30 Advanced Setup
PBK Room Correction
On the rear panel of your subwoofer is a mini-USB input labeled
"PBK Input” which allows for connection of MartinLogan's Perfect
Bass Kit (PBK™). The procedure for running PBK room correction
is outlined in the PBK manual. PBK is sold separately.
The PBK system employs your computer*, connected via USB
to a microphone and your MartinLogan subwoofer, to identify
problem areas in your listening environment. The PBK processes
information from multiple data points and configures the optimal
solution, achieving pinpoint-accurate room response.
Like the best room measurement systems available today, PBK
utilizes multiple measurement points, at least five—but up to
ten—individual data positions, allowing PBK to learn the indi-
vidual characteristics of your room.
The PBK employs your computer’s processor to calculate correc-
tion curves for each measurement point, substantially minimizing
the rounding errors of less sophisticated "calculators", like those
used in standard room equalization systems. Additionally, PBK’s
software is capable of calibrating itself to the individual micro-
phone included in the kit, eliminating interference that would
otherwise skew the data.
MartinLogan’s PBK™ (Perfect Bass Kit) is designed to adjust per-
formance of specific MartinLogan subwoofers to reduce room
induced bass anomalies. PBK is not a replacement for other
room correction systems designed to optimize multi-channel
audio systems.
When beginning the task of optimizing an audio system’s perfor-
mance, the first step should always be proper setup of the front,
center, and surround speakers. Proper setup of these speakers
requires proper positioning, toe in, and (if available) adjusting a
speaker’s built-in bass level controls. The next step should be run-
ning PBK to adjust the subwoofer’s output to account for room
interactions. After running PBK, the subwoofer’s performance and
integration with the main speakers should be optimized by adjusting
the subwoofer’s level, phase, low-pass filters, and other controls.
Only after proper setup of speakers and subwoofer(s), including
running PBK on the subwoofer(s), is it time to run your processor’s
full-range room correction system to help balance overall system
performance within the room.
Although PBK is designed to adjust the subwoofer’s output to mini-
mize sonic anomalies caused by room interactions, it is always
recommended to use traditional methods to achieve a flat response
before implementing digitally based room correction. Remember,
subwoofer placement is one of the most influential parameters when
dealing with anomalous low-frequency room interactions—listening
position is equally important to bass response but is often dictated
by other factors that are more difficult to change. Some users will
find that running PBK and examining the resulting graphs may help
optimize the subwoofer’s placement. To do this, connect PBK and
use the system to take measurements. The resulting graph displayed
on the computer* will likely show peaks and valleys in the mea-
sured room response. Instead of loading the PBK settings to your
subwoofer, move the subwoofer and take the measurements again.
Continue moving and measuring until you achieve a frequency
response without any wide bandwidth response dips. The PBK
will correct the peaks. After you’ve determined an ideal subwoofer
placement, fine tune the subwoofer’s performance by running PBK
one last time and uploading the PBK settings to your subwoofer.
When a computer is connecting via a mini-USB to the PBK Input,
the light indicates the following statuses:
No color:
Idle (no USB device currently connected).
Solid Green:
PBK connection okay.
Solid Red:
PBK connection problem.
*NOTE: Please refer to PBK manual and related instructions for
computer compatibility information when running PBK.
Multi Out—Daisy Chaining
Multiple Subwoofers
If you are daisy chaining multiple identical subwoofers, con-
nectMulti Out from the controlling subwoofer to the LFE In /
Multi In on the next subwoofer. Additional subwoofers may be
connected using this same pattern. The first subwoofer in the
chain will control all other subwoofers down stream (except
for the light brightness setting of individual subwoofers). We
recommend connecting no more than four subwoofers in a daisy-
chain—more may be acceptable, depending on your specific
installation. Experiment and listen for what sounds best to you.
Signal Connection:
1 Connect the first subwoofer to your system using one of the
connection methods previously described in this manual (e.g.
2-Channel Mode, Multi-Channel Mode, or Simultaneous
2-Channel/Mulit-Channel Mode).
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