Coffee anyone? Coffee table RL-P 15 vented encl. design help

[benjatelcom]

Greetings everyone, I am new to the forum, but have owned an RL-P 15 and an EP2500 amp since this time last year. Originally destined to be an IB in the living room, I have new construction plans that have taken away the space intended for the IB.

Moving on to my 600sq ft rec room (slightly rectangular with 8ft ceilings) behind the garage, I have considerably more options with floor space, and attic space. I will have 11-12 feet between the seating and a wall designated as projector screen surface.

I could easily build a 15cu ft coffee table type shape to enclose the driver in, vented, and finished in something durable, with an overall height of around 22in. I'm open to everyones suggestions on designs, and hoping that someone with some software can assist with with enclosure dimensions and vent size/placement.

IB is not out of the question either, the attic has a seven foot peak above the center of the room. But for some reason I envision shaking the popcorn finish off the ceiling with an IB.

Should I be trying to keep my RL-P in a horizontal configuration (was recommended by manufacturer, I think)?

Best regards,

Benjamin

[Mike P.]

Hi Ben and welcome to the Shack. You wouldn't need to build a box that big. 10 cubic feet net tuned to 14hz is a good combination and also recommended by Sound Splinter. One 6 inch flared port 35.5 inches long would do the trick for porting. With input power of 750 watts maximum cone excursion isn't reaches until 13hz. WinISD states Spl is not under 110db down to the tuning point. Then you add room gain onto that. Hope this helps.

[Sonnie]

Hello Benjamin and welcome to the Shack!

You sound like me. I sat on 4 of these subs and the same amp for months pending an IB install. I ended up selling those and ordered 2 more later on and built an LLT. I could not be happier. You should actually get a little better extension/response with an LLT design. I think the popcorn finish could be in worse danger.

Looking forward to seeing some pics of the room and the build.

[benjatelcom]

Thanks Mike, thats excellent advice. With a 35.5 inch long port, what kind of dimensions would be optimal (lets assume we have no dimensional constraints to achieve the correct internal volume)?

Where can I get a flared port from? I haven't seen any that long.

Sonny, I was trying to research LLT construction, but got mixed results. I'm still not sure what it is. I'm in favor of a simple construction, I'm no expert on fine woodwork, but I can build a box :-) I already have some foam panels from parts express, spike feet, and a few other misc supplies. I'm hoping that my one driver can match a large movie projection.

Thanks!

Benjamin

[Mike P.]

Expecting to match a large movie projection with a 15 inch sub in a 600 square foot room is asking alot in my opinion. Maybe you should consider the RL-p18? Or do you have the RL-p15 already?

[Owen Bartley]

Ben, I think if you're going to go with the coffee table sub you should be alright with Mike's suggestion, and it should sound great. If you're considering an IB, you may want to add another driver and then you'd really be cooking. If you already have the 15, I'd probably stick with the coffee table, or an end table that you could corner load.

[Mike P.]

Owen Bartley wrote:

Ben, I think if you're going to go with the coffee table sub you should be alright with Mike's suggestion, and it should sound great. If you're considering an IB, you may want to add another driver and then you'd really be cooking. If you already have the 15, I'd probably stick with the coffee table, or an end table that you could corner load.

If he does have the 15 already and it isn't enough, he can always add another one. 20 x 30 is 600 square feet. That's a big area.

[benjatelcom]

I do already own the RL-P15 and the EP2500. If you guys think the single driver wouldn't run the IB system at a satisfactory level, I will opt for a single driver in a table-like vented enclosure. Easy to build, easy to move.

I don't want to throw money at a second driver (and perhaps a second amp) since I have to purchase another HT system to replace the equipment I am pulling out of my living room.

I can place an enclosure against the wall, under the projection screen, but I won't have a free corner (this is where my A/V/network rack will be located).

I could make an enclosure that is horizontally long, that resides under the screen in front of the wall, and I could use a normal coffee table in that situation. It would also keep people away from the projection surface. In this configuration, would it be best to face the driver out towards the couch, or on the side where it can parallel with the 35 inch port? I would estimate that 24hx24dx120w (inches) would be the maximum dimension constraints of an enclosure under the screen (the wall is 14 feet from the edge of the room to the doorway). The more I think about this design the better I like it. Short cable run from the amp too.

Thanks for the help, even though I am still brainstorming on this project, I'm interested in everyones ideas.

[benjatelcom]

Has anyone had trouble driving the EP2500 off of a -10dBu consumer level source? I found I wasn't able to excite the amplifier very well with a standard PCI sound card, but the Gina 3G sound card's outputs set to +4dBu it kicked it off like a champ (and destroyed the "test subject" speaker in seconds).

I realize this is how the EP2500 was intended to be driven, just wondered if anyone else had to work around it.

[Mike P.]

Thr Pro audio eqipment needs a higher input voltage to work properly. Some consumer equipment can supply the required voltage and some can't, from what I've read. If you need to boost the input voltage, it's done by using something like this.

http://www.reckhorn.com/index.php?ln=en&prod=b1

Creative Sound Solutions sell it for $80. There is also the "Art CleanBox " which I have heard about but I'm not familar with. Do a search on the forums for it.

[Owen Bartley]

OK Ben, I'm going to push this design on you too because I love the project. Check out JoeL's stage/proscenium sub here. He uses two drivers, but you could do something similar with your one. If you keep it downfiring it will be fairly unobtrusive, and maybe almost invisible depending on what you want and how you finish it. Otherwise you can still make it look like a nice piece of furniture and show it off.

[buggers]

32 Inches is about the max length you want to go with on a port. Anymore than this and the port may start picking up resonances.

[Mike Cason]

Hi Benjamin,

Welcome to the forum.....

Because you are still asking for inputs on designs, I'm showing you my sub and comments:

I too, am using the RLP-15's. My avatar photo shows my final design after many rebuilds with many drivers and configurations in the past. I've been working on and rebuilding my system for about 8 years to acheive what I've got now. This subwoofer is a 235 pound beast!

This is a rather expensive way to use two 15's and reach those really good lows in both music and theater explosions and effects. I wanted to hear the really low bass at low volumes for background music and I can do this because of the passives. When I want to go to Eric Clapton or Joe Satriani's music and shake the windows.....It's as simple as turning down the gains on the sub amps and cranking it up!!

My LR is about 600 sq. ft. too, and opens to the dining room and kitchen, making the room even larger. I have 9' ceilings. This single sub fills the rooms with plenty of bass for all applications. I shake pictures off the shelves and walls in the rest of the house.

I used to own a high end Legacy Point One sub, but my sub IMHO, has a much smoother bass without the "punched" sound to it.

You have the added cost of the 4 passive radiators ($80 ea.), but the very low bass extension is really worth the extra bucks. I have been so happy with it I've started another one. I have the drivers here in my office and the cabinet is already started to make a duplicate for a twin sub setup. I can't even imagine having 12 - 15" active and passive drivers in one home theater system.

My cabinet is very close to 5 cu. ft. with driver displacement. The 4 passives are the Dayton PR 15's loaded to 1100 grams. My construction details can be found in the links in my signature and if you have any questions, please feel free to email me.

Passive radiator drivers have their own unique sound qualities and are more difficult to tweak, but I've already done the homework. The low Q of the RLP-15 dual 2 ohm make this an ideal driver for the passive radiator system. You also have a company, Soundsplinter & Mike, that are there for you any time you need 'em! Support from this company is awesome!

Have fun,
Mike

[benjatelcom]

Guys I misled you... I have an RL-s15. Not sure how I got that mixed up... I know that improves on the 600sq ft situation though. After running through some room layout scenarios, I think the subwoofer would be best suited under the screen surface, to mostly serve as a barrier to keep people away from the screen, and although not in at three plane corner, it could be in a two plane corner. Will I get any corner gain with two planes?

One of the sound splinter engineers (Mike) advised against mounting the RL-s15 in a horizontal configuration. I am thinking a basic rectangular enclosure with the driver and vent facing straight forward.

This opens up the dimensional design constraints to around 30 high and almost anything goes in the other two. This design would lend itself useful if find the need for a second subwoofer enclosure, as the wall is 14 feet long.

Do I want to follow the golden ratio for enclosure dimensions if possible? I could just start with the optimal volume of 9.5cu ft and work backwards.

Who makes a really good reflex port? Are there any advantages to aggressively flared ports (like my Axiom Audio M22s)?

Thanks for so much input at the brainstorming stage guys.

And one more question, what software are most of you running for enclosure calcs... I tried AJ's calc and it doesn't like the QTS of my driver.

[Mike Cason]

Hey Benjamin,

Bass Box Pro is a good program to use.

I spoke with Mike at Soundsplinter about doing another sub project to have the ultimate in the bass quality I could get with his drivers. He told me if I were to use the RLS-15, to keep it in a sealed enclosure for the best results. Follow his guidlines in the Soundsplinter home page for optimal box size enclosure. Account for bracing and driver displacement when figuring your box size.

That particular driver has a Qts of .953 which is very high for a ported or passive radiator system. A Q of .4 or lower is more suited for this design. AJ's design program is looking at the high Q of that driver.

I just decided to take my sub off the market and build another one just like instead of starting all over again with new drivers.

Make sure you've got lots of power for that puppy because it needs it.

Good luck,
Mike

[TheEAR]

The RL-s15 is a mighty driver (what I would call TC3000/LMS hybrid). In WinISD I would IMO shoot for an EBS design. If the volume is not suitable,from the optimal work backwards,be sure not to underport the driver,check velocity at max (excusion or allowed wattage ...).

The idea is to get the moxt out of the Xmax and have as little port noise as possible. Flaring reduced turbulence...port noise. Flaring is a MUST in my view if not you need huge ports and huge ports sometimes = extyremly long ports. Then you face port resonance and other issues.

ACOUPOWER sells some impressive monster flares(ports). I mean HUGE pourts to vent even the King Kong like Acoupower 18's. Say 10" flared to...BIG.