J33TM Radial Phono Preamp Direct Box User Guide
- June 12, 2024
- Radial
Table of Contents
J33TM Radial Phono Preamp Direct Box
Product Information
Radial J33 Phono Preamp DI
The Radial J33 is a combination turntable preamp and direct box.
It is designed to interface a conventional turntable with a magnetic cartridge
to both professional balanced audio systems and consumer unbalanced hi-fi
systems. The J33 is built to Radial’s professional standards for sound quality
and durability.
Feature Set:
- Combination RIAA phono preamp and active DI
- Allows connection of a turntable to a recording system, hi-fi, or PA system
- Pair of stereo inputs for the turntable
- Ground lug for proper turntable grounding
- RCA connectors for connecting to auxiliary or CD inputs on a hi-fi receiver
- Simultaneous use of balanced XLR outputs and RCA outputs
- Low-frequency rumble filter to reduce bass rumble and resonant feedback
Specifications:
For detailed specifications, please refer to the user manual or visit the
Radial website.
Warranty:
The Radial J33 comes with a warranty. For warranty information, please
refer to the back cover of the user manual.
Product Usage Instructions
Radial J33 Phono Preamp DI
- Ensure the J33 is connected to a power source using the provided power adapter.
- Connect the turntable to the stereo inputs on the J33. Use the ground lug to properly ground the turntable and avoid system noise.
- If desired, connect the RCA outputs of the J33 to the auxiliary or CD inputs on a hi-fi receiver.
- If using professional balanced audio systems, connect the balanced XLR outputs of the J33 to the appropriate inputs on the audio system.
- Turn on the J33 and adjust the input gain as needed.
- If experiencing low-frequency rumble or resonant feedback, engage the low-frequency rumble filter on the J33.
- Enjoy high-quality audio playback from your turntable through your chosen audio system.
If you have any questions or need further assistance, please consult the Radial website FAQ section or contact Radial Engineering Ltd. via email at info@radialeng.com.
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-fi systems.
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 find 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.
INTRODUCTION
In recent years it has become difficult to find a hi-fi receiver that is
equipped with a phono input. With literally millions of albums floating 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-fi 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-fi receiver. These
outputs can be used simultaneously with the balanced XLR outputs described
below.
The J33 is also equipped with a low-frequency rumble filter. This gently rolls
off 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.
RIAA PREAMP
An RIAA phono preamp is a device that boosts the signal from a turntable and
applies a pre-defined 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 flat 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.
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.
INPUT PANEL FEATURES
-
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. -
Rumble filter
Applies a high pass filter (bass roll-off) when pushed in. -
Gound lug
Attaches to the turntable ground wire. -
RCA stereo output jacks
– 10dB (consumer level) stereo outputs for direct connection to a hi-fi receiver AUX or CD input or any device with an RCA input. -
RCA phono (turntable) input jacks
RIAA equalized stereo input for turntable signals. Use in conjunction with the ground lug.
OUTPUT PANEL FEATURES
-
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. -
Left and right XLR outputs
Balanced low impedance (600Ω) microphone level outputs. Connects to mic input on mixing console. -
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 amplifier to charge and stabilize. -
Full-bottom no-slip pad
This provides electrical and mechanical isolation plus plenty of “stay-put” friction to keep the J33 in one place.
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 off. This will avoid any loud pops in your sound system that could cause system damage.
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 first 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 amplifier to charge and stabilize.
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-fi 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 line-level 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 firmly 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 filter. This
will usually tame low frequency PA system feedback.
You are now ready to spin away! Have fun!
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 filter 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 off 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-fi system?
Great! The J33 is a low noise preamplifier and will outperform the typical
RIAA preamp built into consumer hi-fi equipment.
J33 BLOCK DIAGRAM
J33 Specifications
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 filter| 200Hz cut off, -3dB at 100Hz
Unbalanced outputs| 10kOhm, -10dB line-level
Balanced outputs| 600Ù, -60dB mic-level
XLR pin configuration| 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
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 finish
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 modification 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 CON-SEQUENTIAL 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.
1845 Kingsway Ave., Port Coquitlam, BC V3C 0H3, Canada
Tel: 604-942-1001 Fax:
604-942-1010
www.radialeng.com
Radial J33 User Guide Part #: R870 1090 00 / 01-2023
Specifications and appearance subject to change without notice.
Copyright © 2016, All rights reserved.
Radial Engineering Ltd.
1845 Kingsway Ave., Port Coquitlam, BC V3C 0H3, Canada Tel:
604-942-1001 ● Fax:
604-942-1010
email: info@radialeng.com
References
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