Home Theater Forum and Systems banner

1 - 18 of 18 Posts

·
Registered
Joined
·
229 Posts
Discussion Starter #1 (Edited)
Hello.

I've already built 2 sealed 18" subs, one is the LMS ultra and the other is my first sub, the Maelstrom 18" Gen II.

Here's the old thread:

http://www.hometheatershack.com/forums/sealed-subwoofer-build-projects/16320-dual-box-sealed-18-mal-x-build-begins.html

I was thinking about putting another LMS ultra into the left front sub in my setup, so they are similar.

That leaves me with a Maelstrom with nothing to do!

So I was thinking about building another sub, that could sit in the back corner, between 2 sofas and double duty as a coffee table and perhaps put a lamp on it.

I wan't a low tuning to suppliment the two LMS ultras up front. My plan is that the "back" ported(?) sub will only play from 40hz or so downwards.

Suggestions to suitable alignments, ported, passive to fit as a coffee table and still get good low end performance?

I tried to model in unibox but I'm not sure I'm doing it correctly. I was modelling a Maelstrom 18" Gen II with 2 LMS passives.
 

·
Registered
Joined
·
229 Posts
Discussion Starter #5
I dont mind saving money)

Perhaps I need to increase volume?

Thank for the help btw.

Ohh how long port?
 

·
Registered
Joined
·
229 Posts
Discussion Starter #9
For the coffee end table i Think max outer dimensions are around 80x80x60 wxdxh.

But perhaps i am better off with a sonotube in the back corner which Can be 230cm high!
 

·
Registered
Joined
·
1,747 Posts
Ported is tough to get air speed below 17.3m/s and still have a high enough vent resonance for a normal (IE 80hz+) sub crossover point. You may be looking at around 7-8db more teen frequency bass ourput overall. Not a negligible anount by any means but passive radiators have some definite advantages with the largest subs... IMO PR LLTs are the least problematic.
 

·
Registered
Joined
·
229 Posts
Discussion Starter #13
It appears that the 200 liter Lms ultra with 2 passive generates good output down to 15 hz. My goal is 110db 15-25hz and a very low x over point and this third sub, in my setup, only supplements the low end.
Having the sub near the listeningposition gives me some concern about localization thus I am aiming for low end only.
 

·
Registered
Joined
·
1,747 Posts
Having the sub near the listeningposition gives me some concern about localization thus I am aiming for low end only.
I understand your localization concerns with nearfield placement. It's usually from having the sub near one ear but not the other near 80hz or so. But with two other subs, I don't see it as being an issue at all, and it will clean up room modes even more, which IMO is better than rolling it off early. In fact once you've got this many subs, you can also consider higher crossover points like 110hz and not hear localization, which means better room response and lower distortion than using your mains from 80hz to 110hz. The main thing is getting the SPLs and phase matched to the other two subs :)
 

·
Registered
Joined
·
229 Posts
Discussion Starter #16
I built 2 new boxes, small sealed for 2 LMS drivers. They sit up front.

I actually have my old Maelstrom sealed cabinet, which is 170 liters internal netto volume. It's a 24,5" cube.

How about cutting out two holes to fit in two passive 18" drivers?

Maelstrom Gen II with 2 LMS passives? will it work in 170 liters with a low tuning or is the cabinet just too small?

It would be fast and not add the cost of a new cabinet.
 

·
Registered
Joined
·
229 Posts
Discussion Starter #18
Was hoping to gain 6dB but I guess the cabinet is simply too small.

Perhaps I should just put the Maelstrom back into the old sealed cabinet (170 liter netto). I'd still end up with 3 rather large subs. Fairly cheap all I need is another LMS and amplifier.

To keep cost down, the only other solution would be a massive ported sub to gain any real benefit over the 170 liter sealed.
 
1 - 18 of 18 Posts
Top