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Discussion Starter · #1 · (Edited)
Hey folks!

My brother just asked me if I could build him some subs. My response was; "Sure, why not?!".

The thing is, im such a DIY noob. So I need your help!


First of all, my brother is a bass head like me. The difference though, is that he has a job and can afford to buy a lot more bass than me :mooooh: (Im still a student ;) ). So he is looking for INSANE SPL levels (By insane, I mean at least ~125dB at the listening position). Note: His room ain't that big. 5x5x2m or so.

He wants 2x 18" (for him, it doesn't matter which brand. so I choose SS), and a smaller box than my LLT (260Litres netto) - Less than 200litres will be fine, I think (for each subwoofer).



And now to the problem: Like I have already mentioned, im a DIY noob. I don't know how to model subwoofers yet. The little "knowledge" I have, is that a higher tuning will give more SPL (over the tuning point), and that will also result in a smaller ported box. Im thinking a box with XXX net litres, tuned to 25hz (because he is also watching movies, so it would be a nice tradeoff, perhaps?).

Is it possible to build a box with an internal volume of ~200litres or less, tuned to ~2X hz, pumping out tons of SPL, with a 18" ? Any suggestions / tips?
 

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Discussion Starter · #3 ·
200 liters total for two SS RL-p18s? You'll want to go sealed.
200litres total for ONE SS-rlp18".

Sorry about that, I didn't make that clear enough in my main post perhaps :)

If that is still to little volume for one 18", I'll talk to my brother and ask if he can go bigger (if not, 15" will be the way to go)
 

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Elite Shackster
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200 liters each tuned to 25 Hz with two 30x6" ports. Use enough power, 2 Crown XS900's for example. He won't need a high pass filter with music but if he really wants to push them with movies, I would consider a 2nd order HP at 20 Hz.

Use RL-p18D2's (voice coils in series and bridged amplifiers).

Should be plenty loud (=over 125 dB). :bigsmile:
 

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Agh! I just wrote out a thing and it got messed up....**** IE6! :p

Anywho...lets see if I can jot this down again. :p

I modeled up something for your brother.

200 liters, tuned to 23hz with a 8" port. You could safely "dump" 2kw into each sub without bottoming either as long as you had some subsonic filter in place or didnt got crazy with lowend EQ. Which wouldnt be necessary with a alignment like this but I definitely recommend using a subsonic filter is he will be pushing it hard on movies.

Excursion is kept in check. With 1000w into each the highest it gets (besides unloading) is around 35hz and thats barely 16mm of 27mm being used with 1kw each. Not bad.

With a high excursion 18 and with a high tune + lots of power I would most certainly recommend not going any smaller than an 8" port. The 23hz tune would be a 8 x 28.5 inch tube for each box. This is for 200 liters like you wanted. I would go a little bigger than that if you could get away with it. 300 liters would make things much easier and it could go deeper. But 200 liters could work but I wouldnt go any smaller. EDIT: Whoops! Just noticed Ilkka said "2 6 inch ports each"...I tried that and tuned to 25hz...it would be the same length as the one I said but tuned a little higher. Inroom you would be better off with the lower tune cause then you could go lower, have more protection down low and less of a bump around Fb.

Yup...I think I got it all back on here...just written differently...lolz! :D

I could post some Unibox graphs if that would help...

Cool. Good luck sir! :)
 

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Discussion Starter · #7 ·
200 liters each tuned to 25 Hz with two 30x6" ports. Use enough power, 2 Crown XS900's for example. He won't need a high pass filter with music but if he really wants to push them with movies, I would consider a 2nd order HP at 20 Hz.

Use RL-p18D2's (voice coils in series and bridged amplifiers).

Should be plenty loud (=over 125 dB). :bigsmile:
I was hoping to drive the sub(s) with one or 2x Behringer EP2500 (Unless the Crown is cheaper) if that will be sufficient. And one Behringer EQ (to add highpass filter etc)

Two 30"6" ports means that the box will look weird (more like a sonotube), are there any other tuning options, so I can make the box more cube-like ?

Also: What about 2x SEALED 18" (100litres for each subwoofer, is that sufficient?) - will I get insane SPLs with that?
 

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Discussion Starter · #9 ·
First of all, thanks for taking time to come with suggestions to me. :T
Agh! I just wrote out a thing and it got messed up....**** IE6! :p

Anywho...lets see if I can jot this down again. :p

I modeled up something for your brother.

200 liters, tuned to 23hz with a 8" port. You could safely "dump" 2kw into each sub without bottoming either as long as you had some subsonic filter in place or didnt got crazy with lowend EQ. Which wouldnt be necessary with a alignment like this but I definitely recommend using a subsonic filter is he will be pushing it hard on movies.

Excursion is kept in check. With 1000w into each the highest it gets (besides unloading) is around 35hz and thats barely 16mm of 27mm being used with 1kw each. Not bad.

With a high excursion 18 and with a high tune + lots of power I would most certainly recommend not going any smaller than an 8" port. The 23hz tune would be a 8 x 28.5 inch tube for each box. This is for 200 liters like you wanted. I would go a little bigger than that if you could get away with it. 300 liters would make things much easier and it could go deeper. But 200 liters could work but I wouldnt go any smaller. EDIT: Whoops! Just noticed Ilkka said "2 6 inch ports each"...I tried that and tuned to 25hz...it would be the same length as the one I said but tuned a little higher. Inroom you would be better off with the lower tune cause then you could go lower, have more protection down low and less of a bump around Fb.

Yup...I think I got it all back on here...just written differently...lolz! :D

I could post some Unibox graphs if that would help...

Cool. Good luck sir! :)
That seems like a good option as well, sir! Ty.

I'll see if I can draw a decent cabinet with ~200litres internal volume - and then try to convince my brother that is the minimum size to get. If not, sealed will have to be the way to go (But at what internal volume) - hm - I guess that means he would need TONS of POWER as well.
 

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I guess that means he would need TONS of POWER as well.
Sealed or vented...you will need a good gob of power to get high SPLs. Unless you have pro, high efficiency gear. ;) With a single EP2500 you should be able to get into the 120dB area with both of these. It will just be easier (and sound better imho) with a vented alignment. :)
 

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Discussion Starter · #11 ·
Talked to my brother, and he says 200litres is "OK".

Im curious though, what is the minimum recommended MDF size? I used 3/4" myself, but I guess the 18" is a different beast! Will 1" do? (2" for the front baffel)
 

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Elite Shackster
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I was hoping to drive the sub(s) with one or 2x Behringer EP2500 (Unless the Crown is cheaper) if that will be sufficient. And one Behringer EQ (to add highpass filter etc)
2x EP2500 will be good. I would add the Behringer DCX2496.

Two 30"6" ports means that the box will look weird (more like a sonotube), are there any other tuning options, so I can make the box more cube-like ?
How about if he can go a little bit larger, say, 220 liters each, and then use a single 8x23" port? Would that be too long?

Also: What about 2x SEALED 18" (100litres for each subwoofer, is that sufficient?) - will I get insane SPLs with that?
Good SPL but not insane.
 

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Elite Shackster
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Talked to my brother, and he says 200litres is "OK".

Im curious though, what is the minimum recommended MDF size? I used 3/4" myself, but I guess the 18" is a different beast! Will 1" do? (2" for the front baffel)
1" with good bracing will do. Double baffle is always a good thing.
 
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How about if he can go a little bit larger, say, 220 liters each, and then use a single 8x23" port? Would that be too long?


Good SPL but not insane.
I just modeled up you recommendation and compared it to a 200l sealed box. I am still new to this so I may be misinterpreting things... But these two were closer then I thought they would be in terms of SPL. With the sealed being behind 4dB from 15Hz to 22Hz and then 2dB by 35Hz. Some EQ and 2X the amps could make up the difference.

I have liked building a sealed enclosure as my first DIY sub. There are alot of things I have been learning along the way. For example the room modes between 20-30 Hz are causing larger swings in the SPL the what I mentioned from the different designs. But then again I am not an insane SPL kinda person.
 

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Elite Shackster
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I just modeled up you recommendation and compared it to a 200l sealed box. I am still new to this so I may be misinterpreting things... But these two were closer then I thought they would be in terms of SPL. With the sealed being behind 4dB from 15Hz to 22Hz and then 2dB by 35Hz. Some EQ and 2X the amps could make up the difference.

I have liked building a sealed enclosure as my first DIY sub. There are alot of things I have been learning along the way. For example the room modes between 20-30 Hz are causing larger swings in the SPL the what I mentioned from the different designs. But then again I am not an insane SPL kinda person.
Did you check the cone excursion while making those comparisons? ;)
 

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Discussion Starter · #17 ·
How about if he can go a little bit larger, say, 220 liters each, and then use a single 8x23" port? Would that be too long?
Well, im sure I could add an extra 20 litres. By adding those 20 extra litres, what exactly "happends" then? Also: If I want a box with dual drivers, do I just double the internal volume then?, and use two 8x23" ports?

2x EP2500 will be good. I would add the Behringer DCX2496
He was thinking about using just one EP2500 at the start (and then add another if it improved the performance a lot). And of course the DCX2496 will be added into the mix :)
 

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Discussion Starter · #19 · (Edited)
I ended up buying 2 x Rlp18" D2. They should arrive just before christmas!


I will not stick to the original plan, though. Instead, I'll build ONE 220 litres box for my brother (He will get a 2nd Rlp18 when he gets a bigger room/new house)... And one for myself :bigsmile: It was an impulse buy, really.. Im not sure what to do with it yet - I might just build a 220 litres box - or PERHAPS I'll build a huge LLT for it. Anyway: It is ALWAYS fun with MORE BASS :dumbcrazy:

Fun!!! :devil:
 

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Hahaha, good for you Egil. You should do some playing around, build two different enclosures and you'll have a great frame of reference for what type you like better. Then you or your brother can make any changes (if you want) based on what you actually hear firsthand. Like if you build a bigger ported one and his is a small sealed, etc., then you can hear both and pick which one you like best.
 
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