Designed to connect to virtually any device, the Audioengine HD4 Bluetooth Speaker System provides a 3.5mm input, a stereo RCA input, a micro-USB input, and Bluetooth connectivity with aptX HD support, which allows for wireless connectivity with your compatible devices. Each speaker consists of a 101.6 mm woofer and a 19.05 mm tweeter and output up to 30W per channel RMS, or 60W per channel peak for room-filling sound. For your convenience, all connectivity is via the powered left speaker, which connects to the passive right speaker with speaker wire.
To minimize unwanted resonances and distortion, Audioengine cabinets have thick high-resin MDF walls with extensive internal bracing. Heavy internal sound-damping material is used to reduce unwanted sound reflections inside the cabinet. All cabinet edges are rounded which look great and reduce high-frequency diffraction effects on the front baffles. The P4 cabinet contains tuned, front-port slots.
The HD4 cabinets are available in several handsome finishes, including walnut veneers as well as satin black paint, offering options for complementing room furnishings. Also included are detachable grilles that add further aesthetic advantages as they are firmly held in place with hidden neodymium magnets for a clean look.
Audioengine designs and manufactures their own tweeters, woofers, and other critical components. In other words, these are not box-built speakers with off-the-shelf parts, but custom-designed to Audioengine's specifications. What they do not fabricate directly in their factory, they have made to their designs (parts such as transformers, magnets, and wiring harnesses, for example). The cabinets, drivers, bass port designs, amplifiers, and crossovers are all painstakingly tuned together for each Audioengine model. This, in turn, makes for a much more efficient system that requires much less power than passive speakers and a separate integrated amplifier or similar A/V components.
Studio monitor speakers are used by producers and engineers in recording and production studios. They are designed with a theoretical flat frequency response which allows the engineer to create a final mix in such a way that the recorded music will sound good on most other speakers. Although Audioengine speakers are not designed to be up-close "nearfield" studio monitors, they carry over much of the same higher-end technology, components, and design philosophy for all Audioengine speaker systems.
The Bluetooth built into the HD4 powered speakers features aptX HD coding, which is an advanced Bluetooth audio codec with very impressive sound. And even if your phone or tablet does not have aptX HD, the HD4 Bluetooth solution is backwards-compatible with SBC and AAC codecs, as well as standard aptX, so you can wirelessly stream music from any Bluetooth-enabled device and still enjoy all your music. High-fidelity Bluetooth aptX HD that really works and sounds great.
Most Bluetooth implementations have very limited range, typically within just one room. But with careful signal management circuitry and antenna tuning, we offer a superior solution that has up to 3 times the range of standard Bluetooth for multi-room use, with no degradation in audio quality.
The HD4 Bluetooth receiver and USB input both utilize the PCM 5102 DAC, widely known for its low noise and high fidelity. The PCM 5102 is used as an upsampling DAC and will pad all bit depths to 24-bit, achieving a higher signal-to-noise ratio and lower noise floor. Due to the high signal-to-noise specs of the PCM 5102, the fact that digital signal is upsampled to 24-bit as well as the added benefit of onboard triple redundancy power source conversion and filtering the HD4 Bluetooth implementation presents impressive low noise and low distortion characteristics with a noticeable improvement over other Bluetooth devices.
The HD4 contains a high-performance headphone amplifier based on the OPA2134 low-noise opamp. This amp is able to provide low-impedance, high-fidelity audio, and a 2-volt output which easily drives a wide range of headphones.
The amplifiers in powered Audioengine speakers are located in the left speaker and are a conservatively rated class A/B analog monoblock design. This is a more traditional speaker/amplifier configuration which provides excellent quality audio and greater flexibility. All circuit boards for the power and preamp sections are vertically mounted for maximum mechanical shock protection.
Audioengine uses audiophile-quality, ferrofluid-cooled silk dome tweeters with neodymium magnets. Silk tweeters hold up well under high power and the edge-driven design gives very smooth response. The woofers are aramid fiber woven glass composite with rubber surrounds. Aramid fiber is obviously very strong, which means the woofer retains its shape when being driven at high levels.
Both drivers are directly video shielded and allow the user to place the speakers within a few inches of a video monitor. This shielding also offers protection for hard-drive digital music players.
The speaker cabinets, drivers, innovative bass port designs, amplifiers, and passive crossovers are all critically tuned together for each Audioengine model. This, in turn, makes for a much more efficient system that requires less power than passive speakers and a separate integrated amplifier or similar A/V components. They build all this goodness into the left speaker cabinet to make it super-easy to connect your smartphone, tablet, computer, TV, network player, or any other audio product.
|Amplifier Power Rating||60 W RMS
120 W Peak
|Drivers||1 x 4" / 101.6 mm Woofer (per Speaker)
1 x 0.75" / 19.05 mm Silk Dome Tweeter (per Speaker)
|Ports||1 x Front-Firing (per Speaker)|
|Frequency Response||60 Hz to 22 kHz (±1.5 dB)|
|Wired Connectivity||Active, Left:
1 x Stereo RCA Input
1 x Stereo RCA Output
1 x 1/8" / 3.5 mm Input (Audio)
1 x Micro-USB Input (Audio)
1 x Binding Post Pair Output (to Other Speaker)
1 x Binding Post Pair Input (from Other Speaker)
|Amplifier Class||2 x Class-AB|
|SNR (Signal-to-Noise Ratio)||95 dBA|
|THD (Total Harmonic Distortion)||< 0.05%|
|Input Impedance||5 Kilohms|