Acapella Audio Arts Violin Loudspeakers
Review by Tony Maresch
The Violin loudspeakers, made by Acapella Audio Arts in Germany, are a three-way design with a dynamic woofer in a sealed enclosure, a horn midrange driver and a plasma ion tweeter. Acapella Audio Arts have been manufacturing these types of speakers (including the Plasma Ion Tweeter) since 1978, but only recently collaborated with a North American distributor to sell speakers on this side of the Ocean. A driver compliment as unusual as this certainly invokes thought from all those audiophiles who look at such a magnificently sculptured design. Each driver has been carefully chosen and applied based on its strengths for the frequency range it handles. The conventional woofer reproduces bass, the horn midrange reproduces the midrange up to all but the highest frequencies, and the exotic Plasma Ion Tweeter, reproduces the high frequencies to beyond 40kHz. The tweeter is coupled to a gorgeous gold horn, which increases its amplitude and dispersion characteristics. The midrange Horn is available in a variety of colours, and the cabinet with woofer grill is available in white or black. The Violins' come in three versions, the basic version, with the three drivers noted above, the "high" version, reviewed here, which incorporates a 30 lb heavier and better braced woofer cabinet, as well as Acapella's proprietary ceramic coated silver wiring throughout (the same wire as in their $2,000 loudspeaker cables), and higher quality crossover parts. There is also a "sub active" version which incorporated another woofer per cabinet for deeper bass extension.
To break them in, the Violins were hooked up to the Simaudio Moon W-10 power amplifiers. The Plasma Ion Tweeter needs about half an hour to break in, and although the horn would require more time, it was the woofer that would take over a week to break in. The manual recommends 14 days, and they were given that, 14 days of continuous music.
Dissecting A Loudspeaker -
Plasma ion tweeters are the evolution of William Duddells' "singing arc" which was first shown in London, England in 1900. It was a modification of carbon arc lamps used in London during that era. His job was to reduce the noise of these devices, and he found while working on them that changing the voltage of the arc changed the noise it produced. In 1946 Siegfried Klein got involved, producing a number of patents for his work, and by 1954 had come to the conclusion that confining the arc to a small quartz tube and coupling it to a horn would enable it to be used as a loudspeaker or even a microphone. At that time this technology became of interest to the audiophile and it was called an Ionophone at that time. Some of you may remember the Magnat plasma ion tweeters of the late 1970's, but as far as I know, Acapella is the only current manufacturer of Plasma Ion Tweeters. The benefits of such a tweeter are that it will have no resonance or transient problems. Conventional wisdom has it that the fastest tweeters are ribbons since they have such low mass, but a Plasma Ion tweeter has no mass at all since it is basically a stable electric arc, and therefore should be faster and even more extended in the high frequencies. The Plasma Ion Tweeter works by first stabilizing an arc and then agitating the ions by changing the temperature in its small chamber, which causes the arc to expand and then contract, and therein lies the push and pull of the arc, which moves air at high frequencies. In order to generate and stabilize an arc, power will be required, so the tweeters are connected to your house AC. When they recognize an incoming signal they turn on with three consecutive clicks, which takes less than 30 seconds. They also have a sleep mode (after a few minutes of inactivity, they automatically turn off).
OK, there is the technobabble. Looking at the tweeters when they are on, start as a deep purple at the edges of the arc and change to a deep reddish pink in the center. When the music has the appropriate amount of high frequency information, you can almost see the colours change in intensity a bit. The look is very cool. It has the same hypnotizing effect of looking at the filaments on your first tube power amplifier. This is the identical tweeter used in Acapellas higher model loudspeakers, right down to the adjustable gain dial with a penciled mark on the chassis reflecting the final fine tuning done at the factory for the loudspeakers they are shipped out with.
These are without a doubt the finest tweeters I have ever heard in my life. They are transparent, articulate and extended like no other tweeter I have been exposed to. It is generally accepted knowledge that the human ear does not hear frequencies beyond 20 KHz (in fact, most of us can not even hear quite that high). Despite this, there is clearly something about this tweeter extending to beyond 40 KHz that is responsible for these delicate liquid and crystalline high frequencies. (See below for more on this phenomenon). Acapella claims that the Plasma Ion Tweeter sounds so exceptional due to its lack of mass, producing improved transient capabilities and phase stiffness, resulting from a lack of harmonic and transient distortions. Such is the technical reasoning from the manufacturer. Listening to something perform with such deft agility puts these academic discussions to rest. Like a painting created by one of the masters, its intention to draw the observer into the emotion of the piece leaves the viewer (or in this case, listener) in awe of such superlative mastery of execution.
Although the Plasma Ion Tweeters are horn coupled to improve dispersion (and amplitude) they are still somewhat directional and listeners will find experimenting with toe-in important to getting the sound just right for their own balance between pin-point precision and soundstage. I settled with them 7.5 feet apart (tweeter to tweeter) and listening to them just over 10 feet from that line, with just a touch of toe-in. The added bonus of the adjustable tweeter gain will allow tonal balance to be corrected if a listener dials the toe-in too extremely in either direction or if the room is overly dead or bright. The Violins are very easy to set up and I marveled at their ability to turn sibilance into silkience with such finesse. (Silkience... this is why we become reviewers, to make up words). (Editors note: sheesh, now you readers know what i have to deal with each month. Shazbot!).
The Horn Midrange
I have a confession to make. I was not really a horn speaker fan until I heard horns via Acapella. I truly appreciate the dynamics of horns, and dynamics are one of the hardest characteristics of live music for a hi-fi system to reproduce. I also appreciate how the higher sensitivity of a horn system allows them to be used with smaller wattage and usually simpler circuit amplifiers, and thus a theoretically less altered signal to pass through. However, many horn speaker designs roll off the high frequencies too quickly for my personal taste. The mating of the horn midrange to the Plasma Ion Tweeter is the remedy for my horn issues, proving a well executed design can result in so much more than just the sum of its parts. The beautifully flared horn may share its roots with its predecessors, but unlike the surviving vintage speakers I have heard, there was no metallic ringing flares requiring copious amounts of "soundcoat", or subtle, but once identified annoying wooden resonances, just pure clean and big sound. All of it was there, effortless dynamics, the open soundstage, big, open and airy sounding music. Throw on a smoky voiced female singer and be intoxicated by their performance. You can hear them breathe between lyrics when the recording is up to it. Jacintha's rendition of "Georgia On My Mind" from Here's to Ben (FIM XRCD 020) portrayed the sensual vocals and sax with a breathtaking balance of hearing every detail and breath of the original note and lyric, combined with the delicate decay of those same notes and lyrics. Domnerius playing Antiphone Blues (FIM CD003) filled the room with luscious sounds, what a wonderful front soundstage and all around soundscape!
After the 14 days of break in, the woofer did its part, sounded dynamic and articulate. It is not easy for a dynamic woofer to keep up to the speed of horns and such a tweeter. Despite this, I did not hear where the horn ended and the woofer started as two different drivers with different characteristics. I heard a coherent system with one voice. I suspect that the specially chosen woofer and the larger than usual (for such a sized woofer) cabinet size was designed for its ability to lower the "Qtc" (damping of the woofer in the cabinet) resulting in faster and tighter response. It worked exceptionally well with both the Simaudio Moon W-10's and Audio Research M300 Mk II's. The speakers also sound fantastic with lower powered amplifiers, all the way down to single ended 300B's but their bass response will get a bit looser in absolute terms with smaller amplifiers. This is hardly a deal breaker for single ended users, so to speak, far from it, just a question of synergy and listener preferences.
Most single-ended listeners are prepared to loose a few of the lowest octaves to get everything else correct and in that context these fit the bill extremely well. They still go very deep, but we all know 300B's do not control woofers like high power solid state power amplifiers, or even their tube counterparts. Both the manufacturer and distributor recommend at least 20 watts per channel, but I have heard excellent results with the Manley 300B Neo Classic power amplifiers. I have also heard another pair of these at a local retailer at different times hooked up to various state of the art systems as well as a few very reasonable systems, and they always made beautiful music.
Putting It All Together
As mentioned above, these very different and exotic drivers work with a coherent voice and do not let any individual component stand out from its siblings. I am sure it took much time and effort to produce such a seamless transition from driver to driver. During my time with the Violins, they were connected to, at different times, the Simaudio Moon W-10's and Audio Research M300 Mk II power amplifiers, interconnects and speaker cables swapped in and out were XLO Signature as well as Cardas Golden Cross and Cardas Golden Reference. The mixing and matching between these combinations revealing various presentations from precise, immediate and as exhilarating as an adrenaline rush to rich, smooth and holographic - to a degree the listener feels the music almost wrap around him like a warm blanket. Listening to Anne-Sophie Mutters "Carmen Fantasie" left me melting in the listening chair, the violins were so smooth, the rosin of the bow so intimate. Rebecca Pidgeon's "Spanish Harlem", a song I know well, was more immediate than I can remember ever hearing, setting a new standard for how real this recording can be for me.
Changing music styles, Joe Morello's Topsy and Mission Impossible from Going Places
(DMP CD-497) revealed wonderful micro and macro dynamics with crystalline highs and tight, deep bass. Robert Crays "I Guess I Showed Her" from
Strong Persuader (Polygram LP 830 568-1) has more of a raw emotional feeling to it, which came through beautifully.
The Commitments soundtrack (CDMCASD-10286) came through with a similar raw feel, as it was intended to, although not quite as raw as I usually hear it, another example of the Violins changing step perfectly as one type of music is substituted for another. As the music selections changed to classic as well as modern Rock, another feature of these speakers showed itself with more prominence, their incredible dynamics. Rock and Roll is very dynamic, and the Violins do dynamics incredibly, both micro and macro, talk about invigorating!
Sound Above 20kHz
Many musical instruments produce sound up to 40 KHz and above. The violin and oboe, for example, a French horn can go up to 90KHz and a cymbal crash even higher. The Audio Engineering Society published a study by Oohashi, Nishina, Kawai, Fuwamoto and Imai, titled High-Frequency Sound Above the Audible Range Affects Brain Electric Activity and Sound Perception (AES preprint No. 3207). The tests involved a tweeter (with its own separate amplification) that started at 26kHz with steep filters below that frequency. The listening panel heard the same music through a system with this tweeter turned on at times and off at other times. The listeners consistently found the music to be more pleasing with the tweeter on, even though, under a separate test using only the "super tweeter", they could not tell if it was on or off.
Crossover Frequencies: 800Hz and 4,500Hz
Impedance: 4 Ohms nominal, minimum 3.2 Ohms, flat above 20Hz, maximum approx. 30 Ohms at 37Hz
Load Capacity: 200 watts (Peak handling of 1000 watts at 10 ms with no distortion)
Recommended Amplifier Power: Minimum 20 watts
Dimensions: Pillar: 1170 x 330 x 450 mm
Weight: 110 kg.
Acapella Audio Arts
Tricell Enterprises Inc.