If you’re short on time and just want the highlights of this article, here it is:
The Audioengine HD4 Bluetooth Speaker System is a great all-around option for listeners who are looking for good sound quality and easy connectivity. Its features include a 4” woofer and a 0.75” tweeter in each speaker, customizable finishes, aptX HD coding, extended range Bluetooth, a built-in headphone amplifier, and a 24-bit DAC.
When it comes to sound quality, the HD4 speakers offer full and clear sound with good bass and treble. I was pleasantly surprised by how vibrant the vocals sounded and how clear the treble was. However, I did find some areas in which the HD4 could improve its sound quality, such as increasing the bass response and smoothing out the highs.
The Audioengine HD4 offers excellent connectivity with its 3.5mm input, stereo RCA input, micro-USB input, and Bluetooth connection. The Bluetooth connection is extended range for multi-room use and features aptX HD coding. Furthermore, the HD4 also has a high-performance headphone amplifier and a 24-bit DAC to provide low-impedance, high-fidelity audio.
Overall, the Audioengine HD4 speakers provide good sound quality that is sure to satisfy music lovers. The balanced sound and easy Bluetooth connectivity make it a great option for listening to music. That said, there are still some areas that could use some improvement, such as increasing the bass response and smoothing out the highs. Nevertheless, if you’re looking for a good set of Bluetooth speakers with great sound quality, the Audioengine HD4 is worth considering.
Now let’s get to its bolts and nuts.
Audioengine HD4 Review: Sound quality
Have you ever noticed that there often tends to be quite the opposite opinions about a speaker?
I can understand this for more "personal taste" kinda products like clothing, for example.
But for engineering products like speakers? Personal tastes and preferences probably still play a role. But shouldn't it be less?
Why is it that we can't set a universal metric for sound quality?
First time I asked this question to myself has been a pivotal day.
Because it turns out that in the mid 90's, Electrical Engineer PhD Floyd Toole came up with a method called Spinorama. This is exactly what he accomplished with this. Turns out that his book Sound Reproduction is like the bible of audiophiles.
Put it simply, Spinorama is a set of measurements that gives a comprehensive overview of a speaker's performance from various angles.
It allows you to compare the performances of different speakers before even laying your ears hands on them.
Isn't that amazing?
This is why Spinorama was apparently groundbreaking news for audio industry. Hence in the mid-late 2010's, most brands and magazines began publishing Spinorama measurements, despite the challenges of making such measurements.
Fortunately, now we have the Spinorama data for a bunch of quite popular speakers. Pierre Aubert put all this untidy data together and put it into https://www.spinorama.org/. This is a stunning source. Pretty valuable stuff from him right there.
All good up to this point.
Now there comes a caveat.
Since the sound speakers propagate are in the form of omnidirectional waves, all measurements are obtained in anechoic or semi-anechoic chambers (a super-quiet room where soundwaves don't bounce back, here's how different that room sounds [a mind blowing time-adjusted video]).
This is a problem because it means that Spinorama alone, unfortunately, won't give us all we need. Placement and reflections play an equally important role there too.
This is why most A-class brands (like SVS, Bang & Olufsen, etc) often come up with room correction features, adjusted either manually or automatically. The EQ adapts itself to the placement (room, corner, center, etc) for a better (deeper and more accurate) sound. Which is great.
Additionally they often emphasize the importance of placement, here is an example: https://www.svsound.com/blogs/subwoofer-setup-and-tuning/75365187-the-art-of-subwoofer-placement
The source code under Pierre Aubert's work is licensed under GPL (General public license). He didn't perform any of the measurements himself, and instead he compiled all of them into one place, so that makes sense.
At this point, I thought that if there was a tool that combined both the Spinorama with the room acoustics data, it'd be extremely useful.
Unfortunately, it turns out that there wasn't any.
This is where I stepped in and partnered with an Acoustics and Audio Engineering PhD in order to achieve this.
We combined Spinorama data with room acoustics and came up with Soundton. A very simple, 2D online tool that allows you to:
- Reveal optimal speaker positions in a room,
- Test with real speakers from real brands,
- Compare different speakers and different positions in the room.
It can be very valuable for the vast majority.
The colormap provides you the locations with the best (green) and worst (red) listening experience.
It works the best with subwoofers since Soundton processes low frequency response waves only.
- Soundton is going to be, say, 80% accurate. Not 100%.
- Because, other parameters such as the age/materials of the building, furniture/windows in place also have an impact on room acoustics.
- If you want absolutely the most detailed room analysis, then what you need is an acoustics consultant. Mind you that's going to require deep pockets and patience though... assuming you find the right person and they get the job done.