The Radial J+4 is a product that customers have been asking
for. Why? Well it appears that although there are several
consumer-to-pro interfaces, they seem to fall short on some
key points. This is in fact why we developed the J+4; not
so much because the world needs one, but more so, it seems
that the world is looking for one that works right.
A line driver like the Radial J+4 is designed to take a
-10dB signal and boost the output so that it can effectively
drive a professional +4dB line input. This is fundamentally
a simple task. The difficulty comes when attempting to do
so in a small package and with limited current. The usual
results are less than adequate audio performance and a minimum
of features.
The J+4 begins with 100% transformer isolation. Transformers
are often eliminated in most electronic products as they
are both costly and space hungry compared to active buffers.
But transformers are particularly adept at eliminating noise
caused by so-called ground loops. This type of noise is
most common in the field where controlling the power grid
is often difficult. Given the fact that many of our customers
are in live touring, large system integration and broadcast,
there is a certain expectation that a Radial product will
not only do the job, but will actually help silence the
system. The Radial J+4 will not disappoint! A high performance
drive circuit yields less than 0.004% distortion with better
than 95dB signal-to-noise.
To truly understand how the J+4 works, it is worth understanding
signal levels as a whole, with this table:
| +24dB |
Broadcast Maximum |
Old standard from the analogue telephone
wire days that is no longer used |
| +14dB |
Typical maximum output |
This relates to the +4dB standard output plus 10dB
for 2 times the perceived loudness |
| +4dB |
Professional Standard |
Balanced output level as used today in all professional
audio equipment. |
| 0 dB |
Nominal level |
Reference point |
| -10dB |
Consumer electronics output |
Standard output level for consumer products like CD
players |
| -30 to -20dB |
Keyboard output level |
This is a typical output one can expect from an electronic
keyboard. |
-50 to
-30dB |
Instrument output level |
This is the typical output one can expect from an electric guitar, bass or acoustic |
-70 to
-60dB |
Microphone output level |
This is the typical output one can expect from a
microphone or single coil electric guitar pickup |
The J+4 is designed to boost the signal from a -10dB consumer
electronic device and bring it up to a +4dB professional standard.
Keep in mind that you require twice the power to generate
3dB of gain. This means that the J+4 must generate at least
+14dB to achieve this increased level. The real magic here
is increasing the gain without adding noise. This is truly
what separates the Radial J+4 from other devices.
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