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2 x 12" reflex

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Salc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Salc Quote  Post ReplyReply Direct Link To This Post Topic: 2 x 12" reflex
    Posted: 03 February 2020 at 12:59pm
I have been playing around with different ideas for a reflex design to sit above superscoopers for dub, roots and reggae music. It seems that if people use reflex they traditionally use 2 x 15" reflex to sit above scoops in a 2 x 15 : 2 x 18 scoops ratio. I currently have 2 x scoops and a badly scaled down 15" g-sub and am in the process of building 4 more scoops. So I had originally thought that if I was going down the bass reflex route for upper bass boxes, I could either go for 6 x 15" new single reflex or 3 x 15" new double reflex. I did some modelling and got some reasonable designs for 15" boxes but then thought about trying 12" reflex as I could fit more boxes on top of the scoops. 

So the design I came up with uses 2 x B & C 12 NDL 76 (16 Ohm version) wired in parallel in the box. You could fit 2 of these boxes on top of 3 scoops and 4 on top of 6 scoops. So for a 6 scoop stack you could have 8 x 12" drivers. I then thought you could use these boxes for upper bass and low mid range to be crossed into a 1" or 2" compression driver given that they are 12". So you could have 8 of these boxes resulting in 16 x 12" drivers in total for upper bass and low mids. 

Here are some sims from Winisd of one box with 2 x drivers in. The drivers are 400 W AES and 800 W program. The pictures shown have low and high pass filters applied and a signal of 800 W. I have heard that for every doubling of power and doubling of driver area you get an increase of 3dB. So I calculate that with 8 of these boxes you would get 3 x doubling of power so an extra 9dB and then 3 x doubling of area so another 9dB giving a total of 18dB boost on the graphs shown below. This would be 18dB on top of the 128dB shown in the picture below which would give at least 146dB from roughly  Then an additional 3dB for program power from doubling the power input to each box from 800 W AES (split across the 2 drivers) to 1600 W program power. 

Here is a link to a gallery of images showing cone excursion, impedance, spl and rear port air velocity -- https://postimg.cc/gallery/k7ieikdm/

I know this is not the most cost effective approach but wondering what peoples thoughts were out of interest. 

Cheers.
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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 04 February 2020 at 3:51pm
If you find such a response satisfactory to your needs, that's all that matters.

Reflex cabinets generally offer an extended response below 100 Hz. A -3 dB @ 60 Hz is classed as a intermediate DJ/Live Band bass bin.

Your box is -3 dB @ 75 Hz.

Think about that for a minute....

You are investing in B&C speakers that cost more than the run of the mill off the shelf intermediate reflex bin and, getting a bass response that is less than the run of the mill off the shelf intermediate reflex bin.

Even if you are planning to roll-off the box to a higher frequency, it is better to have a reflex box that can play bass as a standalone unit in the event you need to play in a smaller environment where toting larger cabinets are not needed/wanted.

Best Regards,

 
Elliot Thompson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dub Specialist Sound Quote  Post ReplyReply Direct Link To This Post Posted: 04 February 2020 at 4:21pm
Just to add imho, had many diff type horn boxs over the years, still find myself comming back to sealed/reflex mids once again, fully rebuilt my big sound from top to bottom, 6x sealed mids 12l loaded , imho insane clarity definition, loud , clean and dont worry about thow..plenty to play out doors too...

DS.. 
Musical Roots Reggae Vibration is Life! for music is sound...sound is vibration...vibration is energy... and energy begets life. Therein lies my passion!...MUSIC IS LIFE...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Salc Quote  Post ReplyReply Direct Link To This Post Posted: 20 February 2020 at 1:52pm
Thanks for the feedback from both of you. 

@Elliot - Thanks for pointing out the issues with the design, I think I'll stick to 15inch kick bins then. After thinking about it some more, I am quite interested in trying out the cubo kick 15 design. Do you have any experience with this cabinet design?

@DS - Thanks for the advice re sealed mids. I currently use reflex mids but sounds like it is worth trying sealed 12 mids for the mid section sitting above either 15 reflex or cubo kick 15 kick bins. I was wondering about ratios, do you use 6 12 mids above 4/6/8/ subs?? 

Also, do either of you have any advice over tops?

Thinking of just getting good quality 2 inch CD or coaxial to sit above the mids. Not particularly bothered about bullets if I don't need them. 
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Elliot Thompson View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 21 February 2020 at 2:11am

I have no on-hands experience with Cubos but, there are many happy users here on Speakerplans. If you are willing to invest in coaxial drivers, you definitely won't need any Bullet Tweeters.


Coaxials put you in a different league altogether. It will be harder to find a lot of coaxial users based on the obvious. So, you may find yourself venturing to wards models/brands with very little if any user feedback.


Best Regards,

Elliot Thompson
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 10:08am
I think what elliott was trying to say about your 12" idea was not disregarding the idea in general, but questioning the expensive driver choice compared to the cutoff and versatility of your preliminary box design. 

Cubos are loud, but will be difficult to integrate with your scoops, and you will need separate midrange section anyway. 

I think your original reasoning of using 12" in quantities to do both kick and lowmids is a feasible approach. Just take your time, check out the  various 12" drivers available to you, and do simulations in winisd. It is easy to use and accurate for closed box and reflex .




Edited by bob4 - Yesterday at 10:09am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 10:42am
This is also a roots system I think (Belgium):


This one I'm not entirely sure about:

However they both use Cubo Kick 15's with (HOG) scoops, so I thought it might give you some idea of the routes you can take ;)

Best regards Johan
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