DaveCan said:
The other thing that came to mind when I first saw them was maybe it would be a good idea to line the compression chamber ( on designs that have them) with Baltic Birch ply and just factor that into the measurements, maybe the tone would be better?? Dave
Its tone would be worse IMO since wood 'colors' sound far more than appropriately sized CRS. Haven't you noticed that you can hear a tonal shift as the driver's response begins energizing the cab? Especially a small driver in a BLH? With CRS sheet metal construction you hear more of the driver's sonic signature and less of the cab's except in the form of gain.
GM
GM said:
you are perfectly describing the differences that i am hearing between the metal and birch cabs , now get this after a full on comparison the listeners all say that the metal is better than the wood for everything ,but they all agree that there seems to be less midrange with the steel ,i am a strong believer in the fact that the enhanced midrange is coming from the wood boxes natural resonance, your thoughts?
Bingo! This is no doubt one of the main reasons why the pioneers of audio designed their horns to be made from tin or brass initially and later cast brass throat/initial expansion for the mids/highs with a high Fs/dense grade of plywood that was further mass loaded/sealed with a high solids coating for the low frequency portion. These ~50-10 kHz horns had horrible off-axis response though, so a two way was designed with the < 500 Hz BW covered by a 2x4, 2x6 braced/supported plywood folded horn and tar damped tin sheet multi-cell horn for the > 500 Hz BW.
Here's a pair of circa 1925 Bell Labs/W.E. no compromise all sheet metal ~fullrange horns mounted behind the movie screen. It's hard to tell in this photo, but each one is two flat folded horns merging into a common mouth with two compression loaded drivers/horn, so there's eight drivers total. With only ~8 W/driver to fill a several thousand seat theater, efficiency was pretty much everything.
GM
Here's a pair of circa 1925 Bell Labs/W.E. no compromise all sheet metal ~fullrange horns mounted behind the movie screen. It's hard to tell in this photo, but each one is two flat folded horns merging into a common mouth with two compression loaded drivers/horn, so there's eight drivers total. With only ~8 W/driver to fill a several thousand seat theater, efficiency was pretty much everything.
GM
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Hey Scott,
Nice work!
I know exactly what you mean by the lack of coloration.
Perhaps you’ve seen these…
That’s the Jordan JX-92S in stainless steel. I recently sold them to someone who builds a commercial design with the same driver. He is head over heels in love with them and said they will replace the BBC LS3/5a in his bedroom system.
Krell makes some speakers with metal enclosures. According to a Wes Philips from SoundStage, “they prize… freedom from coloration beyond all other consideration…"
This pretty much concurs with someone else who heard my stainless steel Jordan’s on his 20K system last year… “John brought these over for a listen some months ago and I can say that they are amazing, neutral and precise. Spooky real on a Lost and Profound acoustic number, I've never heard anything ever that provided near the "musicians in the room" feelings...”
If it were not for the cost and extra effort it takes to make metal enclosures, there would be more on the market. Perhaps in time…
Nice work!
I know exactly what you mean by the lack of coloration. Perhaps you’ve seen these…
An externally hosted image should be here but it was not working when we last tested it.
That’s the Jordan JX-92S in stainless steel. I recently sold them to someone who builds a commercial design with the same driver. He is head over heels in love with them and said they will replace the BBC LS3/5a in his bedroom system.
Krell makes some speakers with metal enclosures. According to a Wes Philips from SoundStage, “they prize… freedom from coloration beyond all other consideration…"
This pretty much concurs with someone else who heard my stainless steel Jordan’s on his 20K system last year… “John brought these over for a listen some months ago and I can say that they are amazing, neutral and precise. Spooky real on a Lost and Profound acoustic number, I've never heard anything ever that provided near the "musicians in the room" feelings...”
If it were not for the cost and extra effort it takes to make metal enclosures, there would be more on the market. Perhaps in time…
scottwilko said:
Not at all, just a guy who hands plans and payments to those who are. Two different shops did the work on these. They were originally intended to be a commercial design, but Ted Jordan wasn't interested in negotiating a deal and production costs were very high.
In the meantime I've become an open baffle convert.
GM said:
Hi GM. Pic here. The cab is a 1/4" welded tube with wood end caps. An attempt was made to damp the walls by layering the insides with 1/8" aluminum sheet over linoleum, all held together with Polyurethane glue. It helped but not enough and, other than dropping in a bamboo TB, the project never went much past the point seen here:
http://www.diyaudio.com/forums/showthread.php?postid=445860#post445860
Greets!
Don't know, I never has such major problems, quite the opposite, and while I never used such thick steel, I'd have thought the extra mass would just damp it more, not less. Then again, once excited it would ring louder over a wider BW than thinner sheets through greatrer energy storage, just as MDF does compared to rigid, void-free plywood, so I'm guessing its much increased mechanical/acoustic efficiency was enough to modulate the audibly driver. A BLH OTOH has a filter chamber to damp it somewhat and a golden or acoustic ratio cab would have enough of a uniform particle density to make for smooth reproduction.
GM
Don't know, I never has such major problems, quite the opposite, and while I never used such thick steel, I'd have thought the extra mass would just damp it more, not less. Then again, once excited it would ring louder over a wider BW than thinner sheets through greatrer energy storage, just as MDF does compared to rigid, void-free plywood, so I'm guessing its much increased mechanical/acoustic efficiency was enough to modulate the audibly driver. A BLH OTOH has a filter chamber to damp it somewhat and a golden or acoustic ratio cab would have enough of a uniform particle density to make for smooth reproduction.
GM
It probably has more to do with the overall shape and welded seams. If you think about it's basically a tubular bell with damping end caps. The resonances live up to the mental image. In the buschorn case the non-welded seams (assuming the panels are in physical contact) are natural friction points providing damping.
An educational upside of the exercise, as the resonance fundamentals are well above the bass range they have no impact on lower voice registers. I've never heard comparable reproduction from wood in that range. There's something to be said about a 99.999% unyielded cabinet. Also, nylon screws don't appear to be anywhere near as efficient as stainless at transfering energy from the driver basket. Recommended as worth trying.
An educational upside of the exercise, as the resonance fundamentals are well above the bass range they have no impact on lower voice registers. I've never heard comparable reproduction from wood in that range. There's something to be said about a 99.999% unyielded cabinet. Also, nylon screws don't appear to be anywhere near as efficient as stainless at transfering energy from the driver basket. Recommended as worth trying.
Yes, they exist and historically they're either made with a brick, concrete block and poured concrete construction in subterranean cavities or attics are converted into labyrinths of high density wood construction or added to the end of a room with an outside facing wall. Made from metal, we're talking either battleship hull or space shuttle monocoque construction.
The inventor Tom Danley though has reduced their size considerably by taking the 6th order band-pass alignment to its logical extreme by increasing the internal vent till it's big/long enough to be a 1/4 WL long at Fc when combined with the front/rear chamber volumes and horn tapering it for further gain, creating a relatively compact limited BW bass or sub-bass horn of acceptable efficiency (AKA tapped horn). This could probably be made from well braced 10 ga CRS, so will still be too heavy for most if not either assembled in place like the others or built in several sections and bolted together with steam boiler pipe quality junctions.
http://www.danleysoundlabs.com/tapped_horn.html
http://www.danleysoundlabs.com/pdf/danley_tapped.pdf
http://www.diyaudio.com/forums/showthread.php?s=&threadid=97674
GM
The inventor Tom Danley though has reduced their size considerably by taking the 6th order band-pass alignment to its logical extreme by increasing the internal vent till it's big/long enough to be a 1/4 WL long at Fc when combined with the front/rear chamber volumes and horn tapering it for further gain, creating a relatively compact limited BW bass or sub-bass horn of acceptable efficiency (AKA tapped horn). This could probably be made from well braced 10 ga CRS, so will still be too heavy for most if not either assembled in place like the others or built in several sections and bolted together with steam boiler pipe quality junctions.
http://www.danleysoundlabs.com/tapped_horn.html
http://www.danleysoundlabs.com/pdf/danley_tapped.pdf
http://www.diyaudio.com/forums/showthread.php?s=&threadid=97674
GM
well its all systems go for a small horn subwoofer then, i have a design in my head and will start building it soon but i need a driver first ,i like these two as they complement the speakers i have ,the fe208 sigma which is my first preference or the fw208n, dont think im stupid for choosing these drivers ,but i only need a tiny amount more bass from 60hz down to say 30hz, my speakers roll off at 55hz
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