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Scott's Dual RL-p18 'LLT' design/build thread - Page 2

post #31 of 398
Quote:
Originally Posted by Scott Simonian View Post

Hi Everybody!

Some of you around here have seen me post from time to time. I have a fair amount of experience with 'Unibox' but not too much skills with wood working/tools. That is where I will need the the most help. I already know what I want in terms of performance. With two RLp18's, a EP2500 and a small-ass room. Yep, not worried about a "lack of performance"...heh.

So like I said, I know what I want and have modeled it in 'Unibox'. My problem is with coming up with a build guide for me so when I build this sucker, I know what I am doing. Now, I have some wood working experience. I've built a Adire Tempest vented "Adire alignment" about 5 or so years ago when I was a Jr. in High School. Build the original Adire LCC and 281's the following year. That's about all my "experience" in woodworking. Did wood class in jr. high but I kinda slacked in that class and didn't really take-in what I was supposed to be learning.

Enough with the life story...

Why is your similation using only 500 W????
What I want is TWO large cabs, one each to house one RL-p18 and one 8" ID port. I originally wanted to build the whole thing with a 28" ID sonotube @ about 6ft in height but things like a small door and other circumstances have changed the build from sono to MDF. I want them to be pretty large because I am shooting for 650-800 effective liters per cab. Yep, pretty big. Spent plenty of time looking over this similar build over at HTS. http://www.hometheatershack.com/foru...llt-begun.html

I thought a 3ft9in tall by 2ft wide and 3ft9in - 4ft in length each would net me in that area. ***You can see my problem. I have no idea how to really get an accurate internal volume.*** I wanted to got with 4ftx2ftx4ft cab for each cause it sounded easy to design but quickly changed that so when I move out of the house and into a place with "normal" height ceiling I could still stack these suckers. Not that I would want to too often what with how much they will weigh...

So...here are the facts so far.

1) 650 liters minimum per cab, 700-800 liters optimal.
2) Tune will be 12-13hz approximately. Tune will move up if I feel I am not happy with this, the lowest tune. Easy to trim a port.
3) 8 inch ID sono will be used per cab for port. Length will change depending on internal volume and final tuning.
4) MDF will be used with two or three window braces. Front (and possibly) back baffles will be double layer.
5) Sub driver will be front firing with a rear firing port. This lets me stack them with no worries on clearance.
6) Behringer EP2500 will be used in "bridged mode" to deliver up to 2400w (1400w realistically) total to be distributed between them.
7) No finish has been decided on. Probably anything that is easy, durable and cheap.
8) Already have the two drivers just sitting, waiting to be used. Already have the EP2500. Bridged and running my center channel, atm. Just need to buy wood and the other stuff...

I already know that the driver only takes up a few liters and the port will be around the mid 20's into the 30's in liters of volume displaced. I just don't know how much the bracing and stuffing will take up in volume. I can only do the math on the volume of the whole box by simply entering the 4 x 3.75 x 2 into the windows calculator. Heh, not very good at math too, I guess.

***UPDATE 5/11/07 Changed Unibox graphs to show used volume 1440 instead of 1600. More accurate graphs.***

Unibox FR


Excursion


Port airspeed @ 250w each


Impedance



*********

If you want to model out what my finished project will be...Try: 1440liters, two RL-p18d4 in parallel, 12hz tune with a 20.3cm port each. Minimal leakage, walls lined, and one flush end for port.

*********

So what do you guys say...?

Give me some guidance and help a young man enter bass heaven?

Why are you similating with only 500 W???
post #32 of 398
Quote:
Originally Posted by NEO Dan View Post

TheEAR,
Why such a high tune, you going for SPL???

You should make something big enough to keep you from draging it back and fourth from room to room
You got a JL for that, right.

IMHO I think i'll end up with the box above but tuned between 7.5-10hz, BKA filter modded to bring up the low end and protect the driver

The final box size and tune is subject to change I will do extensive modeling tonight.

14cu ft is on the managable side(220-260lbs box,and size fine)plus 14Hz brings me below the pipe organ limit(save for two freaky large pipe organs that would demand a 8Hz tune!). I will have to build two such boxes,one per driver.That is one biggo sub...

I think that massive output down to 14Hz is fine,I do not demand much.

The Fathom,a great sub for what it is...compact wonder.
post #33 of 398
Thread Starter 
Quote:
Why are you similating with only 500 W???

I figure that will be typical power that they would each receive (250w each) in most circumstances of "medium-level" spl's. They are a good 4-6dB louder than my current sub and goes flat all the way down @ 250w each. But of course I will be pushing it from time to time.

Here is the "realistic" full RMS power charts...







EDIT: For reference...or comparison to what I have currently....here they all are...



Afaik, the plate amp that I used had a "rumble filter" @ 18hz. It was the 250w from Adire not PE. So my curve for the Tempest may slope faster <20hz than what shows on screen.
post #34 of 398
Hey Scott,
Did the RL-p18 come with a spec sheet? I'm currious as to the X-mech limit of the driver

Thanks
Dan
post #35 of 398
Thread Starter 
27.4mm Xmax
46mm Xmech

post #36 of 398
46mm Xmech! That is great,there just in case an unexpected nasty peak... Seriously in the worst case you may reach 20mm excusion one way on loud peaks down deep.

Those RL-p18's are fantastic drivers for anyone with room to spare for huge vented boxes.I have recalculated ...final 18cu ft per driver,14Hz tune. 800W per driver,slot ported (3" x 24" opening).
post #37 of 398
Thread Starter 
Quote:


46mm Xmech! That is great,there just in case an unexpected nasty peak... Seriously in the worst case you may reach 20mm excusion one way on loud peaks down deep.

Hehe, so true. I doubt I will ever mechanically overdrive these things.

Quote:


Those RL-p18's are fantastic drivers for anyone with room to spare for huge vented boxes.I have recalculated ...final 18cu ft per driver,14Hz tune. 800W per driver,slot ported (3" x 24" opening).

Good call! That is going to be one hell of an improvement over the Fanthom.
post #38 of 398
Holy crap, I have been looking for the XMech on that driver for a while, that is just plum insane! That is as much excursion as ANY of the TCSounds drivers (3000 and 5200) and tad more than the LMS! That kind of excursion will help if want to hit super deep notes when linearity isnt as noticeable, and most importantly will most likely prevent it from ever bottoming out.
post #39 of 398
I went to Home Depot and weighed a sheet of 3/4"MDF at 88.5lbs, There was some 3/4" ply called classic birch it weighed in at 66.5lbs, I calculated the weight from the cut sheets to 201.567lbs for MDF and 149.9916lbs for the "Classic Birch" this is just the peices for the box, no port, adhesive, fasteners, ect. All in all I think it's possible to build one in Classic Birch and come in under 200lbs total, the Classic Birch was ~$30 a sheet.


X-mech:
whilst there is room for 46mm of throw without interference, I don't think you'll be able to get there on any regular basis(if at all) without stretching the spider(8" dia IIRC). Is there a spec for X-sus listed?
post #40 of 398
Quote:
X-mech:
whilst there is room for 46mm of throw without interference, I don't think you'll be able to get there on any regular basis(if at all) without stretching the spider(8" dia IIRC). Is there a spec for X-sus listed?

Yeah, maybe I am nuts, but I don't see how the Rl-18 could have a higher xmech than the LMS or even equal to the 3000.
post #41 of 398
I think they could have made the LMS capable of more excursion, but just limited the VC height, maybe to help with some of the infinite variables involved in its design as I don't know just what they do to make it a "linear voice coil". What I do know is that none of these drivers can hit these peaks without massive non-linearities, there was a video posted here from youtube of the TC3000 playing in free air. It was definitely moving its maximum or close to it, but you can clearly see the surround creasing and warping each time it makes a downstroke.
post #42 of 398
http://www.tcsounds.com/lms.htm


I love that video
http://www.youtube.com/watch?v=jbc4fW66U34


Army and Will,
I agree about the excursion, that's why I brought it up. I'm holding out for the LMS-2500.
post #43 of 398
Thread Starter 
I have no intention on trying out the Xmech on any driver, honestly. I am not that kind of guy. Maybe if I made a lot of money and could piss away such a beautiful driver...

Dunno if there was a rated Xsus but the clearance behind the cone is pretty big. Yeah, yeah...it only has a 8 inch spider but I am sure it could still go a clean ~30-40mm.

Ah! Payday today! Gonna pick up the supplies as soon as my check goes through. Wow! Only 200lbs for a complete box sans woofer and such? That...isn't as much as I thought. I mean, its heavy but I should have 2 or more friends over to help me move em/stack em and a little over 200lbs with all of us doesn't sound so bad.

Dan - I will have to look for that particular type of wood. Would it be BB or something similar? You think that "classic birch" would be okay as a full cab? I've never cut that type of wood so I hope it is easy to work with. I thought MDF was pretty messy but not too hard to work with.

Also....something prolly for you, Dan. I think I may have to alter one "little" thing about the design. I think I may need to relocate the port from its position to the opposite side, right on top of the driver. (According to the CAD.) Reason why is cause I only have about 50 inches of clearance in that corner. I'll take a picture at lunch to show you what I mean. Don't have any room to stick this out from the front wall. So it will have to be a front firing woofer and port now.

That and I have maids that come over every two weeks to clean. That means I will flip this sucker over 180 degrees. Woofer on top port on the bottom. Sort of like a even bigger version of Thomas W's fifteen inch version of the AW12. Heheheh. No nasty, angry vacuum cleaners are touching my RLp's.

Hopefully that change wont affect too much in the design. It pretty much is just replacing the port postion where that extra brace is above the driver opening (in the CAD).

Let me know what you think.

EDIT: I took these just a few minutes ago...

This is the corner where I have my Tempest. (Look! Look at all that empty space. ) I am standing behind the couch/futon leaning onto the listening position.



This is the depth from the front wall to the corner where the door way is. I have the tape pushed agaisnt the wall. My current sub is about four inchs out from the front wall in. So if I left about the same amount of room behind this it would be at the corner which is acceptable to me.



Honestly, if I go with the front port, I may just leave the back clean and have the binding post on the side. Eh? That way it could be closer to the front wall and not have to stick out as much. Sounds good.
post #44 of 398
Scott,
It seems every Home Depot has a different selection, I'd just took my digital bathroom scale in, and for ply the "classic birch" at $29.xx was all they had that looked useable, at that location. The Idea of a complete loaded enclosure comming in @ ~200lbs Is enough to make me want to try that material, none of the cuts are dificult so as long as your saw is tuned up, it should be a breeze.

No problem on the redraw. I personally would have done the port on the same side anyway, i'll get on it later tonight.

I'd buy the smallest 8" sonotube you can find, every little bit helps keep the port length down.

Take a bathroom scale and weigh the wood you plan on using, saving 20 lbs per sheet for under $10 might be worth it, just make sure there's lots of plys(no 5 ply stuff)

I got to go cut some wood, be back later


off topic, today locally I located a sonotube dealer, 30" x 12' is $112.44(they said they stock up to 46"). 1400+ liters effective, I could ovalise it. Decisions, decisions, decisions.
post #45 of 398
OH CRAP
I just rembered about the size diference in 4'x8' ply vs 49"x97' MDF, If you buy ply your gonna loose a siginificant amount of space.


EDIT:
That is unless you make it 46"h, 26"w, 49.5d, then it's all good in the hood
post #46 of 398
Post what you buy, or intend on buying. I'll make adjustments based on that.
I'm tired. I'll check back in the morning
post #47 of 398
Thread Starter 


I got boned on my paycheck. Somehow I got overdrafted, TWICE. Lost about $100 off the check.

Mega bummer....

I was so pumped up for this weekend too...ARGH!!!

I'll have to go by or call and see what the stores around me have. I woudn't mind saving some weight but at 200-250lbs each, with the help of two more friends, I could get these suckers moved. I think I'll stick with the original design just with the port on the front. Seems like it will keep things less confusing and you already have the CAD for it.
post #48 of 398
Quote:
Originally Posted by Scott Simonian View Post

27.4mm Xmax
46mm Xmech


Here are more accurate specs :

Xmech =1.6"= 40 mm one way.

At 46 mm the voicecoil will hit the bottom back-plate
post #49 of 398
Would this be more like what you had in mind


post #50 of 398
Thread Starter 
Oooohhh yeah! That's nice. Is all the dimensions the same other than the port being in a new position? I can still use the first version if that is the case. I'll be flipping that thing over so that the port is closer to the ground. I am very afraid of getting these drivers damaged by someone much less careful than I.

Thank you once again, Dan!

Quote:


Here are more accurate specs :

Xmech =1.6"= 40 mm one way.

At 46 mm the voicecoil will hit the bottom back-plate
Report Post

Hmmm... yeah....that does sound more realistic.
post #51 of 398
fear no sweeper


Get some 18" towel bars, make a grill.
Olny the surround will be sticking out, the basket boot should be barely above flush with the face of the box.


Yea the box is still the same dimensions and cuts, i'll work thru some final details and produce the .pdf file I offered.

I tinkered thru the volume calculations so many times the software I use has hit a wall. I'm going to restart from the begining.
post #52 of 398
post #53 of 398
I'm going to change the size and location of the holes in the internal braces to keep the volume above 720 liters. Then I will go back and update the post with the cut sheet pictures in it.
post #54 of 398
Thread Starter 
Quote:



I was thinking something like the one on the left. The other way I thought I'd stack them is in a driver-port-driver-port alignment. That will be one of the things I need to take care of... deals with my stacking and where I decide to place the binding posts.

Quote:


Get some 18" towel bars, make a grill.

Looked at some different types of covers and I didn't like any of them really. I will never have them on when I am living with them. I would only use them for transport or when the maid comes over. Not too important right atm.

Quote:


I'm going to change the size and location of the holes in the internal braces to keep the volume above 720 liters. Then I will go back and update the post with the cut sheet pictures in it.

Even more volume? Heheh. Sure! The exterior height and width are mandatory but I'd like to keep the depth right about where you mentioned last. About 50.5" iirc.

Since I have another two friggin' weeks of waiting ahead *sigh*, I am gonna order a quiet fan for my EP2500 and possible snatch a circle-jig from Parts Express. I don't think we have one of those. That and I am gonna put in as much OT at work I can...
post #55 of 398
Well if your gonna order from PE, get yourself some Hurricane nuts to mount your driver

The 081-1084 is 14"-20.
That's big, so make sure the driver's frame will take 1/4", they have WAY more holding power than any wood type screw setup. If you can't find proper 1/4"-20 bolts locally let me know.

I hooked up the woofer tester to the box with the 4-15" it measured the tuning at 12.4328hz, that's a bit lower than spec(14.3hz IIRC), but that's due to the low level that the test is run at.



I finished the drawings, they are on the first page. Just click the easy button to go there.

post #56 of 398




6db per octave @ 30hz room gain in blue
post #57 of 398
Thread Starter 
Awww, Dan...

You ARE THE MAN!!! Woohoo! Those look great!

Couple of questions...(heheh, you knew they were coming. )

1.) I noticed that the second layer @ the baffle is now setup to allow me to recess the driver. I haven't decided if I want to do that because of the weight of the driver. I'll probably set them in before I move them into position but I wonder how much more difficult it would be to place/remove the driver when they are sitting into the cab.
Plus, I wonder if I should add another cutting behind the extra one so the driver will still have double thickness baffle to screw into.
Thoughts?


2.)Is this an estimate of the finished box in room? I don't know WinISD too well...the red line looks more like the predicted output of my current Tempest rather than the Rlp18. Heheh. I could be very wrong though. I love the look of the predicted in-room, though. Holy cow! Hahaha, just what I was shooting for.

Now that this looks like a finalized design, I can print these out and make some copies. Last things to consider: binding post location and the finish. That one will be tough. I was considering using truck bed liner but then my friend pointed out that they will have a texture, which I wanted but then realized that might make stacking a little tough since I couldn't have a little bit of sliding ability. Just in case I didn't "hit the mark" as soon as one was on top of the other. Maybe they are going to be too heavy for that to be considerable but I'd like to know what you all think about it. I would love to use veneer but I doubt I have the skills and with all this surface area I bet it would be rather expensive. Gloss black sound like a PITA as well.

Quote:


I hooked up the woofer tester to the box with the 4-15" it measured the tuning at 12.4328hz, that's a bit lower than spec(14.3hz IIRC), but that's due to the low level that the test is run at.

Wow! I didn't know you were going with quads! I thought you were just making two, heh. Gotta post some finished pics of those sometime. Maybe some more testing pics too. Are you gonna trim down the vents or keep them as-is?
post #58 of 398
Quote:


Wow! I didn't know you were going with quads!

I thought he was referring to his quad AV15 box.
post #59 of 398
Thread Starter 
Yeah. I thought he was talking about the one's he was building for his father. He mentioned that he was building a pair for him.

That must have been a test shot from his quad Eclipse 88's....
post #60 of 398
You are correct, it's the quad Eclipse 88's, no need to alter the port

The double baffle will take it to 421liters, port oal length goes to 32", you will however need to buy another sheet of wood : (
The removal procedure for recesed driver is to, unscrew all the fasteners, grab ahold of the basket boot while partially inserting a screw into a screwhole in the basket, cockthe screw at a moderate angle until the threads allow you to pick up the woofer enough to get your fingers under it. I know it sounds hard but it's not.
I vote for the recess, it is worth the effort.

If you use the Hurricane nuts to mount the driver it won't loosen up due to vibration or change in humidity, wood type screws are bad for this.

If you seal the box with automotive primer or a polyurethane type finish, you then can use regular interior wall paint. It looks as good as any wall

Go to a fabric or craft store and get some felt you can slide the box on that, just take it out once you have the box in place

The pair of single 15" boxes are comming along


Can you post up a couple pictures of the screws that came with your drivers?

Thanks
Dan
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