Rauna Balder loudspeaker
The Swedish Rauna company, which has been in existence for about five yearstheir little Mk.II Tyr two-way impressed J. Gordon Holt a couple of years back in Vol.9 No.2appears to be dedicated to the use of concrete as an enclosure material. One of the problems with conventional wooden cabinets is that the walls flex and vibrate, adding a spurious and often time-delayed output at some frequencies. It has even been reported that in extreme cases, the contribution of the cabinet to the overall sound at some frequencies approaches that from the drive-units. In theory, concrete should give a rigid construction with any panel resonant frequencies moved up above the critical midrange.
When combined with a suitable binder, as with the Rauna models, the concrete should also provide a relatively high degree of self-damping, reducing the amplitude of any such resonances that do exist. Its high mass will also prove useful in providing the drive-units with a more stable platform against which to work. Again, however, I must emphasize that there is a large difference between theory and practice in loudspeaker design; discussion of the putative benefits of Rauna’s preferred enclosure material will have to wait until the auditioning.
The Balder $1500/pair, named after a Scandinavian god, is a development from Rauna’s earlier Nord model. Standing some three feet high, its enclosure, sculpted for good acoustic reasons, looks like nothing so much as some kind of ship’s ventilator, particularly as the review samples were finished in a light gray gloss paint. Usually, when form closely follows function, the result can be aesthetically pleasing. However, not one visitor to my home felt the Balders to be anything other than ugly. Chacun à son gout!, I say. The sound is what matters.
The Balder follows the now-familiar philosophy, first seen in Bob Stuart’s elegant Meridian M2 of 1980, where two woofer/midrange units are vertically positioned either side of the tweeter. This close acoustic spacing results in an easily controlled symmetrical lobing pattern in the vertical plane, simplifying the design of the crossover. The Balder follows the idea of maximizing dispersion by taking advantage of the use of a cast enclosure to limit the baffle area to just that required to mount the drive-units.
The concrete falls back all around the drivers so that there will be an absence of deleterious diffraction effects, resulting in the Balder’s unusual figure-eight appearance. Bass loading is via a 3.5″ hole in the enclosure’s rear. At first I took this to be a reflex port, but a vertical internal panel splits the fiber-filled enclosure fore and aft, indicating some manner of transmission-line loading.
The drive-units themselves are all sourced from the Norwegian SEAS company. The two 6″ woofers are fitted with polypropylene cones and inverted-roll surrounds, while the tweeter is a version of the 1″ aluminum-dome unit used by Siefert in their Magnum III and Maxim IIIH models, and by Monitor Audio in their R652MD (but not their R852MD and R952MD models, which use an aluminum-dome tweeter manufactured by Elac in England).
A big difference with the Rauna tweeter is that it is front-loaded by a rectangular-flare horn, with mouth dimensions of 4.5″ by 3″. Presumably this is to increase its sensitivity to match that of the twin woofers, a more useful solution than to reduce the drive to the woofers to match the tweeter. (Because of their higher moving mass, metal-dome tweeters in general have a lower sensitivity than their fabric-dome cousins, and tweeter sensitivity always appears to be the limiting factor in system design.) The horn also brings the tweeter into time-alignment with the woofers. A black wire-mesh grille covers the area of the three drive-units.
The crossover, situated in the Balder’s 1.5″-high wooden plinth, appears to be complex, using five air-cored inductors, six plastic-film (MKT mylar) capacitors, and four resistors. Electrical connection is via a pair of 4mm sockets on the rear of the plinth.
After an overnight break-in period with pink noise, as recommended by the importer (footnote 1), I set to listening to the Balders, placed about four feet from the rear wall (they, not I) and toed-in to the listening position. Even at its lowest height, my listening chair placed my ears level with the upper woofer. Serendipitously, this axis seemed to work well, although the lower treble became a little more forward than on the tweeter axis and the extreme HF was a little more depressed. Even though the front baffle is tilted back slightly, as the tweeter is just 28″ off the ground, this is an unrealistically low listening height.
Tonally, the Balder seemed relatively uncolored through the midband, with perhaps just a slightly hollow character in the lower midrange. String tone was excellent. The Dvorak String Serenade on the HFN/RR Test CD, for example, which has a slight tendency to astringency, was smooth but without a concomitant loss of detail. The enclosure seemed about as dead as it would be possible to get: my usual quick check of pushing an ear up to the various panels and playing pink noise, which is very revealing of the honks, bonks, and booms of wooden cabinets, left me none the wiser but with a cold ear! I did get a hint of an upper-bass problem, perhaps associated with the enclosed air volume, but it was hard to get any kind of handle on its exact nature with the noise signal.
The lower treble seemed a little forward, adding more wires to the sound of snare drum; conversely, the top octave was depressed, taking away some of the sizzle of hi-hat cymbals and giving the sound a somewhat shut-in character. This was not unmusicalafter all, how many records are there with a tilted-up HF?but did lead to a lack of treble transparency. That slight forwardness apart, the high frequencies were commendably free from spit, sizzle, and the other common ailments afflicting more conventional tweeters.
Low-frequency quality was not up to the standard set elsewhere in the range. Apart from the slight confusion in the upper bass/lower midrange mentioned above (confirmed on music tracks, particularly symphonic works with dense textures in this region such as the late ’70s Boult/LPO recording of Elgar’s Symphony 2, now on CD: EMI CDC 7 47205 2), the whole bass region seemed a little detached from the rest of the sound. The body of the tone of such instruments as double-bass seemed to lag the leading edges a little. This was not a serious problem, but was noticeable in comparison with the Celestion SL600 and Monitor Audio R952, my small-box references for tight LF behavior. Bass extension was good, though piano left hand and low E on the bass guitar didn’t have quite enough weight. This is still excellent performance for what is basically quite a small enclosure.
Dynamically, the Balders were perhaps a little polite, though rock did come over well: John Hiatt’s already classic Bring the Family was almost as well reproduced as I can remember; the combination of forward lower treble, clean midrange, and slightly over-rich bass (slightly, compared with the Orpheus 808s that I review elsewhere in this issue) gave the music quite a feeling of drive. The drumkit on the HFN/RR CD, too, was lively, and the Balders could be played at very high levels without too much of a feeling of strain.
It was in their ability to throw a well-defined stereo image with appreciable depth, however, that the Balders impressed me the most. Panpotted, multimiked recordings were as effortlessly stripped bare as more natural recordings were allowed to breathe free from the violins-in-the-telephone-booth syndrome. With some speakers, a sense of space is achieved by recessing the upper midrange, which gives an illusory sense of depth. With the Balders, it was the freedom from midrange grunge that allowed the spatial detail to be accurately decoded. The sense of space is real rather than artificial, allowing the diversity of recording techniques to be easily heard, forward balances sounding forward, more distant ones sounding, well, more distant. (An “effects” speaker will impose its own character on every recording, regardless of how the latter was made, reducing the “dynamic range” of differences.)
The Rauna Balder is one of the better affordable dynamic loudspeakers I have auditioned. Well-engineered and -made, it has going for it accurate stereo imaging and superb rendition of recorded depth, an uncolored midrange, and a commendably clean treble completely lacking the all-too-common soft-dome sizzle. Against these positive factors must be set the relatively loose bass definition, the lack of transparency in the upper bass and treble, and the rolled-off top octave. (This characteristic I feel to be associated with the designer’s making sensitivity a high priority, presumably to render the Balder compatible with relatively low-powered amplification. Had he gone for even 3dB lower sensitivity, it would have been possible to get a flatter HF response.)
The idiosyncratic aesthetics must also be mentioned. A speaker to be recommended in Class C of Stereophile‘s Recommended Components, but an audition is mandatory, given the Balder’s particular mix of strengths and shortcomings.
Footnote 1: I found this to be essential. The sound of the Balders straight from the boxes was over-hard in the lower treble. This hardness all but vanished after an overnight warm-up.
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