Duetta a la Gregor – or what I call the “Duetta minimal”
A little less than a year ago, I had the pleasure of hearing Duettas for the first time at Matthias’ place in Darmstadt. After that, I realized that my previous boxes were more nice than good, and that DIY was a real alternative. After jumping in with the SB 15 for the bedroom (very cool sound – but too small for the living room), I really wanted to have/build some Duettas.
Like others before me, the size initially scared me off. But sitting on the famous Lautsprecherbau.de couch, I was eventually convinced that a smaller model wouldn’t really do it. The MiDU was too “bassy” for me, and I liked the SB 240, but not as much as the Duetta.
After some back-and-forth calculations, I eventually finished the assembly plan for the “Duetta Gregor.” The cabinet is in one piece. The bass capacity is 1 liter smaller, and the HMT cabinet is 11 liters smaller than the respective single-piece box. That would still be okay, because you can save on volume in the high-mid-range area with a single-piece cabinet. The exterior dimensions with 22-m MDF are HxWxD: 109.4 x 34.4 x 37.4 cm. That still worked for me.
As you can see from the boxes, there’s not much new on the assembly end. The box is square, practical and functional. The front panel was cut out using a CNC router. I didn’t trust myself to do the piecework with veneers. A professional took care of that, along with the matching base cabinett.
For those of you entering new crafting territory (the way I was…), here are the biggest mistakes I made. Maybe that will help keep someone else from repeating them:
1. Breaking-in time: Before I installed the chassis, I did let it play a little bit, but it took a long time before the Duetta was more or less broken in. That was the first thing – now they’re great, and I couldn’t imagine life without them. So just be patient at first (maybe I also needed to get used to the new clarity…).
2. When applying the oil (I used Osmo hard wax oil and was very happy with it), I put on the first coat with a roller. That wasn’t such a bad idea. But I didn’t clean off enough of the excess oil. Sanding and polishing off the oil residue wasn’t exactly fun.
3. For the second oiling step, I used a cloth. Unfortunately the light was bad and I didn’t apply it evenly enough – so those results weren’t very good either. So I had to sand and polish again.
4. Painting the front was a nightmare. The MDF absolutely needs to be sealed with paint or something similar (not just on the edges). Even clear varnish doesn’t work without a primer, and half a dozen coats didn’t fix the problem. And of course I couldn’t do it in a dust-free environment. Finally, my cabinetmaker did a proper paint job for me, and even he had some problems with it. We were both at the end of our ropes – thank you, Martin!!! :)
5. I attached the front with wooden dowels. The hardware store sold marking spikes that you could use. I only had four spikes, but I wanted to put in six dowels. Using them twice is all right, but it was off by a couple of micrometers. It all worked out, but next time I’ll hold the whole thing in place with a tension belt instead of with weights – then it will be even more solid (or else I’ll just buy two more spikes).
6. I had bought a new soldering iron – it took me a couple of failed attempts to remember that you need to treat the tip with solder first.
I’m not going to say much about the sound. They just sound great to me! Since I don’t have a “normal Duetta” to compare them with, I don’t know whether I lost anything due to the smaller volume in the HMT cabinet. But it definitely doesn’t feel that way.
A couple words of thanks before I finish:
Loudspeakerbuilding.com team, thank you very much for EVERYTHING! The listening session was super! I am infinitely pleased that I came to visit you and then decided on the Duetta! Thank you for your many supportive emails, about everything from the length of the bass channel to the spikes vs. rubber feet debate. :) Your service is one of a kind, and I’ve never experienced anything like it. And I’m sure this won’t be my last project (my home office is already waiting).
Martin, Tom – thank you for the veneering work (and for gluing together the box), and above all for painting the front. The look of the loudspeakers is all thanks to you!
Last but not least, Matthias (DA): Thank you for opening up the world of Duettas to me, and for proving to me that sophisticated loudspeakers and DIY are not mutually exclusive; in fact, they almost require one another.
Thank you to everyone who described their results and experiences here in the forum. It was an enormous help when I was doing my project!
The “only true” Duetta can only be purchased from Intertechnik.