Audio Physic Padua RR Loudspeaker

Speaker design involves science and a kind of combined craftsmanship and musical judgment that one might call art. Judgment comes from the fact that all speaker designs involve certain compromises. Since a perfect speaker is a physical impossibility, each designer makes choices about the sonic attributes most important to him. In the final analysis, these judgments are about music and the perception of musical sound.

Those familiar with Germany’s Audio Physic know it as a master of science. Its slim, $5750 floorstanding Padua RR is full of crafty design features—anti-diffraction baffles, a special way to reduce the ringing of stiff-cone drivers, and so on. But it also offers abundant evidence of artistic judgment, not only in its elegant appearance but in the refinement of its musical sound. (Padua, by the way, is the location of one of the greatest of all works of art, Giotto’s Scrovegni Chapel frescos. Perhaps the name is a symbol of dedication not only to science but to art as well.)

Audio Physic has a reputation for making speakers with the extraordinary ability to vanish into the soundstage, and the Padua is no exception. At first this quality might seem like some sort of magic trick, but it is based on the company’s hard-edged scientific work. Actually, “hard-edged” may not be the right phrase, because it is in fact the absence of hard edges that make this work.

When sound spreads out along a baffle and hits a sharp edge, it encounters a consequent discontinuity in its acoustic environment. This leads to a secondary emission of sound, as if a tiny ghost driver was radiating sound after the main driver. One can actually see this using a refined time/energy analysis called cepstrum analysis. (Cepstrum is an anagram of spectrum, the rearrangement of the letters indicating a shift in the way an impulse response is exhibited.) Popularized by Acoustic Research many years ago, this analysis was used in the design of the Padua. [1] Because the Padua’s rounded edges are carefully designed to minimize such secondary radiation, the ear is given fewer cues that the sound is coming from a particular shape. Like a point source without secondary emissions, it vanishes into the stereo image without a trace.

This can make for a startling listening experience. Something like a cello/piano duo, Starker and Neriki’s Rachmaninoff Cello Sonata on BMG, for example, can produce an almost uncanny feeling of instruments suspended in space in front of you, disembodied from any sound source other than themselves in the position of their stereo images. The Padua does this as well as any speaker I have had in my home. (This effect is easier to achieve in huge rooms when the distance to the side walls is large, in my case, 18’ x 20’.)

Associated with this lack of secondary radiation is an increased smoothness in the speaker’s top-end response. And indeed, the Padua’s top end is quite smooth. The ring-radiator tweeter (hence the RR designation) is claimed to be non-resonant out to 30k (its -3dB point). There’s a bit of extra energy around 10k, and the performance benefited when I removed it with my Z Systems digital EQ (relieving a slightly untoward banginess in the top registers of the piano, for example). The absence of a rising extreme top end—it actually droops slightly—may seem slightly “airless” compared to the rising- to-a-resonant-peak metal domes, but to me, this is more lifelike.

In the mids, the Padua initially made me nervous—and this was before I heard the speaker. Extremely stiff cones have low harmonic distortion and a certain kind of clarity, but too often make for a certain hardness in the sound. Audio Physic claims to have solved this problem with something called ACD (active cone damping), which the company says is comparable to holding a water goblet’s crystal bowl to eliminate ringing. You cannot drive the Padua’s individual transducers separately without opening up the speaker, so I couldn’t look at the behavior of the mid driver alone in any technical way. But to judge from listening, Audio Physic is onto something with ACD. To my ears, the Padua does not quite equal my reference Harbeth Monitor 40’s lack of midrange character, but it comes close.

The Padua is not tall. It’s just under 40″, and you have to sit quite low or tilt the speaker back to be on the flatresponse axis. Although narrow at 5″, its 15″ depth gives some volume to the cabinet. Two side-mounted, oppositefiring 8″ woofers and a large floor-firing port give it deep bass (-3dB at 40Hz). Moreover, when correctly placed, its inroom bass is very smooth and extended. Audio Physic is good at getting inroom bass to work. (In my room, the company’s Minos subwoofer [reviewed in Issue 137] was almost uncanny.) And the Padua does an excellent job from 200Hz and below. The lowest end of the audible range is missing, but the bottom of the orchestral range is nicely covered and solid-sounding.

Now we come to the one problem I had, though it nearly seems unsporting to mention, occurring as it does in a “room-dependent” part of the frequency range. Stereo Review’s Julian Hirsh used to review speakers from 500Hz on up with only a pro forma comment on how far down the bass extended—with no remarks on the range below 500Hz on the grounds that it was “boundarydependent.” Still, most music lives below 500Hz (which is almost an octave above middle C on the piano), and unless you are exclusively interested in soprano recorder and high female vocals, the sub-500Hz frequencies count.

While the issue isn’t overwhelming, I had a hard time getting the 200–400Hz octaves to fill in. Even on the ideal (low) axis, the Padua sounded a bit on the cool side and somewhat uptilted in response. I am not speaking of any specific brightness, but rather of a certain lack of middle bass and lower midrange warmth. I moved the speakers all over but could never entirely rid this effect. I could get the bass up, say, around 100Hz, by placing the speakers closer to the wall, but I could never get the bass to sound unboomy while simultaneously getting a full mid-bass.

Longtime TAS readers are probably thinking that I just love the warmedup BBC sound and miss it when it’s gone. And while my Harbeths are midbass warm, I often listen to them pulled down to absolutely flat through that region, using the Z Systems or some other EQ, and like them flattened out, perhaps even better than au naturel. Yet in any room position, the Padua remains cooler than the sound of flat in-room mid-bass. Admittedly, this might be a room effect. The Padua’s bass driver configuration is unusual. And because my room is a bit on the warm side in the mid-bass, there may have been some incompatibility of the driver/port configuration with the space. But if I had to guess, I’d say this is an aspect of the speaker itself.

To confirm my listening impressions, I did some comparative measurements of in-room response of the Padua versus the Harbeth and the Spendor SP1/2. In this frequency range, as opposed to higher up, steady state in-room measurements are quite representative of the balance you actually hear. [2] Sure enough, the un-EQed Harbeth was a bit above mid-level in the 200–300Hz range, while the Padua was a couple of dB below. The Spendor was in between, though lacking the deep bass of the other two.

In listening terms, the Padua sounds a bit lacking in mid-bass fullness while having plenty of deeper bass farther down. In other positions, it is flatter in the mid-bass but a bit lacking in lower frequencies. Whether this will bother you depends not only on your room but also on what kind of music you listen to. I found it non-disturbing on vocal material, though with orchestral music it made for a somewhat skewed balance. If you are willing to be TacT-ful or use Z-Systems or the like, this can be easily corrected. And when it is, the Padua really comes into its own. At that point, one starts to wonder why anyone would spend more money on speakers unless they had to fill a palatial room with sound.

What emerges is a composite picture. On one hand, the Padua has undeniably elegant looks and equally undeniably refined, precise, clean, clear, and largely uncolored sound. It is a speaker that exudes care, refinement, and dedication to good design and high-quality manufacturing. It is impossible not to respect and admire its visual and sonic elegance. Whether this respect and admiration turns to love will depend on how you react to its overall balance, which in turn depends on how the speaker interacts with your listening room. If you are a serious potential buyer, you should request a home audition. If the Padua warms up in your room, that audition may turn into one that lasts for years.

[1] Cepstrum may be new to readers, but it is available in various audio measurement programs. My Liberty Audio Suite offers it, and it is interesting to see how various speakers fare under the analysis. For those who want to delve deeper into the Padua’s technical background, this and other measured aspects are illustrated on my Web site, regonaudio.com.

[2] Everybody should buy an SPL meter. They are cheap, and work quite well in the lower frequencies—although I actually used the computer-based and very accurate Liberty Audio Suite, which is not so cheap!