Eight Active Loudspeakers
as reviewed by Michael Wechsberg
I heard many glorious sounds while traveling the halls of THE Show Newport Beach recently, but one that stood out came from the room occupied by EARO High Definition Audio, based in Sweden, and fairly new to these shores. EARO was demonstrating their Model Eight loudspeaker, top of their line, and hard to ignore. Not just for their sound, but also for their glowing Ferrari Red finish. Once captured by the sights and sounds, I was intrigued to see the EAROs were single driver horn-type speakers with built-in class D amplification, and onboard digital signal processing. I have never been able to enjoy single-driver speakers, and have been disappointed by past encounters with Class D amplifiers, but the EAROs were speaking to me in a different way, and the unusual configuration sparked my engineering genes. I wanted to learn more about these, and hear more as well. A few weeks after THE Show, local distributor Per Sjofors delivered the demo speakers to my home for a few weeks of evaluation. I have to give Mr. Sjofors and his assistant credit for their fortitude, hauling these 154lb. beasts up two flights of stairs to my listening room, while I feigned back problems.
The EARO Eights are a brilliantly engineered integrated stereo system, combining analog/digital conversion, digital signal processing, digital/analog conversion, signal amplification, and finally sound reproduction in a balanced design, with all input and output interfaces carefully matched. The design reflects a deep understanding of the science of sound reproduction, and uses a combination of old technology (e.g. horn-loading) and new technology (fast digital processors) to overcome the challenges of reproducing music covering 10 octaves of bandwidth in a typical home. The scientific attention to system matching is sorely lacking in our hobby, so I hope designer Mikael Reichel is not the last to go down this road (although I have to admit the ad hoc system matching that we audiophiles practice, using a combination of ears and egos, is part of the fun of the hobby).
First, the EAROs look great and are built to the highest standards. The paint finish is a hand-rubbed, high-gloss polyurethane lacquer that looks fantastic, and is available in five standard colors, with custom colors available on special order. Iím told the finish on new production is further improved. The cabinets measure 38 inches high by 16 inches wide and 22 inches deep. These dimensions arenít huge, but the EAROs arenít going to disappear into your dťcor, especially in their bold colors. The bottom half of the cabinet is the approximately square horn mouth, covered in a black grill cloth. The top half of the speaker contains the single 7-inch driver set back into a carefully contoured cutout designed to transition the wave front coming from the speaker smoothly to air (more about this later). The front panel, which has no sharp surfaces, is carved out of thick MDF, using computer-controlled machinery. The driver looks like one of the Lowther speakers used in other single-driver horn designs, but is in fact a proprietary design from EARO. No details are provided on the internal structure of the speaker, but the design is a folded horn configuration with extensive damping and internal bracing as the cabinet is rock solid, heavy, and vibrates hardly at all. Appearance-wise the EARO looks like a high-end component to be proud of, and no expense has been spared in building it.
The EARO Eights accept analog balanced input via XLR connectors from a line level preamp, or directly from a digital component with an onboard volume control. EARO provides XLR to RCA adapters if your source does not have balanced outputs. EARO has chosen balanced operation to minimize the chance of noise entering the system via the interconnects, but they assert sonic performance is the same whether balanced, or unbalanced connections are used. These inputs are at the bottom of the rear panel of the speaker, together with an IEC connector for a power cord, an on-off switch, a fuse holder, an input attenuator, and a mode switch that selects between always-on, or an auto music sensing mode. In the later mode, the speaker will turn itself off after a few minutes when no input is detected, and will turn itself on immediately upon detecting an input. Each speaker is said to draw less than 150W from the power line.
The EARO Eight has a rated frequency response of 40Hz to 18.5kHz Ī 3 dB. The low end is limited by the size of the driver and the horn. The high frequency response is extended through use of a whizzer cone, concentric with the main driver. Such a design is inherently efficient, and would normally require just a couple of watts to reach a sound pressure level well over 100 dB, but the EAROs use 180W class D amplifiers on each side in order to handle very high transients often found in music. At the same time, EARO cautions that the Eight is not a party speaker meant to blast at high levels for long periods of time. The Class D amplifier is sourced from Hypex in The Netherlands.
The EARO web site contains three white papers that give an extensive discussion of the design theory behind the EARO speakers and why they do certain things. The papers are interesting to read, and quite informative. The EARO design is driven by the attempt to maximize the efficiency of radiating sound into a room, and minimizing the mismatch between the motion of the cone and the physical creation of sound waves. EARO draws an analogy between this mismatch with an impedance mismatch in an electrical circuit, and they note this phenomenon, common to most conventional speakers, destroys the time response of the speaker and adds distortion. The design of the driver, and how it is loaded in the cabinet, the shape of the horn mouth, and other features of the cabinet, are all influenced by the attempt to minimize this mismatch. Finally, EARO recognizes that the physical limitations of reproducing sound in the home cannot be addressed solely with the electro-mechanical design, so they have turned to the use of modern digital signal processing to solve the remaining issues. The papers are silent on the type of processing algorithms used, and designer Mikael Reichel is not sharing, but as you will read below, the combination of speaker and cabinet design, plus processing, works very well.
In order to implement the signal processing, the speaker requires a digital signal. The use of digital signal processing in high-end audio is, of course, not new. Virtually all CD players apply some form of processing to the digital signal before passing it to the digital-to-analog (DAC) stage, and all outboard DACs available for years do their own processing as well. The difference with the EAROs is they include the speakers in the processing loop. EARO assumes, I think, that the incoming signal is flat, coherent, and low in distortion, and they attempt to prevent the speaker from destroying this pristine signal in both the time and frequency domains as it transitions from an electrical form to a mechanical form.
In the EARO Eight, the company has chosen to work with the analog signal, so the first thing it does is convert it to digital. I know this will cause some vinyl addicts out there to wince, but try to keep an open mind for a while. EARO uses a 24-bit A/D converter operating at 48kHz. Reichel asserts that they could crank the sampling rate up to 96kHz, but they have not observed any change in quality, so they are keeping it at 48kHz. The DSP chip they use employs 56-bit arithmetic to maintain the full dynamic range and minimize processing errors. Presumably, the speaker uses a 24-bit DAC with the same 48kHz sampling to convert the processed signal back to analog, where the 180W class-D Hypex amplifier works its magic with the speaker.
I believe we are at the dawn of a new age, where more and more speakers will become available with integrated digital processing and amplification. The converter and processing chips are becoming more affordable, and the computer models needed to design the most appropriate processing algorithms are becoming more sophisticated, accurate, and readily available. Reichel tells me that in the near future the speakers will be able to accept a direct digital input (S/PDIF), eliminating one stage. A wireless input is also being considered.
It took me a while to get the EAROs set up in my room. These speakers can project a very big sound, and my 14 x 20 foot room with 8-foot ceilings may have been on the small side for them. I started with the speakers in the same places normally occupied by my Marten Miles II speakers, about 5 feet from the rear wall, and around 7 feet apart, toed in to the listening position about 10 feet away. The sound resulting from this geometry was on the bright side, with clean and fast bass that seemed to disappear around 60 Hz. I focused first on the bass by moving the speakers closer to the back and side walls. This improved the low frequencies, but the proximity to the side walls caused reflections that seemed to muddy the sound and narrow the bandwidth. I even tried to augment the bass with my subwoofer, but couldnít get a good blend since the EARO bass was so much faster than the subwoofer bass. I finally settled on a position with the speakers about 3 feet from the rear wall, and between 2.5 and 3 feet from the side walls, slightly asymmetrical, and 8 feet apart. My listening position was about 11 feet from the front plane of the speakers. Using my trusty Radio Shack sound level meter and Wilson test disc, I determined the EAROs were flat to between 40 and 50Hz, and then began to roll off quickly. I expect in a larger room good bass down to at least 40Hz should be possible.
Next, I tackled the toe-in. When listening on axis, the sound was very detailed but the highs were too peaky and rough. Facing the speakers absolutely forward made the sound a little dull. I ended up using a good solo violin recording to tune in the toe-in. I found just a few degrees of toe-in (between 5 and 10 degrees) allowed the midrange to bloom, and flattened the high-end response considerably.
I used the EAROs with my E.A.R. 868 preamp and E.A.R. Acute III CD player for digital, and the Townshend Rock 7 turntable with London Reference cartridge for analog. Unfortunately, I didnít have a solid-state preamp in house to use with the EAROs, so all my impressions came about using this tubed equipment. The two E.A.R. components were plugged into the PS Audio Power Plant Premier conditioner using Kubala-Sosna Emotion power cords. I used a pair of XLO Signature 3 power cords for the two EARO speakers, also plugged into the Power Plant. Iíll try not to mention the two E.A.R. components again so you wonít mix up E.A.R. with EARO.
When the EAROs first came to my room, and the EARO folks plugged them into the preamp using the balanced outputs, the sound was attenuated and distorted. The same thing happened when we plugged the speakers directly into the CD player, which has its own volume control. We knew the speakers worked with balanced inputs because they had been used that way at THE Show Newport. There is some unknown incompatibility between the EAROs and my two components. We fixed the problem using some unbalanced interconnects with XLR adapters on one end. Should you buy a set of these speakers, EARO guarantees an installation that meets the expected performance standards.
After the EARO folks left, I found that interconnect cables made some difference in the sound. I started out with the plane Jane cables they left me that were unbalanced with RCA connectors on the preamp end, and XLRs on the speaker end. These cables seemed to contribute to the peakiness I initially heard in the highs, and did not let the midrange sparkle. Changing to a set of balanced Kubala-Sosna Elations with RCA adapters at the preamp end made a significant, and very positive difference. The quality of these speakers deserves interconnects and power cords of similar quality.
With positioning and cables settled, I was ready to begin enjoying the EARO Eights.
I started out playing some compilation CDs with both male and female vocals, some acoustic jazz, and small-scale classical music. In succeeding days, I pulled out recordings with more drive and dynamic range, including some orchestral blockbusters on LP. By the way, EARO supplies a nice demonstration CD with several European and American artist recordings that do a good job of showing off the key features of the speaker. I do most of my listening in the evenings after work, and usually take notes on what I hear, so I have something to go back to when I write the review. However, it only took a couple of days of note taking to benchmark the EARO Eights, and I spent the remainder of my time just sitting back and enjoying my favorite recordings, heard with newfound clarity and dynamics.
One of the most striking things about the EAROs is actually something very subtle. That is, the stability of images in the soundstage. Most good speakers and electronics can reproduce wide, and deep soundstages if such are captured by the recording; however, within recordings Iím used to, some vagueness in positioning of instruments and voices as the notes swing back and forth across the musical scale. With the EAROs, the location of individual voices and instruments were always rock solid. Moreover I could clearly hear the sound waves spread, and reflect off surfaces in the recording venue on some recordings, made with simple microphone techniques. I believe this stability and rendition are due to the absence of crossover components and the phase perturbations they cause, plus the careful attention to matching the speaker-air impedance interface. It also speaks to the success of the digital signal processing used in the EAROs to optimize both the time and frequency response of the speaker.
In looking over my notes from the listening sessions, almost every recording was annotated with descriptions such as "clear", "fast", "tight", "low distortion", etc. You get the idea. The light weight of the single EARO driver, juiced by some of those digital processing algorithms, did an effective job of exposing all the detail present in the recordings with little overhang, or other timing artifacts that obscure, or muddy the notes. Other adjectives I used often were "natural", "full" and "firm". One recording that stood out was one of Johnny Cashís last, where the EAROs let me clearly hear the character and experience in his gravelly voice, tinged with age and smoking.
Many female vocal recordings I played were especially beautiful, with excellent timbres, and naturalness. This was interesting to me, because other Class D amplifiers I have experienced began to break down on similar recordings. The weakest part of the spectrum for these other Class D amps is the upper end, where Iíve heard things sound rather sandpapery. Not the case with the EARO amplifiers that have very tender and extended highs with gobs of detail, and beautiful tonality. I tried to listen critically to high frequency sounds from cymbals, bells, string harmonics, etc. but there was little to complain about. This is a triumph for both the amplifier, and the single driver itself.
The important midrange came across just wonderfully on all sorts of recordings, be they vocal or instrumental. They speakers performed wonderfully on all types of string instruments, jazz instrumentals, and vocals. With the EAROs toed-in just right, the midrange was fast and clear, with just the right amount of warmth reflecting the sonic signature of my E.A.R. preamp. Listened to more on-axis, the speaker could become quite analytical, to the point of harshness if the recording is not quite right. In fact I used this analytical character to help me zero in on the right vertical tracking angle for my turntable set-up.
The lower midrange and upper bass both came across with great power and transient ability, noteworthy especially in large-scale symphonies, and tone poems, as well as big band music. If these types of music float your boat, you will really enjoy the EAROs. The EAROs also have very tight, and tuneful bass, with absolutely no bloat, but as noted earlier, in my room they did not go very low. If big, booming bass is your thing, you should probably look elsewhere. Iíve already mentioned the EAROs can toss out a very wide and deep soundstage with image stability that is fleshed out to the corners of the room. The EAROs play loud, and seem to have lots of headroom, but I was careful not to crank them up to earsplitting levels, as the manual advised they are not "party speakers".
Since the EAROs take analog signals in and turn them into digital for processing, I specifically tried to listen for a digital signature. On CDs, I felt the EAROs did an effective job in going from analog to digital and back. It was not possible to set up an A/B comparison between the EAROs and another set of speakers playing the same discs, but I did use some disks that I am very familiar with, and I could not pin down any negative digital signature. However, when I played vinyl LPs the music was still terrific, but I did feel the EAROs altered the sound. I felt a loss in some low level detail, and some musical instruments seemed to be almost too sharply defined. Coherency and pace that I was used to in these recordings were missing, but only on LPs, and not CDs. If I had to guess, I would guess that the A/D sampling frequency was too low for the wideband signal produced by the London Reference cartridge, but I have no solid evidence for this conjecture.
Do I have anything else to complain about? Well just a couple of things. That last octave of bass would be nice. My brief experiment to match the EAROs with a subwoofer did not turn out well because of the difference in speed between the two speakers. A different subwoofer might be more successful, but for 95% of recordings the very good quality of the EAROs bass will outweigh the slight lack of extension. One other thing is the high frequencies of the EAROs are lacking just a bit of air and transparency compared to some of the best speakers I have heard. This slight loss was common to both CDs and vinyl
The only other suggestion I have is that since the EAROs contain software, some method to upload new code should be considered. Some new and better wrinkle always seems to come up, and it would be nice to be able to take advantage of a new software load, without shipping the speakers back to the shop.
As I mentioned at the beginning of this review, the EARO Eights constitute a brilliantly engineered integrated stereo system that is a full-on, and successful assault on the problems of playing music in the home. $38,000 is quite a bit to pay for a pair of speakers, but you have to remember, you are buying virtually an entire state of the art stereo system for this price. The only other thing to buy is a source component with a volume control. I would say the EAROs are perfect for modern sound systems that use computers and music servers as sources. I expect we will see more integrated active speaker systems like the EAROs in the near future. However, the speakers sound so good playing vinyl that I hope they never give up that analog input. Designer Mikael Reichel is to be congratulated for his achievement. He is someone to keep an eye on. Michael Wechsberg
EARO Eight Active Speakers with built-in
amplification and DSP