VSonics - A Brand new Transmission Line March 2008!!
The painstaking, uncompromising evolution of Aspen products over the last eight years has produced a number of sonically outstanding components. A speaker fully exploiting the sonic potential of these components has long been overdue, and a decision was made in late 2006 to embark upon such a project. After more than twelve months, we now announce the VSonics, a revolutionary, brand new 2-way transmission line speaker. The VSonics are nominally 8 ohm, and are generously rated to 150W RMS. These speakers are also highly sensitive, more so than the AKSonics they replace, and they offer stunning clarity and richness at low kit cost. This is the first pair professionally produced, cheerfully demonstrated here by Martin Walker (aka Supermart) and finished in Victorian Ash:
The VSonics are the ultimate outcome of a 50 year lineage in Transmission Line design. These exceptional loudspeakers were designed by Laurie Menogue, a talented and highly experienced Australian designer. VSonics R&D has consumed more than twelve months, with the speaker intended to complement the new range of Aspen power amplifiers, in particular the Lifeforce and Soraya models. Hugh's brief to Laurie was simply this: 'A two way, with 8" bass driver, transmission line, and third order crossover' - nothing more!! The evolving realisation consumed huge resources, because in truth this is a VERY difficult design brief and only the very latest driver technology has made it possible. This is an Oct 08 photo of Laurie, the designer.
The detailed design and dimensioning of the enclosure of any transmission line is a considerable challenge, but the design of the crossover itself is undoubtedly the most difficult, intractable aspect. The design process has not been made easier by software optimised for bass reflex designs, and hence the fine detail of the calculated results does not always reflect what is happening in reality. Transmission lines are VERY different, and painstaking iteration is the sober requirement!
The VSonics are designed with the DIY builder in mind. They are one of the easiest top end speakers to build, and are constructed with 3/4" (19mm) MDF (or high loading particle board) finished to your preference in stain, veneer, or paint. During development the enclosure design was meticulously reduced in size without sonic compromise to deliver a very compact and highly efficient loudspeaker. Few woodscrews are required; with great care taken cutting all mating surfaces quality PVA glue is the preferred technique. The cutaway below shows the baffle construction, a triple folded line, in an enclosure three feet tall and sixteen inches deep. (It is shown for conceptual detail only; this should not be regarded as a scale model.) Width is 9", little more than the driver - permitting outstanding imaging along with a very compact, pleasing footprint in any room, even a small apartment.
Listening tests have shown that the VSonics can be powered by any quality amplifier over 50W. Their true fidelity and grand scale is fully evident when powered by a Lifeforce or Soraya amplifier.
The following near field, front axis plots were created by XoverPro, the software adopted throughout the design process. (Leap V software was also used for design validation.) First, impedance, showing a benign load at all frequencies with well controlled peaks and outstanding correction beyond 100Hz. Note the first resonant peak (32 ohms) occurs at 18Hz, too low to cause problems for all but the largest pipe organs! Second resonant peak shown in the impedance graph is controlled by the V Transmission Line design and box stuffing. Since the software used was written for bass reflex designs, these graphs are not quite accurate; in fact the peaks are markedly lower due to enclosure and pipe design which strongly inhibits resonant phenomena.
Here is the Amplitude Response showing an almost straight line response with a carefully set 1dB dip from 300Hz to 1500Hz, a 1dB tip upwards for upper midband, and 3dB downward tip beyond 18KHz. Note comments above concerning the appropriacy for non-bass reflex designs. Do not be fooled by the drop below 40Hz; the VSonics deliver a subjective impression of deep, powerful and tuneful bass - the hallmark of a well designed Transmission Line speaker!
The final curve shows Phase Response, which is very important to the correct rendering of image (and image stability) across a wide listening area. For good imaging performance, the driver phase differential should be less than 5 degrees at crossover, here it is less than 0.1 degree, with very strong tracking from only 150Hz revealing almost identical group delay in both drivers. This is a textbook result! Maximum deviation is 85 degrees at 20KHz ,but at this frequency the output from the woofer is more than 50dB down - inaudible, particularly at the levels of signal at this frequency. Result is a very stable, accurate image of uniform 'speed' with no 'sweet' spot. Imaging is clearly evident across a wide depth and width together with scintillating clarity and a completely seamless crossover point.
Because of the front firing transmission line vent, the VSonics are ideal for almost any system or room and can be located right against the rear wall. (Like any other speaker, it is unwise to position the VSonics too close to a side wall since this can produce unwanted reflections.) The convenience of this cannot be over stressed! This unusual flexibility is achieved with innovative enclosure design which evenly loads the bass driver cone at all output levels, and a folded transmission line which promotes low frequency musicality in almost any domestic setting. The VSonics will suit almost any listening environment or program material, particularly favoring well recorded classical, acoustic, rock and vocals!
The new VSonic is a hyper-resolution loudspeaker with extraordinary performance, rivalling designs costing many times more. We will not mention how this speaker casually trounced several well known marques in listening tests; the clarity, layering, imaging, speed and effortless presentation was a revelation for us and will be for you! The VSonics are easy to construct, and their versatility with all genres of music will pleasantly surprise those who in the past have needed a range of speakers to suit diverse musical tastes.
The kit is sold with the completed, tuned crossovers; all fasteners; internal wire; binding posts, some stuffing and all grille material. It is NOT sold with drivers or lumber, and while this may seem odd, recall that shipping drivers and lumber across the pond from Downunder costs almost as much as the drivers!!
The enclosure is simple to contruct, with a detachable top and bottom panel. Cutting, assembly and finish are straightforward, and do not require advanced workworking skills. There are no 45 degree mitre joins! The accessibility of this design has been as carefully formulated as the baffles and crossover; this is truly a speaker for the occasional DIYer with extremely high audiophile standards.
The versatility, resolution, imaging and vitality of these speakers make the VSonics a remarkable DIY speaker of utter practicality. The VSonics are truly an inexpensive, uber quality option for the dedicated audiophile.
BUILDING THE VSONICS:
The kitset comprises:
Two FULLY ASSEMBLED AND TESTED, tuned, premium quality, pcb-based crossovers; a quantity of polyester stuffing and grille fabric; all fasteners and accessories (such as terminal posts); suitable interconnecting wire; grille fabric and a complete set of instructions, with comprehensive diagrams, photographs, directions and labor saving hints.
WHAT YOU HAVE TO SUPPLY:
YOU WILL NEED:
Drivers can be purchased from quality hifi stores or mail order houses like Madisound and Zalytron in the US and Vantage Consulting or WES Components in Australia. The enclosure material can be purchased and cut to size at any good lumber/timber dealer. This depends to an extent on the cabinet material you choose, with availability of veneered MDF somewhat uncertain.
Tools and facilities: