M-AUDIO BX10s User Manual

Studiophile BX10s

User Guide

English

Introduction

What’s in the Box?

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Studiophile BX10s Features

Subwoofer Driver

Power Amplifier

Bass Reflex Port

Enclosure

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Versatile Crossover

Phase Select

Additional Functions

Setting Up the BX10s

Connecting Audio

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Adjusting the Back Panel Controls

Placing the BX10s

Your BX10s Warranty

Warranty Terms

Warranty Registration

Appendices

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Appendix A - Technical Specifications

Appendix B – Block Diagram

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© 2006 Avid Technology, Inc. All rights reserved. Product features, specifications, system requirements and availability are subject to change without notice. Avid,
M-Audio, Studiophile and BX10s are either trademarks or registered trademarks of Avid Technology, Inc. All other trademarks contained herein are the property
of their respective owners.

2 Studiophile BX10s Subwoofer

English

Introduction

Thank you for choosing the Studiophile Series BX10s active subwoofer. M-Audio
is well known for direct-field studio loudspeaker monitors, and now after
extensive research and development, we are proud to present the Studiophile
BX10s subwoofer.

Our designers created the BX10s from the ground up; then we employed some
of Los Angeles’ top mix engineers to help us test and refine the design—ensuring
that it meets the most demanding needs for professional and project studio
monitoring environments. The goal was to develop a subwoofer that integrates
seamlessly with the M-Audio BX5a and BX8a active studio monitors, extending
the low-frequency response of the total monitoring system down to 20Hz.
Moreover, the BX10s is versatile enough to work well with any combination
of active studio monitors in a 2-channel stereo or multichannel surround
environment.

For professional engineers at commercial studios and home studio owners alike,
the BX10s helps set a new standard in studio monitoring.

What’s in the Box?

Your Studiophile BX10s box contains:

< One BX10s active powered subwoofer with removable driver

protection grill

< One detachable AC power cord

< One non-latching footswitch for subwoofer bypass function

< Four removable cone-shaped feet

< This manual

Studiophile BX10s Subwoofer • User Guide

Enclosure

Like the other components, the BX10s’ enclosure has an important role in
shaping the overall sonic response. In order to provide more stable performance,
the BX10s employs a special high acoustic efficiency medium density fiberboard
(MDF) and unique interior reinforcement designed to absorb vibration and
impact generated as the subwoofer reproduces high SPL signals and transients.
Additionally, the cabinet uses carefully placed acoustic foam to absorb internal
reflections and dampen standing waves; the acoustic foam also converts the
air system inside the cabinet from an adiabatic process into an isothermal one,
making the enclosure behave as though it were larger—resulting in a system
more capable of reproducing very low frequency signals naturally and evenly.

Versatile Crossover

You can use the BX10s in a variety of monitoring contexts, from 2-channel to
multichannel (e.g., 5.1) systems, and as an accompaniment to practically any direct­field monitors. To this end, we’ve provided a versatile yet efficient way to tailor
the response of the subwoofer to work well in any typical monitoring system.
For use in a 2-channel system, there is a linked high-pass/low-pass filter control
that allows you to adjust the crossover frequency. You can set it anywhere from
50Hz to 200Hz. It splits the signal by routing everything below that frequency
to the subwoofer and everything above it to your main monitors. And by using a
4th-order Linkwitz-Riley topology, the circuit enables you to achieve the flattest
net response through the crossover point. For multichannel systems, the BX10s
can reproduce just the output of the LFE (low-frequency effects) channel, or it
can reproduce the bass from some or all of the main channels using conventional
multichannel bass management schemes. In this multichannel context, you can
simply “open up” the BX10s fully by setting it to 200Hz (for use with external
bass managers), or you can set it to 120Hz (to comply with the Dolby Digital
standard for the LFE band limit). Further, there’s a 10dB boost switch that allows
you to migrate easily between your calibrated 2-channel and 5.1-channel Dolby
Digital levels.

English

Studiophile BX10s Features

Subwoofer Driver

The drive unit contains a 10-inch composite diaphragm, high-temperature
voice coil, and damped rubber surround. It is designed to deliver a tight and
punchy low-frequency response (in contrast to the “boomy” or hyped response
characteristic of underdamped subwoofers). The driver’s high Bl factor
(electromagnet force factor) creates a powerful motor that allows the cone to
follow the input signal very accurately, resulting in a low-frequency extension par
excellence. Furthermore, the driver’s large magnetic structures are shielded to
ensure the subwoofer unit won’t wreak havoc with nearby devices that may be
susceptible to magnetic-field interference.

Power Amplifier

In order to generate a powerful, tight bass response, the BX10s uses a 240­watt amp, featuring a custom discrete transistor architecture. The amplifier has
a carefully designed damping factor which, in conjunction with the mechanical
and electromechanical systems built into the driver, helps eliminate the natural
tendency of the driver to “ring” after input stimuli have ceased. This is chiefly
responsible for the BX10s’ extremely accurate and controlled bass response. You
will notice that kick drums and staccato bass notes reproduced by the BX10s are
tight and solid, as though coming from a large acoustic suspension system.

Bass Reflex Port

The BX10s has a vented enclosure—containing a custom bass-reflex port tube
with a circular cross section on the rear of the cabinet. The port provides a
means for the rear output of the driver to contribute to the total output of the
system—but only over a very narrow range of frequencies centered around a
“Helmholtz resonance” (determined by the compliance and mass of the air in the
port tube). The port effectively gives the subwoofer a smooth response down to
20Hz, and since its low-frequency contribution complements that of the front­firing woofer driver, the woofer stays linear and distortion-free throughout the
passband (because its movement stays within its maximum excursion limits).

Subwoofer Bypass/Defeat

If you connect the enclosed footswitch to the Subwoofer Bypass jack on the
back of the BX10s, you can use it selectively to bypass the BX10s (including
the amp, driver, and crossover), and send the full-bandwidth program directly
to your main monitors. This way you can audition mixes with and without the
low-frequency extension the BX10s provides—all from the convenience of your
mix position. As a visual indicator, the blue power LED on the front baffle of the
subwoofer flashes red when it’s in bypass mode. (Note: you can use any binary
footswitch—such as an electronic keyboard sustain pedal—but we’ve provided
one for your convenience.)

Phase Select

Because low-frequency signals have long wavelengths compared to the dimensions
of most rooms, subwoofers often tend to cause room modes and cancellations
that can be quite dramatic. For this reason, we’ve included a phase inversion
switch, which—as the name suggests—causes a π (or 180°) phase shift in the
subwoofer’s output. This can allow you more degrees of freedom in choosing
where to locate the BX10s (and consequently, the crossover frequency phase
alignment) in your monitoring environment.

“Sleep” Mode

By enabling this mode, the subwoofer will fall into standby in the absence of an
input signal, using less power and muting the output; the presence of an input
signal can then “wake up” the subwoofer and it will revert to normal operation.
When the BX10s is “asleep” the LED on its front face turns a solid red.

Studiophile BX10s Subwoofer 3

Setting Up the BX10s

AC Voltage Select: Since the BX10s contains its own amplifier, it must be
connected to a power outlet using the detachable AC cable provided. Note that
the “AC Select” switch (located below the IEC socket for the mains power cord)
is user-selectable for 100-120V~50/60 Hz or 220-240V~50/60Hz operation.
Before you do anything, make sure the AC voltage select switch is set to the
appropriate position for your location.

Warning: Use of improper voltage/selector switch combinations may result
in hazardous conditions and/or damage to speaker components not covered by
speaker warranty.

Connecting Audio

2-Channel Stereo Operation: Connect the main left and right outputs of
your mixing console, audio interface, or sound card to the XLR or TRS balanced
inputs on the back of the BX10s; then route the left and right XLR or TRS
balanced outputs to your direct-field monitors. (While the TRS inputs and
outputs will work with unbalanced cables, we strongly recommend you use
balanced cables—in doing so, you’ll have better immunity to inductively coupled
noise from power cables, etc.)

< XLR PIN 1 and TRS sleeve = signal ground (shield)

< XLR PIN 2 and TRS tip = signal positive (+)

< XLR PIN 3 and TRS ring = signal negative (–)

Multichannel (e.g., 5.1-channel surround) Operation: If you’re
mixing or monitoring a multichannel source, you undoubtedly have an external
bass management system and/or you may be sending the LFE (low-frequency
effects) channel directly to the subwoofer with no additional signal redirection.
In this scenario, you can route your subwoofer audio signal to either the left
or right input on the BX10s. Further, you should bypass the BX10s’ internal
crossover by setting the crossover control to the 200Hz position (fully open).

Adjusting the Back Panel Controls

Crossover control* : we’ve touched on this topic already, but to complete
the discussion, consider the following:

< The crossovers of most A/V home theater systems are set to 80Hz

(assuming they’re being used with a subwoofer). So if you’re mixing
multichannel material using the BX10s, we recommend you start with the
80-Hz setting as a reference to approximate a typical end-user listening
environment.

< For easy compliance with Dolby Digital, DTS, and THX recommendations,

we’ve provided calibrated markings on the crossover dial for 80Hz, 100Hz,
and 120Hz positions (in addition to 50 Hz and 200 Hz).

< If you’re using the BX10s with M-Audio’s BX5a direct-field monitors in a

2-channel setup, we recommend you start with 80Hz as your crossover
point and adjust it to suit your particular acoustic environment.

< If you’re using the BX10s with M-Audio’s BX8a direct-field monitors in a

2-channel setup, we recommend you start with 50Hz as your crossover
point and adjust it to suit your particular acoustic environment.

Phase control : as we mentioned before, this switch inverts the signal (the
phase angle from 0° to 180°) that goes to the subwoofer amplifier. (If you’re
operating a 2-channel system with the built-in crossover, the phase function does
not affect the signal going to your direct-field monitors.) You can select the
appropriate position of this switch by listening to the way the sound from the
BX10s blends with the rest of your system. There is no “right” or “wrong”
position, per se—but logically you want the subwoofer to be “phase coherent”
with your direct fields at the crossover frequency. One way to determine this
phase coherence is by playing a sine wave signal at the crossover frequency
you’ve selected and put the phase switch in the position that gives you the
strongest output.

Standby Mode

not using it. In a sense, it’s like an “audio screen saver.” When the switch is set to
“always on” the subwoofer will be continuously alert and operating; whether or
not you’re using it, it’ll stay on. When the switch is set to “auto sleep” and there
is no audio input signal for at least 15 minutes, the BX10s will go into a low­standby mode and its amp will mute; an input signal as small as 7mV will “wake
up” the subwoofer and it will reproduce sound normally. (Note that the blue
power LED turns red when the BX10s is asleep and it reverts back to blue upon
awaking.) The “auto sleep” mode can be useful if you want to conserve energy.
In sleep mode, the power draw falls to one-tenth the maximum current.

: this function allows the BX10s to go to “sleep” if you’re

4 Studiophile BX10s Subwoofer

Studiophile BX10s Subwoofer • User Guide

Gain Boost* : no matter what the setting of the “Volume” knob, you’ll
add 10dB of gain by switching in this function. It’s really most appropriate
for multichannel operation: Dolby Laboratories requires the LFE channel to
be encoded at -10dB relative to the other channels for Dolby Digital. So if
your BX10s is calibrated to have an even level response relative to your main
monitors, and if you’re using the BX10s solely as your LFE reproducer, you
can engage the gain boost and perform your multichannel mix with the levels
set appropriately.

Volume

When the volume control is all the way up, 85mV of pink noise at the input will
produce 100dBA output SPL at one meter from the front baffle. The volume
control affects the level going to the BX10s amplifier and does not affect the
level of the BX10s’ outputs that feed your direct-field monitors. Generally,
we recommend that you try to get the flattest, most even system response
between your subwoofer and your direct-field monitors—so depending on
the acoustics of your environment and how you’ve set up your signal path
and levels, you should spend a few minutes calibrating the respective levels of
the subwoofer and each of your main monitors. If you have access to pink
noise signals and/or swept sine waves (linear and logarithmic), they can be of
great help for ensuring your system has the smoothest tonal balance from
top to bottom.

Subwoofer Bypass

latching footswitch like the M-Audio SP-1 or any sustain pedal for a keyboard
controller. In 2-channel situations, toggling the footswitch triggers a relay
circuit that mutes the subwoofer output and reroutes the full-bandwidth
audio signal directly to your direct-field monitors. In essence, it takes the
subwoofer (with its crossover) completely out of the signal path so you can
easily audition your mixes both with and without the presence of the BX10s
subwoofer’s low frequency extension—all from your mixing position. This
function can also be useful for multichannel operation. Further, if all you have
is a latching footswitch (which is normally open), you can still use it to operate
this function. Note that when the BX10s is in bypass mode, the blue power
LED on its front face turns red.

: you should always send a line-level signal to the BX10s inputs.

: this is a 1/4” mono jack for connecting a non-

*For more information on using a subwoofer for multichannel applications,
please visit www.dolby.com, www.dtsonline.com, or www.thx.com.

Placing the BX10s

The “location location location” cliché doesn’t only apply to the real estate
market. It’s equally (if not more) applicable to the subject of loudspeakers
and room acoustics. As you can imagine, where you place the BX10s in your
room can have a huge impact on how it will sound. In fact, any well-designed,
powerful subwoofer can sound like a complete dud in your monitoring setup
if you’ve placed it poorly. (This tenet applies for any loudspeaker, but it’s
especially true for low-frequency reproducers like subwoofers.)

There are lots of opinions on the best method to determine the optimal
location for your subwoofer—in fact, if you ask three different studio
engineers, they’ll probably give you six different answers. But we can’t
emphasize enough how important this issue is, so please take a little time to
think about subwoofer placement—keeping in mind that the shape of your
room, its dimensions (including ceiling height), the wall construction, and
any acoustic treatment you have can all conspire to affect the subwoofer’s
apparent performance. Remember, also, that the frequency of any given signal
is inversely proportional to its wavelength—so, for example, at 40Hz, one
wavelength is about 8.5 meters or 28 feet; at 80Hz one wavelength is a little
over 4 meters, or 14 feet; etc.

Where to start: first of all, you should always place the subwoofer on the
floor when you are using it—never on a table or speaker stand. One theory
suggests that the best position for a subwoofer in a 2-channel system is on the
floor half-way between your left and right direct-field monitors, with its front
facing forward and in the same plane as the direct-field speakers. From there,
you can adjust the subwoofer’s position until it is most “correct.” Another
theory dictates that you should start with the subwoofer in a corner of the
room’s floor, where the adjacent walls can help the subwoofer maximize the
amount of sound it radiates; and then you can adjust the position to suit
your specific monitoring setup. Both of these methods are valid, but there’s
yet another method that a lot of mix engineers have employed with great
success—i.e., by exploiting the law of bilateral symmetry.

With this method, you would place the BX10s in the chair in your listening
position. (Presumably, this is at the apex of an isosceles triangle between
your left and right direct-field monitors.) Play some music with substantial
bass frequencies into the BX10s at a comfortable listening level. (Pink noise
works great for this too.) Crawl around the floor of your room and listen for
a place where the sound is “fullest” but also “tight” sounding. Wherever that
is—bingo!—that’s where your BX10s will go. If you want to be more precise,
you can use a 1/12th-octave real-time (spectrum) analyzer instead of your
ears and perform the same exercise. (If you do this, make sure you play pink
noise as the test signal and observe where the spectral response is smoothest
and has greatest low-frequency extension.)

Please note that because low-frequency signals radiate omnidirectionally, you
may find that the best location sonically for the BX10s is quite inconvenient—
like in an area of your studio with a lot of foot traffic. If this is the case, you
can simply flip the Phase switch on the BX10s’ back panel and repeat the
exercise, hoping for a more convenient outcome.

Finally, once you’ve placed the BX10s where you believe it will sound best,
give yourself a sanity check and play some material along with direct-field
monitors, listening from your standard mix position. (Make sure the BX10s
level, phase, and crossover are set appropriately.) If something is askew, try
out some new subwoofer locations. As always, please feel free to experiment
with different locations (and different directions for facing the driver)... you
may inadvertently find a better way to place the subwoofer even if you think
its current location already sounds good.

Your BX10s Warranty

Warranty Terms

M-Audio warrants products to be free from defects in materials and
workmanship, under normal use and provided that the product is owned by
the original, registered user. Visit www.m-audio.com/warranty for terms and
limitations applying to your specific product.

Warranty Registration

Thank you for registering your new M-Audio product. Doing so immediately
both entitles you to full warranty coverage and helps M-Audio develop
and manufacture the finest quality products available. Register online at
www.m-audio.com/register for the chance to win M-Audio giveaways.

English

The web sites mentioned above are examples only and are in no way associated or affiliated with M-Audio or Avid Technology, Inc. M-Audio does not
guarantee the performance or availability of these services. Studiophile BX10s is not endorsed, sponsored, or approved by these companies.

Studiophile BX10s Subwoofer 5

Appendices

Appendix A - Technical Specifications

Type

Woofer Driver

Frequency Response

Crossover

Input Sensitivity

Amplifier

S/N Ratio

THD at rated power,
mono mode

Inputs

Outputs

Controls

Input Impedance

Maximum input level

Auto turn off time

Auto turn on input
sensitivity

Protection

Indicator

Power Requirements

Cabinet

Dimensions

Shipping Weight

Bass-reflex active powered subwoofer

10-inch composite (treated paper/fiberglass) cone with high-temperature voice coil and damped rubber
surround

20Hz – 200Hz (-3dB points)

HP/LP linked filter sweepable from 50-200Hz; 24dB/octave 4th-order alignment

85mV pink noise input produces 100dBA output SPL at one meter with volume control at maximum

240 VA average power into 8 Ω, discrete transistor design

86dB (A-weighted)

0.019% (175 W)

Two XLR balanced inputs; two TRS balanced/unbalanced inputs

Two XLR balanced outputs for satellites

Volume/Gain control, 10 dB bass boost switch, sleep mode switch, phase inverse switch, variable crossover
control, subwoofer bypass footswitch jack

20k ohms balanced, 10k ohms unbalanced

+20dBu

15 minutes

7.3mV

Over temperature, turn-on/off transient, subsonic filter, external mains fuse, DC protection, over current
protection

Power On (blue) or Standby/Bypass (Red)

Dual-voltage (selectable by rear-panel switch) for either 100-120V/~50/60Hz or 220-240V/~50/60Hz; powered
via detachable grounded IEC cable

Vinyl-laminated MDF

15 in. (h) x 15 in. (w) x 15 in. (d); 38.1 cm (h) x 38.1 cm (w) x 38.1 cm (d)

54.6 lbs, 24.75 kg

* Above specifications subject to change without notice

Appendix B – Block Diagram

6 Studiophile BX10s Subwoofer

M-Audio USA

060525_BX10s_UG_EN01

5795 Martin Rd., Irwindale, CA 91706

Technical Support

web: www.m-audio.com/tech

tel (pro products):

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fax (shipping): [phone]

[phone]

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tel:

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[phone]

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M-Audio U.K.

Floor 6, Gresham House, 53 Clarenden Road, Watford
WD17 1LA, United Kingdom

Technical Support

e-mail: [e-mail]

tel:(Mac support):

tel: (PC support):

[phone]

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Technical Support

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tel: [phone]

fax: [phone]

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1400 St-Jean Baptiste Ave. #150, Quebec City,
Quebec G2E 5B7, Canada

Technical Support

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phone: [phone]

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Sales

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phone:

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Web

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WD17 1LA, United Kingdom

Renseignements Commerciaux

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Assistance Technique

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MAC :

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Assistance Technique

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Site Web

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