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Funky Waves 18 LMS 5400 + 2 PR build

10977 Views 42 Replies 14 Participants Last post by Warpdrv, Aug 23, 2011

lukeamdman

Discussion Starter · Jun 1, 2011

This build got my attention:

http://www.hometheatershack.com/foru...king-200l.html

Today I emailed Funky Waves about just building the enclosure. The goal is to reach an in room response of about 115db at 20hz. For reference, currently my DD-18 can do about 103-104db at 20hz from my seat 13ft away.

My questions to the DIY guru's:

1. Will 2,000w RMS be enough, or can this driver handle more than what's listed? If 2,000w is all it can handle, would the ep2500/ep4000 be enough since that what they were tested at 4ohm to produce?

2. Say Funky Waves can make the same enclosure, but a little larger. Will that aid output? I think something along the lines of 35 tall, by 25 wide, by 27 long is about as large as I could fit.

Thanks in advance!

UPDATE:

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1 - 20 of 43 Posts

Mrkazador

· #2 · Jun 1, 2011

35x25x27 is about 300l after bracing and drivers. Making the enclosure larger will give you more spl in the lower freq.

200l vs 300l, same tune and watts.
Attachment 213655

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lukeamdman

Discussion Starter · #3 · Jun 2, 2011

I might have the option to get a used Peavey CS 4080hz.

Say I end up with two of these LMS boxes, would this adequately power these subs? It's rated at about 2k RMS at 4ohm per channel.

allanf714

· #4 · Jun 4, 2011

Quote:
Originally Posted by lukeamdman /forum/post/20516710

I might have the option to get a used Peavey CS 4080hz.

Say I end up with two of these LMS boxes, would this adequately power these subs? It's rated at about 2k RMS at 4ohm per channel.

It should adequately power one of the LMS5400s. The only amp that I am aware of thought strong enough to power a pair of those drivers:
http://labgruppen.com/products/fp_pl...es/c/fp_14000/

lukeamdman

Discussion Starter · #5 · Jun 5, 2011

Two more questions:

1. How many pounds of acousta-stuf should I use? The box is going to be about 200l, smaller than originally planned.

2. Would it be better to run the amp in 4ohm stereo, or should I wire the two boxes in a series for an 8ohm bridge? It's going to be a Peavey CS 4080hz.

Thanks!

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Mrkazador

· #6 · Jun 5, 2011

Most people I've seen line the walls in a vented enclosure.

http://www.glasswolf.net/papers/polyfill.html

Quote:
I also found that stuffing gets less effective as box size increases. The morale: The bigger your box is, the harder it is to fool your woofer.

lukeamdman

Discussion Starter · #7 · Jun 13, 2011

I’m in the process of making the box myself. Final outside dimensions are 24” x 24” x 32.5”. Used 3/4" Baltic birch, and the baffles are doubled up to 1.5”.

How do I know how many washers to add to tune the VMP’s? Anything between 15 and 20hz is fine.

Thanks!

Warpdrv

· #8 · Jun 13, 2011

What is the room size....?

If the room is not huge, you may be able to get away with an amp that will put out 2000w per channel @ 4ohms...

Heck, TJHUB just upgraded to twin sealed LMS's in a 6500^3 room and is now running a pair of EP4000's, 1 for each... Up until then it was my extra Crest 8002 which was a trial amp running about the same power per channel...

PR should allow you to utilize less power and get more output.

a 4000w amp per driver in theory should only yield you an extra 3db each.

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keager

· #9 · Jun 14, 2011

I have a LMS ultra5400 with dual vmp radiators. It was running on an ep4000 and sounded good, but it is in my living room and pretty much open to the whole house. I have one of the LG clone amps on order. This should give everything the driver will handle and more and give me an excuse to get another lms/vmp next year.

lukeamdman

Discussion Starter · #10 · Jun 14, 2011

How do I know how many washers to add to tune the VMP’s? I'm looking for something around 15/16hz.

Final outside dimensions are 24” x 24” x 32.5”.

Thanks!

michael hurd

· #11 · Jun 14, 2011

Try 11 washers per VMP, that should be in your range. Measure the tuning with test tones very carefully ( I would start at low power below your tuning point ), where excursion is high, moving up 1 hz at a time to see where the active driver barely moves.

lukeamdman

Discussion Starter · #12 · Jun 14, 2011

Michael,

Thanks for that info!

What does that mean when the active driver barely moves to a specific frequency? If you could elaborate on that I would appreciate it!

michael hurd

· #13 · Jun 14, 2011

At tuning, the passives are moving, but the active woofer is barely moving at all. Above tuning, the passive motion decreases and the active woofer starts moving more.

I would start with say a 10 hz tone at low volume, but enough so that the woofer is moving say 1/2 inch p-p. Increase the frequency of the tone in 1 hz increments, when you have found the point where the active driver is barely moving, that is the tuning frequency.

Frequencies on either side will have the woofer moving more.

lukeamdman

Discussion Starter · #14 · Jun 14, 2011

Excellent! Thank you very much for that information.

michael hurd

· #15 · Jun 14, 2011

BTW, taking 5 washers off of my VMP's in a 7~ cu ft box raised tuning about 2.5 hz or thereabouts.

lukeamdman

Discussion Starter · #16 · Jun 14, 2011

What are the dimensions of your box?

michael hurd

· #17 · Jun 14, 2011

I would measure it for you, but I am a long way away from home. ( 15 + hour drive ) Here's a picture of it in paint prep stage though.

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lukeamdman

Discussion Starter · #18 · Jun 14, 2011

That box looks like it has similar dimensions to mine.

I take it that in that picture you're working on a side where a PR goes, and the front of the enclosure is face down?

michael hurd

· #19 · Jun 14, 2011

Yes, that is correct.

lukeamdman

Discussion Starter · #20 · Jun 16, 2011

Got the driver and PR's yesterday.

Very unimpressed that the washers and nut are just thrown in the box and not secured or tied down in any way. Both PR's have minor dents in the cones from the washers hitting them...

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