Stereo Integrity M3 Carbon 3.5 inch midrange, front view of the carbon fiber cone and dust cap

Stereo Integrity M3 Carbon midrange, rear view of the motor cup and lead wires

Stereo Integrity M3 Carbon frequency response measurement

Stereo Integrity M3 Carbon mechanical drawing with front and side dimensions

Stereo Integrity

Stereo Integrity M3 Carbon | 3.5 Inch Midrange - Pair

Q: What is the Stereo Integrity M3 Carbon?

The M3 Carbon is a 3.5 inch wideband midrange from Stereo Integrity with a carbon fiber cone and dust cap, a synthetic copolymer surround, and a shielded N45 neodymium cup motor. It was refined with FEA and Klippel analysis and is sold as a pair.

Q: What crossover point should I use for the M3 Carbon?

Stereo Integrity recommends a high-pass point of 350 Hz or higher with a 24 dB per octave slope.

Q: Can the M3 Carbon play without a tweeter?

Stereo Integrity says the M3 Carbon plays up to 20,000 Hz and that its low inductance can remove the need for a tweeter when it is used on axis. For off-axis mounting locations, plan on adding a tweeter.

Q: Will the M3 Carbon fit my vehicle?

Stereo Integrity lists a 72.5 mm cutout, a 94.4 mm outer diameter, and a 49.5 mm mounting depth. The mechanical drawing in the gallery shows the full mounting dimensions.

Q: What is the difference between the M3 Carbon and the M350 Carbon?

The M350 Carbon is the newer Stereo Integrity 3.5 inch design. It uses a carbon fiber dome with a 2 inch voice coil and an underhung motor, mounts in 36 mm instead of 49.5 mm, and is recommended from 400 Hz to 5,000 Hz. The M3 Carbon uses a carbon fiber cone and is a wideband driver that plays up to 20,000 Hz.

Q: Is the M3 Carbon sold as a single or a pair?

The M3 Carbon is sold as a pair.

SKU: SI-M3-CARBON

$ 329.99

QUICK SPECS

Type: 3.5 in wideband midrange, sold as a pair
Power Handling: 100W RMS, 4 ohm
Mounting Depth: 49.5 mm, 72.5 mm cutout
Crossover: High-pass at 350 Hz or higher, 24 dB/oct

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Stereo Integrity M3 Carbon | 3.5 Inch Midrange - Pair

$ 329.99

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INSTALLER'S TAKE

SI call the M3 a midrange, but the useful way to think about it is as a wideband. It plays to 20,000 Hz, and the low inductance keeps the top end intact well past the point where a normal midrange gives up. Aimed properly at the listener it can carry a system without a tweeter at all.

Off axis is a different conversation. If this ends up in a kick panel or low in a door firing across the car, plan on a tweeter. The physics of a 3.5 inch cone at 15 kHz do not care how good the motor is.

High pass at 350 Hz or higher with a 24 dB per octave slope. Sensitivity is 86 dB, slightly below the M350, so level match carefully if you are building a 3 way around it.

Choosing between this and the M350: the M3 is the wideband with more top end reach and a 49.5 mm mount, the M350 is the dedicated 400 to 5,000 Hz midrange with more excursion and a 36 mm mount. Pick on where it has to fit and how high you need it to play.

Product Details

Stereo Integrity

M3 Carbon

3.5 Inch Wideband Midrange | Sold as a Pair

Carbon Fiber Cone Shielded N45 Neo Motor Wideband to 20 kHz 49.5 mm Mounting Depth 4 Ohm

A Wideband Midrange for High-End Systems

The M3 Carbon is a 3.5 inch driver built for high-end systems, with smooth midrange, broad bandwidth, and low inductance as its design goals. Stereo Integrity refined it with extensive Finite Element Modeling and analysis data from Klippel USA.

Although Stereo Integrity calls it a midrange, it is really a wideband driver that plays up to 20,000 Hz. Its low inductance extends the top end far enough that it can stand in for a tweeter when it is aimed on axis.

Engineering Highlights

Carbon Fiber Cone and Dust Cap

Carbon fiber keeps the moving mass low for the best possible sensitivity while providing exceptional cone stiffness.

Synthetic Copolymer Surround

A custom tooled synthetic copolymer surround supports smooth midrange reproduction and long-term durability.

Shielded N45 Neodymium Motor

A high-strength, shielded N45 neodymium motor inside the motor cup drives the coil through a single gap with strong motor force.

Nomex Spider, Aluminum Former

The main suspension damping comes from a Nomex spider set between the spiral cut aluminum voice coil former and the cast aluminum frame.

Crossover Recommendation

Stereo Integrity recommends a high-pass crossover point of 350 Hz or higher with a 24 dB per octave slope.

Build a front stage: Stereo Integrity pairs the M3 Carbon with its TM65 mkIV and TM8 midbass drivers for a 3-way front stage, with an M22 or M28 tweeter on top.

Fitment

Outer diameter: 94.4 mm. Cutout: 72.5 mm. Mounting depth: 49.5 mm. Impedance: 4 ohm. Sold as a pair.

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 front stage around the M3 Carbon.

Specifications

Specifications
Model	M3 Carbon
Size	3.5 in wideband midrange, sold as a pair
Impedance	4 ohm
Power Handling (RMS)	100 W
Sensitivity	86 dB
Cone	Carbon fiber cone and dust cap
Surround	Synthetic copolymer
Motor	Shielded N45 neodymium cup, single gap
Voice Coil	Copper on a spiral cut aluminum former
Frame	Cast aluminum
Outer Diameter	94.4 mm
Cutout	72.5 mm
Mounting Depth	49.5 mm
Listed Weight	1 lb
Thiele-Small Parameters
Parameter	Klippel Large+Cold	Small Signal
DC Resistance (Re)	3.47 ohm	3.4 ohm
Resonant Frequency (Fs)	92.86 Hz	126 Hz
Electrical Q (Qes)	0.62	1.14
Mechanical Q (Qms)	3.89	3.14
Total Q (Qts)	0.53	0.85
Voice Coil Inductance (Le)	0.15 mH	0.03 mH
Effective Piston Area (Sd)	5.11 sq in	5.13 sq in
Equivalent Compliance (Vas)	0.91 L	0.62 L
Force Factor (Bl)	4.03 Tm	3.08 Tm
Moving Mass (Mms)	5.0 g	4 g
Suspension Compliance (Cms)	589 um/N	450 um/N
Linear Excursion (Xmax)	3 mm one-way (70% Bl)	3 mm one-way (70% Bl)
Mechanical Excursion (Xmech)	5 mm one-way	5 mm one-way
SPL	86.3 dB	86 dB
Response
Frequency Response	150 Hz to 20,000 Hz
High-Pass	350 Hz or higher, 24 dB per octave
Figures as published by Stereo Integrity. Large+Cold values are Klippel large-signal measurements; small signal values are the conventional set most modeling tools report.

Enclosures

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

FAQs

What is the Stereo Integrity M3 Carbon?

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What crossover point should I use for the M3 Carbon?

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Can the M3 Carbon play without a tweeter?

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Will the M3 Carbon fit my vehicle?

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What is the difference between the M3 Carbon and the M350 Carbon?

+

Is the M3 Carbon sold as a single or a pair?

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Stereo Integrity M3 Carbon | 3.5 Inch Midrange - Pair

Stereo Integrity M3 Carbon | 3.5 Inch Midrange - Pair

A Wideband Midrange for High-End Systems