Home Theater Forum and Systems banner

1 - 20 of 30 Posts

·
Banned
Joined
·
1,074 Posts
Discussion Starter #1 (Edited)
So I went looking at houses today. I may be moving to a new home soon, and not only do I dedicate more than 20 cubic feet to a single sub in an LLT in-car, but I am brain storming my next LLT to use 4x8 sheets as panels. Roughly using 4 4x8 sheets as 4 sides, and cut 1 in 1/2 for the top and bottom. Obviousely heavy bracing will be used. I don't know right off hand if I want to a: tune to 15Hz because I think it is a good balanced point b: 10Hz because I think it is the lowest tune still taking balance into consideration c: 8Hz to include the bottom of organ music or d: use 18" sonotube as my port and make it as long as I can keeping it under 190Hz for the 1st port resonance, and wherever that happens to be, it will be. I doubt that will lead anywhere, and I'll know in a few minutes after I plot a quickie using an 18" port in 110 cubes...but it gives you insight to my train of though.

I know I am working this backwards. I know I am going to hear a lot about "what about room modes and nulls. Why aren't you designing the sub around your room...etc...etc..." and that is OK. I am not conventional, I am not an avid HT guy, and I am not a SQ guy either. I had many many debates on designing my LLT in-car, and I am so very glad I took everyones opinions with a grain of salt. I was very very pleased with it, and, I even raised tuning numerous times only to prove to myself that I did in deed understand everyones arguments, that despite the changes the re-tunings made, they were as I expected and not what I wanted.

So I am going to play. Space is NOT a factor. NO, this will probobly not be a permenant HT build..it is for play. Fun. Learning.

I will most likely run a single 21" Exodus Audio Maelstrom-X in it and have way more power on tap than I will ever need... EP2500. That way later, when I design a well-fitting HT system the "right" way, I will be able to do so without having to purchase another amp. Otherwise, with 100-128 cubic feet available for just 1 driver, I could get a really cheap 200-500 watt plate amp and still have more power than I'd ever need.

So let the opinions, criticisms, ideas, excitement flow. Keep in mind it is fun, no matter how ridiculous. Please!




EDIT:

so first objective, see where 18" diameter sonotube port will be over 190Hz 1st port resonance in 110 cubic feet. Appears to be 12Hz tune resulting in a 30" length with 1st res at 226Hz.

plot 1 gray is default vented, 20 cubes @16.5Hz
plot 2 red 110 cubes 8Hz tune 84" vent 80Hz 1st resonance. if it wasn't for LLT requirement being no LPF, I could cross at 40Hz with good mains, no? Anarchy's!
plot 3 yellow 10Hz 49" 138Hz
plot 4 green 15Hz 14.5" 469Hz
plot 5 blue 12Hz 30" 226Hz

so just brain storming, 12Hz with an 18" sonotube in 110 cubic feet (lots of bracing to fill 128 cubes LOL, combined with port displacement... 18"x30" is 4.4 cubic feet!) 30" length reaches Xmech 40mm at 9Hz with 500 watts. Port velocity peaks at 11 m/s @ 12Hz... will that do? ;)









EDIT2:

more playing around, 10" and 12" port are too small resulting in less than driver's peak to peak excursion in length. Such as leaving the default 16.4Hz tune but raising to 110 cubic feet, 10" port is -.2" and 12" port is 1.48" long. I think the driver, having much more Sd than the port area, moving 4.6" peak to peak ( Sicko-X Xmech 60mm) the port may no longer function, as the air slug excursion would exceed port length.

So trying 14", 110 cubic feet tuned to 16.4Hz makes for a 3.72" port length. If the driver moves more than that and has a greater area than that, I think there could still be some issues...but I'll stick with a 14" port for now.

plot 1 grey defaut 20 cubes @ 16.4Hz 14" port 67" long 101Hz resonance
plot 2 red 110 cubic feet 16.4Hz 14" port 3.72" length 1,820Hz
plot 3 yellow 110 cubes 8Hz 14" port 49" long 140Hz res
plot 4 green 110 cubes 10Hz 14" port 27" long 247Hz

so using a 14" port rather than 18" makes 10Hz obtainable keeping 1st res freq over 190Hz. All are under 21 m/s with 500 watts, it's looking like a 14" port may be better suited. Also, I have NO problem building TWO of these boxes, one for each corner up front, and I could easily run them both off an EP2500 or EP4000 and still have plenty of headroom.









Edit 3:

Dual 21's stereo off EP4000 2 x 1400 so I'll try 14" and 16" ports 10Hz at 1400 watts

14" port peaks at 28 m/s at 10Hz, but it'll never see that







now plotting without exceeding Xmax and using HPF/SSF

gray default [email protected] 1400 watts
red 110cf 10Hz 14" port [email protected] 1400 watts
yellow 110cf 10hz 16" [email protected] 1400rms

red and yellow just kiss 39mm 13-14Hz with 1400 watts, and 14" port v velocity is only 19 m/s at 10Hz





so 14" or 16" port 1400 watts 10Hz looks to be my current goal for the day...for now. Talk me out of it!
 

·
Registered
Joined
·
511 Posts

·
Banned
Joined
·
1,074 Posts
Discussion Starter #3
No! Just add a couple more drivers.
:ponder:

not a chance. already taking up two 4'x4' sections of the room, and I'm still tryin to figure how I am going to be able to build them in the room... I need to re-measure the ceiling!

and I'm certainly NOT going to simply add the drivers going 2 per cabinet...no way!

I had a feeling this would be a dead thread, but, once I start a build log with pics... I'll remember who actually took the time to post in pre-design stages! cuz there will be a LOT of posts in that one for sure.
 

·
Banned
Joined
·
1,074 Posts
Discussion Starter #5 (Edited)
100 cubes tuned to 12 hz with 500 watts gives a SPL peak at 12 hz while giving up 4 or 5 db in the 15 - 20 hz range. If this is for Ht then why wouldn't you design to use the 'HT range"?

Your graphs are hard to see. Under the Plot tab select 3 for width.
so how about a 15Hz tune?

EDIT: I ran it, and I like it! 1000 watts.

X without SSF



why is VV so low? hehehe... I am keeping the Sicko-X in mind... pull the MX, drop in a SICKO! Should still be good on port compression ;)



Looks great to me, this is NOT intended to be for HT, it's just for fun, but I have a feeling I'll keep it that way, cause it looks awesome down to 25Hz, then... oh yeah!



this doesn't look so good, still showing downtime from 25Hz on up



butterworth @ 10Hz

under Xmech





still have 101dB at 10Hz


 

·
Registered
Joined
·
511 Posts
Why delete? Its not like it's an uninteresting idea.
 

·
Registered
Joined
·
19 Posts
If you are set on using that large of an enclosure you should definitely use multiple drivers. That box size is way too big for a single driver. You could even use 4 Maelstrom 21's in a 100 cubic foot box. Plot the output from that and prepare to be impressed.
 

·
Registered
Joined
·
178 Posts
If you are set on using that large of an enclosure you should definitely use multiple drivers. That box size is way too big for a single driver. You could even use 4 Maelstrom 21's in a 100 cubic foot box. Plot the output from that and prepare to be impressed.
I agree.
 

·
Registered
Joined
·
369 Posts
Amusingly the parameters for the 21" maelstrom are so insane that trying to model 4 of them seems to break winisd. It must push some parameter to being larger than the register which is allocated to hold it. Every time I tried it port resonance went into the negatives and no graphs would be shown. I didn't try Unibox, but I might some time just for fun.
 

·
Premium Member
Joined
·
129 Posts
Amusingly the parameters for the 21" maelstrom are so insane that trying to model 4 of them seems to break winisd. It must push some parameter to being larger than the register which is allocated to hold it. Every time I tried it port resonance went into the negatives and no graphs would be shown. I didn't try Unibox, but I might some time just for fun.
Model 1 of the drivers in a quarter of the volume & then add 12db to the overall output for 4 drivers in a box 4 times the size :gulp:

Hopefully WinISD won't break doing that :scratch: :D
 

·
Banned
Joined
·
1,074 Posts
Discussion Starter #15
The living room is split into 2... I didn't realize that when I was first looking at several homes. I planned on 1 128 cube box (4'x4'x8') in each corber leaving the center plenty of room. With it split into 2, I don't think it's going to work. Once I finish signing, I can get in there and take real measurments. If it doesn't work, I may consider dual 6th orders with the enclosures in the basment and the ports exiting through the floor.
 

·
Banned
Joined
·
1,074 Posts
Discussion Starter #17
Bah, sounds to me like you're wimping out. :whistling:
not at all, I am the 1st to chew up space without a second thought.... but the living room is small to begin with, but it's cut in 1/2... I'd knock out the dividers, but I'm gonna need every bit of support as it is!

And now I'm taking a closer look at the 4 21's.... 130 to 16Hz?!


Going back up to read even closer now...
 

·
Banned
Joined
·
1,074 Posts
Discussion Starter #18
If you are set on using that large of an enclosure you should definitely use multiple drivers. That box size is way too big for a single driver. You could even use 4 Maelstrom 21's in a 100 cubic foot box. Plot the output from that and prepare to be impressed.
ya, looks like you're right!

You have to enter the net volume and tuning frequency. As you add input power and vent size you have to re-enter the tuning frequency. Shown is four 21's in 100 cubic feet tuned to 15 hz, 6000 watts input, and a 16" diameter port 12.25" long, 130 db down to 16 hz, plus room gain.

View attachment 17263
ya, it's like that 'ol IB3... gotta keep re-entering :(

Mike, what's vent velocity peak at??

That's insane :whistling: I think i'd be tempted to lower the tuning frequency to allow for room gain, i'm sure that well over 120db at 10Hz wouldn't be a problem :T
I'm an infrasonic nut myself, but, wouldn't I be better off adding 10dB around 16Hz? 10Hz is just so low....15Hz is so low!
 

·
Banned
Joined
·
1,074 Posts
Discussion Starter #19
here's the thing, 2 21's and an ep2500/4000 about $1500

putting 4 in 100 cubes is 25 cubes per sub, and 1500 watts doesn't make sense to me in that "little" of an enclosure.... but OK, 6000 watts, 2 or 3 ep4000's... now we have 4 21's $4800 and 3 ep2500s ( I would actually go for 1 per driver even if I could 'get by' with 2 for all four ) $1000 that's $6000



I think 2 for $1200 and an ep for $350 and a ton of efficiency is better, I'll turn my entire basment into a dual tapped horn if I have to and cut out a small room for the mouth ;)
 

·
Registered
Joined
·
511 Posts
No joke, there is a guy in Peora IL who was cleaning out his basement and realized his basement wall (brick I think it was) had a nice curve like a horn. He ran to the hardware store and bought a bunch of cement and built himself a giant horn that was big enough for me to sit inside! I think he said "I nearly damaged myself" when he ran the first 100 watts through it!

Maybe a horn of some sort is what you're looking for? A horn loaded M-21 would be epic!

All that said, I'm sure whatever you do will be fun! I'm looking forward to your build!
 
1 - 20 of 30 Posts
Top