Beyma SB18

[muri]

Hi!
I am planing to build some new sub boxes for my system. For now I mostly do DJ's house music but I am planing to do some live bands in the future.
I would like to build this box but I don't know how low it would play (singles or in stacks of 4). I assume they would be good for live applications where some kick is required but how low? Could I simulate them in hornresp?
My other option are BR boxes. But I would like to build the beymas because I think they would play better outdoors.
I already have some selenium horn subs but they don't do well indoors and don't go low enough in singles.

What do you think what would be better BR or this beymas?

The plan: http://www.speakerstore.nl/construct...8-2/SB18-2.pdf

Thanks! Luka

[Rademakers]

The SB-18 will go louder then the BR for the same power input. It has a bit of a BP sound to it, so it sounds best crossed low (like 80 Hz).
The f10 is 33 Hz and it gradually drops from 101 dB/W/m around 80 -100 Hz. Personally I like it with drivers of EBP 100 or higher.

The BR is more allround and sounds better in the 80 -120 Hz region imo. Because of this it can be used with tops that don't quite reach low. Also there is a lot of "impact in the 80 -120 Hz" that you'll miss out on with the recommended 80 Hz crossover on the SB-18. The BR will have a flatter frequency response.

If maximum output is your game the SB-18, if flat frequency response is your game or your tops aren't that beefy the BR.

Best regards Johan

[muri]

Thanks for the information!

I have build a test cab and I must say it's playing really good and it's loud. It was loaded with a RCF L18S800 (from a friend) but it has low xmax.
Now I'm planing to buy drivers for it. I'm deciding between the RCF LF18N401 and B&C 18NW100. They have very similar T/S. The RCF has bit higher EBP. I can get them for the same price. What driver would be better in this dessign? Whitch would sound better?
What do you recomend?

Thank you!
Luka

[Rademakers]

The L18S800 is a very efficient driver, with a n0 of 3.93%, Le 1,7 mH and high Fs for an 18". With an EBP of 130 I expect it to perform and sound well in a SB15.

The other drivers have an EBP around 116.

The main difference between the LF18N401 and 18NW100 is the high Le (2,5mH) for the LF18, whilst the Le from the 18NW is similar to the L18S800. The B&C is the least efficient but the EBP isn't significantly lower, because the significant difference in Le might make the LF18N401 to sound "sluggish" in direct comparison with the L18S800 and the B&C, my choice would be the 18NW100.

Best regards Johan

[djk]

The 'specifications' on that box are pure fiction.

It will only be 101dB above 100hz, abd it will be at least 10dB down at 33hz.

It's similar to this EV cabinet, but can't work as well as it's smaller.

http://archives.telex.com/archives/E...L-ER%20EDS.pdf

But on the other hand, many people are satisified with the EV, so you may be satisfied with yours.

Keep in mind:

A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).

The 'horn' on the EV/Beyma is too short to work below 100hz, and the rear volume acts as a vented box below 100hz (and it is tiny).

Note: the correction factor between 2.83V/1M and 4V/10' is +6.67dB

The Beyma is only 2/3 the total size of the EV, so it must be almost 2dB less efficient below 50hz.