Grassroots Home Theater

What about the roofing squares/adhesive backed tar board that some use to dampen their trunk floor for car audio? Never looked into it myself but maybe... Supposed to be available at the Lowe's Depot.

Any new neighborhoods going up near you? Blue or pink foam insulation scraps wrapped in fabric and construction adhesive installed to duct?

And thanks for getting me distracted with home theater again. I finally ordered the capacitors to fix my video switching issue on my Onkyo AVR! I am also now convinced I NEED stereo subs!

VWguyBruce wrote: What about the roofing squares/adhesive backed tar board that some use to dampen their trunk floor for car audio? Never looked into it myself but maybe... Supposed to be available at the Lowe's Depot.

I've looked into a few different types of things like this. I can't get the WAF (wife approval factor) high enough. No way to make them pretty.

VWguyBruce wrote: And thanks for getting me distracted with home theater again. I finally ordered the capacitors to fix my video switching issue on my Onkyo AVR! I am also now convinced I NEED stereo subs!

No problem man. Glad I could help.

DrBoost wrote:

Petrolburner wrote: This has been really cool to follow along with. I'm currently looking to buy a house and now I'm thinking that if there were a space available for something like this I might be interested.

Thanks. It's very doable. The hardest part is trying to do it grassroots, depending on your expectations. I don't expect perfection, but I want to be satisfied when I'm done. When I research different things (sound proofing, sound diffusion, various materials) I find my way to different A/V forums. Well, these folks don't understand Grassroots. My 12X16 room is what some would consider the equipment room, or maybe a listening room....for two! I haven't done all the math yet, but I suspect most of these guys have more into roughing in the room than I'll have in everything, electronics and all! I have one more hurdle to overcome, then I'm done. I'm trying to figure out a way to keep my HVAC ducts from ringing without spending $18 per square foot, or boxing them in.

I used cheap duct insulationg for my motovan insulation. It's sticky foam with foil on the outside, comes in a roll. $7 for 25 square feet. You would probably want to cover it with cloth or something when you're done instaed of leaving it shiny foil, but it would stop the ringing and it's cheap.

http://www.homedepot.com/p/E-O-12-in-x-15-ft-Self-Stick-Foam-Foil-Duct-Insulation-FV516/100028603

Ok so here it's $18 for 15 sq feet, I thought I paid a lot less.

I can't believe this project isn't done, life has been getting in the way. But it's time for another update.
I started the subwoofer build.
I really, really wanted to build a transmission line sub, but there's no proven formula to get it right, and I don't have the time and money to build multiple boxes, that's some expensive trial and error.
I decided on a tapped-horn style cabinet. It's much more complicated, in the design, and build phase, than a sealed, ported, 4th, or 6th order box. When done right, it's pretty amazing. Basically, the size of the throat (small end), mouth (big end) and the length of the horn time things perfectly so when the positive pressure wave travels through the horn it will meet up with the negative pressure wave at the same time. Instead of the waves canceling each other out, you get a 6 dB boost in output.
6 dB might not sound like much, but to increase the output of any speaker by 10 dB, you have to double the input power! So a 6 dB input for free is just too hard to resist. Here's a pic of the box with the side panel off.

It's not done yet, so I don't have any listening impressions, but it is designed to put out 98 dB at 14 hz and stay pretty flat all the way to 100 hz (103 dB) (1 watt/1 meter).

DrBoost wrote: I can't believe this project isn't done, life has been getting in the way. But it's time for another update. I started the subwoofer build. I really, really wanted to build a transmission line sub, but there's no proven formula to get it right, and I don't have the time and money to build multiple boxes, that's some expensive trial and error. I decided on a tapped-horn style cabinet. It's much more complicated, in the design, and build phase, than a sealed, ported, 4th, or 6th order box. When done right, it's pretty amazing. Basically, the size of the throat (small end), mouth (big end) and the length of the horn time things perfectly so when the positive pressure wave travels through the horn it will meet up with the negative pressure wave at the same time. Instead of the waves canceling each other out, you get a 6 dB boost in output. 6 dB might not sound like much, but to increase the output of any speaker by 10 dB, you have to double the input power! So a 6 dB input for free is just too hard to resist. Here's a pic of the box with the side panel off. It's not done yet, so I don't have any listening impressions, but it is designed to put out 98 dB at 14 hz and stay pretty flat all the way to 100 hz (103 dB) (1 watt/1 meter).

Sweeeeeeet.

I thought 3 dB was double power, so at 6 dB it would be 4 times the power. Either way you can keep the volume lower!

Looks good! For reference, how tall is the outer box?

It sort of looks like what would probably happen if I tried to just build a square box (the inside part)...

slowride wrote: Looks good! For reference, how tall is the outer box? It sort of looks like what would probably happen if I tried to just build a square box (the inside part)...

Thanks. I must admit, it looks pretty impressive like that. I almost want to put plexi on the side and display it like that haha. The outer dimensions are about 48" X 18" X 22.5"

RossD wrote: I thought 3 dB was double power, so at 6 dB it would be 4 times the power. Either way you can keep the volume lower!

I went and double-checked my sources and I was wrong. You're right a 3 dB increase would need double the input power!! What I got confused is that a 10 dB increase is perceived as twice as loud. So the design of this box is like quadrupling the power that's actually going in (kind of) and almost twice as loud is it should be.
Maybe I should reinforce my foundation?

Just remember that when you use higher efficiency speakers and enclosures, it gets cheaper to power your system with vacuum tubes!

RossD wrote: Just remember that when you use higher efficiency speakers and enclosures, it gets cheaper to power your system with vacuum tubes!

You're speaking my language brother....and potentially getting me in trouble.

It is finished!!!.....almost. I moved everything down there last night, but there are still 2, or maybe 3 things to do.
1 - build a shelf for the center channel speaker. I TOTALLY forgot about this, but for now I'll run a phantom CC, it'll be fine for now. 2 - get trim to hide the cords running from the TV down. I could have run them through the wall, but I just wanted to move forward.
3 - acoustic treatments. I don't know yet how many and where to place them, so I'll calibrate the room and see what needs to be done.
Here's a pic of the room, looking from the front to the rear

Here's a pic from the back row toward the TV.

The TV looks high, but with elevated seating, it seems fine.
First impressions: Too early to tell yet because I haven't changed any settings for the new speakers. With that being said, holy cow do these speakers sound crisp and clean. In a hour or so I expect to be calibrating them and I'll report back if anyone wants to know.
The subwoofer I build is stinking amazing! I haven't played much through it, and it wasn't anything hard hitting, but wow! I used to have two Infinity Kappa Perfect 10.1s, each in it's own enclosure with a dedicated monoblock amp for each one. I now have only one Kappa and one monoblock (same driver, same amp) and I can't believe the output. Half the power as before, half the driver, and I'm going to have to turn the sub down!

Sweet! Report back!

I just finished calibrating the system. I LOVE the Audyssey room correction software. That's actually the reason I retired my Rotel and picked up this one. I didn't really care about HDMI, I wanted Audyssey and am glad I have it.
Anyway, even without the center channel, the system sounds fantastic! Those Magnepans are just beautiful, beautiful speakers. The sound is light, crisp, simply the cleanest sounding speakers I've ever heard.
Now that sub. Holy earthquake batman! I have half the power and half the drivers I had, but I bet 3X the output. And I NEVER came close to 14 Hz before. I just got done demoing a number of cinema clips (no U571 depth charge scene yet) and it felt like someone was kicking the back of my seat. After 40 minutes of punishment, the subwoofer amp was barely warm. A very efficient design.
In the beginning I promised dollars and cents info. I don't really have to-the-dollar figures, but I'll give my best estimation.
Drywall, studs, the plywood for the ceiling, paint, and misc nails and stuff - in the neighborhood of $350. This would have been spent no matter what the room was used for.
My receiver was purchased used for $300, the retail was close to $2,500, very grassroots. The Soundstream monoblock amp I bought years ago, I think it was $100. Samsung bluRay player, maybe $65 or so? I've had the speaker wire and HDMI cables for years, but they aren't expensive. The subwoofer was about $150 for the wood, the risers were about $100. The carpet was free
The chairs were free
The fabric for the seats was about $100
Add in a few hundred for outlets, Romex, and other stuff I've forgotten and it's not really that bad.
The biggest splurge was the speakers, the rears and center was new, the fronts were used. The set of 5 was $1,100.
That's just a ball-park, in a nut-shell rundown there. My whole reason for documenting this was so others can see that you can indeed to a theater on a budget. The only thing I got that would be hard to replicate is the seats. I was in the right place and the right time and nabbed them before they went to the dumpster. The place I really cheaped out was the sound deadening. I could have, and should have, spend a LOT more money keeping the sound in the room. But, this is a family thing, when we are watching a movie, we'll be together. Who cares if the sound can be heard in the other parts of the house (or county)?

Weren't Maggie's much more expensive in the past? Like twice the price?

Subwoofer design looks awesome. I'm gonna have to take a closer look.

Derick Freese wrote: Weren't Maggie's much more expensive in the past? Like twice the price?

Maggies are still much more expensive. This is the MMG line, developed for home theater mainly. They are smaller, a big plus, but don't play very low because Magnepan knows you'll have a sub. I don't consider the lack of bass a minus though, since I've never heard a set of maggies that I didn't feel needed a sub.
The MMG (my main channel speakers) go for $600 a pair, but they are generally compared to $5,000 speakers and, every review I've heard, they win.
The MMGW (my surround speakers) don't go as low as the MMGs, but for surround, they are great, and even smaller than the MMGs. I can't really commend on the MMGC (center) yet because I need to build a shelf for it. I put it back in the box for now

Nice work.

Any pointers on where to look for that sub design? I kinda want to try building one now.....

Do a search for picowrecker. If you can't find it, IM me. I have a PDF cut list and a Sketchup file too.
The cabinet was designed around two specific drivers that aren't expensive but really perform. It just so happened the drivers I have worked perfectly

In reply to DrBoost:

Thanks! Ill do some digging.

The room isn't 100% done yet. I don't know if I mentioned this already, but here's the finishing touches I'll do in the next few weeks:
The cords that run behind the TV need to be hidden by either a trim piece, or be run through the wall. Either way, I don't want to see them.
Same goes for the right rear channel cable.
I need to build a shelf for the center channel speaker.
Somehow I totally forgot that I needed a shelf for the center. So, for the time being, I have the unit sending a phantom center channel signal to the mains. They are doing a surprisingly good job at it.
Here's a current pic of the front of the room

Here's a closer pic of the subwoofer being used as the equipment stand

I know I've said be before, but I love that sub! I played the depth charge scene from U571 and wow!! The low frequency (sub 20 Hz) just rolls across the floor and sets everything vibrating. Wow.
java, if you are thinking about building the sub, do it. It's well worth it.

Are you going to put some grill cloth over the opening? Consider it because that way you don't have to dust inside of the speaker.

RossD wrote: Are you going to put some grill cloth over the opening? Consider it because that way you don't have to dust inside of the speaker.

Yeah, I think I need to. It'll also keep the kids from rolling Matchbox cars in there.

In reply to DrBoost:

Im still thinking about it!! I need a driver though. Looking at building some overnight sensation MTM's first.