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Modifying JB-sub118 BR to Horn |
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app 
Old Croc 
Joined: 26 December 2013 Location: Finland Status: Offline Points: 2435 |
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 Topic: Modifying JB-sub118 BR to HornPosted: 16 September 2015 at 12:57am |
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Greetings!
Im using JB-sub118(lbb-118) http://www.jobst-audio.de/archiv/97-jb-sub118 After seeing what mtl-46 looks like http://hornplans.free.fr/mtl-46.pdf A thought came to my mind. Would it be possible to modify a bass reflex box like jb-sub118 to a horn like the mtl-46 What do you guys think? The mtl-46 without the inside "port" is just like a BR. JB-sub118 looks like this  and the mtl46 like this  |
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b grade
Young Croc 
Joined: 05 October 2012 Location: Portland OR USA Status: Offline Points: 1337 |
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Posted: 16 September 2015 at 1:16am |
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You could do it, but the side and back panels will need extending so the vent could be larger to form more of a horn effect. The extending of the panel will require some bracing or it would be a very weak joint between adjacent panels. I think it would be easier to just build the new box. Also then if it did not work for some reason, you can just go back to the way it was.
Edited by b grade - 16 September 2015 at 1:26am |
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app
Old Croc
Joined: 26 December 2013 Location: Finland Status: Offline Points: 2435 |
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Posted: 16 September 2015 at 1:45am |
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Sure,it would be much easier to just build a new box. The jobst plan is missing bracing and the space for the driver and grill.
Im not about to change the subs,I like them and still feel like theres more that they can do,like the BR! But for some a box which could be modified to be used either as a hor or a bass reflex would be nice. You could use the same driver and just change the box quickly to horn. But anyway it is possible,good to know! Is there any boxes which can be modified to use as reflex or horn at the moment? |
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Sapro2
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Joined: 31 January 2015 Location: Somerset Status: Offline Points: 354 |
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Posted: 16 September 2015 at 9:16am |
That doesn't look like a horn to me? |
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Splat Soundsystem
Baby Sham pram Soundsystem Sapro - SoundCloud https://soundcloud.com/sapro DJ Sapro. West country free party DJ and Producer. |
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odc04r
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Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5482 |
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Posted: 16 September 2015 at 9:26am |
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It's one of those tricky cases which is more like a hybrid. There is no expansion in the wavefront path but there is a rear chamber and one could argue a throat where it taps into the port/transmission line - with the other end of that line perhaps acting as a cancellation stub. Although the stub might be too small to do anything useful at low wavelengths.
I would still model it as a rear loaded horn, but a horn with no expansion. Akabak would be my goto program, but I bet HR could do it. You could try reflex modelling but I think with such a large port some of the assumptions made might not agree with real life very well. |
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b grade
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Joined: 05 October 2012 Location: Portland OR USA Status: Offline Points: 1337 |
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Posted: 16 September 2015 at 2:52pm |
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I have found with oversized ports they don't really load unless a lot of air is being shifted. You want the air velocity low, but when the vent is too huge, the air just puffs around without direction.
I am still dubious about converting the existing sub. But what you could do is make the new speaker box. Fashion some kind of inobtrusive battens at the mouth of the Horn/vent, and have an access panel, with appropriately sized vent/s on the panel. Perhaps even just a couple decent sized PVC vents. With the panel off it would behave exactly how that hybrid horn behaves. With the access panel on, the horn path would all just become part of the chamber again and all of the air would be channeled through the access panel vents. Gasket tape would be required to make sure that the horn was completely sealed. Very simple to convert too.
Edited by b grade - 16 September 2015 at 2:57pm |
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bass*en*mass
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Joined: 03 September 2009 Location: "unknown" Status: Offline Points: 4009 |
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Posted: 16 September 2015 at 7:30pm |
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doubt the mtl is worth the hassle, if you need more sub built a larger cab..
(18-500s seem to work well in some tapped horns afaik) |
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mini-mad
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Posted: 16 September 2015 at 11:11pm |
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Im liking b-grade idea. A few batons and some t-nuts and you could almost retune by ear with any driver you choose (winISD would help... or bassbox) anything else i would think would require a rebuild im sorry to say....
You could TRY some sort of T18 type setup... |
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If it sounds like a gorilla is trying to escape, turn it down.
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app wrote: