[splatee]

Hello,

I currently have 2 RL-I12 dual 4 ohm subs that i have been using in my truck for almost 4 years or so. These are one of the orginals with no logo on them. I am now thinking about using them in my home theater. I would like to build sealed boxes for them or a slot/ported box like the one for those infities that have been going on. I plan on running a external amp like a Berhinger EP2500 or something similar that can provide power in 2 ohm or 8 ohm because that is the 2 wirring choices i would have with these being dual 4 ohm. Probally go with something in the 8 ohm range because that would be less stress on the amp. I have been using the WinISD program and i am a bit confussed with it. I play around with the box size and it says a 20x20x20 sealed box would give me roughly 32hz. I would like to stay around this size or go smaller if possible.

I currently am running a Phase Technology Octave 1.0 15 inch sub and a Velodyne VX-10. I was originally planning on building another 15 inch and adding a plate amp. But now i am pondering this idea.

Any ideas on box size?
Would it be worth it to even use these subs in home theater?
Should i just go with my first idea and get a 15 inch sub from PE and plate amp.

Thank you

 

[Mike P.]

I was unaware there ever was a RL-i12. Post the T/S parameters for it so we can model it.

 

[splatee]

It was discontinued by them. I guess it was because the RL-P12 was selling more. Here are the specs.

a.. Qts - 0.247
b.. Qes - 0.273
c.. Qms - 2.521
d.. Fs - 18.563 Hz
e.. Re - 5.69 Ohms
f.. Ls - 4.788 mH
g.. Lp - 5.461 mH
h.. Rp - 9.682 Ohms
i.. Vas - 166.5 L
j.. Sd - 0.0457 m^2
k.. Mms - 149.3 g
l.. Cms - 492.2 m/N
m.. Bl - 19.03 T*m
n.. Sensitivity - 87.73 dB
o.. Xmax - 19 mm

They are rated at around 400 watts rms.

Thank you

 

[Mike P.]

Note the Cms spec should read 492.2 um/N.

Here is sealed vs. ported. Both with 400 watts input and both with a HPF at 15 hz.

 

[splatee]

Thank you.

So what should i go with....ported or sealed? I would like to go sealed. So if i were to go that route i would roughly need a box 15x15x15 to give me around 1.9cu. Can i go a bit bigger like 18 x 18 x 18 to give me around 3.7cu and have a lower response? Would that cause any problems? Also how would these perform in a vented type box like the one that is all the rage for the infinity perfect 12.1.

Thank you

 

[Bent]

with the RL-i, I'd certainly not let the EP-2500 seem to low of an impedance.
Not because it would hurt the amp, but the '2500 could effortlessly leave you without a driver(s) in seconds at lower impedance's.

 

[Mike P.]

Can i go a bit bigger like 18 x 18 x 18 to give me around 3.7cu and have a lower response?

A bigger box means the sub will reach Xmax with less watts (300) and have a lower overall SPL. A HPF is still required at 15 hz, low end gain is minimal.

 

[splatee]

Hmmm....ok

So if i go with a smaller sealed box i can run more watts basically? SO i guess my box size would also depend on what amp i end up going with? Also would these speakers work well in a box like the one that is for those infinity perfects?

When you say a "HPF @ 15 hz" do you mean i need to have an equalizer as well? Or the amp will have a setting on it for this?

Sorry for all the noobish questions. I have been reading alot on the forum but still get confused when it comes to the "pro audio" gear.:wits-end:

Thank you

 

[Mike P.]

Post #4 shows what you can expect in both sealed and ported. Both can handle 400 watts before Xmax is reached. a HPF is a high pass filter, also known as a rumble filter or a subsonic filter. You need one at 15 hz to block the frequencies below 15 hz from causing the sub to exceed its Xmax. (bottoming out).

 

[splatee]

Here are a few amps that i am thinking about using. I am planning on running them @ 8 ohms right now.

Behringer EP 1500 or 2500
GEM Sound EXA 2955 or 3955 --- can't find any info about them on forum search.
Samson Servo 600

Also is it going to be neccessary to run a equalizer. Some say no and some say yes.

Thank you

 

[Mike P.]

EP1500 would do nicely. with 1400 watts 4 ohms bridged, wire the subs series-parallel for a 4 ohm load. As for an equalizer, it depends how far into this you want to get. Using REW to determine your in room response would be first, then adjusting the response to smooth it out with a Behringer BFD 1124P would be next.

 

[splatee]

Well i think i have my amp choices narrowed down.

I can get either a.....

Crown xls202
Crown Com-Tech 410 or 810

These are both available on my local craigslist for under $200.

Now i have another question. The crown com-techs were installed in a movie theater from what the seller says. He said that the back has a barrier strip input(speaker wire inputs) but most of the others have a balanced 3-terminal barrier block, which is a stripped xlr input. How would i go about connecting my receivers subwoofer output to this if it has just the speaker wire terminals?

Thank you

 

[Mike P.]

The Crown Com-Tech 810 for under $200 would be the best deal. It has the most power with 455 watts per channel into 4 ohms. I have no idea on the terminal strip connections, hopefully someone else can answer that for you.

 

[splatee]

Hey everyone, sorry i have had things come up and have kept me away from this project.

Well i am still thinking about going the DIY route but still not sure. If i were to go ahead and use the two RLi's and give them roughly 400 watts rms each what kind of performance should i expect? Would i just be better off going with maybe a Ed A2-300 or similar or would going with 2 x sound splinters in sealed boxes be the way to go?

Thank you

 

[splatee]

I am a bit confused still with the box size/calculations. I want to go sealed with these subs. I would like to have them go to 18hz to 20hz room response sealed. Looking at the previouse graph it says volume = 1.8 and 39.19hz. Does this equal to 18hz to 20hz room response? Sorry for the noobness

Thank you

 

[splatee]

Ok, i used the box volume calculator and let me know if this right.

I came up with a box size of 16" x 16" x 16.5" for a sealed box. This was using 3/4" thick. This would give and internal volume of 1.825.

Now i am not sure how to do it if i were to go ported. How big of a port would i need in order to tune it to 18 to 20hz? The graph above says i would need a box with 3.8 volume. Im not sure how to input that in the volume calculator and port size.

Thank you

 

[Mike P.]

A slot port with internal dimensions of 2" high x 8" wide and 28" long will tune a 3.8 cu.ft cabinet to 19 hz. You'll need to figure out the displacement of the port, bracing and sub to find the total internal volume you'll need for the cabinet.

 

[splatee]

I am leaning more towards the sealed box. So do these dimensions look correct? 16" x 16" x 16.5" for a sealed box. I would be feeding roughly 300 to 400 watts. Would i would like to at least go down to 20hz. Is this possible? I would like to avoid running an eq if possible. Or what would be the correct box size.

Thank you

 

[Mike P.]

The box dimension are correct. You might see 103 db at 20 hz depending on how much room gain you get. You will need a hi pass filter at 15 hz with this setup.

 

[splatee]

Out of these 3 amps which would be the best choice. They are all available localy and are under $200.

Samson SX-1200 2 x 300 @8ohms or 2 x 600 @ 2 ohms.

QSC 1400 2 x 200 @8ohms

Crown Power Tech 1 2 x 220 @8ohms

I like the samson because it is more versitile in the power choices since I can either run 8 or 2 ohms on the subs. The crown and qsc seem to be a bit dated so I am a bit hesitant. Any thoughts?

Thank you
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