Radial Engineering JDI Mk3 User Manual page 12

True to the Music
The JDI's parallel speaker connection feature lets you do this by connecting the JDI directly to the speaker cabinet. It is
important to note that the JDI is NOT a load box; you must have a load such as a speaker connected to the amplifier, as
connecting the JDI directly without a load could cause severe damage to the equipment.
Connect your amp as usual, then connect a ¼" to ¼" cable from the second (parallel) speaker cabinet jack to the JDI.
Because of the high impedance and low draw from the JDI, the amp will only see the speaker cabinet so you do not have
to change the amplifier's impedance setting. Depressing BOTH the -15dB PAD switch and the SPEAKER switch inserts a
special circuit that will protect the JDI from overload and allow the parallel speaker connection to be made safely. Depressing
the SPEAKER switch also introduces a band-pass filter circuit that rolls off the highs and lows in order to better emulate
the performance of a typical 12" speaker.
Mechanical attributes
All Radial products display the results of our relentless pursuit of durability. Look inside a JDI and you will note that it is
literally two boxes in one. An internal heavy-duty welded steel chassis which houses the circuitry and connectors and an
external 'book-end' design steel shell designed to protect the switches and jacks from overzealous roadies and other rigors
of touring. Both boxes are made from 14 gauge steel and protected by a heavy baked epoxy finish that will look great even
after years of service.
Inside, the mil-spec PC board is two-sided which means that all components are soldered twice. Further, the dual shell
enclosure makes it impossible to torque the PC board ensuring years of noise free performance without failure.
The JDI is also outfitted with a full bottom no-slip pad for two important reasons: it provides plenty of 'stay-put' friction on
hectic stages to keep your DI from sliding around or falling when stacked, and it also works as an electrical isolator when
placed on or around guitar amps – many amp heads have handles or hardware which is sometimes connected to the amp's
chassis or circuit. The isolation pad helps minimize the possibility of shock hazards, especially with older amplifiers.
J-Rak – 19" rack mount kit
The J-Rak is an innovative rack shelf/chassis that lets you rack-mount up to eight Radial JDIs, J48s or the other similarly
sized Radial DI, splitter or isolator products into a high-density 2-RU space. Each unit can be front or rear mounted allowing
the system designer to have the XLRs on the front or rear of the rack, depending on the application.
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Radial Engineering JDI User Guide