radial J48's input and the thru-put to the guitar amp as shown above. The J48's XLR output would then go to the mixing console and recording system. As the guitarist is playing, you would record his amp using a microphone and simultaneously capture the direct clean sound of the guitar through the J48. Once the track is recorded, you can then send the guitarist home and get to work!

Here's the deal: Once you captured the recording, fixing a botched note is easy when the signal is clean but trying to do so with a distorted guitar track is tough if not impossible. Also, having a guitarist play and play and then play more until you have moved the mics around his amp can often take hours. A tired guitarist does not perform as well as one that is fresh! Capture the performance, then worry about the sound later.

With the J48's dry track, you are now set to send the guitar signal into the Radial X-Amp. The X-Amp is basically a line level to guitar amp converter and distribution amplifier. It allows pre-recorded balanced line signal to drive guitar amps or effects pedals. Hit play on your recorder and then send the signal through the X-Amp back into effects, and various amplifiers. While you are playing back the track have your associate move the mic around the room until it sounds right. This is the magic behind re-amping.