RL-P's Going Into HT - Couple of Questions

[mlstrass]

First off I'm new to the forum and have spent the past few weeks searching/reading and have found a lot of good information. Seems like a good group on here.

I have a pair of D4 RL-P's that I'm taking out of my car and want to use for HT sub duty. Here's what I'm looking at doing using existing stuff I have unless there's a huge advantage to porting lower.

Each sub will go in 10^3, 6" port tuned to 17.5Hz and be downfiring. I already have 2 big enclosures housing 4 Tempests, so I'm going to cut those down some and make new baffles. Boxes are double walled/braced and lined with batting.

The 6" PVC is 20 1/2" which would give me a 17.5Hz tune. Obviously I could get longer PVC if a lower tune would be better, but if this will work I'd just use what I have. Subs will be 70/30 HT/music. I'm not looking for a low end killer per say, just some very solid output with lots of impact.

Currently have an old Hypex amp that does 800watts @4ohm, and I'm guessing that won't be enough to really push them, so I'll probably pick up an EP2500 to power them.

Pros/cons of front firing vs downfiring? Floor is laminate over concrete and the subs will be in a corner about 6' from listening position.

Any suggestions/feedback is greatly appreciated....

[crackyflipside]

http://www.htguide.com/forum/showthread.php4?t=20164&highlight=rlp+subwoofer

Maybe this could help.

[---k---]

Sounds good. You might want to download Unibox or WindISD and model your proposed sub. Iirc, the D4 version want big boxes, your 280L might be a little small. But, the model will show you everythign to confirm if you're on the right track.

I might be able to whip up the model tonight for you if you or someone else doesn't beat me to it.

I don't beleive that there is any sound quality advantage of front versus down. Lots of people do it for pratical reasons, such as: looks, protection of driver, or space limits.

[mlstrass]

Ryan,

If you could work up the D4's for me that would be most appreciated. I have four sons and work 2 jobs, so free time is at a premium right now.

The boxes I have now are 17^3 with 2 6" ports tuned to 19Hz, so I can do bigger than 10^3 for each enclosure. I was just going off what I read on here and the SS site.

I'm hoping you get a chance and I'll try to log on tonight after I get done reffing a high school hockey game. That's my other job/hobby and keeps me pretty busy, but at least I have some $$$ for toys now and then.

BTW...I'm up near Six Flags, but haven't been to Naperville in several years. I've reffed Darren Pang who used to play for the Hawks. He had a son on a youth travel team a few years ago and he coached the team. Nice guy...

[---k---]

Here are the models. The ones from the SS site don't look too bad. I've also modeled up a slightly bigger box for you with a lower tune. You might want to consider it, but it is up to you.

The only thing is the port speed is getting up there. I don't think it is an issue.

That's cool that you know Darren Pang. Never seen him play, but know him as an announcer. You must live close to CJD.

[mlstrass]

Ryan,

Thanks for working those up for me. Looks like the 280L @17.5Hz might have a little more punch for music in the 20-40Hz range, so that might be perfect for me. As I said, I don't need killer lows that shake the house to death.

Heading out, but I'll check back in later tonight. Thanks again...Mike

[mlstrass]

What are the ones from the SS site? I haven't been able to find any graphs on there since they updated the site...

[mlstrass]

Ryan,

One more favor as I was just reading your build thread and it has me wondering. I already have a box that's 480L, 19Hz with 2 6" ports. Any chance you could model the D4's in that box? If it looks decent I'd probably just throw them in there and pick up the EP2500 and be done with it.

[---k---]

Yeah, I can model this up for you. I'm not in front of the right computer right now. Remind me if I don't remember to post the graphs sometime this weekend.

[---k---]

Your existing box doesn't look too bad. I don't see anything obviously bad. The model is for one port end flared. It may not be optimum for some's taste, but I don't see anything that looks bad. It would be nice if Thomas or someone spoke up and confirmed this. I'm only on my second DIY sub,.

You should just throw the drivers in there and see what happens. You can always build a better box later or buy the better amp. Maybe add some bracing.

Just be careful with the volume knob when you're showing off. You'll probably be able to bottom the sub with some real low frequency content - like the War of the Worlds lightening scene.

[mlstrass]

Ryan,

Really appreciate you taking the time to model it for me. I picked up a piece of 10" sono, so I'll be doing a single 10" port out the top, subs bottom firing. I do have the chance to do either 17Hz or 19Hz and still can't decide. :B Bought some heavy duty casters, so the subs will be 5" off the ground firing into laminate over concrete slab.

Box is 1.5" thick all around, braced internally, and lined with batting.

Wonder if 400watts each would get them moving or should I just order the EP2500 and be done with it?

Actually I'm not that big on super low freq's shaking the house to death. I prefer the loud booms that punch you in the chest and will also be using it for music: 80's metal, old school rap/hip hop, 80's club stuff, etc...

Looks like that box would be a pretty good mix of both. I hope to have it going by the end of the week, as I'm in the middle of a new enclosure for the car. I'll be sure to report back on my results/impressions.

Thanks again for your help....Mike

[---k---]

Everyone says that there not into the super low frequency stuff - until they experance it.

This sub will have plenty of power for the slam it in your chest. I wouldn't worry about that. I love to listen to Blue Man Groups's Audio DVD. The 4th song on the DVD has a drum that just about knock me out of my chair the first time I played it with my sub. I don't think the difference between 17hz and 19hz will be really noticable. The room will make a bigger differance.

One reason that you may not have considered yet, as a reason to do a lower tune, is that the lower tune does offer a little more protection against the sub20hz material that is becoming more and more common in movies. There is debate around the net on if/how/why this works. I'm not an expert, but I beleive that the lower tunning does help, it doesn't completely prevent. My sub doesn't noticablly bottom, even during stupid testing and showoff experiments.

Your box sounds pretty big and stiff. I think I was underestimating it originally. Hopefully it is big enough to prevent it from hopping up and down on those caster wheels you're planning. Raisable side-mounted casters may be prudent, so it can be lowered onto some solid legs.

400W/ch will probably get those things moving, but 750W will move them even more. I'm a bigger believe in trying what you have now, evaluate, then buy more. I hate telling people they HAVE to buy something, if they have something that will be nearly workable. If you got money to burn, buy the EP2500.

Also, consider budgeting ~$100 for a Behringer BFD or FBQ to use as a parametric eq to fix some of the bad stuff created by your room.

Maybe after you get this bad boy finished, we can arrange a time for you to show it off.

[ThomasW]

It would be nice if Thomas or someone spoke up and confirmed this. I'm only on my second DIY sub.

Big brother is watching and you're doing fine..... :T

[---k---]

Always good to know.