2 x RLp-18" - SPL Nirvana (No LLT)

**Egil** · **11-20-07, 02:54 PM**

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

(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?

**SteveCallas** · **11-20-07, 02:58 PM**

200 liters total for two SS RL-p18s? You'll want to go sealed.

**Egil** · **11-20-07, 03:07 PM**

Quote:

SteveCallas wrote:

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)

**Ilkka** · **11-20-07, 03:49 PM**

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).

**SteveCallas** · **11-20-07, 04:26 PM**

(see Ilkka, I can suggest *small sealed when appropriate

)

**Scott S** · **11-20-07, 04:50 PM**

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

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

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!

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

Cool. Good luck sir!

**Egil** · **11-20-07, 04:53 PM**

Quote:

Ilkka wrote:

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).

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?

**Scott S** · **11-20-07, 04:58 PM**

Quote:

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

Insane SPLs? Yeah, I guess...but with a Qtc of .84 I wouldnt recommend it.

Plus the bass in the 20-30's wouldnt be so hot but ehh...too small.

**Egil** · **11-20-07, 05:05 PM**

First of all, thanks for taking time to come with suggestions to me.

Quote:

Scott S wrote:

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

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

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!

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.

**Scott S** · **11-20-07, 05:11 PM**

Quote:

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.

**Egil** · **11-21-07, 11:58 AM**

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)

**Ilkka** · **11-21-07, 12:26 PM**

Quote:

Egil wrote:

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.

Quote:

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?

Quote:

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.

**Ilkka** · **11-21-07, 12:28 PM**

Quote:

Egil wrote:

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.

**fumoffu** · **11-21-07, 03:23 PM**

Quote:

Ilkka wrote:

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.

**Ilkka** · **11-21-07, 03:56 PM**

Quote:

fumoffu wrote:

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?

**fumoffu** · **11-21-07, 04:16 PM**

Quote:

Ilkka wrote:

Did you check the cone excursion while making those comparisons?

You mean the way the ported likely hit xmax below 14Hz with 500 Watts?

**Egil** · **11-21-07, 04:19 PM**

Quote:

Ilkka wrote:

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?

Quote:

Ilkka wrote:

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

**Scott S** · **11-21-07, 10:52 PM**

You would do just fine with one EP2500 for a start. I am running dual RLp18d4's off of one now and it rocks the place but I intend on purchasing a second amp sometime. No rush but one day.

**Egil** · **12-07-07, 09:42 AM**

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

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

Fun!!!

**Owen Bartley** · **12-14-07, 02:19 PM**

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.

**Egil** · **12-17-07, 08:50 AM**

Even though I have seen tons of pictures of the Rlp15" and 18" drivers, I still enjoy looking at pictures of them! Not to mention that the drivers always look a lot better when you see them first hand

One of the RLp18s arrived today, and it survived the long trip from Canada -> Norway ..

The driver was well packaged!

The laser etched logo was cooler on the RLp18" than the Rlp15" I have:

The second RLp18" should also arrive in a couple of days. I guess it is time to start constructing some cabinets for them!

**Egil** · **01-10-08, 04:44 PM**

Tomorrow I'll buy mats for 2x subwoofers. Both will be ~220litres, tuned to ~23hz.

There is a couple of things im wondering about the FBQ2496 though:

Does the FBQ2496 have a built in SS filter ? (Can I set it to 23hz?)
Does the FBQ2496 'boost' the signal ? (I have an active Behringer X-Over that I know boosts the signal, but it would be nice to know if the FBQ2496 does that also)
And is it possible to have more than one subwoofer on the FBC2496?

Oh.. And it's impossible to get 1" MDF over here.. I can get 1.5" MDF, but it's so **** expensive compared to what I have to pay for 3/4"MDF. So I'll build both boxes in 3/4" MDF.. I'll be adding a lot of bracing - so I hope it will hold

**Warmon** · **01-11-08, 02:59 PM**

Quote:

Egil wrote:

Oh.. And it's impossible to get 1" MDF over here.. I can get 1.5" MDF, but it's so **** expensive compared to what I have to pay for 3/4"MDF. So I'll build both boxes in 3/4" MDF.. I'll be adding a lot of bracing - so I hope it will hold

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