Stereo Integrity BM-11 11 inch shallow subwoofer, front view of the flat carbon fiber diaphragm and surround

Stereo Integrity BM-11 close-up of the carbon fiber diaphragm weave and surround edge

Stereo Integrity BM-11 rear three-quarter view of the neodymium motor, cast basket and terminals

Stereo Integrity BM-11 low side view of the shallow basket and motor

Stereo Integrity BM-11 Klippel force factor Bl(x) measurement

Stereo Integrity BM-11 harmonic distortion measurement

Stereo Integrity BM-11 frequency response with harmonic distortion components

Stereo Integrity BM-11 impulse response measurement

Stereo Integrity

Stereo Integrity BM-11 | 11 Inch Shallow-Mount Subwoofer

Q: What is the Stereo Integrity BM-11?

The BM-11 is an 11 inch shallow-mount subwoofer from Stereo Integrity. It pairs a ten-piece neodymium column motor and a 3 inch copper voice coil with a flat carbon fiber diaphragm, and it mounts in 3.09 inches while offering 13 mm of one-way linear excursion. It is sold individually in a dual 2 ohm configuration.

Q: How much mounting depth does the BM-11 need?

Stereo Integrity lists a mounting depth of 3.09 inches, a 10.0 inch cutout, and an 11.14 inch outer diameter. That shallow profile is aimed at installs where a conventional subwoofer will not fit, such as behind or under a seat.

Q: What enclosure does the BM-11 need?

Stereo Integrity's specification sheet lists a 0.40 cubic foot sealed enclosure, with a range of 0.35 to 0.70 cubic feet. The BM-11 is also approved for infinite baffle use, and the driver displaces just 0.03 cubic feet.

Q: How much power does the BM-11 handle?

Stereo Integrity rates the BM-11 at 500 watts RMS. It uses dual 2 ohm voice coils, which wire to 1 ohm in parallel or 4 ohms in series.

Q: How does the BM-11 get 13 mm of excursion in a shallow design?

Its dual gap XBL^2 neodymium motor places a shorting ring between two magnetic gaps, which lowers inductance and extends linear travel. The custom S surround is shaped to allow mechanical travel beyond that 13 mm linear limit.

Q: Does Audio Intensity build an enclosure for the BM-11?

Yes. Proline X builds Performance Optimized enclosures designed around the Stereo Integrity BM-11, including sealed wedge builds for one, two, or three drivers, a ported wedge, and a sealed down-fire. They are listed in our Stereo Integrity subwoofer box collection.

SKU: SI-BM11

$ 499.99

QUICK SPECS

Type: 11 in shallow-mount subwoofer, sold individually
Mounting Depth: 3.09 in, 10.0 in cutout
Power Handling: 500W RMS, dual 2 ohm
Excursion: 13 mm one-way linear
Enclosure: 0.40 cu ft sealed (0.35 to 0.70), infinite baffle approved

Hurry! Only 2 left in stock.

Stereo Integrity BM-11 | 11 Inch Shallow-Mount Subwoofer

$ 499.99

Includes Shipping On orders to the lower 48

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INSTALLER'S TAKE

The BM-11 is the shallow 11 that actually works. 3.09 inches of mounting depth and 16 pounds, with 13 mm of one way travel out of a ten piece neodymium column motor. For behind a seat or under a rear bench there is not much else in this class that moves real air.

Be clear eyed about the alignment, because this is where people get surprised. Qts is 0.73, and sealed Qtc can never go below Qts at any volume. SI recommend 0.35 to 0.70 cubic feet, and across that entire range you land somewhere around Qtc 1.27 to 1.43. We build it at 0.40. That is a warm, under damped box by nature. It is not a tuning error, it is the price of the shallow motor. If you want a tight dry sealed sound, this is the wrong driver and I will tell you so.

Worth knowing that the Qts figure is disputed three ways. SI publish 0.73, loudspeakerdatabase lists 0.83, and ResoNix measured 0.85 on a Klippel rig. Every one of those readings puts the driver in the same place, so the character does not change depending on which source you trust.

Dual 2 ohm only, 500 watts RMS, so it wires to 1 ohm in parallel or 4 ohms in series. It is also approved for infinite baffle, which is worth considering if you have a sealed trunk to work with.

Product Details

Stereo Integrity

BM-11

11 Inch Shallow-Mount Subwoofer | Sold Individually

3.09 in Mounting Depth 13 mm One-Way Xmax 500W RMS Dual 2 Ohm Carbon Fiber Flat Piston

Shallow Without Giving Up the Bass

The BM-11 is Stereo Integrity's answer to the usual shallow subwoofer compromise. It is an 11 inch driver that mounts in just over 3 inches, yet it still offers 13 mm of one-way linear excursion. Stereo Integrity tooled a new basket, a flat carbon fiber diaphragm, and a low profile S surround to make that work, and the whole driver weighs 16 pounds.

Motor strength and moving mass are balanced so the BM-11 covers a wide bandwidth for a shallow design, with an in-vehicle response of 16 Hz to 550 Hz. It is approved for infinite baffle use as well as small sealed enclosures.

How It Fits in 3 Inches

Ten-Piece Neo Column Motor

A multi-piece neodymium column motor drives the 3 inch copper voice coil through two magnetic gaps. A shorting ring sits between the gaps to lower and linearize inductance for fast, controlled bass.

XBL^2 Topology

The dual gap XBL^2 layout reduces inductance and extends linear travel, giving the BM-11 13 mm of one-way excursion measured to 70 percent Bl.

Flat Carbon Fiber Piston

The glossy carbon fiber sandwich diaphragm is flat, which keeps the front profile low and the moving assembly stiff.

Custom S Surround

The tooled S surround has an integrated gasket and is shaped for as much surface area as possible while still leaving mechanical travel past the linear limit of the motor.

Enclosure and Power

Stereo Integrity rates the BM-11 at 500 watts RMS with dual 2 ohm voice coils. Its specification sheet lists a 0.40 cubic foot sealed enclosure, with a range of 0.35 to 0.70 cubic feet, and the driver itself displaces only 0.03 cubic feet. It is also approved for infinite baffle installs.

Built for this driver: Proline X builds Performance Optimized enclosures designed around the BM-11 at our shop in Tennessee, including sealed wedge builds for one, two, or three drivers, a ported wedge, and a sealed down-fire.

Shop Proline X Enclosures for Stereo Integrity

Wiring

The BM-11 comes in one configuration, dual 2 ohm. The two coils wire to a 1 ohm load in parallel or a 4 ohm load in series, so plan the amplifier and the number of drivers together.

Fitment

Cutout: 10.0 in. Outer diameter: 11.14 in. Mounting depth: 3.09 in. Displacement: 0.03 cu ft. Weight: 16 lb.

Authorized Stereo Integrity Dealer

Audio Intensity is an authorized Stereo Integrity dealer, and we build enclosures around their drivers.

Call 931-563-5151 and we will help you plan a BM-11 install, from enclosure to amplifier.

Specifications

Specifications
Model	BM-11
Size	11 in
Voice Coil Configuration	Dual 2 ohm
Power Handling (RMS)	500 W
Voice Coil	3 in copper
Motor	Ten-piece neodymium column, dual gap XBL^2
Cone	Flat carbon fiber sandwich diaphragm
Surround	Custom S surround with integrated gasket
Frame	Custom tooled cast aluminum
Terminals	Spring
Outer Diameter	11.14 in
Cutout	10.0 in
Mounting Depth	3.09 in
Driver Displacement	0.03 cu ft
Weight	16 lb
Thiele-Small Parameters
Resonant Frequency (Fs)	33.9 Hz
DC Resistance (Re)	3.1 ohm, voice coils in series
Voice Coil Inductance (Le)	1.5 mH
Electrical Q (Qes)	0.89
Mechanical Q (Qms)	3.89
Total Q (Qts)	0.73
Equivalent Compliance (Vas)	22.68 L
Effective Piston Area (Sd)	63.5 sq in
Force Factor (Bl)	13.0 Tm
Moving Mass (Mms)	231.4 g
Suspension Compliance (Cms)	95 um/N
Linear Excursion (Xmax)	13 mm one-way (70% Bl)
SPL	86 dB (2.83 V / 1 m)
Enclosure and Response
Sealed	0.40 cu ft
Sealed Range	0.35 to 0.70 cu ft
Infinite Baffle	Approved
Frequency Response	8 Hz to 2000 Hz
In-Vehicle Response	16 Hz to 550 Hz
Figures as published by Stereo Integrity.

Enclosures

See every Stereo Integrity subwoofer box and enclosure, each cut for a specific Stereo Integrity driver.

FAQs

What is the Stereo Integrity BM-11?

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How much mounting depth does the BM-11 need?

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What enclosure does the BM-11 need?

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How much power does the BM-11 handle?

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How does the BM-11 get 13 mm of excursion in a shallow design?

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Does Audio Intensity build an enclosure for the BM-11?

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Stereo Integrity BM-11 | 11 Inch Shallow-Mount Subwoofer

Stereo Integrity BM-11 | 11 Inch Shallow-Mount Subwoofer

Shallow Without Giving Up the Bass