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BMS 4592ND performance on a 250Hz tractrix

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csg View Drop Down
Old Croc
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    Posted: 28 February 2014 at 9:58pm
Ive been messing around with several new flares recently with a BMS 4592ND as the mid / high end of my new large format mid high box.

I have never been convinced by the sound of constant directivity flares. Radials / bi-radials better on axis, but worse off.

i took a bit of a punt and ordered a couple of 250Hz flare rate Tractrix flares from Stereolab in Germany with a view that a 250Hz tractix should be able to support a 400 Hz isn high pass, LR 4th order.

straight out of the box, no EQ, just the described high pass gave the response below, taken on a type 1 spectrum analyser. very impressed indeed.



the off axis response i heard this afternoon surprised me though - i thought these would beam like hell high up, but they seem to give a fairly satisfactory 80 degrees or so.


the sound, compared with an electrovoice HP940 and a JBL 2385 is in another league. Early days in this design, but a very promising start.
www.impulseaudio.co.uk
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lycantheleopard Quote  Post ReplyReply Direct Link To This Post Posted: 28 February 2014 at 10:37pm
thats pretty sweet! i'm glad its for a "large format" box though, i bet that horn is quite sizable.
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Old Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote csg Quote  Post ReplyReply Direct Link To This Post Posted: 28 February 2014 at 11:32pm
18" / 450mm diameter at the front. You need a big horn to do this driver justice though i think, i want as much of the vocal range coming from the coax as possible.
www.impulseaudio.co.uk
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keen Quote  Post ReplyReply Direct Link To This Post Posted: 01 March 2014 at 12:06am
awesome stuff csg. thanks for showing us. all the best with the project Thumbs Up
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Post Options Post Options   Thanks (0) Thanks(0)   Quote y2stevo Quote  Post ReplyReply Direct Link To This Post Posted: 01 March 2014 at 1:57am
Nice,
What LF driver are you thinkg on pairing with?
A single or even dual 15 arrangement?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote matty w Quote  Post ReplyReply Direct Link To This Post Posted: 01 March 2014 at 4:16am
Everything about this combo just excites me ,just makes a lot of sense .
Response looks very promising , thanks for sharing
Black to black , red to red , blue to bits ....

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Post Options Post Options   Thanks (0) Thanks(0)   Quote matty w Quote  Post ReplyReply Direct Link To This Post Posted: 01 March 2014 at 4:22am
How stiff is the horn ? With it being quite large plus the intention to use that bms driver nice and low ,as it should be ,you mite want to consider fibreglassing strengthening strips up the length of it !? Also maybe some tar damping around the outside ,all to help keep it sounding natural and not like a fiberglass/plastic ? Horn!
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SMP View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SMP Quote  Post ReplyReply Direct Link To This Post Posted: 01 March 2014 at 4:38am
I hope the updates will keep coming as the BMS is/are of particular interest at present. your results look very promising
nice work
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Teunos View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Teunos Quote  Post ReplyReply Direct Link To This Post Posted: 01 March 2014 at 8:36am
Is there any possibility you could do a directivity plot?
Best regards,
Teun.

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csg View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote csg Quote  Post ReplyReply Direct Link To This Post Posted: 01 March 2014 at 9:53am
I will do some readings at angles once i have access to a suitable space. Anechoic spaces are rare round here, but i do have access to an unused airfield in a very quiet location, just need a dead calm day.

the horn itself being from hifi land is very dead, made from 1cm thick Corian. The makers pride themselves on the horns being non resonant and well damped. Stiffer than fibreglass, much more dead than anything metal.

the only re-enforcement i would in visage is support for the comp driver. Its not heavy, but the worst could happen going in or out of a truck. Someone managed to shear all 4 wheels of a flight case last year coming down a truck ramp.

there will be 2 12" drivers below this covering the 100 - 400 Hz band. I am hoping that i can avoid any significant horn loading here - 2 reasons being i want these to be reasonably wide dispersion, good for one box a side applications, and to avoid any colouration of the sound. The horn needed to give any decent gain in that passband would need to be fairly long too, and i want to keep the box to around 700mm deep. If the 12" drivers can cope in terms of output then great, and a reflex load just around the bottom cross freq. should help keep the efficiency up.
www.impulseaudio.co.uk
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Post Options Post Options   Thanks (0) Thanks(0)   Quote login4 Quote  Post ReplyReply Direct Link To This Post Posted: 01 March 2014 at 11:05am
just look at tannoy VQ range, huge horn Wink

nice project, look forward to the results

CELTIC SUBSONIC SOUND SYSTEMS
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Teunos View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Teunos Quote  Post ReplyReply Direct Link To This Post Posted: 03 June 2014 at 6:42pm
Any progress on these CSG? would love to the cab these ended up in Tongue
Best regards,
Teun.

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