The drive for many innovations is the dissatisfaction with the circumstances where one's work can no longer be found. This is often caused the acquisition of a company by another that resulted in a changed objective. Our Danish neighbours experienced this in the recent past. Their traditional speaker industry was taken over by an American company and put on a whole new foundation. Product lines disappeared, modern technology was replaced by more modern one, and new markets were catered for. This was certainly not a mistake but not every employee wanted to, was able to or was allowed to follow this way and therefore no longer felt that they were in the right place. As a result they founded with their "old" loudspeaker knowledge new companies that transferred this knowledge into new brands. In this way, among others, the company Scandinavian Audio Resources (ScAR) was founded. Its founder Lars Goller and Ulrik Schmidt, who joined as early as 2006, were at Scanspeak responsible for the Revelator series and the ring radiator. In the meantime ScAR blossomed into an illustrious collection of former DST staff. They brought along their development art in the area of stainless chassis production. In 2008 this art was presented at the High End under the name SB Acoustics. The chassis are produced in Indonesia at Sinar Baja Electric, a company with more than 25 years experience in the construction of acoustic transducers. This allows the Danes the freedom to not having to compromise on sound quality in favour of price.
The two chassis we use in the first box with SB acoustics equipment are no longer new to our readers. They have already been introduced in detail in the individual test published in the September 08 issue, For the sake of completeness, however, we would like to highlight again a few characteristics.
First there is the SB17NRXC35-8, the basis for the new speakers. Its powder coated die-cast basket with the narrow double webs and the distinctly raised edge was specifically designed to optimise the flow of air behind the membrane and to minimise the impact of resonances on the magnet system. Therefore we see below the raised, flat centreing huge openings that allow the unobstructed view of the voice coil coiled to a height of 16mm. This, together with a 5 mm-high pole plate, results in a linear lifting capacity of 11 mm. The carrier of fiberglass measures taking into consideration the chasssis size a remarkable 35.5 mm in diameter. In the centre there is the drilled out pole core that has received a copper short circuit ring to keep the THD low. The rubber surround feels very soft. It improves the midrange reproduction due to low damping. The membrane in Nawi shape is very light, but extremely deformation resistant as it is made of cardboard reinforced with papyrus fibers. Not only Lars Goller regards this as the ideal membrane material. Wood fibres and paper are relative to their weight the strongest materials, he said in an interview with Image Hi-Fi, but they are also not free of discolourations. These can be labelled as "tone colour" and the wooden one is very much liked by ear and brain.
We partnered it with the tweeter SB26STC-C4. Its equally complicated name goes well with the name of the BMT. Its diaphragm made of soaked fabric is held by a wide, flat bead of the same material inside the matt gleaming plastic front panel. It looks out a few millimeters above the rounded recess that is used to guide the sound and to boost the level. Furthermore the front is slightly flattened towards the edge. With its geometry the technicians could positively influence the omnidirectional character outside the axis. The 1.2 mm voice coil was coiled onto an unperforated aluminium support and connected with thick stranded wires to the soldering lugs.
The drive train of the tweeter is very special. Not just the arrangement of magnetic ring and pole plates has to be highlighted, on the contrary it is the little things that reveal the thoughts of the designers. Thus the pole core has been pierced and sealed at the rear with a plastic chamber to lower the resonant frequency. A "dome" was put onto the opening to reduce reflexions from this chamber. The pole core has not only been coated with copper to improve the appearance of the tweeter. Ferrofluid in the air gap was not needed by the ScAR engineers. They did not think commercially here.
Measurements as Zip-file
|Membrane:||paper, impregnated||air gap height:||5 mm|
|Surround:||rubber||linear excursion:||11 mm|
|Basket:||Druckguss||magnet diameter:||100 mm|
|Pole piece hole:||ja||mounting holes:||4|
|Centering:||raised flatspider, hochgelegt||outer diameter:||171 mm|
|Shielding:||no||installation opening:||144 mm|
|Voice coil:||35,5 mm||milling depth:||6,5 mm|
|Voice coil former:||Fiberglas||installation depth:||81,5 mm|
|Voice coil:||25,4 mm||Pole piece hole:||yes|
|Winding height:||1,3 mm||Ferrofluid||no|
|Pole plate thickness:||2,5 mm||Mounting holes:||4|
|Linearer excursion:||1,2 mm||Outer diameter:||101 mm|
|Membrane surface area:||6,2 mm²||Installation opening:||70 mm|
|Moving mass:||0,3 Gramm||Installation depth:||40|
|Magnet:||Ferrit||Milling depth:||3 mm|
|Qts||0,79||SPL 2,83V/ 1m||91||dB|
According to LspCAD a bass with 15 litres would have sufficed, but I like settings that make the lowest notes even deeper, but in return faintly audible. There are at least two methods to achieve this. Either the reflex tube can be extended or the housing can be built bigger. I chose both types and increased the volume to 18.5 litres at a setting of just 38 Hz. To do this I needed a reflex channel with a 19 cm² aperture area and 16.1 cm in length. As a building material I chose a 21mm thick multiplex that adequately represented the value of the speaker and treated it with two applications of PU clear varnish. A small shadow gap along the cutting edges took care of the optics, two bags of Sonofil for the inner filling with midrange absorbers. The chassis were sunk concisely into the baffle using a router. Since the construction of the speakers requires no manual tricks, I have done without a pictorial documentation..
Drawing SB 18 as Sketchup-file
A few small tricks were necessary in the development of the crossover, because chassis with an extended frequency response don’t like simple filters. Two problem areas had to be treated in the BMT to avoid any disturbances for the ear. The first one were the resonance spikes between 4 and 7 kHz, as a 3rd order filter robs them of any strength. The second one is seen as a long elongated hump between 300 and 3000 Hz. The correct dimensioning of the components here was crucial for the smoothing.
A nice template was available directly from the manufacturer for the high frequency crossover. It was also set up as an 18dB filter. Level and phase adjustment were done simultaneously by two resistors, one before and one after the network. I did not have to tinker a lot. I had doubled the first capacitor and already found a perfect transition between bass and tweeter shown as a clean addition in the circuit diagram. It was also appealing to linearise the impedance curve in the mid range. An adsorption circuit parallel to the terminal immediately achieved this immediately.
Inside the listening room, I put the SB 18 onto the my multiplex stand known to the reader from many photos and connected it to my system. Once again I used the SAC pre-amplifier/power amplifier combo. Did bot get fed up with the tube but one should beware of too much bias. Mindful of the words of Lars Goller in image HiFi the speakers were not angled towards the listening position, but put up freestanding parallel to the walls. This is in general my preferred set up unless a strongly focussing chassis restricts the sweet spot to head size.
Well, the first few notes did not exactly inspire me, there was hardly any bass, the voices were glued to the speakers and the stage was only wide, not deep. But this is normal if one speaker is wired wrongly, it would only be bad if one does not notice this. So I switched two cables and now Sade sang as I knew her. Crisp bass, drums and finely resolved percussion took the distinct voice into the middle. That’s how it should be. I can definitely confirm Goller’s words about the pleasant sound of the cardboard membrane. The department I like to call "quiet, pleasant bar music" was dealt with to full satisfaction by the speaker.
I stayed with small casts and listened to the sounds of piano, contra bass and drums, played by EST. It is unbelievable how much music these three men could make. Effortlessly the SB 18 produced a swinged listening experience, actually it abstained from any conspiciousness. Unfortunately this seems to be the right to exist for many speakers. Finest caressing of the cymbals remained audible in every nuance, even though all three musicians gave their all. The resonance of drums whose skin was tightly stretched over the body, the rasping of the bass strings when the finger releases them or even the creaking when these fingers struck the wood was rendered by the speakers as live giving a feeling as if you would sit in the front row close to the instruments. The bass played powerfully and with outline, acoustically transparent and clear and above all deep. Not something really expected from a 17. Mahler's first Symphony, structured in three dimensions, earned the name "Big orchestra" not only when the timpani was struck powerfully. Mozart's violin concert No 5 was also a delight. The ear could almost see the movements of the solo violinist. Subsequently good, old rock was played in form of a live concert by the Doors. My test candidates did not expereince an inappropriate culture shock, instead they quickly caused the old bones of the solitary listener to be young again. Now I will treat myself to the seven minutes of "Soul kitchen" without saying a word. The sound description is done and dusted. Now the quick conclusion: SB acoustics produces chassis for the blues class, there can be no greater compliment.
|SB 17 NRXC 35-8|
|SB 26 STC-C4|
|Wood list in 21mm MDF:|
|Construction||Udo Wohlgemuth||39,2 x 31,2 (2x) sides|
|19,0 x 31,2 (2x) lid/ floor|
|Principle||Bassrelex||19,0 x 35,0 (1x) back wall|
|Nominal impedance||8 Ohm||19,0 x 34,0 (1x) back|
|Damping:||2 bags Sonofil||19,0 x 14,0 (1x) reflex board|
|Approx. cost per box:|
|Kit without wood||165 EUR/USD||Wood cutting: 40 EUR/USD|
This loudspeaker kit is available from Intertechnik
Expandability and upgrade of the SB 18 kit: