Thank you for purchasing the Jensen GLX ground loop isolator. The GLX is
the perfect problem-solver for the AV technician and audio engineer because
it will eliminate hum and buzz caused by ground loops in an audio system
by simply inserting it into the signal path. The GLX is fast to deploy and has
excellent audio properties that won’t introduce harsh distortion, excessive
phase shift or limit the bandwidth.
Although the GLX is designed to be plug & play easy to use, please take a
minute to read this short manual. It will give you insight on how to use the GLX
to get the most out of it. If you find yourself asking questions after reading
the guide we suggest you visit the GLX FAQ page on the Radial web site.
This is where we post questions from users and inform you of updates. If you
still do not find what you are looking for, we invite you to send us an email at
[email protected] and we will do our very best to answer you in short order.
OVERVIEW
The GLX has been designed to provide isolation between two line-level
devices such as between mixing consoles, remote speakers, crossovers or
amp-racks. Use the GLX anywhere the source and destination devices may
cause system noise due to different ground potentials (often referred to as
ground loops) and stray DC voltages.
So called ground loops can introduce a 60 cycle hum in the sound system
and other noise. Although there are various solutions that can be engineered
to eliminate noise, the simplest and most effective is to isolate the source
and destination with an audio transformer.
The GLX employs a high-quality transformer to isolate the input from
the output while blocking stray DC currents that cause hum. The GLX is
engineered to handle any buffered line-level signal up to about +15dB with
very low distortion and exceptionally linear frequency response from 20Hz
to 18kHz.
The GLX is inserted in between a source device (like a mixer) and a destination
device (like a powered speaker). The XLR female input accepts a line-level
signal from the source device and the XLR male output sends the balanced
signal to the destination.
SOURCE
MIXING CONSOLE
XLR-F IN
XLR-M OUT
DESTINATION
POWERED SPEAKER
MAKING CONNECTIONS
Before inserting the GLX into your signal chain, make sure all levels are turned
down. This will avoid power-on and connection transients that could cause a
loud pop in the sound system and damage more sensitive components such as
tweeters. The GLX is a passive device. This means that it does not require an
external power source to make it work. As soon as you plug it in, it will spring to life.
BALANCED CABLES
You can connect balanced devices to and from the GLX using standard XLR
cables. The GLX is wired following the AES convention with pin-1 ground, pin-2
(+), and Pin-3 (-).
SOURCE
GLX
RING (-)
SLEEVE (G)
1
2
3
1 2
3
1 2
3
1 2
3
SLEEVE (G)
SHIELDED TWISTED PAIR CABLE
SHIELDED TWISTED PAIR CABLE
SHIELDED TWISTED PAIR CABLE
DRAIN (G)
DRAIN (G)
DRAIN (G)
SHEILD (G)
1 2
3
SLEEVE (G)
COAXIAL CABLE
If your source device uses balanced ¼” TRS connectors you can use a balanced
TRS to XLR adaptor cable wired as shown in the diagram below.
SOURCE
GLX
RING (-)
SLEEVE (G)
1
2
3
1 2
3
1 2
3
1 2
3
SLEEVE (G)
SHIELDED TWISTED PAIR CABLE
SHIELDED TWISTED PAIR CABLE
SHIELDED TWISTED PAIR CABLE
DRAIN (G)
DRAIN (G)
DRAIN (G)
SHEILD (G)
1 2
3
SLEEVE (G)
COAXIAL CABLE
UNBALANCED CABLES
You can also connect an unbalanced device such as a CD player to the using
an adapter cable. This will reduce the signal amplitude by roughly 6dB but for
high output devices like CD players and DJ mixers this is usually not a problem.
Simply increase the gain at the destination mixing console to compensate. The
GLX will convert the signal to balanced and you can use standard XLR cables
from the GLX output to the destination mixing console.
SOURCE
GLX
RING (-)
TIP (+)
SLEEVE (G)
1
2
3
1 2
3
1 2
3
1 2
3
TIP (+)
SLEEVE (G)
SHIELDED TWISTED PAIR CABLE
SHIELDED TWISTED PAIR CABLE
SHIELDED TWISTED PAIR CABLE
DRAIN (G)
DRAIN (G)
DRAIN (G)
SHEILD (G)
1 2
3
TIP (+)
SLEEVE (G)
COAXIAL CABLE
Once the connections are made, slowly increase the volume to test. It is a good
idea to always test the audio system at low volumes. This will further prevent
system damage should a cable or connection be faulty.
ABOUT TRANSFORMERS
The GLX employs a high performance isolation transformer to ensure the
best signal transfer. However, not all transformers are of equal quality. At
Jensen, we take great care in engineering the best transformer for the job
and spend hours listening to the results.
Inside view
The transformer inside the GLX sounds great and does a superb job at
providing isolation from noise caused by ground loops. Note that because the
transformer will block all forms of DC, it will also block 48V phantom power
coming from the console. Phantom power will not harm the GLX.
LIFTING THE GROUND
The only control on the GLX is a GROUND LIFT switch. This switch is
recessed to prevent accidental use during operation. Use a small screwdriver
to access the switch.
Using the recessed switch
When the switch is set to the outward position, the signal ground from the
input to the output is connected via pin-1 at the XLR jacks. When pushed in,
the signal ground connection is ‘lifted’ on both sides by disconnecting pin-1
at the XLR jacks. This further isolates the source and destination devices
and generally results in less noise.
If, after connecting, you hear noise such as hum and buzz try pushing the
GROUND LIFT switch inward. Lifting the grounds can be useful when the
source and destination devices derive their AC power from different circuits
of the AC electrical mains leading to a potential ground loop.
Jensen ISO-MAX
®
Jensen ISO-MAX
®
Jensen ISO-MAX
®
GLX Ground Loop Isolator
GLX Ground Loop Isolator
GLX Ground Loop Isolator
