DUAL RL-P15 Build

[cpiman]

Hello All,
This is my first post but have been looking around for over a year now. I have a pair of RL-P15 that I have built a ported enclosures for and I drive them with a QSC 1450rmx amp 2 ohm load a channel (4ohm subs). This setup has been working good but I feel I am leaving something a the table. I am now using enclosures that are 22 3/4W 22 3/4H 25 3/4 D with 1.5 inch thick walls. Have 2 4" ports out the back of each enclosure. I don't remember the liters of the enclosures were. If I remember the tunning was kinda high around the 20hz range. So You can see why I would like something different.

I would like to go with a LLT with a tune around 14hz (Open on that) I have plenty of room. I would like to go with 2 separate enclosures for ease of moving. I have room for 36" deep 32" high and 110" wide total outside dimensions. I have played around with WinISD but I have to admit I don't really know what I am doing. I don't normally ask for help but I want to make sure I do this right the first time. Any input I could get would be great.

Thanks,
Chris

[Sonnie]

Hi Chris and welcome to the Shack!

I agree... you can do better with those drivers.

I don't know much about designing the boxes and stuff... I had all these other smart guys help me with mine as well. However, you might check out my Behemoth thread (link in sig) and get some idea of the volume needed and a good tuning point for those drivers.

[WillyD]

So you have the Dual 2ohm VC Rl-p's and a single QSC RMX1450?

[cpiman]

WillyD wrote:

So you have the Dual 2ohm VC Rl-p's and a single QSC RMX1450?

I Have the Dual 4ohm VC and a single RMX1450. I am driving the RMX at 2ohm load a channel. Sounded like a good idea at the time If I need to get another amp I don't have a issue with that

[Mike P.]

Hi Chris. I'm learning about LLT design so I'll put my 2 cents in here. I modelled your subs in WinISD and 11.5 cubic feet tuned to 14hz looks good. Tuning would be one 6 inch flared port 28.5 inches long. An 8 inch port would be too long. At 750 watts input power cone excursion is reached at 13hz. Hopefully someone else will chime in here as I'm not sure how big a LLT design is supposed to be. Let's call this a learning experience for the both of us!

[cpiman]

Mike P. wrote:

Hi Chris. I'm learning about LLT design so I'll put my 2 cents in here. I modelled your subs in WinISD and 11.5 cubic feet tuned to 14hz looks good. Tuning would be one 6 inch flared port 28.5 inches long. An 8 inch port would be too long. At 750 watts input power cone excursion is reached at 13hz. Hopefully someone else will chime in here as I'm not sure how big a LLT design is supposed to be. Let's call this a learning experience for the both of us!

So that Per sub? If so WOW that is big...lol Yah, I am trying to learn all this LLT and I found this is the place to do that at

Here is what I was thinking.......

O.K. Here is an idea I came up with. I took a look at Sonnies' build to get some ideas. I think I would like to go with 280L+ box for each sub with a tune around 12hz. I will use a 6" port. Now, I need to come up with some box dimensions. Now that is a long port I will have to try to work with. I can front fire the subs and port out the sides. With both boxes put together a total of 115" outside dimension that will leave me about 3ft clearance from my walls on both sides of the ports. That should work right?

[Mike P.]

The port length is too long. 36 inches is considered maximum length. 280 liters net tuned to 14hz would make a 6 inch flared port 34 inches long. Raising the tuning from 12 to 14hz also gives you more output in the low end.

[cpiman]

O.K. You are right Mike I was not thinking on that one...

Here is what I have come up with......

Inside box dimensions will be 20"H X 34.5"W X 34"D that gives me 13.54cuft of space now take out the sub @ 0.18cuft and the port with a length of 28.1" .53cuft that gives me 12.86cuft. I will run a window brace the with of the box and put 2 more the depth of the box. I will use 1.5 MDF for the front wall. The front wall will have the Sub and the port firing froward in the room. I will try to get a picture of me idea up today so you guys can understand better what I am thinking.

Now, I am not sure how to figure in how much cuft the window braces will take up so some help there would be great.

Does this sound better....lol

[Mike P.]

The dimensions of the window brace would be 20" x 34" x 3/4". That's 510 cubic inches. Subtract half of that for the parts you will cut out. That'll be close enough. Or you could get technical and draw it out and subtract the parts that would be cut out.

[cpiman]

I think that is what I am going to go for. Unless someone thinks something else would be better. I will start cutting wood on Friday. I will post the build here. Wish me luck

[WillyD]

At 750 watts input power cone excursion is reached at 13hz. Hopefully someone else will chime in here as I'm not sure how big a LLT design is supposed to be. Let's call this a learning experience for the both of us!

Well first off, there is no way that QSC will put out a clean 750W at any frequency, let alone 20Hz and below. Maybe 600W @ 20Hz?

Secondly, I actually have the T/S parameters of a Rl-p 15 DVC4 wired in parallel. Naturally they're different, so the sub will model differently.

It looks like you'll have close to 12ft^3 net? I think I'd go ahead and tune as low as possible (36" long 6" port) if you plan on keeping that QSC amp. Might as well gain a little extension since you won't be pushing the drivers too hard. If you ever plan on upping the power, then I'd tune higher.

[Mike P.]

WillyD wrote:

Well first off, there is no way that QSC will put out a clean 750W at any frequency, let alone 20Hz and below. Maybe 600W @ 20Hz?

Thanks for chiming in Will. The above modelling was based on driver limits and not on the QSCs amplifer output. My opinion is it's nice to know what a subs potential is should you decide to use it.

[cpiman]

WillyD wrote:

Well first off, there is no way that QSC will put out a clean 750W at any frequency, let alone 20Hz and below. Maybe 600W @ 20Hz?

Secondly, I actually have the T/S parameters of a Rl-p 15 DVC4 wired in parallel. Naturally they're different, so the sub will model differently.

It looks like you'll have close to 12ft^3 net? I think I'd go ahead and tune as low as possible (36" long 6" port) if you plan on keeping that QSC amp. Might as well gain a little extension since you won't be pushing the drivers too hard. If you ever plan on upping the power, then I'd tune higher.

Thanks for the input Willy. I don't want to leave anything on the table here. What amp would you recommend? EP2500? I can get that for a good price right now. Would you keep the same tune of 14hz with a bigger amp then?

[Rodny Alvarez]

I have two Rlp15s tune to 11hz on a EP2500 and had no problems at all, I'm not an expert on designing boxes but I think you should be OK with the 36 x 6 port like Willy said, as long as you not going crazy trying to play 12 or 14hz tone for long periods.

[WillyD]

Thanks for chiming in Will. The above modelling was based on driver limits and not on the QSCs amplifer output. My opinion is it's nice to know what a subs potential is should you decide to use it.

For sure.

Thanks for the input Willy. I don't want to leave anything on the table here. What amp would you recommend? EP2500? I can get that for a good price right now. Would you keep the same tune of 14hz with a bigger amp then?

Well, if you want to stick to 14Hz, then I wouldn't get a new amp just yet. You could build the new enclosures, set them up, and see what happens. If the amp clips and you want more out of the subs, buy a better amp. The EP2500 would indeed be a step up, or you could go another step up. Just depends.

[cpiman]

Well I have updated my design. It will be a 15.8 cuft box net. I will tune it to 12hz so the port will be 29.1 in long. I went with a big box so I could start out tuning low. If I want I can always shorten the port to raise the tune up if needed.

This way I can hang onto the QSC amp and if it does not cut it I will get something different. Is there any other Amp I should look at other then the EP2500?

[WillyD]

Is there any other Amp I should look at other then the EP2500?

Depends on budget.

[cpiman]

$500.00

[WillyD]

cpiman wrote:

$500.00

Musician's Friend has a sale on refurb Crown XS900s for $399 shipped (with 3year no-fault warranty). I'd say thats a pretty good deal.

[SteveCallas]

Any reason for wanting to tune to 12hz with "only" two 15" drivers?

[WillyD]

Unless his room is particularly large or he has very capable mains and likes to crank it, I don't see a reason not to.

Soho54 has his pair of RSS390 sonsoubs tuned to 13.5Hz...

[cpiman]

SteveCallas wrote:

Any reason for wanting to tune to 12hz with "only" two 15" drivers?

WillyD wrote:

Unless his room is particularly large or he has very capable mains and likes to crank it, I don't see a reason not to.

Soho54 has his pair of RSS390 sonsoubs tuned to 13.5Hz...

The room is 2520cuft that is open to my dinning room and kitchen via a opening in the back of the room that is 7' X 9'. I have no trouble now filling that room with good bass. My mains are JBL Northridge 100 E-Series that I feed with a QSC 850rmx that gives 185watts from 20-20. The mains do very well keeping up now. I just feel that I am missing out some on the lower end. I figured tune low I can alway bring it up.

I went ahead and orderd the Crown XS900.

[WillyD]

Sounds good.

[Exocer]

cpiman wrote:

The room is 2520cuft that is open to my dinning room and kitchen via a opening in the back of the room that is 7' X 9'. I have no trouble now filling that room with good bass. My mains are JBL Northridge 100 E-Series that I feed with a QSC 850rmx that gives 185watts from 20-20. The mains do very well keeping up now. I just feel that I am missing out some on the lower end. I figured tune low I can alway bring it up.

I went ahead and orderd the Crown XS900.

Looking forward to your comparisons.
Its threads like these that get me wondering about big ported subs

[cpiman]

Well, I got the wood all cut and one box almost done. I ran out of heating fuel at 11 tonight and it is -10 so I can't work without it

Here are some pictures so far what I have done........

Sorry for the bad pictures I used my camera phone