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Am I incorrect in saying that the woofer appears to behave like a slot-loaded subwoofer with an underdamped resonance peak at 60Hz? Reminds me of the Janus SW10 subwoofer I used to own.
Hankering for a recording with a greater sense of space and place, I moved to another recording by Les Siècles, one that has become a favorite of mine, Fauré's Requiem Op.48, which adds the vocal group Ensemble Aedes to the mix, both ensembles conducted by Mathieu Romano (24/96 FLAC, Aparté AP201). This piece was recorded in Abbaye de Lessay, in Manche, which offers a warm acoustic without loss of detail. From the first, defining pedal, everything was sweet and clear, and the AURAs delivered the voices and instruments distinct from the enveloping ambience. However, I heard less of the bass line than I have in the past from this recording.
Is it all about the bass?
To follow up on that point, I listened to some recordings that feature oktavists, singers whose range extends below that of a basso profundo, "down to contra B flat and lower in a choral setting." (footnote 3) Among those in my library, the contribution of the oktavists is clearest on Rachmaninoff 's All-Night Vigil (aka Vespers), as performed by Gloriæ De Cantores joined by members of the St. Romanos Cappella, the Patriarch Tikhon Choir, and the Washington Master Chorale, all under Peter Jermihov (SACD, Gloriae Dei Cantores, GDCD 063, also available as a half-speedmastered 45rpm, 2-LP set). This performance incorporates seven oktavists among 22 bassos. The AURAs did a grand job with this landmark performance, depicting the large chorus with subtle, wide dynamics in a wide, tall, deep soundstage. The oktavists contributed greatly to the richness of the chorus, but they can best be heard in Part 5, "Nunc Dimittus," listed as "Now Lettest Thou." As this part is ending, the music descends in pitch until only the oktavists are left to sing the final notes. The AURAs let me hear and appreciate the oktavists' contributions and to contrast this with the many recordings of the Vespers that employ only "regular" bassos. Those deep, otherworldly tones were stunning.
Still, I'd have liked a bit more from the lowest noteswhich by the way go down around 58Hz. Via the AURAs, a normal low voice, such as Hans Theessink's in "Late Last Night" from Burmester's Vorführungs - CD II (Burmester Art for the Ear, no catalog number), displayed the expected gruff tonality in full. The AURAs did justice to the accompanying trombone and tuba. The percussion had kick. But if I pushed the AURAs with "The Flight of the Cosmic Hippo" (Bela Fleck, Warner Bros. 9 26562-2, CD) or with my favorite recording of Mendelssohn's first organ sonata with Thomas Murray (CD, Raven 390), I heard everything there was down to the lows in the second verse of "Hippo" and all the pedal tones in the last movement of the Mendelssohn, but I didn't feel the bass, and there was much less bass energy in the room than I am accustomed to. Although the AURAs have an extended low frequency response as would be expected from their size and use of a 10" woofer, their bass rolloff sounds like it begins rather high upbut hang on just a minute.
I took a detour from stereo and briefly ran the AURAs as L/R in a 4.1 mixdown of the recent release The Trondheim Concertos (2L 2L-172-SABD, SACD+Blu-ray), a selection of baroque concerti associated with the city of Trondheim and a good retort to anyone who thinks baroque music is lightweight. The mid- and lower bass was completely satisfying, suggesting that anyone who finds that the AURAs lack something at the bottom end can get satisfaction by adding a subwoofer. The rest of the spectrum was, as I have come to expect from the AURAs, clean, open, and dynamic.
Resolution
I chose this moment to switch to the Benchmark AHB2 monoblocks to see if what I was hearing was related to amp/speaker matching. It was. I have swapped power amplifiers many times while reviewing speakers. I have even done so with these particular amplifiers, the NAD and Benchmarks, and struggled to describe the subtle differences I heard. But this time it was easy. Using the Benchmarks with the AURAs, the bass was improved so much that the light bass I heard previously was no longer an issue. The above caveats no longer apply.
The gloves are off
I usually save the "big" music for the end of a review, and I am glad I did so with the AURAs, now powered by the monoblock Benchmark AHB2s. The opening drum salvo of Rameau's "Zaïs Ouverture" from Une Symphonie Imaginaire, by Marc Minkowski and Les Musiciens du Louvre (SACD, DGG Archiv 00289 477 5578), was proof positive that all was well. When the whacks got louder to set the tempo, the strings and winds exploded with the joyful melody, filling a wide and deep soundstage.
The ability of the AURAs to project this soundstage with great clarity was confirmed with "Stimela (The Coal Train)," from the album Hope, by Hugh Masekela (SACD, Analogue Productions APJ 82020). Played at a high level, the AURAs thrillingly recreated the aura of this large live event and presented Masekela's voice and trumpet, as well as the other performers, with striking presence and realistic tonality. There was a sense of immersion in the event that is rarely achieved with only two channels. Finally, with a stunning new recording of Tchaikovsky's 5th Symphony with the Pittsburgh Symphony Orchestra conducted by Manfred Honeck (SACD, Reference Recordings FR-752), the AURAs rewarded me with the richness and glory of a symphony in a powerful performance of this Romantic-era classic. The dynamics were all there, as were the power of the brass and the lovely sounds of the winds and upper strings, but something else impressed me more: I heard much detail in the rich underpinning of the cellos and basses. The AURAs did this right.
A comparison
I compared the Estelon AURAs with my KEF Blade 2 Metas, driven by the Benchmark amps. The results were fascinating. Direct comparison highlighted the AURAs' impressively pellucid and detailed soundstage, which, by contrast, made the KEFs seem somewhat relaxed. The AURA soundstage stretched across the room, with lots of immediacy in the speaker plane, while the KEFs depicted a soundstage that was both wider and deeper.
The AURAs' bass was somewhat less full and less extended than that of the Blades, but this might have escaped my notice had I not been sensitized to it by my prior experience with the NAD amp. Perhaps a different amplifier would relevel the playing field, even more than the Benchmark amps already had. Moreover, this is the part of the spectrum most affected by room acoustics and placement. I should also note that the AURA's tight bass will suit the tastes of many listeners and will certainly be kinder to neighbors. For those still not fully satisfied, adding a subwoofer could resolve this, if not for their neighbors.
Conclusions
I have spent weeks listening to the Estelon AURAs and thoroughly enjoying the music. They are among the most transparent speakers I've reviewed, and they present voices, instruments, and ensembles with refreshing immediacy and impact. Never did anything, including its bass performance, disturb that enjoyment or distract from it. The choice of amplifier is critical, however, for the AURAs' potential to be fully realized.
While my original attraction to the Estelon AURAs was based on appearance, I believe they are just as beautiful when I listen to music with my eyes closed.
Am I incorrect in saying that the woofer appears to behave like a slot-loaded subwoofer with an underdamped resonance peak at 60Hz? Reminds me of the Janus SW10 subwoofer I used to own.
Kal and John,
Thank you both again for another interesting review, measurements, analysis and assessment, all of it.
Something that remains a little unclear to me is in the details of the moving dolly utilized during the measurements. Was it utilized in the nearfield measurements of the woofer? If so, was the top surface of the dolly providing a flat continuous non-leaky boundary, extending well beyond the perimiter of the loudspeaker's plinth, providing good simulation of the floor?
I ask because loudspeaker's plinth has a large hole through the center, with the plinth providing venting geometry, and with the floor serving as the lower boundary in that semi-enclosed vented air cavity below the woofer. So, raising the loudspeaker onto a moving dolly of a type with an open top framework would increase the volume of that semi-enclosed air cavity and would greatly increase venting in the region of the dolly casters. A leaky top dolly (spaced decking) would change the venting. If the dolly did not have a continuous flat surface extending well beyond the perimeter of the plinth, then that would affect venting. Any of those changes in the woofer loading and alignment would have some significant effects in the electro-acoustic response of the woofer. However, if the dolly had a flat, continuous, air-tight top extending well beyond the perimeter of the plinth, then I would expect its use would not have any significant effects in the nearfield measurements of the woofer relative to measuring same with the loudspeaker placed on the floor.
While some of the engineering appears decent, the absurdly low impedance and laughably bad woofer alignment are complete deal breakers. I'm surprised Kal liked these as much as he did.