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J33
Phono Preamp DI
User Guide
Radial Engineering Ltd.
1845 Kingsway Ave., Port Coquitlam, BC V3C 0H3, Canada
Tel: 604-942-1001 ● Fax: 604-942-1010
www.radialeng.com
email: info@radialeng.com
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True to the Music
Radial J33 User Guide
Table of Contents Page
Introduction .......................................................................2
Feature Set .......................................................................2
Input Panel .......................................................................4
Output Panel.....................................................................5
Making Connections .........................................................6
FAQ ..................................................................................8
Specications ...................................................................9
Warranty ....................................................................Back Cover
Congratulations on your purchase of the Radial J33 combination
turntable preamp and direct box. This handy device has been developed
to interface a conventional turntable with magnetic cartridge to both
professional balanced audio systems and consumer unbalanced hi-
systems.
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As with all Radial products, every attempt has been made to make
the J33 ‘plug & play’ easy-to-use. However, please read this manual
thoroughly to ensure the best possible results.
Should you have any questions on your new J33, please consult the
Radial website FAQ section as this is where we publish answers from
users after a product has been released. If you do not nd the answer
you are looking for on-line, please feel free to send us an email at
info@radialeng.com and we will do our very best to get back to you
promptly.
www.radialeng.com
Radial Engineering Ltd.
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True to the Music
INTRODUCTION
In recent years it has become dicult to nd a hi- receiver that is
equipped with a phono input. With literally millions of albums oating
around the world, a need has emerged to capture these recordings and
transfer them to today’s digital formats.
The Radial J33 provides a solution with a simple device that is ‘plug &
play’ easy-to-use and built to Radial’s professional standards for sound
quality and durability. Equipped with an RIAA preamp and choice of
-10dB consumer line-level and pro mic-level outputs, the J33 is right at
home in the studio, on the stage and in the DJ booth.
FEATURE SET
The Radial J33 is a combination RIAA phono preamp and active DI that
allows you to connect a conventional turntable with magnetic cartridge
to a recording system, hi- or PA system.
The J33 features a pair of stereo inputs for the turntable. A ground
lug is provided to properly ground the turntable to avoid system noise.
This signal then feeds the preamp that boosts the phono signal while
introducing the RIAA equalization curve.
Next to the turntable inputs are a stereo set of RCA connectors that can
connect to the auxiliary or CD inputs on a typical hi- receiver. These
outputs can be used simultaneously with the balanced XLR outputs
described below.
The J33 is also equipped with a low-frequency rumble lter. This gently
rolls o the bass to reduce the low frequency rumble and resonant
feedback that can occur when spinning records in high volume
environments such as on stage or in nightclubs.
To connect to professional balanced systems, the Radial J33 is
equipped with a pair of male XLR connectors. The active balanced
drivers convert the signal to a low impedance (600Ω), microphone
level, stereo signal. The J33’s balanced XLR outputs can drive turntable
signals well over 100 meters (328 feet) without appreciable loss or
noise. This makes the J33 ideal for driving turntable signals through a
snake system on stage and through the patchbays and complex wiring
systems in the professional studio.
The Radial J33 may be powered with 48V phantom or with the included
15VDC power supply. The J33 will automatically select the power
source and the two LED on the front panel will illuminate, indicating
power is present.
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RIAA PREAMP
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An RIAA phono preamp is a device that boosts the signal from
a turntable and applies a pre-dened equalization curve. The
RIAA equalization curve is applied as pre-emphasis EQ during
the cutting of the metal master, and as a de-emphasis EQ on
playback. In other words, a record is cut with the low frequencies
reduced and the high frequencies boosted (pre-emphasis),
and on playback the opposite occurs (de-emphasis). The RIAA
preamp in the J33 provides this required de-emphasis EQ.
The result is a at frequency response, but with noise such as
hiss and clicks arising from the surface of the record itself reduced
(or “attenuated”). The RIAA equalization curve has operated as
a global industry standard for the recording and playback of vinyl
records since 1954.
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This is the RIAA EQ curve that the J33 applies to the turntable signal. The
exact opposite curve was encoded into the signal when the vinyl LP was
pressed.
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INPUT PANEL FEATURES
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1. LED power indicator
For left and right channels. Illuminates when the 15VDC power
supply is connected or when 48V phantom power is applied from a
mixing console.
2. Rumble lter
Applies a high pass lter (bass roll-o) when pushed in.
3. Gound lug
Attaches to the turntable ground wire.
4. RCA stereo output jacks
-10dB (consumer level) stereo outputs for direct connection to a
hi- receiver AUX or CD input or any device with an RCA input.
5. RCA phono (turntable) input jacks
RIAA equalized stereo input for turntable signals. Use in
conjunction with the ground lug.
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OUTPUT PANEL FEATURES
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6. Bookend design
14 gauge steel outer shell creates protective zone around
connectors and switches and wraps around a welded case with
I-beam construction for maximum durability. Finished in tough
baked enamel.
7. Left and right XLR outputs
Balanced low impedance (600Ω) microphone level outputs.
Connects to mic input on mixing console.
8. 15VDC power supply connection
The 15VDC power supply is connected here for powering the J33.
There is no power switch and leaving the J33 on will not harm it.
This jack is not used if the J33 is powered with phantom power
from a mixing console. When switching from 48V phantom power
to the external DC supply, or back, please wait 15 seconds to
allow the RIAA amplier to charge and stabilize.
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9. Full-bottom no-slip pad
This provides electrical and mechanical isolation plus plenty of
"stay-put" friction to keep the J33 in one place.
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MAKING CONNECTIONS
Using the Radial J33 is easy. Before connecting, start by making sure
all volume levels are set to zero and the audio system is turned o.
This will avoid any loud pops in your sound system that could cause
system damage.
Left RightGround
Detail of turntable connections showing the left and right
signal outputs and the turntable's spade ground lead.
Begin by connecting the turntable outputs to the J33 using the RCA
connectors and securing the ground lead from the turntable to the
ground lug on the J33.
The J33 may be powered in two ways. The rst is with 48V phantom
power from a mixing console. The second is with the J33’s external
15VDC supply. To use 48V phantom power the J33 must be connected
using its XLR connectors to a mixing console equipped with phantom
power. If your mixer is not equipped with phantom power or if you
are connecting to unbalanced systems through the J33’s RCA
connectors you will need to use the J33’s external 15VDC power
supply. Performance is identical with either power supply and the J33
will automatically select the power source depending on how you have
it set up. As soon as you connect the J33’s external 15VDC power
supply or turn on the mixers phantom power, the J33’s front panel LED
indicators will illuminate. When switching from 48V phantom power to
the external DC supply, or back, please wait 15 seconds to allow the
RIAA amplier to charge and stabilize.
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Make the connections from the J33 to whichever piece of gear you would
like. The unbalanced -10dB outputs are commonly known as consumer
line-level outputs. These will drive inputs found on hi- equipment
and the unbalanced line-level inputs found on mixing consoles. The
balanced XLR outputs on the J33's rear panel are mic-level so that they
will match up with other direct boxes and microphones, thus enabling
the J33 to be used along with microphones in snake systems, mic
splitters and through console mic preamps.
You can use any or all the output connectors at once, enabling you to,
for instance, connect your turntable to the J33, the -10dB RCA linelevel outs to a DJ mixer and the balanced XLR outs to a PA system.
Depending on how the equipment is connected to the AC mains, there
can be a potential for ground loop hum when using both the balanced
and unbalanced outputs at the same time. If a ground loop hum
develops, a possible solution is to lift the ground at the PA mixer and
use the J33’s 15VDC external power supply.
Once your connections are made, turn on the sound system. Begin at
low volume to make sure the sound system is working properly, get
your favorite album and listen. The sound should be clear. If you hear
any hum or buzz, check the ground wire, as this is the usual culprit.
It should be rmly held by the J33’s ground lug. If you are driving
your system at high volume levels and begin to hear low frequency
resonance, try depressing the rumble lter. This will usually tame low
frequency PA system feedback.
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You are now ready to spin away! Have fun!
Mixing Console
DJ Mixer
Radial Engineering Ltd.
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Dashed line represents
turntable ground wire.
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FAQ
What is an RIAA pre-amp and why do I need one?
When vinyl albums are produced, a preset EQ curve is introduced. This
EQ curve is the RIAA phono response curve and has been a standard
since the introduction of the long play record or LP. The RIAA response
curve was developed to get better performance out of the medium.
When the record is played back the signal needs to be restored by
applying the exact opposite EQ curve as the one introduced during
production. This is what the RIAA preamp section of the Radial J33
is doing. Without an RIAA preamp, LPs would not sound as they were
intended to.
Can I use an active phono cartridge with the J33?
No. The J33 is designed to use magnetic cartridges which make up
99% of all turntable cartridges ever sold.
What if I depress the rumble lter and still have feedback?
Try using an isolation pad such as the Primacoustic IsoPlane
(www.primacoustic.com). This will reduce the vibration going into the
turntable and help eliminate low frequency resonant feedback.
Can I connect other devices such as keyboards or computer
sound cards to the J33's input?
No. The J33’s input is pre-equalized with the RIAA curve. This curve is
designed for LP records and would make any other source sound bad,
plus these line-level devices would overload the J33’s sensitive input
circuit and cause distortion.
Why is there no ground lift on the J33?
Because the ground lift would disconnect the pin-1 on the XLR, which
in turn would shut o the phantom power.
Can I rackmount the J33?
Yes. The Radial J-Rak will allow as many as 8 direct boxes to be rack-
mounted in two RUs. Go to the Radial website for more details on the
J-Rak. (www.radialeng.com)
What should I do if the LEDs do not light up?
Check that the external power supply is connected or, if connecting to
a mixer through the J33's XLR outputs, make sure the 48V phantom
power has been turned on at the mixer.
How will the J33 sound with my hi- system?
Great! The J33 is a low noise preamplier and will out-perform the
typical RIAA preamp built into consumer hi- equipment.
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J33 BLOCK DIAGRAM
J33 Specications
Frequency response 20Hz ~ 20KHz ±3dB
Total harmonic distortion 0.005 % @ 1KHz
RIAA curve +19.5dB @ 20Hz
-19.65dB @ 20kHz
Reference: 0dB @ 1kHz
RIAA deviation +/- 0.5dB maximum
Max. phono input level 50mV @ 1KHz
High pass lter 200Hz cut o, -3dB at 100Hz
Unbalanced outputs 10kOhm, -10dB line-level
Balanced outputs 600Ω, -60dB mic-level
XLR pin conguration AES standard: pin 1 ground
pin 2 hot (+)
pin 3 cold (-)
Power (auto-switching) 15VDC or 48V phantom
Size (W x D x H) 3.25"x 5"x1.75" (83x126x45mm)
Weight 1.5 lbs. (.7 kg)
Warranty 3 Years
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THREE YEAR TRANSFERABLE LIMITED WARRANTY
RADIAL ENGINEERING LTD. (“Radial”) warrants this product to be free from
defects in material and workmanship 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 nish
and wear and tear on components under normal use) for a period of three
(3) years from the original date of purchase. In the event that a particular
product is no longer available, Radial reserves the right to replace the product
with a similar product of equal or greater value. In the unlikely event that a
defect is uncovered, please call 604-942-1001 or email service@radialeng.
com to obtain a RA number (Return Authorization number) before the 3 year
warranty period expires. The product must be returned prepaid in the original
shipping container (or equivalent) to Radial or to an authorized Radial repair
centre and you must assume the risk of loss or damage. A copy of the original
invoice showing date of purchase and the dealer name must accompany any
request for work to be performed under this limited and transferable warranty.
This warranty shall not apply if the product has been damaged due to abuse,
misuse, misapplication, accident or as a result of service or modication by
any other than an authorized Radial repair center.
THERE ARE NO EXPRESSED WARRANTIES OTHER THAN THOSE ON THE
FACE HEREOF AND DESCRIBED ABOVE. NO WARRANTIES WHETHER
EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO, ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE SHALL EXTEND BEYOND THE RESPECTIVE WARRANTY
PERIOD DESCRIBED ABOVE OF THREE YEARS. RADIAL SHALL NOT BE
RESPONSIBLE OR LIABLE FOR ANY SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSS ARISING FROM THE USE OF THIS
PRODUCT. THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, AND
YOU MAY ALSO HAVE OTHER RIGHTS, WHICH MAY VARY DEPENDING
ON WHERE YOU LIVE AND WHERE THE PRODUCT WAS PURCHASED.
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1845 Kingsway Ave., Port Coquitlam, BC V3C 0H3, Canada
Tel: 604-942-1001 Fax: 604-942-1010
True to the Music
www.radialeng.com
Radial J33 User Guide Part #: R870 1090 00 / 01-2023
Specications and appearance subject to change without notice.
Copyright © 2016, All rights reserved.
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