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Old 12th October 2002, 04:41 PM   #21
Bull is offline Bull  United Kingdom
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Thumbs up reply to Slicemaster101

Replying to Slicemaster101.

If properly designed,scoop bass bins can sound amazing.But also to consider is size and weight,a scoop bass bin is very large and difficult to transport,mainly because of the size,the weight can be overcome by fitting castors and large metal handles.
Good drivers to use are the Eminence Kappa 15 lf,Eminence Kappa pro 15 lf,
Eminence Sigma pro 18,Eminence Omega pro 15 and 18,and the Eminence Kilomax 15 and 18.And if you can afford even better.Electrovoice,RCF,Precision Devices are the best speaker drivers to go for;[in terms of quality of materials,value for money,specs,and ruggedness and durability].
Enough said,but in my opinion i prefer the sound of W-bins,deeper bass and chest thumping bass notes.Only thing is W-bins are hard to find,Apart from one manufactor called Sonic Speaker,which is seriouslly overpriced.
P.S. I've got a pair of scoop bass bins custom built from a shop in London,Called Henry's and they use 15 inch FANE Collossus 15 inch rated 600w rms,they cost me £300 each speaker plus cabinet.
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Old 13th October 2002, 07:34 PM   #22
bob4 is offline bob4  Germany
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Unhappy still awaiting help

OK,

I hope that somebody will answer this time.

I want to build at least one pair of scoops. (They're intended for PA use)

I already have the drivers.

And yes, I am aware of the fact, that somebody has already posted this:
Quote:
Originally posted by ThingyNess


If you have a driver you're planning to use, you'd be better off designing a horn around it than taking a current horn design and trying to "shoehorn" a replacement into it.
Still, I think I'll build the scoops (they look soooo nice )

Of course the scoop isn't the ideal solution, neither from the HiFi- Horn enthusiasts point, nor a professional sound company, but I don't have the money to buy some real gooood drivers.
I want to build some cabs that get more bass out of my drivers, it doesn't necessarily need to sound 100% neat.

I would be very pleased if somebody could give me some formulae, so I could calculate if I have to do modifications on the design to match it to my speakers.

I own a pair of Eminence Kappa 15 and a pair of Kappa 15LF.

the design I intend to use is the same as the one presented by slicemaster. http://www.dancetech.com/aa_dt_new/pa/15-scoop.cfm

I have found some info & formulae on horn design (http://melhuish.org/audio/horn.htm,).
Tell me: are the formulae OK for my purpose? I'm not sure if the formulae for calculating the compression chamber are of any use for me.

I would also appreciate it, if some kind person could suggest me a better design for my speakers (and perhaps send me some plans).

thanx
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Old 13th October 2002, 08:10 PM   #23
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Default If you want to design/optimize your own

Ok, in that case I’d play around a little with Martin King’s Rear-loaded Horn model to try and squeeze the most out of the rear-loaded horn. I am only browsing quickly because semester test and exam season is upon me and don’t have a Bookmark handy (try searching for his MathCad simulations and see what you can do with optimizing the parameters by hand)

If you want to do a front-loaded horn, the best thing would be to get that (sorry, no time to search) AES pre-print (By Marschall-Leach or some such) and to play around with those formulas in a spreadsheet. Have a look at http://expert.ics.purdue.edu/~sheerin/design.html ,perhaps you could even e-mail him for his spreadsheet based on the above. To simulate a front-loaded horn, David McBean’s hornresp.exe is probably your best bet.

All the best
Martin
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Old 13th October 2002, 08:42 PM   #24
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Default Re: Perhaps this is a case of go big or go home

Quote:
Originally posted by mgoedeke
About horn bandwidth: the bottom end is dictated by two things: the surface area of the mouth and the geometry of the horn (length, flare rate, etc.)
A horn is usually limited to a 3 or 4 octave bandwidth. 40->300 Hz is 4 octaves.

How low they go is very much determined by mouth area. The picture shows a pr of horns (each horn is divided in half for easier transport) that was designed to go to 50 Hz (sitting on the floor) -- those are 15" drivers to give you a sense of scale. IIRC the effective mouth is 66"x48". By using a Lowther Super Acousta type design i was able to use the fronts as direct radiators to extend their top-end range. I crossed them at 300 Hz.

Click the image to open in full size.

dave
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Old 13th October 2002, 08:49 PM   #25
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Quote:
Originally posted by slicemaster101
what do you suggest to make those “notes” stick out rather then all capital letters?
Slice -- use color or bold. All Caps is defined by Netiquette to be shouting.

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Old 13th October 2002, 09:08 PM   #26
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Dinsdale's 3-part Horn Article is a good read for anyone starting to look at horn design. With this as background, any of the available horn design programs will help you go thru iterations (it is long and time consuming to do it with just a calculator -- the horns i posted the pic of were done using the Dinsdale articles, an HP calculator, and a lot of pencil lead -- if i ever get to doing a Mk III version i'll use Martin King's simulator).

The horns pictured were powered with a Bryston 4B for each side (1 channel/cabinet [ie for a pr of 15s]) and they definitly slammed you when bottom end was present.

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Old 13th October 2002, 10:24 PM   #27
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Default EAW horn philosophy

EAW's site says that the main area of concern isn't the driver's size, but rather the horn's size. Their 22Hz SuperSub horns use 12" woofers. What about driver excursion as a consideration? Could one use home-theater sub drivers at sizes of 10" and 12" and build horns that would be as good as a dual-18" direct-radiator?
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Old 13th October 2002, 11:43 PM   #28
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Default Re: EAW horn philosophy

Quote:
Originally posted by BAM
EAW's site says that the main area of concern isn't the driver's size, but rather the horn's size. Their 22Hz SuperSub horns use 12" woofers. What about driver excursion as a consideration? Could one use home-theater sub drivers at sizes of 10" and 12" and build horns that would be as good as a dual-18" direct-radiator?
Yes. Look at the LABhorn that's been posted about before. Uses 2 x 12" drivers, similar in design and construction to many DR subs, but <i>carefully optimised</i> for the application. But probably not in a rear horn.

I haven't read the EAW site, but horn mouth and throat size, length, driver T/S parameters and rear chamber volume will all affect the bandwidth amd efficiency, and need to be juggled to produce the results you desire. I bet EAW have the drivers they use made to their specifications, so an off the shelf sub, designed to work in a ported box may not work optimally in a horn.
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Old 14th October 2002, 10:21 AM   #29
bob4 is offline bob4  Germany
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Thumbs up Thanks a lot

Thanx mgoedeke & planet 10,

Those links look very promising.

I'll read them all through and do a little calculation work, and will post again by the time I've made up a promising design.

regards,

bob
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Old 14th October 2002, 05:17 PM   #30
bob4 is offline bob4  Germany
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Unhappy still confused

PLanet10,

I have already once read through the "Horn loudspeaker design"- article by Dinsdale, but there are still some issues that puzzle me:

To get a low cutoff frequency and a flat response down to it, you have to go for a looooong horn with a big mouth, right?
According to the tables in the Dinsdale paper, the scoop design has a low cutoff frequiency of about 80- 100 Hz.
Does that mean, I'd have to go for a different design (longer horn, bigger mouth), if I want a horn that reproduces anything below 80 Hz properly?

I remember hearing, that a couple of horns stacked properly act like one big horn (like in the picture you posted).
If I build 4 scoops (2 using the Kappa 15, 2 with the Kappa 15LF) and stack them, do I get increased response below the individual cutoff freqs' of the single horns?

Would that mean I would always have to drag around all the four Bins??


And last but not least: The paper doesn't say anything about how to match your speaker to the horn. Can I just make an ideal scoop design according to it, and then mount the drivers in? I doubt that !!!!!
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