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21" reflext enclosure needed
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smitske96 View Drop Down
Young Croc
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Points: 1009 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 05 December 2020 at 4:36pm
Round ports would be the best, but can be difficult to omplement if they need to be long (and enough cm2). Slot ports can make inplementing much easier. The point in the end is that triangle shaped ports need to be bigger to be equal in terms of compression and the resulting distortion.
If you use said port area, you would get velocity of around 26m/s (with 1600 Watt AES input). If you go with something like 800cm2 you'll around 18m/s. I have write up somewhere from a fb forum were the 3 ports are compared. 

Personally i don't dig the 6dB crest factor measurements a lot (for any manufacturer). It only tells you one part of the story. Therefore I think CEA2010 would be more suitable.
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MarjanM View Drop Down
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Points: 7708 		Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 05 December 2020 at 4:49pm
Why dont you just buy some subs? DIY is not always the answer.
Marjan Milosevic
MM-Acoustics
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Mel_Gibson View Drop Down
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Points: 36 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Mel_Gibson Quote  Post ReplyReply Direct Link To This Post Posted: 05 December 2020 at 5:09pm
Because I can't afford subs that would give me the same performance as the custom subs i'm thinking of building or having built. I'd say to buy a pair of subs 21" that would be as good as ones I can custom make would probably cost about £1,500 each.
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MarjanM View Drop Down
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Points: 7708 		Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 06 December 2020 at 12:36am
And what is your actual budget? 
BTW that Beyma 21 inch is not in the highest ranks of 21 inch drivers.
Marjan Milosevic
MM-Acoustics
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knet94 View Drop Down
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Points: 1482 		Post Options Post Options   Thanks (0) Thanks(0)   Quote knet94 Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2020 at 12:15pm
Originally posted by Mel_Gibson Mel_Gibson wrote:

Because I can't afford subs that would give me the same performance as the custom subs i'm thinking of building or having built. I'd say to buy a pair of subs 21" that would be as good as ones I can custom make would probably cost about £1,500 each.

I can't see the design that you have posted up costing anywhere near £1,500 each to build. 
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knet94 View Drop Down
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Points: 1482 		Post Options Post Options   Thanks (0) Thanks(0)   Quote knet94 Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2020 at 12:18pm
Have you considered going the 2nd hand route. Seen some really good cabs going for small money recently. Tho tbh far bigger than the Beyma ones.
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smitske96 View Drop Down
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Points: 1009 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2020 at 1:37pm
Originally posted by knet94 knet94 wrote:

Originally posted by Mel_Gibson Mel_Gibson wrote:

Because I can't afford subs that would give me the same performance as the custom subs i'm thinking of building or having built. I'd say to buy a pair of subs 21" that would be as good as ones I can custom make would probably cost about £1,500 each.

I can't see the design that you have posted up costing anywhere near £1,500 each to build. 

He meant a factory cab with that 1500 each.
Secondhand would also be a good one. You can get some hefty subs for that kind of money (or even less).
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Mel_Gibson View Drop Down
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Points: 36 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Mel_Gibson Quote  Post ReplyReply Direct Link To This Post Posted: 08 December 2020 at 8:55pm
Yeah I meant to buy a brand new subwoofer which would or could be as good as a custom made one using the Beyma 21LEX1600Nd I believe would cost around £1,500 brand new. Obviously it wouldn't cost £1,500 to custom make the subwoofer. The driver is around £450 but I have no idea how much someone would charge me to build me an enclosure for the driver. 
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Mel_Gibson View Drop Down
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Points: 36 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Mel_Gibson Quote  Post ReplyReply Direct Link To This Post Posted: 08 December 2020 at 8:58pm
Originally posted by knet94 knet94 wrote:

Have you considered going the 2nd hand route. Seen some really good cabs going for small money recently. Tho tbh far bigger than the Beyma ones.

Yeah I have but one problem is finding the right pair of subs that are as compact as the Beyma 21LEX1600Nd Beyma enclosure plan which could give me the same kind of spl output and depth of bass is i've found near impossible. Even a pair of Martin Audio WS18x are smaller, tuned higher and wouldn't be as loud spl wise. 
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Mel_Gibson View Drop Down
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Points: 36 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Mel_Gibson Quote  Post ReplyReply Direct Link To This Post Posted: 08 December 2020 at 9:06pm
Originally posted by MarjanM MarjanM wrote:

And what is your actual budget? 
BTW that Beyma 21 inch is not in the highest ranks of 21 inch drivers.

Maybe not their 21" but their 18LEX1600Nd I read somewhere was voted by Pro Sound Web as the best subwoofer driver in 2014. I don't mind going for the RCF LF21X451 driver it's cheaper, has an xmax of 14mm, it's rated at being able to handle 2,000 watts continuous average power and according to the frequency response chart is -3db at 45hz which I believe is free air and has a sensitivity of 98db at 55hz with a pretty flat'ish curve. It states it's good for reflex as well as horn loading. 
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Mel_Gibson View Drop Down
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Points: 36 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Mel_Gibson Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2020 at 8:49pm
If I was to buy an RCF LF21X451 driver who could design and build me an enclosure for it and how much would it cost? 
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MarjanM View Drop Down
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Points: 7708 		Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 11 December 2020 at 1:46pm
I dont really have much time for internet these days, but you should know few things.
That Beyma 21 inch driver is not that good as you think it is. 
One good reflex 21inch sub will never be louder then two good 18 inch subs. 
It might go lower, but not in a "compact" box.

If you buy any driver for like 450, and you pay 350-400 or so for the box, (which i purely speculate the cost) , how will that box look at the end?
Will it have professional box fit and finish?
What will be its resale value?

I am all for a DIY, but not when you can not actually do it your own but you have to pay someone to make it for you. That does not make any economical logic. At the end you will spend 1000 for a box that will kind of look well done, but not as good as a professionally made one.
Marjan Milosevic
MM-Acoustics
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https://www.facebook.com/pages/MM-Acoustics/608901282527713
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