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In the Forum: Audio Discussions
In the Thread: Another topic on vitavox s2
Post Subject: S5/S6Posted by anthony on: 4/24/2025
Apparently there were two type of S2 diaphragms made: aluminium with paper former till serial number 4941 in May 1972 and the direct wound type with polyester surround. Apparently the S5/S6 diaphragms are interchangeable and are also direct wound but feature a a more compliant (thinner) polyester surround. Finding those diaphragms would be difficult but perhaps is a path of experimentation.
Regarding the 15"' woofers, Vitavox did make lower Fs cones for them, at least lower than the AK150, AK151 and K15/40 more commonly seen. I had a pair here but the cones were not in great condition although I did try them in my midbass boxes. Mike did figure out which model they were based on measurements and cone markings but I will have to go back through the email trail to figure it out. See below the open air impedance sweeps of all four used K15/40 drivers I have with their original cones...
Two are obviously not K15/40.
I put the lower Fs pair in one midbass box along with one of the new K15/40 and re-coned the other two K15/40 and put them in the other midbass box with the remaining new K15/40. All the K15/40s now had cones from the same production run. I measured the frequency response of the two different midbass boxes and no surprise the spls were quite different, especially in low bass production. I played with low pass filters quite a bit and listened a lot and in the end, although the lower Fs driver had the delightfully soft and pillowy lower bass production I could not abide by the looseness of its sound and decided to recone them to K15/40. This is not to say that you could not get these lower Fs cones to work well but I could not get them to do what I needed them to do within the constraints of my cabinet dimensions in my room. To get them to work better I think larger boxes are required and given their higher output I could probably get away with using just two of them each side rather than three. Mike did mention that he is able to make these lower Fs cones as the major differences between any of the any 15" variants is voice coil (8r or 15r) and treatment of the surround. Rerurn to Romy the Cat's Site