Beginner subbuilder looking for advice on 18" dual subs

**clausdk** · **01-19-09, 03:12 PM**

Hi!

Having had great experience on this forum with REW and BFD and general tips I went ahead and read everything I could about sub building.

I already own a SVS PB12+ and as much as I like that sub I want more!

My plan is basicly to build 2 subs and have them painted white (gloss) to flank a furniture in a white finish with black front made of wool.

I got the building down, that shouldnt pose a problem I hope.

My plan is to build 2 subs using 18" drivers and sealed cabinets and then use the Behringer E2500? amp to drive them both.

My questions are as follows:

1) 90-100 liter (per sub) cabinet ok for dual 18" subs?

2) What kind of output can I expect in a 2500 cubic feet room with 2 such subs? (modelled with WINISD and it says 118 db 30-50hz?)

3) Can I use my behringer 1124 DSP to EQ those 2 sealed subs correctly? (one on left channel, one on right?)

4) Will I need other hardware other than E2500 AMP, DSP 1124 and a surround reciever?

5) Does anyone from Europe read this? if so, do you know any suppliers of good 18" drivers?

6) Any US folks reading this, know any international shippers of good drivers?

Basicly I'm looking for a template to simply duplicate a working 18" sealed construction.

My problem atm, really, is finding decent 18" drivers in Denmark (suppliers i mean)

Recommendations?

Kind regards

claus linde

**Ricci** · **01-19-09, 03:40 PM**

Hello Claus,

100L is very small for an 18" driver even sealed. The only one that I know of that was really at home in that small of a box was the TC Sounds LMS Ultra/5400 which is very rare and not being currently produced. It is also very expensive and very power hungry. You can use other 18" drivers in that size box but you will need a lot of power and EQ to bring the low end up.

Can you increase the box size to the 170-200L range for each? This is a roughly 22"-24" cube. There are a few good 18's that will work in this much airspace here in North America. I'm not sure, what is available there in Denmark, or were you going to import something?

These 18's will all be great in 170L sealed.
Exodus Audio Mal-X
SoundSplinter RLP 18
Mach5 IXL18

The Mach5 is the least expensive. The other 2 are significantly more but are also of arguably better quality and output potential since they have more displacement.

You will likely need an EQ with any sealed set-up to bring the low end up, but depending on the shape and construction of your 2500cu ft room you may not. You would probably have all of the output you could want with a pair of sealed 18's in that size of a room.

**clausdk** · **01-19-09, 04:11 PM**

I just calculated a bit, and I only have to add a few inches to drasticly increase volume, so 23" cube would be ok I think - need to check with wife :P wanted it as small as possible.

Soundsplinter RL-18p is the one I used in WINISD actually, but I dont think I understand the program fully, because it looked to me as if I got really good numbers with just 100 liter, but as I mentioned, really new at this.

Guess if I could find some dealer to ship 2 x soundsplinter RL-18p I would be set.

One amp would be enough?

And btw, dual coil, 2 or 4 omh?

**Blaser** · **01-20-09, 06:10 AM**

I have tried both one and 2 amps configurations. I must say it depends on how hard you wanna drive the subs.

**clausdk** · **01-20-09, 06:18 AM**

Might have found a dealer in a nearby country do Denmark, they sell the Exodus Audio Mal-X and Fi Audio waiting on price info, otherwise I'll import yes.

Doing more calcs, using the FI audio Q18. With a 170Liter cabinet seems to perform fine?

Not sure how hard I wan't to drive them. My SVS PB12+ is very good but I think this dual 18" setup, even if going with smallish cabinet should blow my mind.

I think I'll have all the SPL I could ever want, only REAL concern I have (besides my ears) is the actual sound quality of a home build sub?

My priorities are sound quality for music before anything else.

**Ricci** · **01-20-09, 01:35 PM**

The Mal-X calls for a bit smaller sealed box than the RLP, so that would be the first choice, followed closely by the RLP's. They both should be very high output in pairs with excellent SQ too. The Fi Q18 needs a much larger box to get the same system response.

A pair of any of these 18's with just the one amp should be better in every way over your SVS. I think you can go with the single amp at least at first because you have 220v electrical service in Denmark (correct?), which should allow your amp to perform better than it would here in the US with our 110v lines. if one is not enough then you can get another or upgrade.

**clausdk** · **01-20-09, 05:10 PM**

I think I should be able to get some Exudos Q18s maestrom, the new ones by april march from a nearby dealer in my region!

Pretty much set on a 22-23" cube now that will flank my stereofurniture, which is 23" high, but mounted on the wall. Then the 2 subs will be flush with that, think it will be awesome looking!

And yes, youre correct, 220volts, so I can start with one amp I guess then.

Did more modelling, becomming familiar with the program :=)

Basicly what I need now, is an expert opinion on specific design, and I am thinking about volume of the box - 170 liter?

**clausdk** · **01-27-09, 05:58 AM**

Quote:

Ricci wrote:

The Mal-X calls for a bit smaller sealed box than the RLP, so that would be the first choice, followed closely by the RLP's. They both should be very high output in pairs with excellent SQ too. The Fi Q18 needs a much larger box to get the same system response.

A pair of any of these 18's with just the one amp should be better in every way over your SVS. I think you can go with the single amp at least at first because you have 220v electrical service in Denmark (correct?), which should allow your amp to perform better than it would here in the US with our 110v lines. if one is not enough then you can get another or upgrade.

Aiming for 2 Mal X now as soon as they become available in europe - should be marts april I hope.

I am more or less going to copy this build here: http://www.hometheatershack.com/foru...m-x-build.html

I'm about to set off for the home depot wood supplier and have them cut out the wood for me.

Wife's a bit concerned with a 24.5" cube - sooo I'm trying to size it down just a bit to 23".....

Will I need a subsonic filter?

I'll be using the reciever with 80hz crossover most likely, then through my DSP 1124 then to the EP2500 then to the sub.

Thanks for all the input so far, please let me know if im missing something in my thoughts on this build.

/claus

**Mike P.** · **01-27-09, 12:29 PM**

A 23 inch cube will give you a net volume of 155 liters.

Quote:

Will I need a subsonic filter?

No. With the EP2500 producing 650 watts per channel into 4 ohms for each sub, the Xmax of the sub is no where near its limit.

**Ricci** · **01-27-09, 01:29 PM**

Yep. No need for a filter here. You may need an eq to boost the low end a few db's. A 23" cube should be fine.

I think that the EP2500 will likely put out quite a bit more than 650w per driver in bursts. The 220v in Europe is quite a bit more stout than the 110v in north America. It should help the amp produce closer to it's rated power.

**Mike P.** · **01-27-09, 01:47 PM**

Quote:

The 220v in Europe is quite a bit more stout than the 110v in north America

Good point.

**clausdk** · **01-27-09, 02:48 PM**

Ok to one EP2500 should do I think for my 2500 cubic feet room. Also I do have a Behringer 1124DSP EQ that I am using right now with great succes

I am still really really torn about the size for the 2 subs.......my desk here is littering with designs and shapes and sizes hehe.

Enlighten me on the whole enclosure size thing to me it seems I get better group delay, less cone excursion the smaller box and according to WINISD I only lose a few db?

I'm a newbie I know so I'm gonna go with the advice I get from here.

My recent design ended up with a 61.5cm on all sides, thats 24.21" thats the biggest I can do. I wan't to do smaller, but I wont give up on actual sound quality.

Atm my SVS does around 100db at 20hz - I'd like that around 106 with this setup.

Doable with smaller design or am I just gimping an excellent subwoofer driver doing that?

Kind regards

claus linde

**Ricci** · **01-27-09, 03:11 PM**

You won't lose too much by going a little smaller, but you could use as much efficiency as possible since you are going to be amp limited. The smaller box will roll off slightly sharper and quicker also. The difference between a 24" cube and a 22" cube won't be night and day, but I would favor the 24" slightly.

These 2 18's with the EP2500 should have way more headroom in every conceivable way. They have over 4 times the cone area and displacement, plus you'll have 4 times the power.

**clausdk** · **01-27-09, 04:46 PM**

My current 61.5 cm (24.21") design tells me 178 liters, then I need to subtract the woofer, filling and internal bracing. Im guestimating around 18 liters for that ending at around 160 net internal volume. Thats gets me a Fsc at 33.22hz as far as I can tell.

Hope wife doesn't get too shocked

Recommendations on speakerwire for this type of design?

**Ian M** · **04-13-09, 07:44 AM**

My two cents worth (as a starter here I need 3 more posts).

If you drive each bass driver of a closely mounted pair with one channel of a stereo power amplifier, you will see a +6dB gain due to mutual coupling. You can see this in WinISD by halving the enclosure volume, halving the input "system power" and removing one driver. If you physically separate the boxes and position them more than approximtely 1 wavelength apart (say for 40 Hz thats 8.6 metres), you get only 3dB gain from the second sub. I have had great success with a pair of obsolete JBL 2241H drivers each in adjacent 100 litre sealed enclosures and with a 12dB/octave ESP processor in front to compensate for natural roll-off below resonance (approx. 75 Hz in my case). 120 dB at about 25 Hz using a 365 Watts input to each driver. A much better, faster and punchier result than using a ported enclosure. However! Beware of the requirement for lots of power at lower frequencies with this kind of EQ and possible amp clipping and it's consequences.

Oh. Speaker wire. Use any heavy gauge cheap speaker wire sufficient to carry the current. At a given gauge there is no difference in sound quality whatsoever between different wires on bass frequencies.

Advertisement