July / August 2005
Why is it that music reproduction has come full circle? Vinyl records, single-ended tube amplifiers and horn loudspeakers are getting rave reviews throughout the world. After all, the new millennium is upon us! Has new computer technology lead us on the wrong path to audio nirvana? Solid-state amplification, high technology Aerogel loudspeaker drivers and carbon fiber interconnects are all new savoir-faire. Have the scope jockeys been exposed to too much CRT radiation? Why is it that, with all our technological know-how, horn loudspeakers using paper cone drivers seem to produce among the lowest distortion and possibly the highest in musical enjoyment?
Lastly, a spherical horn has a controlled dispersion pattern and therefore approximately 85% of the sound is directed to the listening position. While horn-loaded highs and midrange do not require super sized horns, a horn-loaded bass system would be inherently large (refrigerator sized like the aforementioned Lowthers). Therefore another method was chosen to better accommodate the home listener.
It Is All In The Details
Instead of using conventional paper cones, the 10T300 drivers use special paper-pulp that is passed through a special sieve and then gently air-dried. The excess materials drip through the purpose-built sieve so that a special irregular structured surface appears on the rear of the cone. Avantgarde Acoustic claims this irregular surface provides "incredible stiffness and acoustical neutrality, thus eliminating harmonic distortions and interference in the upper frequency range".
The included 200-watt amplifier powers both 10-inch drivers. Both RCA and XLR preamplification inputs are augmented by loudspeaker inputs for flexibility for any system. The phase is adjustable as is the crossover frequency and volume output (lower knobs). An additional internal circuitry continuously controls the velocity of both drivers' movements. This circuitry promises lower distortions while insuring the loudspeakers are reproducing the proper signal. Another benefit of this design is that the subwoofer system itself is 100dB/W/m sensitive in this 11.8 x 21.7 x 21.7 (WxHxD in inches) enclosure weighing in at approximately 100 lbs.
Careful Setup Is Key
I found that positioning the Duo 2.0 (or the Uno 2.0 version also on hand) was not as finicky as their first, version 1.0, counterparts. While the first versions were highly transparent, setting them up was a challenge as finding a balance between positioning and overall smooth frequency response was an affair unto itself. The new PRO subwoofers are leagues ahead of their original counterparts. The originals were simply not as fast, nor as smooth as the new SUB225 CTRL PRO.
Lastly, a tweak I learnt from the great Kurt Strain, wise man of audio on the internet, was to angle the top-mounted midrange unit by laying the speaker system on it's back. Then loosen bolts that connect the woofer, tweeter and midrange modules. Then lower the front of the bolts on the midrange unit by one hole so that when the unit is standing up, the midrange module is angled slightly downward. While I did not need to do this, you may need to lower the tweeter module down one set of holes on the mounting brackets.
Sound the Horns!
First up for critical listening was Chesky Records new CD titled The Agnostic [CD202]. This wonderful orchestra with chorus and pipe organ was audiophile quality with minimal microphone techniques and recorded with 24-bit/96kHz digital technologies. The dynamics go from eerily quiet to full intensity. Only the best systems will be able to decipher the wide and deep hall with its natural acoustics. The Duos are incredibly articulate at providing wide dynamics. Individual voices in the chorus could be clearly heard while the grand scale of dynamics was easy to follow. Imagine the speed of electrostatics yet without their general dynamic limitations. While I am guilty, at times, of playing music at higher than normal volume levels, there seems to be a touch of compression with some loudspeakers either in the lower auditory levels or louder sections. While we might not be talking the great speed of the best electrostatics, it is close yet without the dynamic constraints smaller electrostatics provide. This seemed especially true is the lower midrange where the Duo truly showed its superiority to the Unos.
The Duos seemed to effortlessly fill the room with hall "sounds". The ambience and timing of the reflected sounds a hall provides is a good part in the overall musical experience. The 47 Laboratories Gaincard and also the Wavelength Audio Cardinal really mated well with the Duos in this regard as compared to other amplifiers in my humble abode. If there is one thing the Duos will certainly let you know, it is the quality of the equipment it is mated to. This Chesky recording offers a reviewer such as myself a real reference for the low level resolution of a piece of gear while also getting a great dynamic workout. The Duos handled everything extremely well and I was especially pleased with the clarity of the subtle details. Properly sized imaging (not fake pinpoints) and complete rendition of overall soundstaging was left bare for my enjoyment was improved over the Unos. The Duo hornspeakers were more harmonically correct than the Unos too. My concerns for better lower midrange support from the Unos were definitely answered with the Duos. Still, I felt that the Unos subjectively had a touch more clarity in some of the louder passages. Could I be mistaken? Read on...
Next up was the incredible Willie Nelson Stardust on CBS Master Sound Half-Speed mastered vinyl [HC 45305]. The clarity of Willie Nelson's vocals on the song "September Song" was such that with eyes closed there was more than just clarity, there was body and flesh n' blood sound that put Willie in the room. Clarity is good and all that goes with it, yet there is a point to where some speakers seem to have it at the expense of striping away the soul of the music. In a musician's sense, it is the difference between playing the notes well, or playing the music. In fact during this review process my music loving audiophile parents stopped by for a listen. They both sat in proper listening position and Willie sang his soul. Both my parents were so moved by the music that tears filled their eyes. My dad, who got me hooked on music and music reproduction long ago, also heard some pipe organ (E. Power Biggs if you must know) and Sheffield Lab's direct disc vinyl recording Wagner Die Walküre: Ride of the Valkyries [LAB 7]. While my father has an impressive system himself and has been to more live concerts performed by the greatest musicians over the past many decades than I care to begin to mention, he was truly impressed. From the deep pipe organ notes clearly and easily energizing the room to the mass orchestra attack of the Sheffield Lab recording, the man not easily impressed needed a crowbar to be removed from my listening chair! Let us get back to Willie Nelson.
The one thing I was having a hard time with was the possibility of a slightly diminished transparency in sound of the Duos as compared to the Unos. So there I found myself removing the Duos out of the room and reinstalling the Unos. Let then settle in for a few days and listened to Willie, Wagner and the Chesky Records recordings very carefully. Then I removed the Unos and brought back in the Duos. Listened to the same musical passages and realized that it was not that the Unos were less transparent; it was the deceiving nature of slightly augmented midrange and highs! If you have had the opportunity to use a truly transparent equalizer (i.e. the Z-Systems rdp-1 as in Ultimate Audio Volume 2, Number 1) you can easily add a few dB of upper midrange and slightly lower the midbass and presto change-o, you seem to have better imaging and added clarity. This is a neat trick that seems to find its way into quite a few audiophile loudspeaker designs... including the Lowther. While it is hard to define how much the Lowther augments the 1kHz to 2kHz range as there are more cabinet designs and super tweaks to reduce the frequency peak, careful listening to a truly smooth frequency response design will allow one to know the truth.
Another caveat of the Duo is in mating it upstream equipment. While the Avantgarde Acoustic Uno was happy with my few years old Western Electric WE300B, it seems the slightly rolled off highs of the WE300B helped to smooth out the subjective brighter sound. Naturally other 300B variants (mesh plates) were a better match. It is when you get to the Duo, or electrostatic loudspeaker "microscope" is when you truly realize the good, the bad... and the ugly.
Speaking of ugly, I gave the subwoofers a good workout as the compact disc Prodigy Fat of the Land [Maverick 9 46606-2] went through its paces. For those unfamiliar with this recording, there are pulsating fast 32nd notes in the bass region. Imagine normal rock song, which is 1-2-3-4. Now in the same amount of time, yet instead of four beats make it 32 beats. That is eight beats to each single beat you previously imagined. Very fast! While this is not something one would ever normally hear in acoustic music, it will easily show whether a subwoofer will be fast and clean, or simply fall on it's face with a slow tubby tones. The SUB225 CTRL PRO seemed to keep right up with the music until we reached louder than your typical dance club or rock concert levels. Then it seemed they simply ran out of juice while the horns could keep going a bit louder. While one could criticize the subs for not being able to obtain the same volume limits of the self-powered subwoofer, how loud do I want my music to really go?
Power Handling:150 watts
Warrantee: 10 years for material fatigue, five (5) years on the lacquer finish and one (1) year on the electronics.
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