(4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

[badman]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

I hate to keep harping but seems like some light stuffing might be a big help. The bracing system's fine stylistically, but it needs more coupling points (like 2-3x as much) IMO.

[nyt]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

I hate to keep harping but seems like some light stuffing might be a big help. The bracing system's fine stylistically, but it needs more coupling points (like 2-3x as much) IMO.

There's really no need for the stuffing. Any resonances here will be out of the passband this will be used in. Sweeps confirm nothing ugly and I don't want to end up lowering the tuning further. More bracing wouldn't do much either, as there are no points on any panel with more than 10 inches of unbraced space. Part of the experimentation of this build, was seeing if damping would be necessary or if I could get away without ridiculous bracing. I used to go the overkill on the bracing, but it's a lot of work that doesn't really make a difference in cases like this. I'm keeping it simple with this build. I might add a strip on the top/bottom where I can't easily cross-brace due to the subs. What I've heard so far sounds great. I'll be dragging it inside in the next day or two and comparing to the sealed enclosures inside. I'm not looking forward to re-eqing everything :( Hopefully running the minidsp at 48khz instead of 96 will make it behave a little better. We'll see.

[xmax]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

I guess the manufacture thinks us silly music fans don't know ohm's law! 14,000w out of 120v!
How many amps is that if the amp was 100% efficient? 116.666 amps! It's probably a good thing
you only have 30 amps available otherwise you might kill yourself!

[nyt]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

I guess the manufacture thinks us silly music fans don't know ohm's law! 14,000w out of 120v!
How many amps is that if the amp was 100% efficient? 116.666 amps! It's probably a good thing
you only have 30 amps available otherwise you might kill yourself!

14kw is a program rating, not sine wave rms. These are some of the more beefcake amps you can get.. Powersoft being one of the other ridiculously powerful amps. There are a few out there.

Capacitors are your friend.

[xmax]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

I am a big believer in switch mode power supplies, I have been able to improve the sound quality
of some well regarded consoles via multiple blind test!

[xmax]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

What output devices are those?

[nyt]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

What output devices are those?

the amps? fp14000s

I've gotten this one all painted except for one side, gotta wait for tomorrow so i can flip it to do the top. These things look so much more imposing when painted black. so big.

[xmax]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

Yeah, can you see the number on the mosfets or whatever? what is the surface area of the ports?

[xmax]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

You have only built one cab so far?

[badman]

Re: (4) 2x 18" LMS Ultra 5400 in 15hz 27cube slot ported enclosure

Fair enough- I tend to design my subs to be able to play as high as the driver limit, where your box limits the HF to where standing waves are an issue in that enclosure. Thanks for responding without getting worked up- people often don't like to be questioned If you're using <50 entirely, then I agree, it's not a major issue. It's hard to tell from the pics that there's no more than 10" unbraced- looked more like 20" gaps to me, so that's more in-line with what I was saying.

[xmax]

Re: (4) 2x 18&quot; LMS Ultra 5400 in 15hz 27cube slot ported enclosure

I tend to agree with badman here, with so much passion time and loot invested,
the cabinet construction worries me, logistics of moving them aside.

[nyt]

Re: (4) 2x 18&quot; LMS Ultra 5400 in 15hz 27cube slot ported enclosure

You have only built one cab so far?

Only one built do far. this was kind of an experiment. I'll be building three more soon. I need to finish painting this one today.

[xmax]

Re: (4) 2x 18&quot; LMS Ultra 5400 in 15hz 27cube slot ported enclosure

Have you tested the one experimental enclosure yet?

[nyt]

Re: (4) 2x 18&quot; LMS Ultra 5400 in 15hz 27cube slot ported enclosure

Have you tested the one experimental enclosure yet?

Yes, I posted graphs and everything in this thread. Huge gains over sealed.

[xmax]

Re: (4) 2x 18&quot; LMS Ultra 5400 in 15hz 27cube slot ported enclosure

Just measurements? or listening test?