J+4™ Balanced -10dB to +4dB Signal Driver

Part No. R800 8015

  • Stereo preamp boosts signals to +4dB balanced line level
  • Increases gain for low output instruments & music players
  • Transformer isolated to eliminate noise caused by ground loops
  • Plenty of connector options - Plug and play easy to use

The Radial J+4 is a stereo interface designed to accept unbalanced low output level devices such as instruments, computers or CD players and boost the signal to a balanced +4dB level for easy manipulation in professional environments such as broadcast, recording studios and live touring.

The design begins with 100% discrete components for optimal signal transfer. Careful attention has been paid to eliminate noise by combining the advantages of active signal buffering with transformer isolation. The J+4 delivers better than 95dB signal to noise while ensuring hum and buzz caused by ground loops along with spurious noise from clocking does not pollute the signal path. For ease of use, controls have been kept to a minimum. This includes a stereo level control, a high pass (low cut) filter and ground lift. The choice of input connectors include a stacked set of ¼" jacks for DJ mixers or keyboards, RCAs for CD players and a mini 3.5mm for iPods®.

As with all Radial products, the Radial J+4 is built tough to handle the extreme rigors of professional touring. A unique 14-gauge steel I-beam inner frame ensures the sensitive PC board will not be subjected to outside stress which could potentially cause solder joints to fail. An innovative book end outer shell creates protective zones around the controls, switches and connectors to further improve dependability while a full bottom no-slip pad provides both mechanical and electrical isolation.

The Radial J+4 balanced line driver delivers exceptional sonic performance, plenty of headroom and ultra low noise making it the ideal companion for today's more demanding professional audio systems.

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  • "The Radial J+4 sounds great, is well built and practical. It seems like somebody actually thought about making a good product and then actually did… Great stuff!"

    Jimmy Douglass - Engineer Producer
    (Justin Timberlake, Rolling Stones, Jay-Z, Led Zeppelin, Foreigner, AC/DC)
    Jimmy Douglass
  • "Radial is making some of the best engineered solutions for the many audio needs that I come across for both stage and studio."

    Derek Williams - Production manager
    (Bonnie Raitt)
    Derek Williams
  • "In all my years I've never used a DI that sounded this good and solved problems this easily. Radial DIs are head and shoulders better than anything I had used previously."

    Jeff Worrell- FOH
    (America, Pat Benatar, Fleetwood Mac, Edgar Winter )
    Jeff Worrell
  • "I am a proud owner of a Radial J+4. it enhances the sound of my vintage keyboards with a clean, warm and punchy sound. Ground Loops? Nope… I've got my Radial and I love it!"

    Mauri Sanchis
    (Mauri Sanchis Band, Bill Evans, Dean Brown, Joey DeFrancesco, Frank Marino, Vargas Blues Band)
    Mauri Sanchis
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J+4™ - Applications
Using the J+4 to boost a stereo signal

Increasing the output from a CD player to a +4dB balanced signal is easy. Just plug into the RCA inputs, adjust the volume level and the J+4 does all the work. Transformer isolation eliminates ground loops for quiet performance every time.

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Using the J+4 with your computer

Today, computers and laptops are being used in all types of audio-visual systems. The J+4 makes it easy to interface with a built-in 3.5mm (1/8") TRS jack. Plug in and the J+4 will boost and balance the signal and deliver a professional line level signal.

Using the J+4 with a keyboard

Many keyboards and synthesizers do not have enough output to effectively drive the line level input on a mixer. This is particularly troublesome on older keyboards such as a Rhodes piano. The J+4 makes it easy with built-in ¼" inputs and balanced XLR outs.