Which enclosure for cheap 18"?

Haven't simulated it but a quick look seems to indicate horn or possibly bass reflex. Q is a little low for sealed IMO. Not a lot of xMax but with 18" it may not be needed. The question in a horn would be whether the cone structure is strong enough for the pressures. Sometimes that can be a problem with large drivers. Other than asking the manufacturer I do not know how you would discern this by yourself.

Now that I think about it the fs is probably a little low for a horn anyway (Unless you are after subsonics primarily). I would model some ported enclosures and see how it comes out. Free software like BoxPlot et.al. are very nice for this purpose.
 
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Guess it depends on what sort of performance you're after. For instance, four with 400 W on tap in 20 ft^3 tuned to 16 Hz has enough theoretical peak SPL to either blend to some room gain and/or EQ it flat all the way down or meet THX cinema reference down to 25-30 Hz. Trade some peak SPL for more damping to further 'tighten' it up to better mate to horns.

Or you can use two drivers/400 W/20 ft^3 in a TH to get similar results to 80-100 Hz.

GM
 
dynaBel PA-1800_T-TQWT

FYI:

b:)
 

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Ah! So it is you! The City of Bergen didn't 'ring any bells' with me.

Merry Christmas to you also! ('Sounds' strange nowadays, what with all the political correctness 'forcing' folks to use 'Happy Holidays')

Well, you know me, 20 ft^3/dual 15" is just a good starting point for getting serious, but your horns already take up a sizable percentage of living room 'real estate' if it's the same as you sent pics of several years ago.

GM
 

Frode

Member
2003-05-04 8:49 am
Bergen
Ah! So it is you! The City of Bergen didn't 'ring any bells' with me.

Merry Christmas to you also! ('Sounds' strange nowadays, what with all the political correctness 'forcing' folks to use 'Happy Holidays')

Well, you know me, 20 ft^3/dual 15" is just a good starting point for getting serious, but your horns already take up a sizable percentage of living room 'real estate' if it's the same as you sent pics of several years ago.

GM

Yeah, it's me. I guess we Norwegians are less political correct than you.;)

I still have the Oris setup, but last week I received a pair of 300Hz Iwata/LeCleach horns from Poland. The drivers are the coaxial 2" BMS 4592ND. Right now I'm not sure in which direction I should go. I could sell the Oris top and use the bass section for the Iwata, sell the complete Oris and make a new bass system for the Iwata or simply keep everything.

Frode

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Numbers...

Efficiency bandwidth product at 74.1935..........puts it in the ported camp. I got 6.370851892 Cubic feet ported for an F3 of 33.83327096 Hertz. An impressive size enclosure for an equally impressive size driver. A straightforward slot style port on the bottom.....as finding a six plus inch pre-made port-tube might be hard to find.


_____________________________________________________Rick.........
 

tb46

Member
2006-01-09 7:04 pm
Texas
Hi Y'all,

Some more Hornresp numbers:

A compound reflex port/front horn @ about 220 Liter net has a nice impulse response in Hornresp. A bit bigger than a standard BR, but may be worth the effort to match with the Iwata/LeCleach horns mentioned above.

A 600 Liter tapped horn would average about 109 dB in the pass-band, and provide 106 dB @ 20Hz; this is driven to Xmax=4.5mm with Eg=14V. Not very impressive (?).

Regards,
 

Pirium

Member
2008-01-31 4:20 pm
Hi Y'all,

Some more Hornresp numbers:

A compound reflex port/front horn @ about 220 Liter net has a nice impulse response in Hornresp. A bit bigger than a standard BR, but may be worth the effort to match with the Iwata/LeCleach horns mentioned above.

A 600 Liter tapped horn would average about 109 dB in the pass-band, and provide 106 dB @ 20Hz; this is driven to Xmax=4.5mm with Eg=14V. Not very impressive (?).

Regards,

I have no use for 20hz-response, is it possible to tune the system a bit higher to gain SPL, or do you have to tune near FS when building horns?
 

tb46

Member
2006-01-09 7:04 pm
Texas
Hi,

A tapped horn tuned to a similar low end corner as the BR will be about 300 Liter, and be about 1.5 dB more sensitive. I recommend you fire up Hornresp, and give it a try there are just too many different results that can be achieved in a simulation.

My recommendation would still be along the BR/front horn line.

Regards,
 

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I recommend you fire up Hornresp, and give it a try there are just too many different results that can be achieved in a simulation.

Yeah, just running the numbers tuned to Fs, it gets pretty big at ~409 L net with the high Vas, but with 800 W on tap it has good enough dynamic headroom for a HIFI/HT app (2pi):

GM
 

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