ELAC Concentro S 507 Floor-Standing Loudspeakers Review

These lovely speakers from ELAC feature a bevy of proprietary drivers in an extremely over-engineered cabinet that was not only beautiful to look at but was also capable of producing an intoxicating musical experience for the listener.

I have enjoyed auditioning ELAC speakers at various trade shows (before COVID, that is) but never had the opportunity to evaluate a pair in my own system and room. So I was quite excited to give these Concentro S507s a run for their money.

They impressed me from the minute I pulled them from their boxes as the build quality was much higher than I expected at this price point. Then, over the ensuing weeks, I became enamored with these speakers and the musical performance they laid down.

I wouldn’t claim they are the most neutral speakers I have auditioned but they were endlessly fun and had so many positive qualities, it became hard for me to part with them. Please read below for the details!

ELAC has released two new models in the very popular and successful Concentro Line of speakers. The two new models are the S 507 and the S 509. Both of these models share an abundance of trickle-down technology from their big brothers. I will be evaluating the S 507 which is the smallest “entry-level” model in the Concentro range.

In a nutshell, the ELAC Concentro S 507 is a 4-way floor-standing speaker with a total of 7 active drivers per speaker! You read that right, seven drivers a side.

The basic format of the S 507 shares a lot of commonalities with many high-end speakers these days – they have four side-mounted woofers that are wired in phase. There are many examples of this design concept from numerous manufacturers. The setup has many advantages and is akin to the design of my beloved reference speakers, the VIVID KAYA 90s.

Similar to the VIVID speakers, the ELAC S 507’s are bass reflex but in the case of the ELAC’s, the port is down-firing. The ELAC woofers in the S 507 are modestly sized at 6” each. Also, the box volume is significant but not super large. Don’t let any of that fool you as these speakers sing with some very serious bass extension! I will have a lot to say about this in the below sections where I discuss my subjective listening impressions of the speakers.

I’ll discuss the other divers in a minute but to start things off, let’s talk about how the S 507 differs from the original Concentro speaker. The biggest differentiator comes in the form of the cabinet shape. The original Concentro and Concentro M have a very curvaceous shape while the S 507 is closer to a box shape. I am sure the cost saving with the smaller S 507 stems largely from the fact the cabinet is probably much easier to fabricate. But it is not too easy as it is still curvy and does not have a rectangular cross-section: it’s a trapezoid. ELAC states the following about the cabinet shape, “The key acoustic design element of each Concentro Speaker Cabinet including the ones of the Concentro S series is the front baffle with its special shape. The front baffle features a 3-dimensional convex shape with a much superior dispersion of midrange frequencies compared to planar baffles found elsewhere.”

ELAC does not provide further details regarding the cabinet construction, so I am not sure if it is wood or some other material. What I do know is that the cabinet is one of the most inert cabinets I have experienced when subjected to the knuckle-rap test. And of course, the finish was impeccable on the gloss white samples I received.

As mentioned earlier, the bass port fires out of the bottom of the cabinet. So, the speakers rest on a fixed set of legs that ELAC refers to as a “high heel” look. My wife did not like the look and I was largely agnostic about it. My feeling is that they were fine-looking speakers and the heels are not really visible when listening and the speakers sounded so great, who cares what they look like?

As far as I can tell, every driver in this speaker is proprietary. The highest frequencies are produced by a very unique concentric tweeter/upper-mid unit known as the StepX-JET. This array is the first coaxial driver I can remember that features a folded-ribbon tweeter. This smaller form of the array was made possible as ELAC designed an extremely compact ribbon driver which is nestled inside an aluminum cone upper-mid driver. The tweeter is the JET5c with the “c” denoting the driver is “compact”. This unit operates over the frequency range of 400 Hz and up, crossing over to the ribbon at 2,600 Hz.

The StepX-JET assembly is enhanced in the S 507 by way of three tuning rings that are attached by powerful magnets. These rings are essentially three distinct waveguides that have differing grinds/shapes that provide varying degrees of focus to help tune the sound to each setup. I’ll talk a little about these in the Setup section below.

The lower-mid driver is a lovely 7” with an AS-XR cone. AS-XR stands for “Aluminum Sandwich membrane with Extended frequency Range”. This driver material is a deformed aluminum glued to a paper substrate in a quasi-sandwich construction. This design promotes stiffness, reduced break-up modes, and increased power handling. Interestingly, the driver operates under a narrow (but important) frequency band that is less than two octaves!

The robust inputs allow for bi-amping or bi-wiring. They also feature a pair of solid gold-plated jumpers for people like me who typically use a single pair of speaker wires.
ELAC provides no details on the divider network, outside of the basic crossover frequencies.

Kudos to ELAC for the packaging of these speakers. There are so many speakers I get that are impossible to get out (or especially) in the box, you would think the manufacturer did little if any field testing. Not so with the S 507s. I was able to unbox them myself and only needed a little help to get them back in the boxes at the end of the review period. The boxes opened on the side and the padding/supports were easy to arrange. Thank you, ELAC!

Well, so I was warned that the spikes are absolutely necessary for peak performance. This was apparently due to the down-firing reflex port. Without the spikes, the speakers put out “too much” bass. What? Well, I like bass as much as the next guy, but it was way too much bass without the spikes. In fact, I even added the little cups under the spikes later because our carpet is so thick. Even then, the speakers could tend to be a little bass heavy. This prompted me to suggest to ELAC that they ought to provide spikes that are 2” – 3” long so the end user would have even more control over the bass tuning.

As mentioned briefly above, the S 507s include three color-coded waveguides. These are interchangeable and are affixed with very strong magnets. I had to use the edge of a butter knife to remove them. ELAC calls the rings DCRs (Directivity Control Rings). They are color-coded and primarily intended to tune the sound for different seating positions, near to far. Ring N is “normal” and has a green dot. This is the one for typical listening positions and has a balance of direct and diffuse sound.

For closer seating positions, one would employ the F, focused ring that provides a dominant direct-radiating sound. This one is signified by a red dot. Farther seating positions would use the S, spacious ring. This one had a blue dot and provided the most diffuse sound field.

I played around with these at first, during the “getting to know you” phase of my evaluation. The effects were subtle, and I wound up using the default green dot ring for all my serious listening as my seating position is roughly 10’ (3m) from the plane of the speakers. I did find these speakers required less toe-in than my reference KAYA 90s.

When I set up speakers for review, I always start with them in the typical position where I place my reference speakers. In the absence of any direct guidance from the manufacturer, I also start with the same amount of toe-in that is used when listening to my reference speakers. Then, over the course of a few days, I sometimes find myself tweaking the speaker locations slightly – usually forwards or backward as opposed to wider or narrower. I also play with the toe-in amount over this early evaluation period.

The ELAC Concentro S 507 speakers did have some very serious bass and I toned it down by adjusting the position in the room. In my room, even shifting the speakers a few inches can have an audible effect on the bass response. I eventually found a “sweet spot” for the S 507s.

Once I had the bass balance where I wanted it, I set about tweaking the toe-in to optimize the soundstage and treble response. I wound up with about 15 degrees less toe-in than with most speakers.

Once I had everything dialed in, I was ready for some serious listening. I started by attempting to drive these speakers with a Pass Labs INT 25 integrated amplifier. This amplifier is rated at a modest 25 wpc but in reality, it is closer to 75 wpc. I also use this amplifier to drive my VIVID speakers to excellent effect. Sadly, the ELAC Concentro S 507s had what I assume was too great a current demand, and this amplifier was not a good match. So, I brought out the big guns and used the 300 wpc Parasound A 21+ stereo amp for the balance of my evaluation. This amp was an ideal companion to the S 507!

As discussed above, the Concentro S 507 had bass to spare and I want to discuss this a little here before moving along. I have reviewed many large speakers over the years. They all have claims about their bass response, particularly in reference to the bass extension. Almost all of these speakers fall short of these claims during the objective bench testing. Even the ones that meet their specifications sometimes benefit from a nice subwoofer. Take my VIVID Kaya 90s – these are amazing speakers with full-range sound, but I find they really open up when I augment the bass with a subwoofer. By contrast, the Concentro S 507’s had such incredible bass response, I never even thought about adding in a subwoofer. In fact, the S 507’s was one of only a handful of large speakers where I felt a subwoofer would be completely irrelevant as the S 507’s bass was clean, tight, and extended.

This meant that the ELAC Concentro S 507 was tailor-made for some of today’s hottest music because, well, how else are you going to test the bass!!!

When writing this review, I revisited this album as I was just going to listen to a few passages to refresh my memory, but it sounded so good, I wound up listening to the entire album all over again.

The two plots immediately below are the white noise tests I ran with the mic 1 meter from the mid-woofer driver.

For the on-axis test, you see a very smooth response envelope from 400 Hz to 4 kHz. There is a significant bass hump in the 40 – 70 Hz range. This explains the subjective impression of strong, extended bass. The treble response also looks choppier than I expected, but most treble energy above 7.5 – 10 kHz would just be harmonics and not program-related treble energy. So, this was not heard as problematic in actual use.

This off-axis test indicates the speaker response was much smoother when offset like this. This explains why I used less toe-in than I do with other speakers. The results still show lots of bass and treble energy in the room!

The next two plots are the basic THD tests I run with the mic tip 1m (3’-4”) from the driver under test. I ran the 1 kHz tests at 90 dB and 100 dB. Even at the higher SPL, the THD would be completely inaudible at 0.64%. This is a very excellent result for a dynamic driver.

Moving up the audio band, I ran a 100 dB THD test at 5 kHz. This was from the coaxial tweeter assembly. Again, even at 100 dB, the distortion readout was another inaudible result at 0.63%.

The next test was a 10 kHz sine wave at 90 dB. The distortion is even lower: 0.10.

Moving down the scale, the 100 dB test at 500 Hz yields a THD of 0.63%.

The lowest bass test I ran was just above the low bass roll-off. The THD at 100 dB at 40 Hz was 2.38%. This means that the ELAC Concentro S 507 are one of the few speakers I’ve tested that have inaudible distortion levels throughout their native response envelope. This is a sign of top engineering and production methods. Very well done.

The ELAC Concentro S 507 floor-standing loudspeakers have impressive engineering design, incredible build quality, and engaging musicality to go along with some amazing bass response.

These speakers provided a very unique performance that was easy to enjoy. They had a fun wow factor like a lot of other very popular speakers on the market. They could play loud and clean with chest-rattling bass when listening to modern music. Or they could really shine on acoustic works at a more pedestrian volume setting.

These were one of the few passive speakers I have reviewed that didn’t need any bass augmentation from a subwoofer to sound their best.

They did shine best with a strong, solid-state amplifier driving these speakers. So be sure to take this into account when considering these incredible speakers for your system.

In the end, the ELAC S 507 offered excellent value for the money, and I would be more than happy to make these my main speakers. They are highly recommended.