Dual RL-p15 D2 LLT Sub Project...

[SteveCallas]

Good news. As I mentioned earlier, with your room gain, 570 effective liters and a 13hz tune should work great. That's an 8" diameter port that is 34" long.

[Sonnie]

That sounds good to me.

Right now I'm at 581 liters... I suspect there will be more than 11 liters occupied by the bracing and subs, so I probably need to up that some.


Is that 34" including the ¾" wall? That would make the pipe part actually 33¼".

So can I stretch the internal height to say 36" and adjust the width if needed... then place the port center of the box either ported up or down?

[SteveCallas]

Make the actual port (I'm assuming you'll use sonotube) 34" long and then roundover in addition.

The port should be firing out one of the sides on the long 90"+ dimension. 36" definitely won't cut it, the internal port opening wants to be a minimum 8" from any obstruction, preferably more.

[Sonnie]

Will do!

Thanks!

[Sonnie]

SteveCallas wrote:

I'm assuming you'll use Sonotube

I'm not sure I'll find Sonotube around here. Lowes may have something similar to Sonotube, but I know we have 8" PVC pipe that's very easy to come by.

[Chrisbee]

I have a few reservations.

Physically moving that huge and heavy box into place.

Panel resonance will have to be dealt with by bracing.

Bass localisation. The Plus2 is quite a compact source in comparison.

Phase-related response errors.

If the box is ported at one end with the driver at the other the physical separation of the sound sources might prove problematic for the nearest seats.

Have you considered placing the enclosure(s) in the garage firing through the wall into the HT?

Only the slight noise escaping through the panels to worry about.

You can have two widely spaced enclosures for a better bass spread without cluttering the HT.

Much greater freedom in design without worrying about finish.

[steve nn]

If the box is ported at one end with the driver at the other the physical separation of the sound sources might prove problematic for the nearest seats.

Because of NF seating, this was my first thought.. I'm thinking that orientating the port with the drivers might serve you best, but you don't have the height for a single.

[Sonnie]

Chrisbee wrote:

Physically moving that huge and heavy box into place.

True, it will be heavy, but nothing that can't be handled and it will only have to put into place once.

Chrisbee wrote:

Panel resonance will have to be dealt with by bracing.

Yes... it will need proper bracing, no doubt. Rodny will be helping me and he's really good at it... not that he's built one this big, but together I'm sure we can handle it.

Chrisbee wrote:

Bass localisation. The Plus2 is quite a compact source in comparison.

Keep in mind I will have the levels matched and I have a pair of Plus/2's. They are crossed over at 80Hz and these in the rear will be crossed over at 60Hz.

Chrisbee wrote:

Phase-related response errors.

I've not experienced any problems with this thus far with the rear sub at 0 degree phase. I've tested it in 30 degree increments up to 180 degrees. I don't see how swapping subs will change this, but maybe I don't understand something I need to understand.

Chrisbee wrote:

Have you considered placing the enclosure(s) in the garage firing through the wall into the HT?

You can have two widely spaced enclosures for a better bass spread without cluttering the HT.

Much greater freedom in design without worrying about finish.

That would be ideal, but I can't take up the room in the garage. The attics stairs fold down next to the outside of that back wall, so anything protruding into the garage would be a nono. Plus it's a small hallway to an outside door... I don't see that working, even though it would be nice. What would be even mo betta would be my wife allowing me to extend the room all the way through that hallway, but it would require moving the stairs and a whole lot more I just really don't wanna get into.

Chrisbee wrote:

If the box is ported at one end with the driver at the other the physical separation of the sound sources might prove problematic for the nearest seats.

There will be two drivers and the plan is to locate them 1/4 distance from each end...



It would seem like the simple solution to this is two discrete enclosures with a port for each one.



I believe Stevecallas stated I would need at least 260 effective liters and a 6" diameter port that is 31" long. Would this be correct for a 13Hz tune?

Speaking of tuning to 13Hz... is not the purpose of the port to augment the tuned frequency? If so, how is anyone going to localize 13Hz?

At any rate... would sealing off each driver for two discrete enclosures be the best solution?

[SteveCallas]

If the box is ported at one end with the driver at the other the physical separation of the sound sources might prove problematic for the nearest seats.

Speaking of tuning to 13Hz... is not the purpose of the port to augment the tuned frequency? If so, how is anyone going to localize 13Hz?

It's not that you would localise port output, it's that due to the length of the sub and your proximity to the drivers, the driver output and port output may not have had enough space to mesh by the time the driver output gets to your seat, and the driver output would be louder in relation. You could solve it by placing the edge of the sub where the port opening will be the same space from your seat as the center point between the two drivers. I'd probably face the port side towards the side wall corner too, keep it about 1' away though. Ideally such a sub would be a good 6' or so away from you, like say, in the front of the room where some other ones are , but I think you already covered that.

Keep in mind, 570 liters is pretty big

I believe Stevecallas stated I would need at least 260 effective liters and a 6" diameter port that is 31" long. Would this be correct for a 13Hz tune?

No, the 260 liter, 6" diameter port that is 31" long would be for the more common ~15hz tune design. You'd have to do something like 320 liters and a 6" diameter port that is 35" long to get it to work with a single driver sub. That's definitely doable, but I don't see what you are gaining, as the ports would still be best firing out the sides.

[Sonnie]

SteveCallas wrote:

You could solve it by placing the edge of the sub where the port opening will be the same space from your seat as the center point between the two drivers.

I'd probably face the port side towards the side wall corner too, keep it about 1' away though.

Ideally such a sub would be a good 6' or so away from you, like say, in the front of the room where some other ones are , but I think you already covered that.

I'm not sure I have a lot of options, but it will all be around 6 feet from the main listening position, which is just in front of the steps you see in the pic below. The back row is generally where we put the kids that complain about reclining and they probably couldn't tell the difference one way or another... actually, I'm not sure I could tell a lot of difference...

Here's an idea of what it will look like (excuse the old photo but it was the only one with no furniture in the room)...

SteveCallas wrote:

No, the 260 liter, 6" diameter port that is 31" long would be for the more common ~15hz tune design. You'd have to do something like 320 liters and a 6" diameter port that is 35" long to get it to work with a single driver sub. That's definitely doable, but I don't see what you are gaining, as the ports would still be best firing out the sides.

I was only thinking it might make it better for the back row if we make it two enclosures... at least each port will be closer to its own sub... like this...

[Sonnie]

How about doing away with the down-firing and have each sub fire out the side right beneath the port...



Would I lose any extension... seems like I read somewhere that downfiring gained some extension.

[SteveCallas]

If your own seating position is ~6' away, then I wouldn't worry at all. Two enclosures would definitely make constructing and moving the subs a lot easier. Downfiring won't add extension per se, but I often see it associated with smoother FR's in room. I think what you were referring to is when the baseplate is close to the drivers though, like with an SVS sub. The drivers essentally couple with that air between the baseplate and it acts to lower the Fs of the driver a bit. That's not necessary for this sub though.

Make sure you are taking breathing room for the external port opening into account as well - at least the diameter of the port, preferably more.

[Sonnie]

Separating them into two enclosures seems to make more sense... although we will be cutting it close on the port clearance. The internal width could only be about 45" or so.... a 35" port tube will still leave us 10" of clearance.

As far as external port clearance... they should be about a foot from each angled side wall.

[steve nn]

Sounds like a plan is formulating. My thinking was that you sat in the chair that backs up to the sub/subs. We certainly didn't want your head a ft away from the port

The internal width could only be about 45" or so.... a 35" port tube will still leave us 10" of clearance.

Your good, I've built tighter in a pinch..10" is very doable.

[Sonnie]

Sounds like a plan is formulating. My thinking was that you sat in the chair that backs up to the sub/subs.

We put folks we don't like back there... Just kidding of course, we actually don't let anyone we don't like in the room at all.

[steve nn]

We put folks we don't like back there...

Well you got to do something witham

Ok!.. so now we have to figure out what veneer you would like to go with lol

[Sonnie]

Veneer... (emoticon placing money back into pocket)

I figured I would finish it with the textured finish like my Plus/2's. I think Rodny has a pretty similar textured paint he has used before... and of course he has the spray gun.

[---k---]

Sonnie,

I've been busy and not around many parts recently, but this looks like a great project.

If you end up building one similar to mine, I can promise that you will be blown away. This thing has tons of power and can really dig low. There is no boom from mine, it is very clean.

You're showing 580L right now, but I don't believe that you've subtracted anything for bracing, the port volume, or the drivers. For my sub, I calculated that all that took up around 60L. So, you're down to somewhere between 500L and 520L, which puts you right around the same ballpark as Steve's and my sub. So, looking good. You'll be happy with the results.

For my port, I went to Lowes with a tape measure and tried to find the smallest 10" diameter Sonotube I could. It was around 9 3/8" ID. I haven't gotten around to making a grill cover for mine, so I wish I would have attempted to spray paint the inside of the tube black.

My box came in at 200pounds plus 60pounds for the drivers.

[---k---]

Oops, just noticed page 2. it looks like you're thinking two separate boxes. Either way would be good.

[steve nn]

If you end up building one similar to mine, I can promise that you will be blown away. This thing has tons of power and can really dig low. There is no boom from mine, it is very clean.

Hey Ryan...This is what we all like about our LLT's Sonnie. Sure there are plenty of other great options out there, but for a vented sub, I really like the characteristics of a LLT. I have always noticed my boughten subs tend to sound better the lower they're tuned, (others might disagree) so when I went DIY, I just had to give the LLT a notice since space was a secondary concern. Although I like to play around and build a smathering of subs, I still haven't came across any sub (that I have built or bought) that sounds any better than the last sono LLT's I built. It's like K/Ryan says..there is no boom!..just unadulterated well behaved bass.

I figured I would finish it with the textured finish like my Plus/2's. I think Rodny has a pretty similar textured paint he has used before... and of course he has the spray gun.

A option that I somehow figured wasn't in the plans

plus 60pounds for the drivers.

Kinda light RL-p you bought there Ryan. Mike didn't send you the 12'vs did he?

[SteveCallas]

steve nn wrote:

Although I like to play around and build a smathering of subs, I still haven't came across any sub (that I have built or bought) that sounds any better than the last sono LLT's I built. It's like K/Ryan says..there is no boom!..just unadulterated well behaved bass

And this guy has "been there" and "done that"

[Rodny Alvarez]

Hey Sonnie!! I'm going to charge you by the pound... .......... ...........

[aceinc]

I'm glad my idea was some benefit.

A few aditional random thoughts;

When designing ports, don't forget multiples, bends and outside the box ports.

With some bends you could fire the port(s) out the bottom. This might blend with the drivers output better.

If this box is to be permanently mounted to the wall I vaguely remember that there was a baseboard on the wall. Could you use the gap between the cabinet and the wall due to the baseboard as a type of outside the cabinet port? 3/4" adds up when you are dealing with this large of a cabinet.

Consider that a 3/4" gap by 38" wide gives the same area as a 6" diameter circle. If you were to seal a 38" wide channel that exits the back of the cabinet near the top, and travels to the bottom, the signal would then merge with the driver's front wave and you would have a port that doesn't take up any internal volume of the cabinet, doesn't require any pipe and should minimize the multiple source problem.

Of course the downsides are there as well, you would need to mount/seal this cabinet securely to the wall. You might also want to put in some way of getting to the drivers without removing it from the wall. Lastly if this design sucks sonically, it would be a pain in the butt to fix.

I am glad that I do not have to move this beast.

Paul

[Sonnie]

I wonder just how heavy this thing would be if I made it one piece... and Rodny... I don't mind paying by the pound as long as it's no more than 10 cents per pound...


Ryan... 260lbs... that is serious! Thanks for chiming in too!


Paul, I think I'm gonna go with a pair of boxes and with the regular porting so that they can be moved easily if need be. I'm thinking it makes sense to port out the sides to help with the driver and port "meshing" (I think that's the word I read earlier).


Well I reckon I need to get me a pair of subs ordered from Mike at SoundSplinter, and the EP2500 amp from my distributor.

I'm gonna have to have a crossover too. I can get this for about $65...



It should more than do the job.

I'm assuming PVC is okay to use for the ports?

What about binding posts..... is something like this okay:



For the most demanding high-current applications,
this input terminal is top dog. Binding posts accept
both banana plugs and raw wire up to 4 gauge!
Posts are 2-3/8" on-center and each require a 1-1/4"
diameter cabinet hole. The proper polarity is easy
to determine from the handy color-coded stripes
on each post. Comes with built-in solder tabs on
the rear of the unit that can accept 1/4" female
disconnects or will readily accept a hardy soldered
connection. Outside Dimensions: 4-3/4" x 2".


I like T-nuts to mount the drivers.


Do I need polyfill?


I appreciate all you guys help!

[SteveCallas]

Why do you need an additional crossover? I wouldn't assume the FR effects would be the same until you measure, and I'd cross such subs over to SBS-01s pretty high, like 120hz. Port on the sides but drivers will still be downfiring, yes?