Help plan oneplustwo's listening room/home theatre/family room/

[oneplustwo]

Yes, I'm debating whether I should get one. Seems like a great deal but it's also not cheap. I'm thinking it might be the best option though. I'm a little worried about the ability of Dirac or parametric EQ to manage the line arrays, but I could try to work out a more optimized solution with two channel playback if it's not good enough. Plus, when I started this whole idea, I was originally JUST going to use parametric EQ. So I suppose it's an upgrade to that original plan already so perhaps I'm setting the bar too high.

[oneplustwo]

Well, I pulled the trigger on the XMC. Couldn't resist the discount price. I'll wire and install the 4 Atmos speakers in the ceiling. The rear wall will have a wet bar so I don't have room for in wall rear speakers. I've seen those installed in the ceiling too though. Is that ok?

I also found a couple four channel amps... a iNuke NU4-6000 (4x1600W) and an older Europower EPQ304 (4x75W). The iNuke seems like overkill for speakers that are only rated to about 75W in the first place. But it's only $350. The EPQ304 is about $240 but it's probably plenty for surround speaker duty. And it's only 1U tall so it's nice and tidy. Eventually, I can get one for the four Atmos speakers and stack it with the first one that will power the sides and rears. I may even be able to disable the fans since they'll only be used for surround duty.

[scottvalentin]

Have you thought of a chip amp kit? A 4X50w should be plenty for surround duty. Check parts express's selection of Sure amp boards. The board and a PSU will probably run you around $100 and my experience is that the sound quality of those boards is pretty good. Plus then you get to build it!

[oneplustwo]

Have you thought of a chip amp kit? A 4X50w should be plenty for surround duty. Check parts express's selection of Sure amp boards. The board and a PSU will probably run you around $100 and my experience is that the sound quality of those boards is pretty good. Plus then you get to build it!

I didn't find their chip amp but I did find a 4x100 class D module. That could work... although after you add all the enclosure and other stuff, the price difference isn't really that much. And to be honest, I've built so many amps, DACs, preamps, etc. that I'm less excited to do that work these days. Sacrilege, I know. But I'll look into options at least for the fun of it!

EDIT: I just came across this. It's designed for amplifying your home but with 12 channels, it can cover all my surrounds, the center, and also a couple exterior speakers I have in the plan. It's also Class D and passively cooled so no fans. 60 Watts per channel is probably a good place to be also. And at $600, it's a reasonable value given how many channels it's driving.

[Hdale85]

http://emotiva.com/products/amplifiers/700

110wpc x7

[oneplustwo]

I liked it but it's short 5 channels. But still an option I'm considering. Plus, it matches the XMC-1. And I'm in no hurry so maybe I can get it on sale over the holidays.

[oneplustwo]

Update to line array built into frame:

[oneplustwo]

Hmm, turns out the framing requirements are structural in nature after all so I can't just move 2x4's as I would like. However, I have an idea to basically make the top of the array open into the ceiling joists and have a sealed volume up there to accommodate what I'm missing directly behind the drivers. It's not exactly elegant, but I think it should work fine.

[oneplustwo]

The house is coming along nicely. We're in rough plumbing and electrical now. Solar panels are up and running. Will start putting radiant heat plumbing in shortly and getting insulation and drywall up after that.

Question for the group since I'm getting to the point where I need to run speaker wires.

I'm planning on wiring for 7.4.2 protecting for potential Atmos speakers. I will have the 2 side channel speakers in the wall but the two rears will be in the ceiling since I have a wet bar directly behind the couch. Keep in mind this is not a huge room... 12' wide by 20' deep with 7'6" ceilings roughly.

So the question is, how close to the edges should I put the 4 Atmos surround speakers? I was considering keeping them about 2' away from the corners. That makes them about 8' apart. But I also considered putting them right at the corners thinking that might minimize some unwanted reflections and perhaps create a greater illusion of sound stage. Same question for the two rears... Should they be in the corners or a couple feet away? It's a little uneven for one of those rear speakers since one corner opens into a hallway but that can't be helped.

Thanks in advance for the input!

[dar47]

If the rear surrounds have some tweeter focus ability, mine could be tilted forward a bit the distance behind the seating should take this in to consideration. You don't want the rears to close to the side surrounds, again I used 1/3 the width of the room and placed them out from the side wall that distance and of course inline with each other. This gave great fill and seamed coherent.

[oneplustwo]

I think I'll be able to get them 1/3 the width as you mention for the rears. And a little bit behind the seating position. I think the Atmos speakers are supposed to be a little closer to the edges though based on the Dolby website.

Like this:


Here's a pic of the house while I'm at it:

[oneplustwo]

Progress shot and a question.

Here's the room where all the stuff is going to go. It's just a shot of the insulation and rebar ahead of the concrete pour tomorrow. But any who...


Also, speaker wires have been run for 7.1.4 and HDMI and power are run for the ceiling mounted projector. The in-wall/ceiling surrounds have been purchased and my old ZDT 3.5 center has been re-acquired from my brother. Will need to build the line array and IB subs when we move back in. Most of the other pieces are also ready to go but I still need the projector screen which leads me to my question.

First, I'm thinking about getting this:



I think 120" will fill the wall nicely and still leave room for the arrays and the IB subs (about 1' space between the screen and walls). The question is whether it's ok to mount it so the top is right at the corner of the wall and ceiling. I'm wondering if there will be some wash out with light bouncing off the ceiling. I've seen others like this so I think it will be fine. Reason I want it up high is to make sure I have room for the IB sub holes to the other side of the wall. And also to make as much room as possible for all the amps, center channel, etc. that will be taking up residence in the front.

EDIT: one more question... opinions on white, gray, or silver screen? Projector is the Sony VPL-HW45ES (1800 lumens) and the room will be a mix of totally controlled light and not. For serious viewing, I will have blackout shades and such. But if we're entertaining and such, it may not be so controlled and in which case, I probably don't care so much about how it looks then anyway.
Thanks! I do plan on viewing some 3D but it isn't a huge priority.

[oneplustwo]

One more question. I think I can get 28 of the TC9 in each array. So I'm thinking four groups of 7 for a 14 ohm nominal load. Any other ideas for something better? (I'm driving these with Ncore 400.)

They are pouring the cement next week so I don't know for sure yet, but there's a chance I may need to go to 27 drivers. And that makes for a more difficult decision (24 or 2.7 ohm.). Hope that's not the case. Might need to go to 25 drivers for a 5x5 for a 8 ohm load if so. But that would leave a few inch gap in the array.

[oneplustwo]

I had read someone had separated five drivers at a time in their own enclosure for some reason. It was something about making sure the drivers that were wired in series didn't share the same space as the others. I'm not sure why this would make a difference though. Minimizing the standing waves going up and down the column is the only thing I was thinking would be a design consideration. So I'm missing something?

Second question... is it better to mount these from the front or the rear? From the rear, I can just round over the front face with a 1/2" or 3/4" bit. Then I don't need to scallop the rear. And the front acts a bit like a horn although I don't know if anyone has actually measured this. And it also makes grill cloth installation more straight forward.

[chrisn]

Mounting them from the rear would let them breathe easier, and likely look better.

[chrisn]

Regarding horn loading/diffraction differences between front and rear mounted small woofers, I don't recall seeing any testing done. I do happen to have to no longer used baffles with HiVi B3N drivers mounted in them, from the front, with a 45 degree chamfer on the back side. I took one baffle, and reverse mounted the drivers, and left the other baffle as is. I don't have cabinets to mount these to, so I had to improvise a rear chamber.



Sorry for the low quality of the photo. Hopefully you can see the chamfer, which measures about .375", and the straight through cut portion, which measures just under .50". The thickness of the baffle is about .75". I think a much wider chamfer, or roundover, would perform better, but it's not router weather

This is the response with the drivers mounted from behind:




The other baffle, with the drivers conventionally mounted (only one driver connected):



Some of the difference, mostly level, is due to the mic being further away from the driver when rear mounted. It was too noisy to attempt far field measurements, which may mitigate some of the issues. Hopefully this is of some use to you.

[oneplustwo]

Hmm, interesting. The conventionally mounted ones look smoother to me for sure. I assume these both are with just one driver connected? You mentioned it for one but not the other. I wonder if it's more interesting to see the results with the mic farther away?

Regardless, thanks for taking the effort to do this quick and dirty test. I imagine there must be some white paper or other previous work done on this subject?

[chrisn]

Yes, those were all done with one driver at a time. I re-tested, using two drivers in parallel, at a greater distance.

Both drivers front mounted:



Both drivers rear mounted:



I wanted to see how much effect the small chamfer has versus a larger one, and few things are as invigorating as routing baffles when it's -1 Fahrenheit with the wind chill :rf The large chamfer measures .75", almost double the original size. There wasn't enough meat to cut a roundover on the existing chamfer.



These measurements were done with just one driver, with the mic positioned between each driver, at a distance of 4 feet.

Small chamfer:



Large chamfer:

[oneplustwo]

Interesting. Thanks for pushing through the extreme conditions! Large chamfer seems to be a bit better behaved IMHO. Wonder if the width of the baffle itself with respect to the size/position of the hole and chamfer makes a difference.

[chrisn]

I believe it does. This is on a 5.5" baffle, and the rear mounting diffraction effects seem to coincide with the peak caused by the baffles width. Of course there is no edge roundover on these baffles when I flip it around, so I think it's the worst case scenario. When I performed those measurements, I also tested a Zaph B3S design, with a 5" width, front mounted driver, and .50" roundover, and it's relatively smooth, aside from the room effects:

[oneplustwo]

Interesting. This is a bit of a stretch from the last few posts, but I'm considering a bit of a horn type design for the array now too.



Line array baffle would basically just be a 45 degree baffle in the room corners. And then I would figure out some way to have some sort of horn profile along the height of the array to create this effect. The radius would be about 3" or perhaps a little bigger. Might try using styrofoam to validate the concept first and if it works out then I could build something more permanent.

Thoughts?

[chrisn]

I'm really not sure how a large radius would would effect them, it should provide a boost somewhere. The Murphy corner arrays are mostly just a flat baffle, with a large, wide, dip in response. I couldn't find any tests using other baffle sizes or shapes. Do you plan to build a test box? Perhaps mounting the drivers off center could be of benefit?

[oneplustwo]

Now that I look at the volume I'm planning for (about 2.2L) and using 25 drivers to get the 5 series/5 parallel wiring setup despite having vertical space for 28 drivers, I think I can get the baffle to be a bit narrower. And as such, the space to the side of the drivers would be less to the point that the drivers are nearly in the corners. So I'm thinking I'll forego the additional profiling. Also, I'm not sure it would pass the WAF test.

I am still debating front vs rear mounting though. Rear mounting means less volume in the cabinet but maybe better response with the round over per your tests. It would be easier to do grill cloth too. So I'm leaning that way now using a 1/2" thick baffle. Feel better about that now also because the baffle width will be 7" compared to 8.5" as originally planned.

[chrisn]

I wasn't sure how high the WAF would be with brightly colored pool noodles on each side Is the baffle going to be removable?

[oneplustwo]

Baffle will be removable. Basically, it's just going to be screwed directly into the walls since I have plywood shear walls to screw directly into. I'll probably seal with some foam tape. I need to think a bit about the top and bottom but at the moment, I'm thinking I'll just have a triangular piece that will meet the baffle already installed so I don't have any problems actually angling it into place.

Also, thinking front mounting now with maybe some felt (in orange) going top to bottom to the corner to smooth out that junction and prevent higher frequency reflections. And then grill cloth (in pink) covering it all.

Like this:

[flamethrower1]

I had read someone had separated five drivers at a time in their own enclosure for some reason. It was something about making sure the drivers that were wired in series didn't share the same space as the others. I'm not sure why this would make a difference though. Minimizing the standing waves going up and down the column is the only thing I was thinking would be a design consideration. So I'm missing something?

Second question... is it better to mount these from the front or the rear? From the rear, I can just round over the front face with a 1/2" or 3/4" bit. Then I don't need to scallop the rear. And the front acts a bit like a horn although I don't know if anyone has actually measured this. And it also makes grill cloth installation more straight forward.

I built the IDS25 clones this way (5 drivers in each compartment) per JMs recommendation due to differences in BL from all of the speakers.
All of the other array builds I have seen did not do this, not much help I know, hope it helps some what

[oneplustwo]

Thanks for the input. I'm thinking I will likely not split up into totally separate compartments but I may add some bracing that will cut down on resonances and also reduce the risk of standing waves. Part of the rationale is to maximize the available volume while minimizing the baffle width.

[oneplustwo]

Been busy learning a little Fusion 360 to more accurately model the enclosure. Also, a member at DIY audio had a model of the TC9 that I was able to use. Still trying to figure out if I'm ok with the back wave being so close to the driver. And whether I can get away with a 1/4" aluminum baffle that's 160mm wide. It will be screwed into the wall every 84mm so it should be quite rigid. I may line it with mass loaded vinyl as well. And there's also the option of doing a layered baffle with either plywood or MDF. Or I could just do a 3/4" ply baffle with bracing. Lots of options. Notice there are also 2" holes to the side of each driver that will lead to a space stuffed with fiberglass to get the Q a bit closer to .8 or so.

[TEK]

are you able to cut the side of the baffel at 45 degrees so that it will be flush with the wall, instead of it just beeing a sharp edge that connect it to the wall (left side on picture)?
Or add a small pice of wood along the wall on the back of the baffle that it can rest on (right side of picture)?

[oneplustwo]

Yes, I should be able to make that cut. Either with my router or on my table saw with an aluminum cutting blade.

[oneplustwo]

Since the idea is to isolate the baffle from the wall though, would it be better to let the edge rest against the neoprene? Would that not reduce the amount of energy transferred to the walls?

[oneplustwo]

Progress... will start the line array build soon.

[chrisn]

Looks sharp. What size screen did you end up using?

[oneplustwo]

120" fit perfectly. Will be nice when 4K projectors come down into my budget!

[oneplustwo]

Getting close... room is done. Still need to build the line arrays but planning the AV cabinet and the subwoofer integration now. Behind the wall, there's actually a bit of a concrete foundation the entire way across that goes to about 8" above the floor. I'm thinking I could drill some pocket holes in some 2x4's for the mounting frame and tap con through those holes into the footer. That would pretty much isolate the subs from the wall and I think prevent vibration from getting to the house in general. True, that leaves half of the frame attached to the wall itself, but I feel much better about this than not doing so. I'm still considering having the two woofers facing each other with forces canceling each other out. But that still leaves potential for vibration in the cabinet itself and I'm sensitive to that given I will have a record player on top. The first method leaves the AV cabinet isolated from the subs entirely.

Thoughts?

[JonMarsh]

A record player on top of the sub woofer? You are indeed a brave man... A DAC, I might not be too worried about, though some people do go all OCD about vibration into any kind of component. I'm having trouble visualizing from your verbal description- any chance of a sketch?

Force cancellation in a common cabinet can't help but be a good thing, but I'm getting the impression you're talking about two separate cabinets facing in to each other?

[oneplustwo]

Indeed. I'm now considering Tapcons down into the concrete floor and then back into the foundation footer ONLY with no connections to the wall at all. That shouldn't vibrate anything.

I'll draw up a sketch shortly... I think it will do the trick though. It will take a little more effort but not much.

[Steve Manning]

A sketch would be good ..... though having done some vibration control for vacuum pumps and other stuff, any kind of rigid connection will typically have a tendency to transmit vibration. You might want to look at McMaster Carr, they might give you some ideas since they carry of bunch of vibration control goodies. https://www.mcmaster.com/#vibration-...ounts/=17x9gfi as an example.

[oneplustwo]

I see your point. I was also planning on layering some butyl sheets between the sub and the concrete so it wouldn't be an entirely rigid connection. Think that would be good enough? Plus the concrete slab is rebar reinforced and 6" deep. And the foundation footer is 12" tall, 12' wide, and about 4' deep. So there's lot of mass there.

[oneplustwo]

Here's a sketch of the room for context.



And a basic layout of the components overlaid on top of an older photo of the wall.



And here's what I'm thinking the cabinet would be like. To clarify, the sub enclosures would not be attached... the face frames and such would be more like a facade. Also, the lighter brown color is grill cloth to hide the drivers of the subs and the center channel. The other components just sit on the floor. Finally, the top of the cabinet would be hinged so I can access the turntable.

Any input welcome!

Edit: another thought would be to cover all of it in grill cloth. I think it's transparent to IR. Or I can use an IR repeater if not.

[Steve Manning]

I see your point. I was also planning on layering some butyl sheets between the sub and the concrete so it wouldn't be an entirely rigid connection. Think that would be good enough? Plus the concrete slab is rebar reinforced and 6" deep. And the foundation footer is 12" tall, 12' wide, and about 4' deep. So there's lot of mass there.

The butyl sheets ought to do the trick I would think .... I'm sure you could go with something exotic, though probably not worth the investment.

[oneplustwo]

Been a long time since an update.

One of two floor to ceiling line array speaker baffles milled into Swiss cheese to accept drivers. I love the smell of cutting fluid in the evening!

The 3” hole saw rings like crazy though. Enough that I need hearing protection and I’m pretty sure the neighbors are glad I stopped before starting the second one. That said, it got through the first 28 holes without any real problems. I'm hopeful it makes it through the remaining 28 as well although I have a backup if need be.

On a side note, the big Jet drill press I got worked pretty well. I had to reseat the chuck once after I pushed it a little too hard but otherwise, smooth sailing with some cutting fluid and a soft touch.

One more to go and then I need to mill the wood supports/mounting strips and get the drivers mounted/wired up.

[chrisn]

Looks straight and aligned. How long did it take to make all those cuts? Isn't it annoying when the chuck falls off?

[oneplustwo]

I did it in stages. First measuring and marking all the holes. Then drilling all the mounting holes with my tiny press. Then I tried the big hole but my tiny press wasn’t close to capable. (It’s a harbor freight one that I got for free years ago.). Then I had to research and buy the upgraded Jet drill press. Long story short, a long time. The hole saw holes were probably only about 3 min of actual cutting each though. Not too bad.

EDIT: The first time the chuck fell off I thought I sheared the thing off for good. Thankfully, I figured out how these things work in short order...

[TEK]

That is just so cool!