Dual RL-p18 LLT begun

[tjambro]

brucek wrote:

That was my first impression until I looked back at the linked picture, where he says:

The first shot is the backside of one of the front panels showing the ring I made for more support for the driver mount.

That would indicate the driver is mounted against the ring and then bolted from the back?

brucek

Nope, Steve is right, I did it wrong! I'm glad you guys are here to straighten me out. I did notice when I was fitting the driver to make sure the t-nuts were lining up that they tended to pull out a little. After I posted the pictures last nite, I was thinking maybe I could put t-nuts on boths sides of the baffle so that it would be more secure. I think I'll re-do it so they are on the back side only as Steve suggested. Thanks again fellas...time to make yet another trip to Lowes to get bigger bolts to go all the way thru the ring.

I believe some people put pieces of plywood behind the mdf to get a better bite. Is this only when t-nuts are not used or should I go ahead and add some plywood blocks since I have to re-do it anyway?

-Tom A.

[Rodny Alvarez]

I think you might want to add a couple of braces close to the sub, from the front to the back!!
Its looking good !!

Did you know that one port is higher then the other one??

[tjambro]

Rodny Alvarez wrote:

I think you might want to add a couple of braces close to the sub, from the front to the back!!

Good advice, thanks Rodny! Boy you guys are really helping me, I appreciate it!

Rodny Alvarez wrote:

Did you know that one port is higher then the other one??

Yeah, yeah, that was not my intention. They were supposed to be at the same height but when I was cutting the driver hole for the second box, somehow I screwed up and cut it in the same configuration as the first box so basically I ended up with two right hand boxes. Rather than buying another piece of mdf, I just flipped the baffle over (notice all the dark streaks on the left baffle?...that was supposed to be internal to the box) and moved one brace. Now of course, the box is "upside-down". Hey, I bet you can't tell this is my first sub project. It shouldn't affect anything sonically should it?

-Tom A.

[tjambro]

tjambro wrote:

Yeah, yeah, that was not my intention. They were supposed to be at the same height....

Actually, IIRC, I think I messed up on the port. When I was building the second box, I should have placed it beside the first box to help me with orientation. Somehow I thought the bottom of the box was the top, etc. You can only imagine my horror when I went to place the what should have been correct baffle on the box only to realize I now had two right boxes...Okay, laugh, I dare you.

Oh well, at least they won't be seen, they'll hide behind my screen. If I keep making mistakes, I guess I'll have to hide back there too.

Please at least tell me it shouldn't make a difference sonically. I mean come on, the difference is only an inch or two.

-Tom A.

[SteveCallas]

No, it won't make a difference, and yes, I'd go ahead and add some plywod behind the baffle

[Bob_99]

As with all DIY projects, the first one is good practice for the next one. You'll be really proficient by the third one.



Bob

[tjambro]

Bob_99 wrote:

As with all DIY projects, the first one is good practice for the next one. You'll be really proficient by the third one.



Bob

Thanks Bob. I don't think I'll tell my wife about the inevitable third box at this time. She doesn't understand this project yet, I can only imagine what she would think if I told her I need two more boxes in the back of the room to compliment the two in the front.

-Tom A.

[Owen Bartley]

Bob, if these monsters get replaced with a second and then a third project, I'll make a bet the project after that will be structurally re-enforcing his house!

Great progress Tom, keep at it!

[tjambro]

Owen Bartley wrote:

Bob, if these monsters get replaced with a second and then a third project, I'll make a bet the project after that will be structurally re-enforcing his house!

WAF is fairly low right now, I don't think I'll push it. Actually, she doesn't mind the boxes since they are in MY room and they will be behind the screen but she is worried about the potential for shaking the foundation. She's already made me agree to no submarine movies while she is in the house.

-Tom A.

[Bob_99]

She's already made me agree to no submarine movies while she is in the house.

Ah yes! I have the same contractual deal with my wife. Nothing with explosion, fighting, etc, etc. In other words, nothing with a decent sound track. I can see future marriage nuptials being rewritten to accommodate home theater fans.

Bob

[tjambro]

Did a little more work today. I went and re-did the driver mounts with the t-nuts on the bottom side of the baffle this time. It does make a difference, thanks Steve! Instead of adding plywood chunks to the second layer of mdf I added 3/4" thick "cubes" made from 2"x2"s that I had left over from the framing. I also installed the four front to back braces that Rodny recommended, thanks Rodny!



I applied silicone to the insides of both boxes, this picture shows my sloppy silicone job on the right hand box.



This last picture shows the closed cell foam install on the left hand box.



I applied this with 3M 77 adhesive. It works very well and sets up rather quickly. If I have extra foam I will finish covering the port supports as well as the port itself. I think I will have enough but I want to wait because it's gonna be close. I didn't get the foam installed on the baffle as I was getting tired and hungry and I had two beef filets in the 'fridge that were ready for grilling so I quit for the day. The baffle foam install is going to take a little longer since I will have to leave spaces between the foam for the braces that the baffle will be secured to. I didn't have time to install any foam in the right hand box either. I guess I'll get to that next Saturday.

-Tom A.

[tjambro]

Rodny suggested that I add two braces in each of my boxes from front to back. I thought this was a good idea but I thought Rodny was only trying to make my sub better. But now I have come to the conclusion that Rodny was conspiring to be the only person who could fit in his subs and he suggested the braces so that I could not fit in mine.

Well, my subs may not be as comfortable, especially with the two braces Rodny suggested, but I still wish to join the Sit In Your Sub (SIYS) Club.

Here's Rodny lounging in one of his SLLTs:



and here's my official documentation that I am formally submitting to the president of the SIYS Club so that I too may be a proud member of SIYS.




-Tom A.

[Rodny Alvarez]

Lol...I'm not only a client, but I'm also the president of SIYS!!!
If you want to joint the club you need a BIGGER BOX!!!!


One more thing .... your left sub might be one or two Db's higher than the right side,..... this is because

Spoiler

the left side port is about one or two inches higher

[tjambro]

Rodny Alvarez wrote:

Lol...I'm not only a client, but I'm also the president of SIYS!!!
If you want to joint the club you need a BIGGER BOX!!!!

But doesn't two count for anything? Please, oh please, Mr. President, can't I join SIYS also?

One more thing .... your left sub might be one or two Db's higher than the right side,..... this is because the left side port is about one or two inches higher

Who said my floor is level, maybe the left side of my theater is lower than the right, yea, yea, that's the ticket, I DID THAT on purpose so that...

Spoiler

my overall dB would balance out between the lower left floor and the right floor.

-Tom A.

[Rodny Alvarez]

After seeing the picture I guess your IN!!

welcome to the club!!

I hope your back still in one piece!

[brucek]

Can you tell me how long the port is Tom?

Are you using the D4 driver with the two coils in parallel?

brucek

[Jerm357]

Thats hilarious

[SteveCallas]

This guy is nuts.............I love it!

[tjambro]

brucek wrote:

Can you tell me how long the port is Tom?

It's an 8" diameter port 25 5/8" long, not counting the flare at the end. I used a 3/8" roundover bit for the flare. I was shooting for an effective volume of 550L with a 14.5Hz tuning. Unibox said the port should be 25.94" long. I'm probably gonna be just under 550L by the time it's all done.

Are you using the D4 driver with the two coils in parallel?

brucek

Yes, one D4 driver with dual coils in each box running in parallel. Each driver should see 900 watts per channel into 2 ohms with my Carvin HD1800.

-Tom A.

[tjambro]

Rodny Alvarez wrote:

I hope your back still in one piece!

Let's just say I won't be getting in the boxes anymore!

-Tom A.

[tjambro]

SteveCallas wrote:

This guy is nuts.............I love it!

Coming from a guy who thinks a couple of 6.5' tall obelisks in the middle of his den which happens to be in an apartment is not enough, I feel like I am among family.



-Tom A.

[brucek]

Yes, one D4 driver with dual coils in each box running in parallel

Yeah, I guess the SoundSplinter site show the Re and BL for series coils, so I had to use the trick with WINISD to calculate them when in parallel.

WINISD shows the 8" port at 27.5" inches with one end flared in a 545 liter box tuned at 14.5Hz.

It looks real good at least to my novice playing around. The experts could comment.

Here's SPL of one box with 900 watts applied with a 10Hz, 1st order highpass filter to account for the electronics dropoff down low and a single BFD filter at 48Hz with a cut of -6dB with a Q of 0.7
I guess room gain comes into play and maybe the BFD filter would be less (or none).

SPL




Here's the cone excursion at full power. The Xmax is 27.4, so that looks good to me. It's shows only a bit out of the linear range at full power. The graph goes below Xmax just above 500 watts. That seems good.

EXCURSION @ full power



The velocity exceeds the 5% of speed of sound (~17m/sec) when full power is applied which I'm told is into the chuffing range. But who runs full power. At 500 watts it's about 19 m/sec

VELOCITY



And of course you have two of these monster.

Here's a tip: Don't sit in it when playing full power.

brucek

[tjambro]

brucek wrote:

WINISD shows the 8" port at 27.5" inches with one end flared in a 545 liter box tuned at 14.5Hz.

I haven't messed with WINISD much. If it's not too much trouble, can you tell me what tuning I can expect with a 26" port assuming the same 545L?

Here's SPL of one box with 900 watts applied with a 10Hz, 1st order highpass filter to account for the electronics dropoff down low and a single BFD filter at 48Hz with a cut of -6dB with a Q of 0.7
I guess room gain comes into play and maybe the BFD filter would be less (or none).

I don't have a BFD yet. I plan on running it without at first and then pick one up if absolutely necessary. I guess I need to get REW installed so I can measure, huh? I plan on doing a FR on my current pair of Def Tech 2002 (each one has a built in 12" sub) just for kicks. I'm sure the SS's will dig much deeper.

Here's a tip: Don't sit in it when playing full power.

brucek

Excellent advice!

-Tom A.

[brucek]

I haven't messed with WINISD much. If it's not too much trouble, can you tell me what tuning I can expect with a 26" port assuming the same 545L?

>>>> 14.83Hz at 26" with a 8" port with one end flared at 545L.

brucek

[tjambro]

brucek wrote:

>>>> 14.83Hz at 26" with a 8" port with one end flared at 545L.

brucek

Thanks, I can probably live with that.

-Tom A.