The 4 Ohm 3W Speaker 3 inch Round is an electroacoustic transducer engineered for clear voice reproduction, background audio playback, and wide-band sound reinforcement in compact electronic enclosures. Featuring a high-compliance paper/composite cone with a flexible foam/rubber surround and a high-flux ferrite/neodymium magnetic motor assembly, it delivers balanced frequency response with high vocal clarity and minimal distortion. With its standard 4-ohm nominal voice coil impedance, it pairs directly with low-voltage Class-D amplifier ICs (such as PAM8403, PAM8302, and TPA3116) and microcontroller audio modules (e.g., DFPlayer Mini, ESP32 DAC), making it a staple in intercoms, smart home devices, DIY Bluetooth speakers, and arcade cabinets.

Specifications

• Transducer Type: Moving-Coil Dynamic Loudspeaker (Full-Range)
• Nominal Diameter: 3.0 Inch (Approx. 77 mm to 78 mm Outer Flange Diameter)
• Nominal Impedance: 4 Ω (±15% at 1 kHz / 1.0 V)
• Direct Current Resistance (DCR): Approx. 3.4 Ω to 3.8 Ω
• Nominal / Rated Power Handling: 3.0 W RMS
• Maximum / Peak Power Handling: 4.0 W to 5.0 W Peak
• Resonant Frequency (F0): Approx. 220 Hz to 280 Hz (±20%)
• Effective Frequency Response Range: 180 Hz to 15,000 Hz (15 kHz)
• Sound Pressure Level (Sensitivity / 1W/1m): Approx. 86 dB to 89 dB SPL (±3 dB)
• Total Harmonic Distortion (THD): ≤ 5% at rated input power (1 kHz)
• Cone / Diaphragm Material: Treated Acoustic Pulp Paper / Poly Composite Cone with Inverted Dust Cap
• Surround Type: High-Compliance Elastic Foam / Rubber Rolled Edge
• Frame / Basket Material: Stamped Steel Basket with Anti-Corrosion Zinc / Black Plating
• Magnet Type: High-Energy Sintered Ferrite / Rare-Earth Magnet System
• Terminal Type: Dual Solder Lug Terminals (Polarity marked with '+' and '-' / Red Dot)
• Baffle Cutout Diameter: Approx. 68 mm to 72 mm
• Mounting Depth: Approx. 26 mm to 32 mm
• Mounting Hole Spacing (Pitch): Standard 4-hole diagonal screw pattern (~60 mm to 65 mm center-to-center)
• Net Weight: Approx. 60g to 85g

Features

• Optimized 4-Ohm Voice Coil: Maximizes output power delivery from standard single-rail 5V DC Class-D amplifier modules (like the PAM8403) without requiring high supply rails.
• Balanced Full-Range Frequency Output: Delivers clear midrange vocals, intelligible high frequencies, and modest low-end punch when enclosed in a properly ported or sealed cabinet.
• Compliant Roll Surround: Elastic surround enables high linear cone excursion (X max) without bottoming out the voice coil during dynamic audio peaks.
• Standardized 4-Hole Flange: Symmetrical mounting ear tabs allow flush or rear-mount installation into wooden baffles, 3D-printed project boxes, and acrylic enclosures.
• High Durability: Treated cone materials resist mild environmental humidity, maintaining acoustic compliance and tonal stability over extended operational life.

Common Applications

• DIY Bluetooth & Smart Speakers: Building portable battery-powered mono or stereo wireless speakers using PAM8403 / TDA7297 boards.
• Intercom & Doorbell Systems: Voice output speaker for apartment intercom panels, smart video doorbells, and two-way security terminals.
• Arcade & Retro Gaming Consoles: Cabinet sound reproduction for Raspberry Pi-based bartop arcade machines and retro consoles.
• Voice Synthesis & Embedded Audio: Paired with DFPlayer Mini, WT588D, or ESP32 boards for automated vending machines, robotic speech, and queuing token systems.
• Radio & Media Players: Replacement speaker for portable FM/AM radios, desk alarm clocks, and electronic musical toys.

Usage Tips

• Acoustic Enclosure Requirement (CRITICAL): Never operate the speaker out in the open air without a baffle or enclosure. Without an acoustic barrier separating the front and back sound waves, acoustic phase cancellation will completely eliminate all low and mid-low frequencies, making the audio sound tinny and quiet. Mount it inside a sealed or bass-reflex enclosure for full, punchy sound.
• Amplifier Matching:
  • Pair with amplifiers rated between 2.5W and 5W per channel at 4Ω (e.g., PAM8403 running on 5V supplies ~3W into 4Ω).
  • Avoid using overpowered amplifiers (>10W) at full volume, as excessive voltage will cause voice coil overheating and mechanical cone separation.
• Observing Polarity in Stereo / Multi-Speaker Setups: Connect the positive terminal (marked with a '+' or red dot) to the amplifier's positive (+) output, and the negative terminal to ground/negative (-). Inverting polarity on one speaker in a stereo pair will cause phase cancellation, degrading stereo imaging and bass presence.
• Soldering Precaution: Solder the hookup wires to the lug terminals quickly (under 2 to 3 seconds at 300°C–320°C). Excessive heat can melt the plastic terminal collar or damage the delicate braided tinsel lead wires going from the lugs to the voice coil.
• Baffle Sealing: Apply a thin bead of silicone sealant or a soft foam ring gasket between the speaker frame flange and the mounting panel to prevent air leaks and eliminate cabinet rattling at higher volume levels.