www.radialeng.com J48 User Guide Radial Engineering 1638 Kebet Way, Port Coquitlam BC V3C 5W9 tel: 604-942-1001 • fax: 604-942-1010 email: info@radialeng.com • web: www.radialeng.com Radial Engineering is a division of C•TEC (JP CableTek Electronics Ltd.
RADIAL J48 MK2 USER GUIDE TABLE OF CONTENTS PAGE Introduction ..............................................................................1 Input & output panel feature set .............................................2 J48 - Quick start for pros ........................................................4 Direct box basics .....................................................................5 Features and functions ............................................................8 Frequently asked questions ..
True to the Music INTRODUCTION Congratulations on your purchase of the Radial J48™ direct box. Three years in the making, the J48™ is a unique direct box that has been designed to handle the new generation of active battery-equipped acoustic guitars and basses that often overload typical direct boxes and cause distortion. Best of all, the J48 does so without the use of batteries.
True to the Music INPUT AND OUTPUT PANEL FEATURE SET 1. -15dB pad switch A provisional -15dB pad reduces the input signal to the circuit to ensure a clean and distortion-free signal is obtained. 6. XLR male output This male XLR output connector is wired to the AES standard with pin-1 ground and pin-2 hot and puts out a 600-ohm mic level signal. 2. 48V check LED Used in conjunction with the low-cut filter switch to check for phantom power. 7.
True to the Music 11. Welded I beam construction For maximum durability, a 14 gauge steel welded I-beam construction for a lifetime of trouble free performance. 14. Power supply transformer The transformer in the power supply helps eliminate ground loops by isolating the power coming in from the XLR’s 48V phantom feed. 12. Silent, high cycle switches Super high repetition switches withstand heavy use and heavy fingers. “Make before break” design eliminates pops and clicks when toggling switch positions.
True to the Music THE J48 QUICK START This section is for advanced users. It provides a quick set of instructions for those that are familiar with direct boxes. For up and coming engineers, we suggest that you read through the manual before using your Radial J48. Caution! When connecting or disconnecting any audio device always ensure the power is off or all levels are set to zero.
True to the Music DIRECT BOX BASICS What is a direct box anyway? The name ‘direct box’ comes from direct insert box. This is why these marvelous contraptions are also called DI’s. ‘Direct Insertion’ means exactly that: To insert a signal directly or take an audio signal from the source and send it directly to a mix point or recorder.
True to the Music Getting to know your Radial J48 As a rule, all direct boxes follow the same basic procedures when connecting them to a sound system. The instrument plugs into the IN, the musicians’ instrument amplifier connects to the THRU, while the mixer or recorder is connected from the XLR ‘OUTPUT’.
True to the Music Dynamic headroom Years ago when the first phantom powered active direct boxes came around, the “instrument” of the day was a passive Fender Bass. These instruments would typically generate 1 or 2 peak volts at best. This seemed to work well. Then all of a sudden, someone decided to put a battery powered pre-amp in the instrument and the output levels increased. Today basses and acoustic guitars will easily output voltages as high as 7 volts.
True to the Music THE J48 FEATURES AND FUNCTIONS The ¼” input and thru-put connectors The J48 features two ¼” jacks on the input panel. These are designed to accept normal instrument input levels such as from basses, acoustic guitars, keyboards, and drum machines. The left ¼” input is normally connected to the source instrument. The second right-hand ¼” connector is normally used as a ‘thru’ connector and feeds the instrument signal to the musician’s amplifier.
True to the Music High input impedance The J48™ presents the instrument with a high input impedance to minimize pick-up loading. This means that low output instruments such as old Jazz or P-basses will not sound different when connected to the instrument amplifier. Note that the instrument is now feeding both the instrument amp and the direct box signal simultaneously.
True to the Music The ground lift switch It is common practice to ground all electrical devices in a sound system. Proper grounding assures safe use and generally helps reduce system noise. As the Radial J48 is an interface, it is often placed between two grounded AC powered devices such as a keyboard and a mixer. Often, these two devices will be connected to different AC outlets or may have very different ground reference potentials.
True to the Music The balanced XLR output The J48 features a mic level, balanced output jack that uses a standard XLR male connector. This jack is wired to the AES (Audio Engineering Society) standard with pin-1 ground, pin-2 hot and pin-3 cold. Today, pretty much all equipment is manufactured using this standard. Connection is made to the mic-level input of the mixing console or to a standard mic pre-amplifier.
True to the Music electrical isolator when placed on guitar amplifiers. Most guitar amplifier chassis are bolted directly to the amp carry handles and these can sometimes be electrically charged. The isolation pad helps minimize shock hazards, especially with older amplifiers. If the pad ever wears down, it can be replaced by ordering a spare from the factory.
True to the Music FREQUENTLY ASKED QUESTIONS What is the difference between active & passive? Active DI’s have a built-in pre-amp requiring power to run while passive DI’s use a transformer to convert the signal. Both transform or convert the instrument’s high-impedance output to a low impedance balanced microphone level. This allows long cable runs without adding unwanted noise. Passive boxes have the advantage of providing isolation over typical DIs, which can reduce ground hum and noise in systems.
True to the Music How does Radial increase the rail voltage? We take the input voltage and drive it through a special custom made DC-to-DC transformer. The transformer is coupled to a timing chip that essentially drives the signal the same way as the newer switch mode or digital power amplifiers work. This brings the current up to a workable level and creates a higher internal rail voltage to handle the dynamics.
True to the Music BLOCK DIAGRAM AND SPECIFICATIONS J48 MK2 Specifications Type: Input impedance: Output impedance: Frequency response: Linear performance: Total harmonic distortion: Phase distortion: Maximum input voltage Size: Weight: Construction: Finish: Radial Engineering Active 48V with switching supply Unbalanced 220K-Ohms Balanced 600-Ohms 10Hz to 80kHz +/- 0.12dB from 20Hz to 20kHz 0.06% @ 20Hz, 0.005% @ 1kHz 0.02º at 1kHz 3.12 Volts RMS ( 9V peak ) 3.5" wide, 2" high, 5.
RADIAL ENGINEERING (a division of J.P Cabletek Electronics Ltd.) warrants this product to be free from defects in material and workmanship to the original owner and will remedy any such defects free of charge according to the terms of this warranty. Radial will repair or replace (at its option) any defective component(s) of this product (excluding batteries, finish and wear and tear on components under normal use) for a period of three (3) years from the original date of purchase.
