Underfloor subwoofers

For livingroom sound better than in a theatre.
Post Reply
Message
Author
StephenH
Posts: 3
Joined: Sun May 28, 2017 10:51 am
Location: Vancouver, Canada

Underfloor subwoofers

#1 Post by StephenH » Sun Jun 11, 2017 3:12 pm

Hi,

For background - not related to this question: I do DJ work - mainly in small Gyms, mainly for charity, and mainly for fun. I've built a pair of T39's (19" 3012LF). I use a QSC PLX1804 with a Symnet DSP (8x8 Cobra Net - similar to a Drive Rack), for high/low crossover, voltage limiting, and high pass for the subs.

My question relates to putting subs in my house.

In the house, I have approximately 40 backboxes (for background music), placed throughout the house for ceiling speakers, which I'm gradually filling in with drivers as I have time.

My plan is to put an underfloor subwoofer in the living room. The living room is approximately 10x30 ft, with a 9ft ceiling, and opens onto the kitchen as well. We have a TV on a rolling stand that we roll into the living room to watch movies, and I DJ private dance parties with up to 40 people in the living room - playing dance hits from the 1960s to present.

The sub will be mainly utillized for the dances (and for background music). I may also plug the TV stand into the 'house' system down the road, and use it for the sub and maybe some ceiling speakers for surround. The current TV stand contains a $20 set of 2.1 computer speakers, which is fine for what we use them for.

For the house I have a Mini-DSP for the processing for the sub.

The basement is unfinished, with a workshop under the living room.

As stated in the title, I want to install an underfloor sub.

The sub needs to fit in the following cavity:
- 14.5" wide (maximum) to fit between the floor joists. I could go to 14.5" wide inside dimensions if I include the existing framing (which I know I will have to confirm is all air tight).
- 10 feet long (could be folded to get more if required)
- Approx 14" tall (negotiable) - at 14" the cabinet will stick down approx 7" below the cieling in the basement.

My current plan is to 'unwind' a T39', and use a 10" driver. I took the T39 plans and examined he horn dimensions in AutoCAD. Except for the final flare at the exit of the cabinet, I can replicate the T39 shape in this cavity.

I will do a sub-crawl, but since there is really no single 'listening position' - it's likely that a corner installation will be the best. I will put a grate on the floor to allow the bass to come into the living room.

I'm looking for alternate suggestions to the T39. Anybody have the plans CD and can suggest a better match?

thanks

/steve

billkatz
Posts: 225
Joined: Mon Jan 21, 2013 9:30 pm
Location: San Rafael, CA

Re: Underfloor subwoofers

#2 Post by billkatz » Sun Jun 11, 2017 7:36 pm

The long style table tuba would actually fit your size requirements - it can be built 14" wide, is 15" tall and 60" long. Unfortunately it is end firing, but perhaps it would be possible to do something like the front firing version of the THTLP. The front firing THTLP can be built 15" x 18", so that will hang down a little farther but might work.
Built:
1 Omni-15 Tall Boy
2 DR250s
2 Titan 39s

User avatar
DJPhatman
Posts: 5394
Joined: Mon Aug 14, 2006 5:08 am
Location: Warren, MI
Contact:

Re: Underfloor subwoofers

#3 Post by DJPhatman » Mon Jun 12, 2017 2:39 pm

billkatz wrote:The long style table tuba would actually fit your size requirements - it can be built 14" wide, is 15" tall and 60" long. Unfortunately it is end firing, but perhaps it would be possible to do something like the front firing version of the THTLP. The front firing THTLP can be built 15" x 18", so that will hang down a little farther but might work.
+1. But, I would do at least 2, at opposite ends of the room. There are going to be quite a few power alleys and voids in a room that small. Spread the bass love. I would also recommend a pair of TLAH. Use the in-ceiling for your HT surrounds and zones.
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice

caddylackn
Posts: 122
Joined: Tue Apr 15, 2014 8:24 am

Re: Underfloor subwoofers

#4 Post by caddylackn » Thu Jun 15, 2017 9:20 pm

I can tell you that the THT and the Table Tuba will fit between the 14.5" joist opening. The THTLP will not fit, the mouth opening is too large by an inch. I don't know if the side firing THTLP would fit.

I installed the THT under the floor with great results. I have a grill on it now and a lazy boy placed next to it and it vanishes in the room.
Image

Here is my build http://www.billfitzmaurice.info/forum/v ... 71#p254743
16.5" AT w/ 860w
TLAHs w/ 9 mids & 16 tweets
17" THTLP w/ Dayton RSS315HF-4
16" TAT w/1060w
18" TT w/ Dayton DCS-205-4
5.5" TrT w/ DCS-205-4
T-18 w/ DCS-205-4
33" THT w/ Dayton Titantic 1200
Building--DR200s

StephenH
Posts: 3
Joined: Sun May 28, 2017 10:51 am
Location: Vancouver, Canada

Re: Underfloor subwoofers

#5 Post by StephenH » Sun Aug 20, 2017 10:38 am

Thanks for the responses!

Although I love that THT install, it would would stick too far down into the basement workshop, so the long table tuba seems like the way to go.

I've purchased and received the long table tuba plans - I'll make it 14" wide outside dimensions, and use a 10" driver.

It was a fairly small change to the plans to have it fire out the front (up into the living room), rather than the end. The horn dimensions only changed slightly (horn length: increase by approx 1 inch, mouth area: smaller by approx 7 square inches). I'm assuming this will only have minimal impact.

My current issue is with the driver access port. In the plans, the port is not covered, and the plans state the port acts as a second sound source, and has specific instructions on placing the port near a wall or floor.

My port is in the dusty basement workshop, so I'm planning to cover it to keep out dust.

- Is it OK to cover the port?
- If it's OK to cover the port, how much impact will this have on the audio from the cabinet?
- If it's not OK to cover the port, are there any suggestions for keeping dust out of the driver?

/steve

User avatar
Bill Fitzmaurice
Site Admin
Posts: 25791
Joined: Tue May 02, 2006 5:59 pm

Re: Underfloor subwoofers

#6 Post by Bill Fitzmaurice » Sun Aug 20, 2017 11:24 am

You can cover the port, the difference won't be that much.

Post Reply