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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: damcard on April 22, 2004, 02:32:32 pm

Title: LAB Sub for home use???
Post by: damcard on April 22, 2004, 02:32:32 pm
I am interested in building a horn sub for my home stereo/theater. I am building a pair of main round tractix horns that will use the Fostex Sigma 6.5 inch driver when ever they come off back order.  I want to use a horn to match my mains.  Will a LAB horn enclosure work in this case or will that heavy cone not be able to keep up?  The room will be about 30' x 30'.  I was planning on building two.  How low do my mains have to go, or in other words how high can I get the LAB horns to go?  Thanks.
Title: Re: LAB Sub for home use???
Post by: Michael_Elliston¶ on April 22, 2004, 10:44:05 pm
will that heavy cone not be able to keep up?

Yes it will be able to 'keep up'

http://www.adireaudio.com/tech_papers/woofer_speed.htm

The issue of labhorns in homes have been discussed perhaps 2 dozen times.

1 with EQ or just 2 in a corner = very loud

http://db.audioasylum.com/cgi/m.mpl?forum=hug&n=50917&am p;highlight=labhorn+home+labhorn&r=&session=

http://db.audioasylum.com/cgi/search.mpl?searchtext=labhorn& amp;b=AND&topic=&topics_only=N&author=Don+Bunce& amp;date1=&date2=&slowmessage=&sort=score&so rtOrder=DESC&forum=hug

Cheers!
Title: Re: LAB Sub for home use???
Post by: damcard on April 23, 2004, 01:55:44 pm
Thanks.  Those links answered my questions.  Funny, I guess I am just incapable of doing my own searches.  (I did try)  Smile  I had already put in my request for 4 of the new B12 drivers from Wayne Parham.  Mmmmmm, two LAB horns should be nice.  My neighbors will hate me.  Twisted Evil
Title: Re: LAB Sub for home use???
Post by: Brad Litz on April 24, 2004, 12:24:23 am
I'm building a pair for my home theater. I must be nuts.
Here's a photo part way done. Still sanding the glue off before staining. Cool
index.php/fa/31/0/
Title: Re: LAB Sub for home use???
Post by: Timmahh on April 24, 2004, 11:17:31 pm
all i have to say is DAMN BRAD, those are going to be BEAUTIFUL when you get them stained!!! i Suggest CHERRY OR WALNUT, or maybe Mahogany, but thats just me.  post a reply on how your WOOD access covers work out? what do you plan on Sealing them with?
Gr8 Job!
Timmahh
Title: Re: LAB Sub for home use???
Post by: Brad Litz on April 25, 2004, 01:18:19 am
I used a stain color called antique maple. I guess I picked it because the plywood is maple on the outside.
http://www.minwax.com/products/woodstain/gelstain-color.cfm

I'm going to use a tung oil finish
http://www.woodworker.com/cgi-bin/FULLPRES.exe?PARTNUM=860-0 57

I'll seal the covers with some speaker sealing caulk from Parts Express. It is a lot like Mortite non hardening caulk. I'll just put a little ring of it on the inside of the cover bolt circle. It dampens vibration, fills gaps, and I won't have to tighten the screws too tight. If I ever have to take them off I might have to put in some screws to pull with. Maybe a suction cup will work. I could put a recessed handle in them.

The covers have 16 1/4 inch screws holding each one on and they are a full 3/4 thick. They are only 14 inches in diameter at the outside. They should be fine.

My assembly pictures are here. http://www.geocities.com/hulkss/LABsubWebPhotos/

Title: Re: LAB Sub for home use???
Post by: Michael_Elliston¶ on April 26, 2004, 12:50:48 am
Funny, I guess I am just incapable of doing my own searches
half the time search engines dont even work properly  Rolling Eyes

and when your new,u dont know what to search for Razz

ive designed my own 33hz basshorn that shud fit in my car(using a lab12)

Cheers
Title: Re: LAB Sub for home use???
Post by: Finn on April 26, 2004, 03:32:36 am
hey brad, those pics look awesome!  what type of plywood did u use?  and also... the baffle boards are "V" shaped/on an angle.  what version of the lab sub is this? and are there any changes in performance?
cheers,
Finn.
Title: Re: LAB Sub for home use???
Post by: damcard on April 26, 2004, 03:45:23 pm
Hello Brad,

I actually did find your cabinets on another post.  They look great!  Can you tell me why you opted to open the mouth to the center, or is that just for the picture?  I will try to load mine into the corner on the left and right but may stack them on one corner.
Title: Re: LAB Sub for home use???
Post by: Timmahh on April 27, 2004, 12:01:50 am
As I understand it, Brad made some changes to allow for a higher cut off point,  just over 200 hrtz if I m not mistaken, it it dubbed V3 i beleive, but ofcourse, Brad would be much better suited to answer these questions, but if you do a search of the forum, you ll find much of his ponderings and such posted already, includeing this info.
Timmahh
Title: Re: LAB Sub for home use???
Post by: Timmahh on April 27, 2004, 12:03:03 am
i beleive it is an actual Mouth Extension he has added to extend the freq, down to 27 htz i think.  I may be wrong, but>>>
Timmahh
Title: Re: LAB Sub for home use???
Post by: Brad Litz on April 27, 2004, 02:24:24 am
I used Europly  Cool

http://www.columbiaforestproducts.com/products/hardply/europ ly.html
Title: Re: LAB Sub for home use???
Post by: Brad Litz on April 27, 2004, 02:33:14 am
Yep, they are modified as Timmahh says.
A comparison of predicted response:
index.php/fa/38/0/
Title: Re: LAB Sub for home use???
Post by: Brad Litz on April 27, 2004, 02:50:38 am
I wanted to extend the response a bit so I needed a bigger mouth area and a longer horn. Aiming them into a corner will work too, but I wanted to eliminate the comb filtering problems caused by two low frequency sources. Also I need to x-over around 80 to 100 hz and I don't want to localize on the sub off center. I modeled my room in "Soundeasy" and the center location looked good.

Check this out:
http://www.falstad.com/interference/
Title: Re: LAB Sub for home use???
Post by: BullFire on May 15, 2004, 08:12:10 pm
Very nice Lab sub Brad Smile  I must say, you have done a really great woodwork . When do you think the horn's are finished, and in place in your homecinema?
If the Labhorn is a success for homecinema use, maybe I build one or two for may self.
Title: Re: LAB Sub for home use???
Post by: Eric Wong! on May 16, 2004, 12:14:20 am
That is awesome, thanks so much for the pics.  I may get started on mine as soon as tomorow but mine would be more for DJ/PA use.  The mouth extenders are awesome.  Infact that would be perfect in a house, cause the subs could double as speaker and a TV stand.  Wow.  

Oh yah, how do you think the Europly would stand up to a PA enviroment where it will be moved around.  
Title: Re: LAB Sub for home use???
Post by: Brad Litz on May 16, 2004, 01:22:31 am
Actually, I just finished assembly today and ran a few sine waves through them in my garage. They seem to work just fine. I'll try to get some measurements tomorrow, otherwise, it will have to wait for next weekend as I have a business trip this week. I should have them set up and playing music soon.
Title: Re: LAB Sub for home use???
Post by: Brad Litz on May 16, 2004, 01:33:49 am
The Europly is half alder and half birch with various outer veneers, usually maple. It's expensive. It's quite strong and holds screws well. It is not as strong as the best baltic birch from old stands of birch trees. The maple on the outside helps it cut splinter free and the alder is softer then birch so you can drive screws into the edge and the plys don't split. It is a full 3/4 inch thick, most baltic birch is 18mm.
Title: Re: LAB Sub for home use???
Post by: BullFire on May 16, 2004, 07:29:01 am
Brad I'm looking forward to see some pictures from your cinema when the Labhorn is installed.

Is it possible to build a mouth extension like this? I don't want my screen so high up on wall.
index.php/fa/75/0/
Title: Re: LAB Sub for home use???
Post by: Brad Litz on May 16, 2004, 12:46:43 pm
The only issue might be that the horn mouth will be about 4 feet from the front wall. This will cause a cancellation from the front wall reflection at about 70 Hz.

Hang some MiniTraps to reduce the reflection. Keep them spaced off the wall and install some angled along the ceiling/wall corner like the web site shows.

A big TV on top flush with the horn mouth and some panels flanking it on each side would also prevent the reflection. Hopefully the TV can handle the sound pressure. I have never heard of a subwoofer badly vibrating a TV?

I'm using a front projector with an acoustically transparent screen that hangs partially in front of the horn mouth.

http://www.realtraps.com/index.htm
Title: Re: LAB Sub for home use???
Post by: Mark Seaton on May 16, 2004, 01:30:01 pm
Brad Litz wrote on Sun, 16 May 2004 11:46

The only issue might be that the horn mouth will be about 4 feet from the front wall. This will cause a cancellation from the front wall reflection at about 70 Hz.


This is very much a reality.  For this situation you would be better off building out the front wall and flush mounting the speakers creating an effective "baffle wall," even if only 1/2 the depth of the sub, which is a nice placement anyway.  The subs could form a functional stage.

Interestingly this is one problem I have tracked down to many "lack of puch" impressions about BassTech7s when used inside.  "Well yeah, you have a big notch/null at 75-80Hz!"

Brad Litz wrote on Sun, 16 May 2004 11:46


A big TV on top flush with the horn mouth and some panels flanking it on each side would also prevent the reflection. Hopefully the TV can handle the sound pressure. I have never heard of a subwoofer badly vibrating a TV?



We put a B-DEAP-32 in a home theater with a 73" Mitsubishi rear projection set which vibrated violently at very high levels and specific frequencies.  A good bit of the vibrations were transmitted mechanically through the floor.  When you look at the costs, you are much better off with a less expensive projector in this situation if at all possible.  Your picture is better and more easily upgradable anyway.
Title: Re: LAB Sub for home use???
Post by: BullFire on May 16, 2004, 01:45:38 pm
If I build this setup, I want to make a baffle wall, so the horn is completely inside the wall.
I have a barco crt projector and I don't want the horn mouth behind the screen because of screen vibrations.
Title: Re: LAB Sub for home use???
Post by: Tim Padrick on May 18, 2004, 05:14:49 am
If the ceiling height were 8', would the 70Hz cancellation not be desired? It would cancel the 70Hz mode of the ceiling height, which I'd think would be pretty bad in any domestic-sized room with a lab or two in it.