Help! With a rear horn loaded scoop bass bin

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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.
 
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:
ThingyNess said:
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 :D )

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. PA Systems, sound systems, speaker boxes, live Sound - Dancetech

I have found some info & formulae on horn design (403 Forbidden).
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
 
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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Re: Perhaps this is a case of go big or go home

mgoedeke said:
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.

mcphee-bass-MkII-4up.jpg


dave
 
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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.

dave
 
Re: EAW horn philosophy

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.
 
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? :confused:

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

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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Re: still confused

bob4 said:
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?

You can make the horn shorter by making the throat larger, decreasing efficiency and distortion -- it has an effect on bandwidth as well IIRC.

According to the tables in the Dinsdale paper, the scoop design has a low cutoff frequiency of about 80- 100 Hz.

That is about right

I remember hearing, that a couple of horns stacked properly act like one big horn (like in the picture you posted).

To do it properly, you design the big horn and then slice it into pieces -- you need a driver for each slice.

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

Yes

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?

The Dinsdale article was written a long time ago and should be considered as a background. There is a Marshall Leach AES paper that goes into great detail wrt mating a driver to the horn. It is the next text in the puzzle.

dave
 
Re: Re: still confused

planet10 said:

The Dinsdale article was written a long time ago and should be considered as a background. There is a Marshall Leach AES paper
that goes into great detail wrt mating a driver to the horn. It is the next text in the puzzle.
dave

This horn construction thing gets more and more exciting. :D

The AES paper by Leach has already been mentioned a few times.
Does anybody in here have a copy of it? I know I can order it from the AES directly for about 4-5$, but the shipping would probably take a long time????

Please post a link or something, or E-Mail it to me (if possible)

planet10,

what does IIRC mean?
 
scoop bin blueprints coming soon.......

HEy Folks,

Some nice person mailed me the AES paper by Leach.

As soon as I have read through all the material I've got with the help of you all (special thanx goes out to planet10 & mgoedeke), I will make up a design.

regards,

bob
 
Re: Re: Re: still confused

bob4 said:
I know I can order it from the AES directly for about 4-5$, but the shipping would probably take a long time????
For future reference, AES email you a PDF of the paper you purchase, usually within a couple of hours (if you pay by credit card). Each PDF is at least a meg in size, so if you order a few, make sure you have a large enough mailbox!
Cheers
 
Optimizing horn around a given driver

Now what one needs is a program that would by means of an iterative process give one the possible horns suitable to a certain driver. An analogy to an alignment as in the case of ported boxes would be in order. I myself don’t have that paper so I am guessing but perhaps it gives one that as well. As I see it, it gives one the means of getting the T/S parameters ideal for a given horn (with two knee points, a given efficiency and bandwidth) T. Danley supposedly has such a beast (amongst others) and so does AJ Horn, but that is currently out of my reach. Any ideas?

Martin

And credit where credit is due to other forum members and the contributers to the LAB Horn project. Read through that for lots of quality info, especially the earlier posts in the design phase.
 
Horn design

Then perhaps I have some math students to speak to (or my dad even, just he doesn’t have the time for such things) My math skills are rather scary and the only modeling I could do is the odd population model and only by hand. That is something for after the exams though. I don’t suppose somebody has such a thing, or? Perhaps we should open another thread on bass-horn design (or did my search miss something)
 
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