Building a Dinner Theater w/ DIY Speakers, Subs, etc... - Page 3

That 5x5 birch is supposed to be the highest quality birch...well except for marine grade plywoods, but I don't know how they fair sonically. I'm sure just fine.

MDF has the advantage in deadness by a small amount over plywood due to weight/inertness.

I actually like working with MDF. My 4PI's cabinets with sanding primer.

i bought 6 sheets of 13-ply 5x5 Baltic Birch @ $45 each to build my speakers and subs, and i'll not use anything else.

but again, some here are also big fans of MDF.

Thanks, I like the way it reacts to the router particularly the round over bits. The cabinets do get heavy.

thats some impressive work thus far!! Do you already have the drivers?

In a 45x30 room, I'd cluster subs rather than spread them. Spread out subs makes for a good 'sweet area' in smaller rooms, but makes for lobing/interference problems in larger rooms higher in the sub freq range.

If you will use subs beneath the stage (do you need real low freq support for the stage?) I'd run them separately from the screen subs, to avoid interference issues.

Your room is at the border of the 'spread subs or not' debate. A little bigger, and I'd say cluster them, for sure. Smaller, and I'd say spread them for a nice sweet spot in the middle.

I say cluster them. Keep 4 beneath the screen, and 2 under the stage. Don't run all at once. In fact, if the stage will mainly be live music, use different subs that are more efficient from 30-40Hz on up.....but the F20s should do well there too.....

Also, one more thing: The L/R screen channels may need to be outside the area of the screen for good integration with the surround arrays.....something to think about, but not critical.

Point the surround array individual speakers at the 2/3rds point on the opposite end of the room. It doesn't always equal 45 degrees down-slope....

Each 'level' of surrounds (distance-wise) will require a delay so that sound coming from the mains and surrounds at the same time will hit listener's ears at the same time...at the differing distances.....


JSS

My friend, I believe you dodged a bullet/got lucky here. I would not make a habit out of letting the big box store do any cutting, other than maybe halving a 4x8 if I didn't have a truck. Myself and others have had inaccuracies of 1/4"+ and I'm not picking on Lowes, this is the case with any store with a big panel saw of questionable condition and adjustment, used by a variety of employees.

sounds like you are probably done with needing cuts made but I thought I'd post this because I didn't want anyone reading this getting too much of a false send of security. I had a sub that ended up smaller than planned due to inaccurate, and out of square cuts.

Sweet place you have there, I'll have to check it out some time.

I was wondering what was going on with this winery.


Ha, I'll pick on 'em. I had them cut a 4x8 in half so I could get it home. They didn't lock the blade and the sheet walked 4"...I got the sheet for half price.

DYI = Do Yourself In? Looking at the size of those things, it might be fitting! *Outch, the back!* Sorry, can't resist, I always think that when I see DYI!

I am interested in this.

I'm not big on wine by any stretch of the imagination, but I sure would love to watch a movie there when it's all done.

Very nice looking. Wish I were local to you when it's all completed.

Yeah, that would be an awesome place to check out sometime. It may have been mentioned earlier in the thread, but where are you growing the grapes at, and who is your brew master?

You'd save a lot of time if you built all the speakers of each type at once. Since most of the time is spend doing "setup" and little actually cutting wood you'll gain a lot of efficiency.

The winery is looking great. My ancestors settled in NM in 1864 to set up a winery in the Rio Grande Valley. My great grandmother ended up torching the vineyards to keep her sons from becoming alcoholics. All their presses and stuff is in a museum here in ABQ.

You have a big room, so clustering subs is a good idea. Use all four F20s. Cross to the 4Pis at around 80-100Hz, a good AVR will do this for you. Use Room EQ Wizard to delay the 4 Pis with respect to the F20s. After that, the only thing left would be whether or not you will delay each surround pair individually or not, it may not be something that will be a deal breaker if you cannot.

An AVR that has a good auto setup function or adjustability should do the trick.

This is one of the threads I have been following for a while...

JSS

I'm in Australia, so can't help you there but someone offered to pay me to measure their system and room. I realised then that there was a demand and now offer it as a service locally. My suggestion - offer to pay someone to measure the system and help with integration. Someone who knows what they are doing. It's very worthwhile. If you can afford to renovate, I'm sure you can afford to spend enough to compensate someone for giving up their Saturday.

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In theory you can get any kind of sub to work with other subs, although some combinations are definitely easier than others. You don't want to delay F20 at all, but instead delay the mains so the sub can catch up. This can also be true of direct radiators. With a horn you move the acoustic centre forward down the horn, but it will still probably have more delay due to around 4m of horn length. Any sub will require the mains to be delayed if you want it "time aligned."

Couple of points about the F20 - I've built one and simulated with different drivers. Seems to work best around 20 - 60 Hz, I doubt you will get good results running up to 80 Hz because it is a highly compromised horn. A full sized 20 Hz horn can be made to extend up high, but it must be far bigger. Also, the horn does not protect the driver well below about 25 Hz, so as a rule it's a good idea to run a high pass at that point. Probably around 2nd order.

How low do your mains go? I suspect you might have a bit of a gap between your mains and where the F20 would like to work. You don't really want a 12" low sensitivity sub in your situation. Perhaps a better solution is ported mains that can get down to 60 Hz, high pass at that point and F20 running up to 60 Hz. I'd be wanting to measure to ensure a good integration. Rythmik audio have an article about phase alignment of mains and subs, with either sealed or ported mains:

http://www.rythmikaudio.com/phase1.html

JBL 2226 is a high sensitivity 15 that doesn't like to go low. 30 Hz is highly optimistic. 200L box with 30 Hz tuning and it's -3db @ 80 Hz, or -6 db @ 30 Hz. A 60L box with that driver tuned to 50 Hz gets down to 60 Hz and could then be made to work with F20. That is probably more like what you have.

Confirms my suspicion. Shown as around 98 db on that chart, with 97 dB @ 100 Hz, and 3 dB down from that at 65 Hz. If your box is tuned low, then you could probably put in a high pass relatively low, perhaps 40 Hz and bring in F20 around 60 Hz or so. That's not a bad starting point. You are best to use measurements to take it from there.

Dutch, due to a lack of options, your only choice is to put the subs - all of them - in your front baffle wall. It would be better if you could disperse them throughout the room, but it doesn't sound like you can. HP them around 20-24hz and set the AVR's XO at 60hz. As paul already mentioned, that should get you off to a good start. You'll have a few hours of measuring a head of you, and that hardwood floor is not going to help anything!

Off topic, but do you know about mosquito pee? It's fermented lemon aid which utilizes old wine yeast. I'm going to be brewing some for this summer.
http://skeeterpee.com/Skeeter_Pee/Recipe.html/