Polk audio MM100, MM120 User Manual

MM100 10" Subwoofer

MM120 12" Subwoofer

P O L K A U D I O / M O M O D E S I G N

A M E R I C A N P O W E R , I T A L I A N F I N E S S E

The Story of Dynamic Balance

®

Your new Polk speakers employ Dynamic Balance, a technology which came out of a joint
research project between Polk Audio and Johns Hopkins University. This laser imaging
research enables us to view the entire vibrating surface of a driver or tweeter, allowing us to
observe the resonances which develop on speaker cones as they move. These resonances are
the root cause of frequency response distortions.

As an x-ray enables a physician to discover the root cause of a symptom and thereby pre­scribe the right treatment for a cure, this laser imaging technique allows Polk engineers to
find the right combination of high-tech materials, geometry and construction techniques to
tune out the offending resonances. The benefit of Dynamic Balance is the dramatic
improvement in the sound quality of our speakers, which every listener can appreciate. You
no longer have to choose between excellent bass and smooth, clear midrange and highs.
Now you can have it all, thanks to Dynamic Balance technology.

A Wo rd From Matthew Polk

Dear Music Lover,

You have just entered a new realm of car audio! I am
extremely excited about these Polk Audio/MOMO high
performance speakers; this is the first time that the
exclusive MOMO Design house of Italy has co-branded
a product. We’ve partnered with them to produce the
best sounding, best looking car speakers ever. They are
going to make your car look and sound great.

They may not look like any other Polk Audio speaker, but make no mistake: They contain
the latest loudspeaker technology and many of our exclusive sound innovations, like
Dynamic Balance®for clean sound and low distortion. You can be assured of outstanding
performance and unmatched quality, as well as an exciting new look.

Please take a moment to read through this manual. It will help you get the greatest
possible enjoyment from these fine instruments. If you have questions, or would like
more information on building the car audio system of your dreams, don’t hesitate to
call our Customer Service Department at [phone] from 9am to 6pm Eastern
Standard Time, Monday through Friday.

Gratzie!

Matthew Polk

Polk Audio—A History of Excellence

Like the way these great new speakers sound in your car? You’ll love the way Polk Audio
speakers sound in your living room! Polk Audio has been making world-class loudspeakers
since 1972. Polk’s dedication to fundamental research has resulted in over 25 patents.
Polk loudspeakers have earned the praise of audio experts the world over, garnering
dozens of awards for innovative, high-quality design. Whether you desire audiophile­quality sound for your home, car or even your multimedia computer, Polk loudspeakers
deliver unmatched performance and value.

See the full line of Polk Audio loudspeakers at your Polk Audio dealer, or at
www.polkaudio.com

Concentric breakup of cone

produces distortion

Laser Interferometry tests produced holographic “photos” of drivers

in motion. The “bad” drivers are experiencing modal breakup that

results in performance-robbing resonances. A “perfect” driver would

look like a cake (flat on top), more, like the photo on the right.

Radial breakup of cone

produces distortion

Polk “Dynamic Balance”

design results in

low distortion

P O L K A U D I O / M O M O D E S I G N

A M E R I C A N P O W E R , I T A L I A N F I N E S S E

Acoustic Suspension Enclosure s

As the Polk/MOMO subwoofers are optimized for
acoustic suspension enclosures, we suggest you use this
type of design. The acoustic suspension cabinet is a
sealed airtight box, and is the easiest box to build. It
also is a very predictable enclosure with easily calcu­lated parameters, and it has a smooth natural sound.
Properly built acoustic suspension cabinets have a flat
frequency response that begins rolling off at 12 dB per octave at
the frequencies below its cabinet resonance. This works very well inside
a car because of a natural phenomenon called “room gain” or “transfer function” that
gives you a 12 dB per octave increase in bass frequencies. You can roughly calculate at what
frequency this gain begins by using the equation F= 565/L. F is the frequency at which bass
gain begins, and L is the longest dimension of your “room.” If, for example, you measured
the longest dimension of your car as 5.65 ft., the room gain begins at 565/5.65 or 100 Hz. If
your goal was perfectly flat frequency response you would design your cabinet for this par­ticular car to have a resonance frequency of 100 Hz. Since most people want more bass than
a flat frequency response yields, tuning the cabinet at a lower frequency, say 50 Hz, would
give you a gain of 12 dB per octave between 100 and 50 Hz and flat response from 50 Hz
down. The larger the cabinet, the lower the resonant frequency, and the lower the efficiency.
Two identical systems will sound very different in a Honda vs. a Cadillac. The bigger the car
the lower the frequency at which room gain begins.

Tools You Will Need To Build Your Enclosure

If you have decided to build your own enclosure for your Polk Polk/MOMO subwoofers,
here is a list of the tools you should have available to you.

• Calculator

• Assorted Drill bits

• Screwdriver bit for drill or manual screwdriver

• Circular saw

• Tape measure

• Drill — electric or cordless

• J i g s a w

All Polk Audio/MOMO Loudspeakers Feature :

• Futuristic cast aluminum baskets that mimic MOMO Wheel designs

• Elegant matching Motor Cup conceals a beefy magnet structure

• Rugged, highly conductive pro-grade nickel-plated binding posts

• Polymer/mica composite cones

• Aramid fiber spiders for better sonic imaging and more dynamic range

Who Is Going To Build Your Subwoofer Enclosure?

Since the subwoofer enclosure is so critical to getting the best performance from your
Polk/MOMO subs, you should ask yourself the following questions:

1 . Do I really enjoy working with my hands?

2 . Do I have good woodworking and mechanical skills?

3 . Do I have, or have access to, woodworking and electrical tools?

4 . Do I have a solid understanding about musical reproduction in an automobile?

3 If you answered NO to any of the above questions, we recommend you choose one of

these two possible alternatives: First, there are pre-built subwoofer enclosures on the market
from manufacturers like Q-Logic and R/T, or enclosure kits from BassLine and others. The
second alternative is to have your authorized Polk Audio dealer design and build a woofer
box for you.

3 If you answered YES to all of the above, let’s review some basics before you begin.

Building Your Own Enclosure

The Polk/MOMO subwoofers have been optimized to give you flat bass response in small
sealed enclosures. Some listeners may want response other than “flat,” or may want to
trade-off depth of response for greater efficiency by using a vented enclosure. There is no
way we could provide all the information for all of the options here. This manual will give
you enough information to build a great sounding, small sealed enclosure. If you are inter­ested in a greater choice of enclosure designs, your Polk Polk/MOMO Series dealer has
extensive experience designing woofer boxes and will be more than happy to work with you.
If you prefer, you can call our Customer Service Department from 9AM to 6PM, Monday
through Friday, Eastern Time at [phone], or visit http://www.polkaudio.com.