Essential Setup - JBL SYNTHESIS SDR-38 Manual

Essential Setup

Before you use your Receiver it is essential that you enter
some information into the Setup menus about your speaker
configuration. This allows the Receiver to process any
surround sound digital source to exactly match your system
and give you the ultimate surround sound experience.
There are three pieces of vital information which are outlined
in the sections: 'Speaker Types' , 'Speaker Distances' and
'Speaker Levels' .
The way you enter this information manually into the Receiver is
given later in the 'Setup Menus' section on page EN-30.
When calibrated using Dirac Live room equalization the
speaker levels and delays will be established automatically
and applied when the equalization is turned on, speaker
types however must be manually entered. For use with
equalization turned off, the speaker size, speaker distance
and speaker levels settings must be entered manually. It is
important to understand why these speaker settings must
be entered, which is why this section is presented before the
section on equalization.
Speaker types
You need to set the type of speakers that you have connected
to your Receiver:
Large capable of full frequency range reproduction
Small not capable of full frequency range reproduction
at the low frequency end
None speaker not present in your configuration
The terms 'Large' and 'Small' do not necessarily relate to the
physical size of your speakers. As a rule of thumb, if a speaker
cannot reproduce a flat frequency response down to about
40Hz (and very few can!) it is often better to consider them
as 'Small' for setup purposes of home cinema.
When a speaker is set to 'Small' , very low frequency sounds
are redirected away from that speaker to a 'Large' speaker
or a subwoofer, which are far better suited to reproducing
these low frequency sounds. Many prefer to set even very
full-range speakers to 'Small' to optimize the dynamic range
of the system and to more fully utilize the Dirac Live Bass
Management room EQ.
Note that it is not possible to set all speakers to 'Small' unless
there is a subwoofer in your speaker configuration. If you do
not have a subwoofer, you will be forced to set your front
speakers to 'Large' .
(Some users may wish to automatically override the 'Small'
speaker setting for purely stereo music listening when not
watching movies. This can be achieved in the 'Input Config. '
menu – see page EN-31.
Crossover frequency
If you have set any speakers as being 'Small' , then you will
be required to set a value for the crossover frequency. This
is the frequency below which signals are filtered away from
these Small speakers and redirected to ' Large' speakers or
the subwoofer (if present). 80 Hz is usually the best crossover
frequency, since it sends non-directional low frequencies
to the subwoofers which are best-suited to handle low
frequencies and can be placed optimally to reproduce only
the lowest frequencies.
A Certified JBL Synthesis Calibrator will select the
appropriate settings during the calibration process.
Use Channels 6+7 for
If not used in the main zone, it is possible to assign the
Surround Back channels to Height 1, bi-amp the Front Left/
Right channels or to provide an amplified output to Zone 2.
Speaker Levels
Finally the levels of all the speakers in the system need to
be adjusted to match each other at the listening position,
to create a proper surround effect. To help with this the
Receiver can generate a test noise for each speaker which
should be measured with a sound pressure level (SPL) meter.
The meter should be set to 'C' weighting and slow response.
Several smartphone/tablet apps are available which can also
perfom this function. The level of noise measured at the
listening position from each speaker should be adjusted on
the Speaker Trims page of the 'Setup' menu so that the meter
reads 75dB SPL. It does not matter what the system volume
setting of the Receiver is before turning the test noise on
as the volume setting is over-ridden for the duration of the
speaker noise test.
NOTE: Moble phone apps are limited in accuracy
unless an external microphone is used. Consult your
dealer for recommendations.
There are several basic SPL meters on the market at
reasonable prices aimed at home cinema enthusiasts. Check
your local technology store, search online or ask your dealer.
If you do not have an SPL meter or suitable app, you can
try to adjust the noise level of each speaker by ear. In this
case it is not possible to adjust the speakers to the absolute
75dB SPL volume level, but you should aim for all speakers
sounding equally loud. Setting speaker test noise levels by
ear is not recommended as it is very difficult to do accurately.
A Certified JBL Synthesis Calibrator will ensure all levels are
set properly.
EN-28
Speaker Distances
It is essential for the distance from each speaker to the
listening position to be accurately measured and entered
into the 'Setup' menu. This ensures that the sounds from the
various speakers arrive at the listening position at the correct
time to recreate a realistic surround effect. The distance can
be entered in centimeters or inches.