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Radial JD•7 Questions and Answers:
Q: Can I use all the JD•7 outputs to my amps at the same time?
A: Yes. The JD•7 is a high-impedance, unity gain distribution amplifier. This means that it takes the original signal and then amplifies it so
that the output signal to each connected amp is the same as if only one amp was connected.
Q: Whenever I have tried to connect more than one amp together in the past, I have experienced all kinds of hum and noise. How does
the JD•7 get around this problem?
A: The problem you were experiencing in the past was caused by what is commonly known as a ground loop. Each amplifier is different and
as such, has different chassis voltages referenced to ground. When you connect these together these voltages combine to cause noise and hum.
The Radial JD•7 is equipped with isolation transformers on most of the outputs. These electrically isolate the amplifiers from each other thus
solving the ground loop problem.
Q: I have tried many A+B boxes but they always change the sound of my guitar. Why?
A: If you simply Y-jack the output of your guitar, the signal going to each amp is cut in half or to be more precise, you will experience a 3dB
loss at the input. You loose punch, dynamics and drive which makes your guitar sound lifeless and thin. Most A+B boxes are simple passive
devices that cause this problem. The next level AB box uses inexpensive drive circuits (opamps and IC's) to step-up the power so that you do
not experience the power loss. These circuits are cheap to build and unfortunately sound like it. They are brittle and unnatural and ruin the
sound of the guitar.
Q: Will the JD•7 change the sound of my guitar?
A:
The JD•7 is as perfect as perfect can be! The JD•7 has been designed to reproduce your guitar as faithfully as technology will allow. In
other words, although nothing is perfect, the JD•7 is as close to perfect as possible. The JD•7 does not employ any opamps or ICs it is 100%
discreet Class-A. This is what audiophiles insist on for best reproduction. Further, the JD•7 uses the worlds finest Jensen Transformers. The
best circuit with the best components produces the best results!
Q: Can you explain Drag control?
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A:
After we built the 1 JD•7 prototype, we knew it was exceptionally accurate. It was perfect. In fact it was too perfect. The problem was
that it did not sound right. After many hours of testing, we found that there was a relationship between the guitar and the amplifier that was
being lost. When a guitar is connected to an amplifier, the amplifier's input section, tubes and transformers combine to create a load on the
pick-up. This 'loading effect' combined with the type and length of cable further causes a noticeable tonal change, especially on lower output
single coil or vintage humbucking pick-ups. Although subtle, the change is more than tonal; it has to do with the feel and grind of the guitar.
This was the problem: When the guitar was connected through the JD•7, the natural loading and resistance was lost. The guitar no longer saw
the amplifier; it was seeing the perfect input on the JD•7 while the amp was seeing the JD•7's perfect output. The relationship was lost. The
amp was no longer 'dragging' down the pick-up. Drag control recreates this effect by allowing the musician to adjust with the guitar's
impedance and resistance before it is sent out to the amplifiers. Drag is subtle yet absolutely awesome!
Q: Can I use a foot switch to control the JD•7?
A:
We do not provide a foot switch however you can connect the JD•7 to a custom switching system and it will work fine. I am sure that the
Radial Design Team will one day produce a foot controllable system for live use.
Q:
Can I control the level going to each amplifier independently?
A:
Yes. We have a device that you can purchase called the Radial Trim-Set. [hyperlink] It has 3 inputs, volume controls, and an amplifier
Drag offset circuit. You simply connect the Trim-Set between the output of the JD•7 and the amplifier and you can now fine-tune your amp
input levels in the comfort of your chair!
Q: I notice that there are two effect outputs on the JD•7. Can these be used as extra outputs?
A:
Yes. Maybe we should have called the JD•7 the JD10... The effect loop outputs on channels 5 and 6 are always engaged. Depressing the
loop switch on the channel front panel turns the 'receive' on. This means that you can use these outputs for other devices such as guitar
tuners.
Q: Can I use any amp with the JD•7?
A:
Yes of course. However please keep in mind that in order to keep noise down and to avoid getting a shock, you should always use
properly designed equipment with 3 prong plugs. The 3 ground plug is there for safety and using older 2-pronged amplifiers can be both
dangerous and noisy.
To prevent noise, we recommend that channel-1 always be connected to a relatively new amplifier with proper grounding. This is where the
JD•7 derives its ground. You must make sure that any old amplifiers be set to the correct electrical polarity.
matter as this will not only protect you from shock
Q: Is the balanced out on the JD•7 line level?
A:
No. It is mic level. The output is about the same as what you would get from a direct box. This allows the JD•7 to be used in a concert or
recording splitter snake system. The JD•7 balanced output should be connected to a mic preamp or mixer mic input.
Q: Where can I buy a JD•7?
A: The Radial JD•7 is a professional box sold through professional audio and recording outlets. Please contact Radial Engineering for the
name of a dealer near you.
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, but it will also reduce noise.
Read the owner's manual on this
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