Information supplied by Wouter Luyten
Some information about my speakers:
-MDF 28mm; height: 100cm, width: 28mm, depth: 40cm
-Pritex against all 'walls'; but I will do some tests with filling the rest with wool
-Closed design (60l.)
-T27 6340, B110 SP1003 and B139 6171
-I used exact the same filter from the old Concerto, but changed the coils into air-cored coils (for the B139 coils with 1,4mm wires) and the electrolytes into MKP ones.
The sound is amazing!. The bass is extremely tight and goes really deep!
I still have to do the finishing (veneer, spikes,...), so the design will change.
My father has the original Concertos, and I will change the filter to the same components as I have used. We will also do some tests with closing the reflex-port and the internal damping.
I am very, very satisfied with the result of my speakers. I nearly can't believe that these units are 30-35 yars old! Things have changed, but changes don't always equal improvements... I also have a pair of Cresta 3 (bought them new 4 years ago). I like the sound of these new ones; but nothing compares with the old ones! Maybe the treble of the Cresta's is better: It is not so sweet as the T27, but it lives much more, it is more direct. This also counts. For the mid-range I prefer the B110. This one is slower than the mid of my Cresta, but the B110 sounds so warm...
The only pproblem I have now, is one B139: the voicecoil 'rushes' against the magnet. The membrane is also a little bit diagonal. I have mounted the B139 inverse as originally, but I fear damage of the voice coil.
I also owned a pair of B&W DM2 (with HF1300 and Coles supertweeter). I really liked the sound of these speakers, but I sold them to make space in our cosy appartment. Now, in our new house, I have more space for my hobby!
My brother now owns an RSPM4 from IMF and I don't think he will change this in the near future! My brother bought the speakers for 500 euro! The owner used to sell IMF during the IMF Glory Days, and used them in his studio. So they have never been moved to another place or room. And that can be seen! The speakers (cabinets, fronts, speaker units) are like new. It seems, they have never been used before...
I will send you new pictures when I have changed things (veneering or other