Jamo Reference R 907 loudspeaker Page 2

3) The effects of a dipole's rear radiation on the speaker's frequency response and the size of its soundstage are at the mercy of room dimensions, room surface treatments, and speaker positions. This is the responsibility of the user, and accounts for the poor showing of the R 907s in that Manhattan hotel room. Normal listening rooms such as mine will be much more hospitable. It should be noted, though, that the R 907's tweeter has a sophisticated rear enclosure; only the woofer and midrange function as dipole drive-units.

Now that I've got the two of you alone . . .
The Reference R 907 looks snazzy and svelte, but with much of its mass in its cast-iron base it's surprisingly bottom-heavy, and hard to embrace and maneuver. After coaxing the pair of them into my listening room, I hooked them up to two channels of the five-channel Classé CA-3200 power amplifier with AudioQuest biwire cables and began fine-tuning their placement and orientation. Although I reversed Jamo's recommendations to site each R 907 3' from the front wall and 4' from the sidewall, I found their suggestion of a 10° toe-in angle ideal. This resulted in the two speakers' on-axis radiations crossing just in front of my listening position, as suggested by Blumlein, and which I usually prefer to having the axes cross behind me. Jamo also advises using soft, damped surfaces in the vicinity of the speakers, and that was no problem: I had an Echo Buster on each sidewall, an Echo Buster Phase-4 tower in each front corner, and a wall of acoustically lined drapes across the wall behind the speakers.

All should have been fine. At first, however, the Jamos sounded thin and a bit bright. Partly this was a temporary subjective response, due to their very tight and nonresonant bass, compared to box speakers, but I quickly adapted to that. The real problem was that, in my infinite audiophile wisdom, I had removed the R 907s' front grilles so that I could enjoy them en dishabille. Not a good idea. The front and rear grilles are sturdy, and the open-weave cloth of their outer layer is sonically transparent. However, the inner lining of the section of grille covering the midrange and tweeter is a very thin but closely woven cloth that greatly affects the transmission of sound. It seems that Jamo has voiced the R 907 with its grilles; if you want to hear this speaker at its best, I urge you to leave the front grille on.

Their front grilles back in place, the R 907s had an extremely transparent and open sound from top to bottom. The midbass was notable for its lack of boom or excess bloom, which is to be expected from a properly placed dipole. What surprised me, however, was the low-end extension, which, while not equal to that of a good subwoofer, qualified the R 907 as a true full-range speaker. When I played Pipes Rhode Island (CD, Riago 101), the weight and growl of the organ-pedal tones were not only impressively reproduced, but sounded tight and tonally well defined all the way down. Adding a JL Audio Fathom f113 subwoofer below 50Hz made a difference that I could feel more than hear, but I used the sub only for this recording. For normal listening, the R 907s needed no help.

The R 907's midrange and treble were equally clean and open. With some recordings, such as of live opera or concerts where the microphones had not been optimally placed, they brought the soloists a bit forward. On the other hand, the lovely balance between Jennifer Warnes and the backing singers on "A Singer Must Die," from her Famous Blue Raincoat (CD, Cypress) was slightly askew; Warnes's voice was somewhat detached from the warm, supporting chorus. A swap of power amplifiers from the Classé CA-3200 to the Bel Canto REF1000 monoblocks (with the obligatory Environmental Potentials EP-2450 line filter) restored the balance. The Bel Cantos aren't as forward in the midrange and treble as the Classé, therefore were a perfect complement to the Jamos, and remained in service from then on.

In order to appreciate the Jamos' spatial presentation, I needed to sit with my ears at the level of the R 907s' tweeters, which are 43" from the floor—much above that and I lost too much treble. (No, I didn't sprawl on the floor to hear if the treble's vertical radiation was symmetrical.) I also needed to stay carefully centered between the speakers to remain inside their rather small sweet spot—wider than I remember having with the Staxes, but narrower than with the Apogees or, for that matter, the B&W 802Ds. But sitting still isn't too much to ask of anyone listening seriously and paying attention to the music, is it?

With me and the Jamos properly positioned, aural images were deep and detailed. There was great specificity of voice and instrument placement, and ensembles seemed simultaneously coherent and continuous—very lovely, especially for recordings of soloists and smaller ensembles. With larger groups, the clarity and depth were excellent, but the soundstage width was mostly confined to the space between the R 907s. Remember that, with dipoles, the breadth of the soundstage is more than usually dependent on the surrounding surfaces. Because I'd already been able to meet Jamo's setup guidelines in my room, I didn't experiment much with repositioning the acoustic devices; perhaps a slightly more reflective environment would have helped. Even turning up the volume to high levels made for little change in soundstaging, though it did demonstrate that the R 907 is capable of sustained high-level output, especially with the Bel Canto REF1000s (1000W into the Jamo's 4 ohm load).

This surprised me. My experience with dipoles has suggested that the multiple reflections of the sound radiated behind the speakers help widen the soundstage, sometimes to an exaggerated degree. However, as noted above, the R 907's tweeter is not a dipole radiator, and therefore doesn't contribute to the rear radiation. In addition, the R 907's very wide but curved front baffle might also have been affecting the dome tweeter's radiation pattern. Considering that the midrange crosses over to the tweeter at around 2500Hz, the rolled-off rear radiation probably makes less of a contribution to "audiophile airiness" than with some other dipoles. Though such added spaciousness is likely a spurious addition, most of us find it satisfying and enjoyable.

Conclusions
I'm wondering if I've made too much of the Jamo Reference R 907's imperfections. Taken together, all of them were not enough to seriously detract from the glories and pleasures of listening to all types of music through these loudspeakers. I found the Jamos second to none in their sonic purity from the top of the audioband to a surprisingly deep bottom. The total elimination of box resonances was enduringly refreshing, and the imaging was beautifully precise within a deep soundstage. Of a modest size and with a striking appearance, the Jamo R 907 provides state-of-the-art performance at a competitive price.

COMPANY INFO
Jamo USA
3502 Woodview Trace
Indianapolis, IN 46268
(877) 456-5266
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