Voxativ Ampeggio loudspeaker Letters

Letters

Voxativ Ampeggio Impedance Peaks #1
Editor: Horn loudspeakers was my main subject as B.Sc.E.E. in 1980. . . Ideally a sound should travel from the diaphragm through a horn and into the air without any sound reflected, and traveling back to the diaphragm. A sudden change in the horn shape will cause a sudden change in acoustic impedance, and sound will travel back to the diaphragm. The end of the horn wall, at the mouth, does make such a sudden change. But if the mouth is large compared to the wavelength, the acoustic impedance has almost changed to that of free air, and the reflected sound is small.

This is similar to reflections in HF cables caused by impedance mismatch. . . The Voxativ Ampeggio mouth is small compared to a 70Hz wavelength, so there is a big change in acoustic impedance from the mouth into free air. Secondly the horn is made of conical sections and bendt, so the traveling sound meets many smaller sudden impedance changes. All this causes sound to travel back to the woofer cone and this is measured in the electrical impedance.—Ole Lund Christensen, olelundchristensen@yahoo.dk

Voxativ Ampeggio Impedance Peaks #2
Editor: In the August 2011 issue of Stereophile, JA measured the impedance of the Voxativ Ampeggio loudspeaker and noted impedance peaks at about 80, 140 and 190Hz, which he stated are "unexplained." (The peak around 27Hz is presumably the driver resonance peak.) There are also measured peaks in the acoustic responses at either the woofer or horn mouth near those frequencies.

I found a schematic cross-section picture of the Ampeggio cabinet on the 6 Moons website, and measuring the length of the three straight sections of the folded horn gives approximate distances of 18", 24" and 40". If we assume these sections behave like quarter-wave pipes (, like organ pipes), this gives resonant frequencies of 190Hz, 140Hz, and 85Hz, respectively, which is close to the resonant peaks measured, so I strongly suspect that that is the mechanism involved.

As a completely unrelated comment, I have played a couple Schimmel pianos in stores and they are very fine sounding and playing instruments.—James Lin, jlin712@earthlink.net

COMPANY INFO
Voxativ GmbH
US distributor: Audio Arts, Inc.
1 Astor Place, Suite 11(h)
New York, NY 10003
(212) 260-2939
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COMMENTS
jeffreyfranz's picture

Oh, boy, another $30K speaker, what a bargain.  I love Art Dudley, but this kind of thing I do not need. It is what is wrong with audio today, and what has turned what used to be a hobby into a garish exercise in conspicuous consumption. I'm sorry to be a crab, and my comment will undoubtedly bring some cleverly snide response, but I still remember having a great time with my Dynakit Mk. III tube amps, for which I paid around $120 each, even in the 1980s. I thought audio was a lot more fun back then.  

nunhgrader's picture

On the other hand, I love to read about high end - high art pieces that I will never be able to afford - lol! Fun stuff - if I only read about things I could afford how boring would I be?

 

I do understand jeffreyfranz's points but, this review should do nothing to change the way you enjoy the hobby. There are plenty of entry points for all budgets.

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