Hello Fellow Audiophiles,
1) The CIAudio Class D amplifier is rated at 400 watts into the speaker load, which has a high impedance of 11-ohms per woofer. However, the amplifier will put out 525 watts into a "normal" load. So, the output power depends on how you want to rate it. At peaks into a 2-ohm load, the amplifier would put out around 800 watts. Although many people do not like the sound of Class D amplifiers, they are listening to midrange and treble artifacts that used to be present in a few of the original Class D amplifier designs. Deep bass and midbass frequencies of this amplifier may be state of the art in sound quality, based on the transient speed and distortion specs. When combined with the custom-built Accuton ceramic/Kevlar woofers, the bass is extremely fast and very detailed, with no trace of "speaker sound." The engineers at Accuton and Channel Islands have been working on this design with me for almost five years, so I believe we got it right. Thankfully, customers and reviewers also agree.
2) The CIAudio Aktive amplifier is not actually a full stage design, but is actually an output stage, designed to be used with another amp taking the place of a normal input gain stage. In simpler terms, the amplifier takes the signal from the main driving amplifier and "boosts" it up to drive the relatively inefficient woofers. This means that the tone quality is derived from the main amplifier, and you do not actually hear the Class D stage since it was designed to be neutral in all respects. The combination of the amplifier, woofers, and cabinet loading are a "system" and was carefully thought out before the prototype was built. We believe the VR-55 Aktive could very well be a new reference in terms of accurate bass, and the icing on the cake is that our customers can adjust the bass volume level to match their room condition and/or listening tastes.
3) Although the custom-built Accuton midrange driver can accept a very high input power and will go down to 54Hz in theory, I did not want to modulate the midrange frequencies by running it direct from the main amplifier. Accordingly, there is a high pass filter on the crossover board that limits the mid drivers response at bass frequencies and increases clarity and power handling by several times. The crossover point and slope on both the leading and trailing edges of the filter are proprietary and I don't want to publicize this information. I can say this: the parts are of the best quality available to avoid any coloration or absorption of low level detail, and the filter set is both simple and complex at the same time. There are only two parts in series with the midrange driver, although there are 18 parts used in the midrange filter set alone. Most of the parts are used as ground shunts to control impedance and phase. The series parts form a very simple and direct circuit, for greatest transparency, but the ground shunts (often called Zobels) are complex and were designed using a computer at JPL using measurements I took in our design studio. Please see Robert Harley's tour of my studio to see some of the three different measurement systems we employ. I can say that Mr. Harley said that I had the largest and best equipped speaker design lab he has seen, and he has visited Wilson, Magico, Rockport, Focal, and quite a few other factories. Since I get to play with some really fantastic measurement gear and have friends at big laboratories that design aerospace equipment, I have been very fortunate to have the opportunity to do nothing but pure Research and Development. Anyone could have designed this speaker if they had my resources and insight, along with enough time and patience to get everything "just right."
Please feel free to ask more questions about this design, as the very comprehensive review being conducted by The Absolute Sound will not be published for another few months. There is a "sneak peak" on the new TAS Buyers Guide published on their website a week ago, however, which indicates that the reviewer, Mr. Greg Weaver, is very impressed.
As always, I am available by telephone, email, or this forum to answer your questions.
Happy Listening,
AVS
