I don’t really know what I’m talking about; I am swiping all of this information from JA’s review, which you can read in our September issue. I do know, however, that the thing is heavy. I helped Aaudio Imports’s Brian Ackerman carry the speakers into JA’s room. At over 300lbs, the Violoncellos are easily the heaviest speakers I’ve ever lifted. The tweeter module alone weighs over 30lbs and measures 6” H by 12” W by 10” D.
Most impressive, however, is the tweeter’s distinctive violet-tinged flame. I was looking directly into the tweeter’s brass horn when Ackerman ignited the flame, triggering a sound not unlike that produced when lighting a gas stove, only more crisp and sudden. Jump factor? I nearly jumped through the ceiling. Cool.
Learn more about the Ion TW1S tweeter module here. The Acapella High Violoncello II is the most expensive speaker JA has ever had in his listening room. Find out what he thought of it in our September issue.
COMMENTS
Hope that the technology has improved-- a plasma tweeter once almost killed Nelson Pass at an audio show once upon a time. (Was testing it in his room, and ended up going to the hospital with breathing problems relating to ozone inhalation.)
It wasn't a plasma "tweeter" that Nelson Pass was demming but a complete. direct-radiating speaker. The ozone production was therefore signficant. The Acapella tweeter in the High Violoncello II speaker didn't emit ozone in any amount I could detect.
In 1979 to 1980 I sold the Hill Plasmatronics speakers at Audio Vision in Dallas. They retailed at the time for $10,000. Each cabinet had a dedicated amp driving a 12 inch woofer, plus Dr. Alan Hill's plasma mid-tweeter (which required a separate amp).The Hills did produce some ozone. However, I never had any complaints from anyone who listened to them of any discomfort whatsoever.The sound was the absolute best I've ever heard from any loudspeaker. In some ways, the physics of the Ion seems similar to the Hill plasma driver. For example, the driver is mass-less relative to the air it is moving. However, the Hills used a tank of helium as a source of inert gas to create the plasma. The Ion uses air. Also, the Hill driver was radiated in a 360 degree pattern. The Ion is a horn.Steven
"Speaker wires in the photo are on carpet, i thought one needs cable elevators for things to work correctly? JA, do you know that?" The speaker cables are on Shunyata Dark Field Elevators, George. The cables on the carpet are AC, USB, headphone, and Toslink."Why the delay in bowls, when these speakers function in the room, that hardly looks prime time acoustically?" I worked hard and long on the acoustics of my listening room. Not only did I use strategically placed traps and diffusors, three of the walls are placed with LPs, CDs, and bookshelves. The room has an uniform reverb time of around 250 milliseconds through the midrange to the mid-treble. Though this a little on the short side, hence drier than most, the room is relatively uncolored. You can see from the room response graphs I publish in my speaker reviews that the bass modes are relatively benign.
"Lighting a flame in a residential environment, to listen to music is more than slightly DUMB."The plasma is about 10" inside the speaker at the throat of the horn. It is no more dangerous, less so in fact, than the pilot light of a kitchen stove.
I'm just wondering JA; your listening room resembles a lab more than a typical listening room, which I fully understand in your case, but don't you miss being able to listen and relax in a more traditional, softer, parlor style room? And I gotta ask about those records; do you use them for any purpose other than you describe above as sound diffusers?
It only looks like a lab at the "business end," FSonicsmith - you can find another photo at http://forum.stereophile.com/photopost/showphoto.php/photo/2275 - but as the editor of Stereophile, I must have a room dedicated to assessing components. But music does sound gorgeous in this room. You can find a photo of my listening chair at the other end of the room at http://forum.stereophile.com/photopost/showphoto.php/photo/166 .I don't listen to LPs as much as I would wish these days, unfortunately.
As an owner of the Acapella High Violons (which use the same tweeter) I am looking forward to your review. I have had a number of issues with mine which have been rather tricky to solve, but I am getting there. Despite the quoted sensitivity, my speakers are more difficult to drive than expected - in part because of the wicked impedance curve of the bass cabinets.
Keith,For 2010 Acapella has re-designed their entire range of loudspeakers. All models now have new transformer coupled crossovers which eliminates low impedance drops in the bass. In addition all drive units have been updated. The Violon and High Violon are now in the MKV version. Older models are unfortunately not upgradable. Brian AckermanUS ImporterAcapella Audio Arts
From the specs it seems that Acapella uses this more as a supertweeter instead of a tweeter, as it kicks in fairly high in the band. Only makes sense, as they're known for being the inventors of the spherical horn, so I'm guessing that the mid-horn is the most compelling feature. Maybe Brian can elaborate, as I've heard that the Acapella tweeter kicks in @ 5k, so I'm guessing that the horn is operating through to about 8k ??
Thank you for your response, Brian. FWIW I have tried an autoformer which does solve the bass problem but "dries out" the upper frequencies - however this is with the speaker running full range from the amp. I would imagine that a transformer in the bass cabinet alone would be a very satisfactory solution. CVince, I am not sure about the current model but my midrange horns start to roll off at 5kHz at about 12dB/oct however my measurements are not entirely reliable as they were taken in-room. The tweeter has a "brick-wall" filter that sharply cuts off anything below 5kHz, which is what you want anyway thanks to the physical limitations of the flame size. While the tweeter is the main attraction, that midrange horn is not bad either :-) Well actually it is bloody good!! You will not be able to hear the difference between the horn and the tweeter. The two integrate so well that they sound like a coherent unit. The bass cabinet is a different story, but mine is an early iteration of the Violon.
Keith,Thanks for the info. At 12dB per octave rolloff, you'd have output at the horn at 10k (-12dB), and at 7.5k (-6dB) - which is probably good in this case giving the very high frequency where the supertweeter kicks in. But because the wavelength @ 5k is really small, I'm guessing you can't really be too close to these speakers as you'd have to be far enough away for the outputs of the horn and the tweeter to converge, and they are BOTH constant directivity and fairly narrow dispersion (I would think, given that they are horns).What's your experience of this?
CVince you are correct. You have to sit at least 3m from the speaker. In my case, I sit 4m away. From this distance the integration between midrange and tweeter is superb. The speaker is also very sensitive to toe-in and listening height. It was a real bear to place the speaker right - too much toe-in and the soundstage suffers, too little toe-in and the image is blurry. Too far out and bass suffers, too far in and soundstage depth is compromised. I have not yet found the ideal solution, and have settled for soundstage width over precise imaging. More experimentation is necessary.
They don't seem to say what the Horn Curve is - exp, straight, or some other curve. Dr Bruce Edgar showed us that the TRACTRIX is the ONLY Curve for the essential midrange to eliminate reward reflections from the horn mouth back toward the throat that causes standing waves and comb filtering characteristic of other horns... So even if the Ionic drive were safe, the horn realization might not be the best ...
| Loudspeakers Amplification Digital Sources |  |
Analog Sources Accessories Featured | |
Music Columns Retired Columns | |
Show Reports | |
Features Latest News Community | |
Resources Subscriptions |
© 2024 Stereophile
