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EAW BH882 plans for you all!!!

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discomusic1978 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote discomusic1978 Quote  Post ReplyReply Direct Link To This Post Posted: 31 October 2017 at 12:07pm
Hey cool are you using an RCF L18-851kn which is what EAW made the BH882 for or are you using something else....

I am building a couple also but want to get down in the 20 something herz....range?
If I do that the box will have to be a few inches deeper to accommodate the deeper frame woofer....?

Let me know your thoughts on that

And thanks for getting back to me

Anthony

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Post Options Post Options   Thanks (0) Thanks(0)   Quote re-production Quote  Post ReplyReply Direct Link To This Post Posted: 31 October 2017 at 2:34pm
Hi Anthony,

I am using oberton xb 1500. Most ”horn suitable” drivers came back with similar Sims so I made the decision based on tone. For this one we didn’t modify the dept and probably should have so that it would more suited to modern drivers. Personally I wouldn’t see the need for the horn to drop down to 20hz, 35hz seems low enough for my ears but depends what you want to use it for.
One thing I would certainly recommend is splitting the box into two, known as emeralds, this means you can actually move them around if you need to.
If you are ever around Suffolk/Norfolk way you are more than welcome to come have a listen!!
Andrew
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Post Options Post Options   Thanks (0) Thanks(0)   Quote APC321 Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2017 at 3:16pm
Court Black Box: 1100mm wide x 750mm high x 650 deep.

EAW BH882:       1511mm wide x 1066mm high x 910mm deep.

I know its not a direct comparison, but the Court Black Box is just too big and heavy to be practical, so the EAW is insane.

People may say that the EAW is for installs, but in my experience the bigger the boxes that you install, the faster that the club goes out of business. (Murphy's Law?)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2017 at 4:32pm
The Black Box is the same size as most dual 18" boxes, how many of those do you see?!

It really isn't that impractical, especially if split into Emeralds. Big boxes are needed if you want to get low and loud, and have directivity in low frequencies, which the Bertha does well especially with the horn.

Edited by toastyghost - 01 November 2017 at 4:33pm
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discomusic1978 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote discomusic1978 Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2017 at 7:54pm
I am trying to see if installing different woofers would make a difference
and needing to deepen the box to accomidate a deeper woofer driver.
by about 3 inches....

using an RCF L18P400
or a RCF L18X451

do you know or know someone that can help answer that and if modifications are needed what they would be...?

Thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote APC321 Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2017 at 10:02pm
Kyle makes a fair point about 2x 18", so I did some looking:

L'Acoustics SB28:   1300mm wide x 550mm high x 700mm deep.

Court Black Box:    1100mm wide x 750mm high x 650mm deep.

EAW BH882:          1511mm wide x 1066mm high x 910mm deep.

EAW BH882 divided   1511mm wide x 533mm high x 910mm deep.
into two (Emerald?)

I think that the minimum dimension out of width, height and depth has a bearing on the "practical useability" of a box. ie. Getting through a standard width door, or perhaps going up steps of restricted width etc.

So yes if the BH882 divided into two is used then it compares more favourably (533mm)with the L'acoustics SB28 (550mm - industry standard box)in terms of its minimum dimension.

But power density is also an issue. ie. The Emerald has just one driver against the L'Acoustics that has two drivers in a 'similar' sized box.

I can think of two examples of people that I know who previously used "big" boxes.

1) He originally used Hog scoops, but moved to Funktion One 2 x 18"s. Said this was a much easier van / truck pack

2) He had Funktion One 2 x 18"s along with infra-bass and matching infra horns. He sold the infra horns, as when they were loaded into his van there was hardly any room for anything else.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2017 at 10:17pm
Lemme put it very simple. If these cabinets don't blow a candle from at least 10 meters then it's a no go project ! Big smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2017 at 11:31pm
You don't necessarily need power density when you have the benefits of horn loading. A Bertha is a very particular type of cabinet with a heritage in a particular type of music and venue though, I don't think anyone is really advocating touring a bunch of them for live music or similar.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Laurin Quote  Post ReplyReply Direct Link To This Post Posted: 05 November 2017 at 7:37am
Ha!
Bertha too big and heavy.
We are stacking a Void Incubus on a weekly basis. 

Practical is a Bertha not at all!
It can not reach 20Hz without the Levan horn, and even then it will be more than -10 dB.
The driver will not change how low it will play, that defines the horn not the driver.

If you build a Bertha please keep in mind to build the rear chamber the right way. 
The parts between the throats are empty.
Very small changes, change the sound drastically with horns! 

Free knowledge:
Best drivers in a Bertha are not typical low QTS horn drivers but drivers with T/H more suited to BR.

Will add a picture that shows how to build the rear chamber.

  




Edited by Laurin - 05 November 2017 at 7:37am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Laurin Quote  Post ReplyReply Direct Link To This Post Posted: 05 November 2017 at 7:39am
Originally posted by toastyghost toastyghost wrote:

A Bertha is a very particular type of cabinet with a heritage in a particular type of music and venue though,


Like always we think alike. Tongue
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Post Options Post Options   Thanks (0) Thanks(0)   Quote discomusic1978 Quote  Post ReplyReply Direct Link To This Post Posted: 05 November 2017 at 3:37pm
Thanks for the info I appreciate it.
I am just stuck on this box for a large venue
I am a mobile dj coming out of retirement.
looking to custom build all of my boxes Tops and bottoms.
this way for small sized gigs I can use just the tops
and medium sized gigs a set of tops and a set of front loaded double 18"s
and for Large gigs 1 to 2 sets of tops and 1 to 2 sets of front loaded double 18's
then for extra large gigs use all tops all front loaded double 18's and the added treat of a couple Bertha's with the Levan lenses.

That is my vision but one thing I might do is split the Bertha's into 4 single 18 boxes with extension lenses for easier transporting

my question has been if I put a newer style driver instead of A JBL 2240 or an RCF L18-851kn.
and use a RCF L18-P400
          or RCF LF18X451
          or A BMS Neo Driver that is rated down to 25hz and a db rating of 95

having to deepen the back of the box and thicken the speaker baffle plate to allow for longer x-max but keeping the actual horn structure the same will it impede the sound making it better or worse in the low frequency range...?>
the Efficiency is their being at either 95db or 98
need some technical input on this question

what do I need to change on the Bertha box if anything at all

Thanks Anthony

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Post Options Post Options   Thanks (0) Thanks(0)   Quote RoadRunnersDust Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2017 at 5:57am
The Bertha will only split into 2 single 18s? do you mean splitting a pair of berthas down into the 'Emerald' boxes? they are still a two-man box to move around.
Instead of making the box any deeper, you'd probably get away with making the rear-chamber come forward more and making the initial expansion shorter

I assume that yours are the ones that Brad was building, Re-pro?

Most of the sources of information I've found have pointed towards a pair of Emeralds having more output than the Bertha on its own which persists to confuse me unless it has something to do with the interaction of the two drivers within the horn...

As for the drivers, I found that the horn was of such a low compression rate that it didn't seem to change output by any considerable amount as you simulated different drivers... 
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