The different projects


I read about the Wharfedale SFB long time ago but thought it was an outdated design. Then I read Troels Gravesens new interpretation of the design and got intrigued. I have heard rely large open baffle speakers sounding good (Audiotronic Megatrend with each speaker having 18 KEFB200 8" drivers and a baffle area close to 2 m2) I have a scruffy packing crate plywood sheet 1200x1600x12mm. I have eight Seas alnico 10" woofers with a Qt of 0.7 and Fr of 34 Hz. And several other Seas vintage drivers. To that I bought 12 meters of wood with the cross section 120x21mm to the cost of about 15 dollar.

I cut the board in half and cut holes for the drivers, then I added a 120 mm deep frame around the perimeter of the boards as well as some extra braces with leftovers.

I screwed the driver in place with 104 screws!
Added a crossover consisting of electrolytic capacitors from West-Germany.
So 4 Seas 25TV-EW per side then 1 Seas 21TV-EW capacitor coupled and finally  3 of the Seas 9TV-LG that is mounted on a metal bracket angling the outer tweeter about 15 degrees to the side.

Mounting the drivers on the baffle lowers the resonance from 34 to 28 Hz. Two impedance peaks at 55 and 70 Hz turns up as well

A Omnimic measurement just in front to one of the dust caps show the dips in response at 55 and 70 Hz otherwise good response from 30 to 300 Hz.

Listening test
Room 6x4 m with the speakers on the standing about 1 m in front of the shorter wall.
Equipment: Philips CD473 NADC320 BEE, the cheapest cables and loudspeaker cables with visible oxidation.
Reference equipment: Maranz CD5001, Cambridge C500 SAnsui BA-F1 Stridbeck TLS (think IMF80) Decent cables.

Music  NADs first test CD, BIS CD-232 Kroumata Percussion Ensemble, Laleh and Rammstein.
I have heard the KODO drummers from the NAD cd and the Kroumata group several times live as well as heard it using my large TLS speakers. I had little expectations for these flimsy baffles.

To my surprise it sound really good, the baffles connect to the room in a way that I last had at home with DIY Klipsch corner horns. The piano on the NAD CD is in the room more so than how it sound with the large TLS. The percussion on Kroumata and Kodo is better with the baffle closer to what I remember of live sound. More than just bass there is a bass that gives space and volume to the music.

Lalehs singing and acoustic music is portrayed well. Finally Rammstein at close to concert level to get that physical experience. Loud and clean and only about 2mm cone motion. Probably not much bass below 50 Hz or so. The baffle vibrated a lot as did all the braces.

I have to build proper baffles, a modern interpretation of the SFB. I will not have a sand filled baffle as the original Wharfedale nor have 2x25mm plywood as Troedsen. But some lamination of MDF and bitumen as suggested by Hobby HiFI.  Drivers from Norway, eight of them per set adding the kick, the name of the speakers has to be Sleipnir.

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