Ever since I caught the bug with two Mystery Subs built as part of a Mystery Party for my office, this website has had me completely under its spell. After four years of fun with the Mystery, I sold it – which meant it was time to update the speakers in my living room, by now a bit long in the tooth. The old boxes, of British origin, feature 2-way technology and a wobbly bass. They had done their job for 30 years, and now it was time to migrate them to the home office. After a few emails and a quick phone exchange with Intertechnik in which we explored my musical preferences, the obvious choice for a new project was the SB18.
The future home of the boxes required a pedestal box instead of a shelf box, so I converted the original form of the SB18 to a pedestal box with the required 18.5 liters and created a drawing with SketchUp. However, the originally planned 19-mm MDF, with a planned height of 94 cm (so that the tweeter is in the right position for the listener’s ears), made the fronts too narrow for the 17-cm basses. So it was back to the drawing board, recalculating everything with 22-mm MDF and a width of 20 x 20 cm. To get a volume of 18.5 liters, the cabinet needed an intermediate floor measuring 15.6 x 15.6 cm at a height of 78.30 cm. In addition, the chassis elements were to be protected by a frame covered with acoustic fabric.
I’ve provided the SketchUp plan here as a zip-file.
The midpoint of the holes to be cut out
Front measured from the top:
for the tweeter: 6.50 cm
for the bass: 23.00 cm
measured from the bottom:
for the reflex tube: 20.00 cm
for the terminal: 30,00 cm
I took these specifications to my friend René, a professional cabinetmaker. He cut the MDF to size, including the cutouts for the chassis and the frames for the covers. The assembly also took place in his shop.
I had actually planned to paint the boxes silver. But after we talked about how absorbent the untreated cut edges of the MDF were, René disappeared into his warehouse and came back with a brushed-silver formica board.
It was quickly cut to size on the panel saw with an overlap of one centimeter, glued onto each side with Pattex glue and then pressed until dry. After 4 hours, it was cut flush with the cabinet using the stationary router. The area around the chassis was left open and painted matte black, which harmonized very well with the planned frame. That way the appearance doesn’t change when you take it off. In addition, it makes the box look like it’s standing on a pedestal.
I made the covers right at the end. Even though they had already been painted with clear varnish, I had to apply three coats of matte black before the edges met my standards.
On the back, you can clearly see why I planned the front panel with a width of 20 cm – the outer dimensions of the chassis are fairly close to the edges of the box. In order to prevent undesirable contact between the covering and the membranes, I had the area countersunk 3 mm deeper. The 45-degree edges make the 12-mm thick edges seem even narrower. I attached the material with double-sided auto-body adhesive tape. Despite the strong adhesion, it still allows for later corrections without damaging the material.
The material is simply cut flush with the edges; gently lift up the corners and press them down at a 45-degree angle with minimal overlap. Then you just hammer in the frame pegs with a bolt.
As with the assembly for the Mystery, I mounted the electronic components on a circuit board and connected them with bridge wire. The spacers were originally dowels; I just cut them off and attached them to the circuit boards with hot glue.
Because there have already been extensive reports on the sound of the SB 18 here in the forum, I couldn’t resist – as soon as the first box was finished, I hooked it up to my Onkyo TX-7730 in the office right away and had a listening session until 4 in the morning. My first impression: amazing! In the Doors’ “Soulkitchen,” a snare drum turned up that I had never heard before on my old office boxes.
After finishing the second box, we moved to the living room the following weekend for the final sound test, with various musical genres. I should mention that the boxes are in the middle of the room, with a listening distance of about 3.5 meters and 5 meters between them. My big Onkyo and the good old Dual 731 Q turntable were happy to welcome their new companion. With Bach’s “Toccata and Fugue in D Minor,” a huge pipe organ suddenly appeared before me, the likes of which I had never seen at home before. The missing wall behind the boxes was not a problem; on the contrary, the SB18s used the space to create a generous stage for the instrument and the eyes. Clear high notes and pure listening pleasure down to the basses, with a natural echo like in the Passau church. Then Dire Straits took the stage – the drummer’s sticks moved all the way across the room, and every note on the steel guitar came out clearly. “Jailhouse Rock” by the Blues Brothers sounded anything but locked up by the record player. Cassandra Steen’s “Eis” sounded very warm from the little silver disc. I’ll spare you a list of all the other artists who performed for several hours after that, with just a quick summary. Snoop Dogg’s “Sweat” makes you sweat just from constantly tapping your feet – it’s a great sound with a huge stage, whether you’re listening to vocals, instrumental, classical, pop or rock from the SB18 pedestal box. I just can’t get enough of it! It’s simply great, balanced with brilliant high notes, an excellent mid-range and an unexpectedly large but not overbearing bass despite the 17-cm membrane.
Hats off to the SB Acoustic technicians and of course to the team at Loudspeakerbuilding.com for their great coordination of the volume, chassis and crossover as well as for their consistent help.
If you want to build the SB 18 by yourself you can order the complete assembling kit here.