SB home theater by Klemens
It all started when my wife expressed a desire for “surround sound” while we were watching a movie. And so it began: days and nights of reading forum posts and reports. The effect of my internet research is probably already familiar to most readers here: the more you read, the more you realize that you need to read even more. First let me describe the path from gathering knowledge to ordering the do-it-yourself components. As a starting point, I had a stereo set purchased in my youth (about 20 years ago), consisting of an Acoustic Research integrated amplifier, Goodmans shelf boxes and a Harman Kardon CD player. The price for the set from Schilling at the time: 15,000.00,-.
It goes without saying that the stereo amplifier wasn’t designed for 5.1. But surely I could keep using the same boxes? Well, sure, but Goodmans hasn’t been around for years, and it would probably be hard to find other loudspeakers that go well with their sound. Inspired by the internet community and the test reports, the Wharfedale and Dali speakers made it into my final round of decision-making. Fortunately I happened to stumble across a retailer in Linz who sells (and demos) both brands. After the first listening session with shelf loudspeakers, the Dali Zensor series was judged to be good. Unfortunately the pedestal loudspeakers weren’t in stock, so I decided to wait until the retailer had them back in the store.
Unfortunately for the retailer, I ran across the creations at Loudspeakerbuilding.com in the meantime, and it was quickly clear that it needed to be a DIY project, especially because the necessary resources were available in my father’s workshop. The site’s support features are first-class – most of you already know that, but it’s still important to mention. After a couple of emails, I decided on the SB36, SB30 Center with SB-26-STC and SB15PC.
The next step was planning the box shape. The original shape of the SB36 wouldn’t work because the conditions in the room called for a front box about 70 cm tall. In order to keep the front of the BS36 from getting too bulky, I decided to use round sides. Given that it was my first DIY attempt, I had no idea how much extra work that would involve. Udo approved my sketch was approved, and the shape of the AB36 was decided. With an interior floor area of 598cm², that meant about 63cm interior height (with consideration for the inside reinforcements). The SB15PC and the SB30 Center were allowed to keep their original shapes for the time being.
Now we come to the assembly phase. I had the wood cut to size in my local hardware store, using 19-mm MDF. To my surprise, the cutting was free of charge. I won’t go into any more detail about the assembly of the rear boxes (SB15PC) – a few pictures can speak for themselves.
Building the center speaker was just as unspectacular, with two exceptions. I discovered that my original plan did not pass a visual quality check, and it needed to be integrated into the shelf. In addition, the beech veneer I had been given was so stubborn that it inevitably ended up with cracks along the edges. I fixed these quirks with a beech putty mixture, so they are barely noticeable in the finished product. Looking back, I can say that these cracks could have been avoided with a little more practice, even using the beech veneer...
Compared to the other boxes, building the Custom SB36 was a completely different caliber. First I transferred the interior floor area and cut it out roughly with the band saw. Then I held together all of the lid, floor and frame panels with C-clamps. Thanks to the belt sander, they ended up with identical shapes in just a few minutes.
I cut out the holes for the chassis using a router template I had bought on eBay. This additional tool really makes it very easy, but it is time-consuming. It probably took me several hours to finish the eight holes for the front panels. In order to keep the skeleton at the right angle while I was gluing it with joint glue, I gave the lid an additional frame. The projecting MDF on the front and back sides was trimmed using an electric hand-held planer. You need to know that the planer can easily rip out pieces of wood at the end of the stretch. It’s not so bad for surfaces that will be veneered or painted later, since those patches can still be puttied over.
For the round sides, I chose a combination of 3-mm HF boards and 19-mm flexible MDF. I made the flexible MDF boards myself on the circular saw, by making deep cuts (1.5 cm) in the boards about 1.2 cm apart. First the 3-mm HF board was shaped. Even for these relatively thin boards, the small radius of about 33 cm required a massive amount of force. During this step, it is good if you have four hands to help out. After a curing time of at least a day, the sealed cabinets were made one step at a time. I spread a generous amount of joint glue along all of the inside edges just to be on the safe side. For the flexible MDF, the “bending ridges” were filled with a mixture of polished meal and glue. In my opinion, the advantage of this method is that the glue doesn’t run right back out, so you can keep your glue consumption in check. I still needed more than 2 kg of glue for both boxes. The bending involved more brute force. In addition, the very slippery side panels were held in place using Spax. Once it had hardened, I took out the screws and puttied over the holest.
Since the floor and lid surfaces were hard to sand because of the glue that had oozed out, and I wanted to avoid more puttying, I decided to glue 3-mm HF boards over them. That was a very good decision, as it turned out. The HDF boards were cut out roughly with the band saw, and then cut flush using the router once they were glued on. Oh yes, and the often-used magnets for attaching the stretcher were also countersunk into the front.
I got the satin walnut veneer from a local dealer, the Keplinger company in Traun. This wholesaler also has a real stone veneer in stock that looks amazing. But since I’m sure it is very tricky to work with, I didn’t dare use it for my maiden project – especially because it’s many times more expensive than my not-especially-cheap wood veneer.
In order to achieve a beautiful “butterfly look,” I had to join the veneer. First, I very carefully gave the sheets nice even edges with the cutter. It works well along the grain as long as you apply gentle pressure and go over each veneer sheet at least three times. Then I clamped the two matching sheets between two 45° 19-mm wood planks and sanded the edges until they were even. That way you can have the two sheets overlap slightly. I assembled them using veneer adhesive tape that I bought at the veneer store. IMO it’s really important to reinforce the veneer with painter’s tape on the front before you iron it on, to keep it from tearing off like it did on the center. The ironing itself has been described several times already, and after the how-to in the workshop exercise, it works perfectly with a little practice. I did replace the method with the triangular file, using #120 sandpaper stretched over a 90° angle. Then I sanded it using #120, 240 and 320 paper, and sealed it with three coats of clear Clou hard wax oil. Before the last coat, I sanded it again with #400 paper. That gave me a matte shiny surface.
Let me mention something else that could probably only happen to me: a #17 chassis disappeared during the four-month assembly process, and it never turned up again. “Fortunately,” you can always order another one… ;-) Oh well, maybe someday I’ll want to build the SB18, too.
Finally, the installation of the crossover, which was mounted to the rear wall with hot glue, the insulation, the chassis, the terminal and the BR tube – that was the fun part.
About the sound:
Except for my old Goodmans boxes, I don’t have any grounds for comparison in my own four walls; but what comes out of the SB pieces speaks for itself. In home-theater surround mode, the sound is amazing, assuming you have the right source. You can hear details that you’ve never noticed before. Voices come across very well, and they can be heard clearly even when there are loud background noises. Still, I don’t think you really “need” the Blues Class for a home theater.
For stereo mode, let me first say something about the SB15PC. I had been using it for about two months before it was replaced by the SB36 speakers. The little guys are fantastic! I would never have thought that so much sound could come out of such a small “PC box.” When I replaced them with the SB36 units, I have to admit I was a little disappointed by the SB36 – but there were two reasons for that: First, my expectations were too high; and second, the chassis needed to be broken in. In defense of the SB36: Why should it sound that much better than the little SB15PC? Aside from the bass range, it can’t and shouldn’t really sound much different. Now that the chassis has been broken in after a month and a half, with many hours of playing, I am very happy: the sound is great in every musical genre I own, whether the system is converting Massive Attack, Manowar, Metallica, Reinhard Mey or Maria Callas into sound waves.
Summary: The DIY community has a new member. I’m already thinking about which boxes will come next. But first I need to build a decent stereo amp. ;-)
Thanks to Loudspeakerbuilding for presenting the various projects and for the support; thanks to the model builders, and to my family for doing without me for so long...
You can order the assembling kits at SB 36 at Intertechnik:
The complete assembling kits include all loudspeaker drivers, capacitors, inductors, resistors, Sonofil damping, cable, terminal, cross over plan and screws for one box. The wood for the cabinet is not included.