Page 2 - Physical Look - Hardware
If you are planning to put the Audioengine HD6 on your desk, then you better have a pretty large desk. Simply put, the Audioengine HD6 is huge. At specified dimensions of 30cm tall, 18.5cm wide, and 25cm deep, you know these bookshelf style speakers are not made for the common man by sheer size alone. It is even bigger than the A5+. If you are looking for something a little smaller that fits well on your desk, look out for the A2+ instead. Meanwhile, our particular unit came in a flawless Cherry Wood Veneer finish, but if you want, you can get it in Satin Black Paint or Walnut Wood Veneer as well. In my opinion, the HD6 looks simple yet elegant, and aptly looks the part as a piece of premium audio equipment. I am also happy to see detachable speaker grilles are included. They are held on magnetically, and automatically align themselves in place like magic when put on. Of course, we can never judge acoustics by the way it looks, so let us talk about its internal construction.
From the front, both the left and right speakers look nearly identical. At the bottom is a 5.5" Kevlar woven glass aramid composite woofers with rubber surrounds in die cast aluminum woofer baskets, and at the top is a 1" ferro fluid cooled silk dome tweeter with neodymium magnets. Together, their frequency response is rated at 50Hz-22kHz ±1.5dB, and unlike its predecessor, the A5+, you can expect nearly flat studio-like response all the way down to 50Hz. We will talk about that in our evaluation on the next page. The use of high end materials for construction allows reduced distortion at high volumes. Signal to noise ratio is specified at >95dB, THD+N at <0.05%, and -50dB stereo crosstalk. At the bottom, Audioengine's logo is printed on a brushed aluminum metal piece. A volume control knob is located on the left speaker, which can be turned infinitely in both directions, being active only when the internal amplifier is turned on. A white LED is situated behind a shiny ventilated cover on the opposite end of the volume control knob, where an infrared receiver for the remote control is also located.
Here is a shot at the back of the Audioengine HD6 powered desktop speakers. By "powered", it means it comes with an internal amplifier. What we have here is a dual class AB monolithic amplifier located inside the left speaker that provides 50W RMS and 75W peak per channel. As such, the left speaker weighs -- shown in the right, as you can see in our photo above -- an extra five pounds more than the right; where Audioengine specifies a weight of 17.5lbs and 12.5lbs, respectively. A bass reflect port opening slit can be seen at the top. Power is supplied by an internal power supply with low noise gapless core toroidal transformers. A large black heatsink is used to dissipate the extra heat into the air. Here, you will also find a rocker style switch to turn off the power supply off, voltage selection switch to choose between 120V or 240V, as well as a user replaceable external main fuse.
As you can see in our photo above, Audioengine offers an extremely generous array of input and output connectors on the HD6. The company advertises it as their "most versatile speaker yet", and I have no reason to doubt this claim. On the input side, we have a 3.5mm stereo mini-jack, S/PDIF optical, and RCA. For my particular setup, I used the 3.5mm stereo mini-jack for input from my personal computer, since I have an Auzentech X-Fi HomeTheater HD sound card. The optical input is hooked up to my cable box, which I occasionally use. Like most powered computer speakers with multiple inputs I have used in the past, if multiple sources are active, the Audioengine HD6 will simply mix the signals together, and output both. The Audioengine HD6 also features stereo line level output via a pair of RCA jacks. This allows you to send audio to other speakers using an optional wireless adapter. For most people, it will probably be used for a subwoofer, which I have done so in my setup.
On the wireless side, Bluetooth operation depends on an external antenna, which you can see in our photo above. Personally, I find it a bit unsightly, considering it is quite easy to implement an internal antenna nowadays. However, having something like this has its advantages. For one thing, the HD6's wireless range is incredible. I can plug in my speakers on the second floor of my house, and still have reception from my phone in the basement... at the opposite side of the house. I do not believe this is an entirely realistic scenario, but a strong wireless subsystem will allow for higher consistency and more bandwidth, which in turn may translate to better sound quality and improved user experience.
To start, simply hit the white LED button labeled "Pair". Protocols supported over Bluetooth include aptX, AAC, and SBC. SBC, or Subband Coding, is the default Bluetooth audio codec with reasonably good audio quality and low processing power requirements. aptX is a time domain ADPCM compression algorithm that promises "CD like quality" according to the people promoting it -- but so does MP3 at 128kbps, which, in my opinion, is quite an overused marketing term in the industry. Do not get me wrong; it is probably still an improvement compared to the standard profile, since it has a more efficient encoding algorithm and higher bitrates. In case you are asking, Apple devices does not support aptX, but many high end Android devices do, like my Nexus 9. Fortunately, for Apple users, the HD6 supports AAC as well, which communicates at about 250kbps from the source. In case something new comes along in the future, Audioengine advertises an upgrade path for the HD6, so its wireless capabilities will not become obsolete down the road.
Inside, the digital to analog converter is an Asahi Kasei Microdevices AK4396 that can sample at up to 24-bit, 192kHz with upsampling support. This is a very famous chip among audio enthusiasts known as the "miracle DAC". With all its digital input options -- namely, Bluetooth and optical -- a quality DAC is the key to success. Most people do not own external DACs or have anything more than integrated sound from their motherboard, and having an AK4396 inside will allow you to digitally connect your devices to your HD6 without worrying about bottlenecking the potential of your $750 speakers.
If you are familiar with home theater equipment, then the speaker connectors from the powered left speaker to the passive right speaker should not be new to you. In fact, the Audioengine HD6 uses standard 16AWG speaker wires to connect the left and right unit together. The included cable is four meters long, which should be more than enough for most people. To add a bit of classiness in a no expenses spared style, banana jacks installed on both ends of the speaker cable.
The Audioengine HD6 is built with 20mm thick, high resin reinforced MDF cabinets. Internal sound dampening material is implemented to reduce undesired internal sound reflections. The speakers are also magnetically shielded; while non-magnetically shielded speakers will definitely not fry your hard drives anytime soon, it is something nice to have, especially being computer speakers. (Just for reference, if you ever want to damage any hard drives using magnets, you will need pretty much military grade stuff.) Our photo above shows the bottom of the HD6, which has a thin layer of foam to dampen it from the surface it resides on. This is most likely your wooden or glass desk, which can be very useful. A standard 1/4" insert is present for wall mounts.
Audioengine also includes a remote control to go with the HD6. It is a stylish rectangular piece cast with a single piece of aluminum; if you are thinking Apple, you are not too far off. It is one of those things where you hold and go like, "How the heck do I replace the battery?" Fortunately, a paperclip hole at the back allows you to disassemble the unit where the black piece is to do a battery swap. The remote control itself is relatively simple. It has only four buttons: Two for controlling the volume, one for mute, and one for standby. Using mute or standby will both fade out your music if they are playing at the time you depress the button, and send the white power indicator LED in front to fade in and out. If you are a little perplexed as to the difference between mute and standby, as they appear to do the exact same thing, it really comes down to power consumption. Mute simply turns the volume all the way down, and your HD6 is still using 6W of power. Standby shuts down a few items, probably the amplifier, which reduces your power consumption down to 4W according to Audioengine.
With all this in mind, it is now time to put the Audioengine HD6 through APH Networks' infamous subjective audio tests.
Page Index
1. Introduction, Packaging, Specifications
2. Physical Look - Hardware
3. Subjective Audio Analysis
4. Conclusion
