Pro Audio Blowouts

Pro Audio Blowouts
THX 44
Security Cover Installed
Security Cover Removed
Great video is easy; great audio is hard, but a THX 44 makes it a lot easier. Read at least this boxed section and you’ll
be on your way toward great audio.
Hook-up is intuitive: In from the controller, Out to the amplifiers. Just follow the silkscreened legends on the rear of the
unit.Use either the RCA jacks or the DB-25 connectors.
Familiarity with other graphic and parametric equalizers makes the THX 44 just as familiar. If this is your first equalizer, be gentle; it can overwhelm you.
Use the BYPASS switch as an aid in comparing equalized results with unequalized results. Pushbutton in and locked
(LED on) is the bypassed (unequalized) mode; pushbutton out and unlocked (LED off) is the normal equalized mode. See
the included “Home THX Audio System Room Equalization Manual” for the alignment procedures required. See the
Operating Instructions on the back page for more information.
Install the supplied security cover after completing all settings. Be sure the POWER light fits snugly into the hole in the
security cover.
Never connect anything except an approved Rane power supply to the red modular jack on the rear of the unit. This
is an AC input and requires special attention if you do not have a power supply exactly like the one originally packed with
your unit. See the full explanation of the power supply requirements on page Manual-3.
WEAR PARTS: This product contains no wear parts.
햲 Graphic equalizer filter level controls. Each of the Left, Right and Center Channels have eleven slide controls used to set
the individual levels of the interpolating constant-Q filters. Their range is ±6 dB. The grounded center-detent design ensures
all filters are off when positioned to 0 dB.
햳 Parametric equalizer LEVEL control sets the amount of boost/cut for this section. Same grounded center-detent design as
the Graphic Equalizer sections. The range is ±4 dB for the Left, Right, and Center Channels, and
±6 dB for the Subwoofer Channel.
햴 Parametric equalizer BANDWIDTH control sets the Bandwidth for this filter section. The range is 0.7-3.5 octaves for the
Left, Right, and Center Channels, and 0.5-2.5 octaves for the Subwoofer Channel.
햵 Parametric equalizer FREQUENCY control determines the center Frequency for this filter section. The range is 1k-10
kHz for the Left, Right, and Center Channels, and 20-80 Hz for the Subwoofer Channel.
햶 POWER indicator lights any time power is supplied from the Rane model RS 1 power supply (included). To avoid
confusion a distinction is made here between electrical and political.
햷 Overall BYPASS switch & indicator. This pushbutton switch activates the “hard-wire” BYPASS function. When engaged
(red BYPASS LED on), the INPUT connectors directly tie to the OUTPUT connectors (hard-wired). Engaging this switch
converts the THX 44 into a relatively expensive patch cord, albeit one with pretty lights.
During the initial timed power-up sequence, or power loss of any sort, the THX 44 automatically goes into BYPASS mode.
햲 Remote POWER supply input. The unit is supplied from the factory with a Model RS 1 Remote Power Supply suitable for
connection to this input jack. The power requirements of the unit call for an 18 volt AC center-tapped transformer only. This
is not a telephone jack. Never use a power supply other than the one supplied, or a replacement approved by Rane Corporation. Using any other type of supply may damage the unit and void the warranty.
햳 Chassis ground. A #6-32 screw is used for chassis grounding purposes. See CHASSIS GROUNDING below.
햴 RCA OUTPUT connectors. Active unbalanced design. Use high-grade RCA cables or the DB-25 to connect to the power
amplifier inputs. You may use both simultaneously when required to feed different amplifiers.
햵 RCA INPUT connectors. Active unbalanced design. Use either high-grade RCA cables or the DB-25 for interconnect to
the controller outputs. Do not use both the RCA and the DB-25 input connectors—the Inputs do not sum.
햶 DB-25 connectors. Wired per the Home THX Interconnection Standard. Refer to the silkscreened legend on the rear for pin
identification. Use only THX approved DB-25 Interconnection cables. Other DB-25 cables may not function properly.
If your system exhibits excessive hum or buzzing, there is an incompatibility in the grounding configuration between
units somewhere. Your mission, should you accept it, is to discover how your particular system wants to be grounded.
Here are some things to try:
1. Try combinations of lifting grounds on units that are supplied with ground lift switches or links.
2. If your equipment is in a rack, verify that all chassis are tied to a good earth ground, either through the line cord
grounding pin or the rack screws to another grounded chassis.
3. Units with outboard power supplies do not ground the chassis through the line cord. Make sure that these units are
grounded either to another chassis which is earth grounded, or directly to the grounding screw on an AC outlet cover by
means of a wire connected to a screw on the chassis with a star washer to guarantee proper contact.
4. Sometimes cable TV systems can introduce another ground loop in combination with grounded amplifiers. Using an
isolation transformer between grounded audio components may solve the problem. See Rane models BB 44x or BB 22.
Refer to the Home THX Audio System Block Diagram in
the THX 44 Data Sheet for proper location of the THX 44.
When first connecting the THX 44 to other components,
leave the power supply for last. This gives you a chance to
correct mistakes before damaging fragile speakers, ears and
Inputs are actively unbalanced and fitted with parallel
RCA phono pin jacks and DB-25 connectors. Use only one.
They do not sum. Attempts to use both results in severe
The Outputs mimic the Inputs with one big exception: you
may use both if desired. Use cables meeting the Home THX
Interconnection Specifications available from Lucasfilm.
The THX 44 is designed for Home THX Audio reference
levels of 0dBr (150mV rms), and provides a minimum
headroom of 34.5 dB above reference, making it virtually
With all LEVEL controls located in their 0 dB detented
positions, the THX 44 operates with unity gain from Input to
Output. No additional gain settings are necessary. Use the
THX 44 only for specific equalization.
Follow the alignment procedure specified by Lucasfilm
Ltd. as described in the “Home THX Audio System Room
Equalization Manual” supplied in this manual. Use only the
recommended test equipment. It is not possible to align a
Home THX Audio system without the use of proper procedures and a one-third octave realtime analyzer with averaging, and the special THX “Wow” Laserdisc (only supplied
with some THX controllers or a licensed THX installer). It
cannot be done by ear.
The purpose of the THX 44 in a home cinema system is to
flatten the response between speakers and the room. There are
no special curves to follow; these are within the controller—
not the THX 44. The THX 44 should be aligned for a flat
average response from each Channel.
Though the THX 44 meets Lucasfilm’s THX specifications, it is also suitable for Dolby Pro-Logic systems so that
Left, Center, and Right Channels to have matching responses.
Though the THX 44 can help non-THX speakers, ±6 dB may
not be enough boost/cut to compensate between different
speaker designs. Left/Right and Center speakers should first
be chosen that have a similar sound, and the THX 44 can do
the “fine tuning”. Use a one-third octave realtime analyzer,
and “flatten” the system as described in your analyzer
manual. The THX 44 must be connected between the controller (or preamp) and the power amplifiers.
The THX 44 is perfectly suited for discrete 5.1 systems by
following the same principles of flattening the room response
of each channel. The surround channels may be accommodated by using another THX 44, ideal when the processor has
outputs for stereo subwoofers or a sixth main channel.
Otherwise, the Rane THX 22 controls duplicate the THX 44’s
for the surround speakers, making it an ideal match for the
THX 44 in 5.1 systems.
Our unique interpolating constant-Q circuitry makes
setting curves easy. For the graphic sections, what you see is
what you get – more so than on any other equalizer. Referring
to your room result curves, begin by positioning the sliders to
create the inverse curve shown by the instrumentation.
Remember, most applications require only a few dB of boost
or cut. If more is required, use architectural and mechanical
means: add, remove, or relocate acoustically sensitive items
(speakers, drapes, carpets, mirrors, etc.) as required.
The THX 44 provides you with an overall BYPASS
switch & indicator as a useful tool for optimizing settings.
Use the BYPASS switch for making quick “A-B” comparisons, i.e., comparing “A”, equalized (BYPASS out, LED off),
versus “B”, unequalized (BYPASS in, LED on). To do this
freely, without danger of system damage, you must pay
attention to how much equalization is being used. Failure to
do so can produce alarming results.
Since the THX 44 always operates at unity gain in the
BYPASS mode, comparison when a lot of boosting, or cutting
has been done, can result in startling level differences
between the two. Therefore you want to keep the system level
down until you first use the BYPASS switch. Be careful the
first time you use it.
Two situations can cause hum or grounding problems:
A. When the THX 44 is installed at a distance greater than 10
feet from the controller or amplifiers (which is not recommended for unbalanced wiring).
B. When an amplifier with a balanced input is connected to
the unbalanced Output of the THX 44.
For solutions, see RaneNote 110, “Sound System Interconnection”, downloadable from Rane's web site.
The best option is the Rane BB 44x, a 4-way balancingisolating-level matching device with RCA and XLR connections. Again, see our web site.
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL (425)355-6000 FAX (425)347-7757 WEB
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