Product Review - Celestion A-1 Bookshelf Speakers - August, 1997

By James D. Moretti


Celestion A-1 Speakers - Click for large image
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Celestion A-1 Bookshelf Speakers; Two-way design; One 7" polypropylene woofer; One 1" titanium dome tweeter; Vented box design; One 2 1/4" flared port on rear; Cloth grille; Frequency response 43 - 20 kHz 2 dB; Sensitivity 88 dB/w/m; Nominal impedance 4 Ohms; Bi-wirable; Size 16"H x 9.5"W x 14"D; Weight 31 pounds each; Cherry veneer: $1,499/pair; Rosewood: $1,699/pair; USA Distributor: Adcom, Inc., 11 Elkins Road, East Brunswick, New Jersey 08816; Phone 908-390-1130; Fax 908-390-9152.

Celestion is a reknown maker of speakers in the UK, having been founded in 1924. Their A series of speakers was introduced a short time ago, including the A-1, A-2, and A-3. We obtained a set of A-1s, which are the bookshelf version, in a beautiful natural cherry veneer. The speakers are finished on all sides, including the back, where there are two sets of five-way binding posts (for bi-wiring, bi-amping), and one flared port. The edges are rounded to aid in reducing diffraction effects. Instead of just bending the veneer around the edges, as most manufacturers do, the A-1s have been finished with cherry corner posts, making them look like furniture [click here to see photo]. This is very unusual, and evidence of fine craftsmanship. I also noticed that the polyurethane or lacquer is very thick. This helps a little with damping, but mostly it will keep them from getting water marks and other types of moisture damage. When I knocked on the enclosure, there was very little resonance, indicating good internal bracing.

There was a great deal of computer simulation that went into the design of the A series, including the shape and composition of the woofer cone. It is flaired, rather than a simple cone, meaning that a line drawn from the outer edge of the cone to the outer edge of the dust cover is curved rather than straight. Secondly, the cone is made of polypropylene and mica flakes. When the cone is formed, the mica flakes line up in the direction of the injection molding, which can be controlled. During use (playing music), the mica absorbs some of the flex energy of the cone, reducing "breakup" (cone flexing rather than proper forward and reverse movement). The use of mica is not new, but computer modelling allowed the Celestion engineers to develop the right blend of rubber and mica, along with the way to form the cones in the manufacturing process.

Celestion not only makes their woofers, but the tweeters as well. Tweeters in the A series are titanium dome, with a Faraday ring placed at the rear of the pole piece (the pole piece is an extension of the magnet structure and comes down very close to the voice coil). One of the central problems with speakers is that when the voice coil is made to move in the field of the speaker magnet, it generates its own magnetic field due to induction of current in the coil by the very fact it is moving in a magnetic field (this is how a generator works). The magnetic fields of the voice coil and the speaker magnet interfere with each other. A Faraday ring, which is a ring of copper in the A-1, helps to reduce the magnetic field produced by the voice coil. The bottom line is less distortion. On the A-2 and A-3, Faraday rings are placed on the woofers too, but in the A-1, it is just on the tweeter. Again, Faraday rings are not new to speaker design, but in this case, many computer models were used to predict how the speaker would perform, rather than just building a whole bunch of different speakers and seeing which one works the best. This saves a lot of time, and ultimately results in a better speaker at a good price to the consumer. I don't have extra money to burn, and when I hear "good price", my ears perk up.

We listened to the A-1s using several setups. One consisted of an Audio Alchemy CD combo, an AE-1 preamp, White Audio B-80 monoblocks, and Bryston 3B-ST power amp. A second was comprised of a McCormack Audio CD package, Balanced Audio VK-5i preamp, and LLano SA-3 Monoblocks. Cables were AudioQuest and Nordost Flatline. CDs varied from movie soundtracks to Vivaldi to modern vocals.

The first thing I noticed about the A-1s was their smoothness. There were no obvious dips or peaks anywhere. These are some of the most even-sounding speakers I have ever heard. No harsnhess, no boominess. Just music. Someone who is not familiar with the high-end sound might think these speakers are boring and that something is missing. That is, until they realize that what's missing is distortion. Funny that a lack of distortion can sound boring! I sort of felt that way too at first. Especially after listening to my bass guitar the evening before. I use signal processing to actually increase distortion for some tunes. It adds a buzz or edge to the notes and makes them carry in a noisy bar. But after continued listening to the A-1s, this effect wears off, and suddenly I found myself at peace with the sound. No fatigue. "Easy Listening" is a good term. I sat through an entire album of Baroque music (Vivaldi) and enjoyed every minute (it's not my type of music, but that was what they had on in the lab when I came by to pick them up). We all preferred the Bryston power amplifier with these speakers. The Bryston has a "bite" to it that gave us just the right effect. Still no harshness, and they were easy to listen to, but some edge, or maybe snap, that we really liked. Vocals were very natural. Enya and Natalie Cole are two of the favorites in the lab. It is real easy to hear any boominess or chestiness that is added by speakers. They sounded completely natural, and the Bryston amp made Cole's slight rasp come through. But not overly sibilant.

Frequency Response (Room Response), left channel only, 1 meter, on-axis, grille cloth on, volume set to 80 dB at 1 kHz :

20 Hz - 60.4 dB
25 Hz - 65.1 dB
31.5 Hz - 67.8 dB
40 Hz - 74.5 dB
50 Hz - 67.9 dB
63 Hz - 76.5 dB
80 Hz - 71.2 dB
100 Hz - 83.3 dB
125 Hz - 67.4 dB
160 Hz - 83.6 dB
200 Hz - 78.5 dB
500 Hz - 83.5 dB
800 Hz - 79.3 dB
1 kHz - 79.7 dB
2.5 kHz - 75.8 dB
5 kHz - 84.0 dB
8 kHz - 82.8 dB
10 kHz - 80.2 dB
12.5 kHz - 85.4 dB
15 kHz - 83.0 dB
18 kHz - 80.1 dB

Frequency Response (Room Response), left channel only, 13 feet, on-axis, grille on, volume set to 80 dB at 1 kHz :

20 Hz - 74.9 dB
25 Hz - 80.0 dB
31.5 Hz - 88.5 dB
40 Hz - 80.2 dB
50 Hz - 62.6 dB
63 Hz - 84.1 dB
80 Hz - 88.2 dB
100 Hz - 86.6 dB
125 Hz - 84.1 dB
160 Hz - 82.7 dB
200 Hz - 94.5 dB
500 Hz - 82.9 dB
800 Hz - 92.9 dB
1 kHz - 79.4 dB
2.5 kHz - 77.4 dB
5 kHz - 82.8 dB
8 kHz - 81.2 dB
10 kHz - 86.8 dB
12.5 kHz - 79.9 dB
15 kHz - 83.7 dB
18 kHz - 81.7 dB

The A-1s have a smooth room response. Any large peaks or dips were room effects. I could hear harmonics when the 25 Hz sine wave went through during the far field test, but that's not unusual. Speakers this size aren't really made for deep, deep bass.

All in all, I would classify these speakers as top notch, both in physical beauty, and in sound. Depending on your auditory tastes, you might want to match them up with a Bryston or similar amplifier if you prefer a little edge to the music.

J.D. Moretti

Copyright 1997 Secrets of Home Theater & High Fidelity
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