"Shh, No Talking" Home Theater... - Page 8

Thanks for the comments :-)

As far as the 3 inch panels sucking up too many frequencies on the side walls, that will be a nonissue. I WANT the panels to suck up as many frequencies as possible, the issue I would run into is if I placed too many acoustical panels on the sidewalls which will over dampen the room, not because of the thickness of the panels though...

I am running a 4000 amp with my subs, I also have a 1124 feedback destroyer in line as well. I have run REW a few times, actually a lot of times, so I have an idea of where my bad points are. Room treatment will be a big thing right now because I have a huge dip and peak at my rear seats, yes I can EQ the peak out but it will hurt the front rows performance. For ha ha's, I'm going to take a bunch of that fiberglass I bought and put it in the back of the room and see if that helps with the low-frequency peaks/dips and just go from there.

Here is what I picked up for $37, $30 of that was spent on gas...



It's 3" thick and I believe it had a density of 6pcf.

So, I'd like to whine for a minute...

Waaaaaaaaahhhhhh waaahh waaahhh waaaaaaaaaaaaah!

Ok, I'm done.

Why am I whining? I'm STILL at the "acousitcal tuning" phase of my build and I am getting no where! Nothing is making much sense to me, and it doesn't help that I'm getting different answers to my questions and different theories on how to treat my room. It doesn't help either that I SUCK at understanding the features of REW and feel like I'm totally mis-using them. I can't read ETC graphs well because I don't know if I'm even taking them correctly. How does an ETC graph even work with a sweep? I imgined it using a single short "noise" like a pop or crack and then reading the delayed reflections from it. Idk...

Also, response graphs and waterfall graphs. I understand how to read response graphs and kind of know how to read waterfall graphs. When I add bass traps (superchunks in my case), I can see how the decay is shortened with the traps so I kind of understand the waterfalls. As far as the response graphs go, after I added the superchunks, it helped with some freq below 100hz but hurt others between 100-200hz, I don't understand.

Just for ha ha's, I put a few of those large pieces of OC705 at the first reflection points and one in the rear center of the room and it just made things worse. It seemed to lessen the overall volume of the sound track. It made the room a bit dead I think, in the higher frequencies anyway, it just seemed to make the room a bit stuffy I thought. And that's just from 2 large pieces on either side wall and one in the back! I thought I was just taming the first reflections, to get one of those "reflection free zones", and yes, not to exact placement but for testing purposes I thought it was going to be good enough.

Another thing, when I clap my hands, decay times seem to be tamed a bit but I still hear a "zing" off some of the walls... Almost like if you took two metal stress releif balls and struck them together, that's the sound I hear when I clap my hands in the room. Can I get rid of this?

Now, about my back wall containg my rear surrounds. I don't have a lot of room for treatment back there. 24" from each corner is filled with the superchunk bass trap, then after a foot or so you will run into my rear surrounds and then I have about 3.5' in between the rear channels but loose height because of my PJ box... ughhh. Should I remove my rear surrounds and treat the whole back wall?

On top of all that, my LCR speakers response sucks so that DIY project seemed to have tanked, and the highly appraised infinite baffle system that I wanted to experience for myself was probably not the best idea.

I need help, my head is spinning and I don't see light at the end of the tunnel yet

I'm at one of those stages where I just want to give up because the room will never be what I want it to be, and that make me feel sad.

What have I done?

Well, as many of you could have predicted, it worked!!!

I decided to throw a 2nd sub into the mix and well, what do you know? It helped

I disconnected two of my 18's, wired the outer two to one channel on my amp and hooked up my table tuba from upstairs to the other channel on the amp, set my gains so that both "subs" separately put out the same spl and voila! Out came more even response across both rows!!

Again, most of you are like, yeah, uhh, Duhh!

But, I had to see for myself and see what it could actually do. So, what does this mean? It means that I'm wiring in one or two subs in the back of the room!!! Haha, some light finally peeped it's way through the crack

Here are few graphs to show what happened...

Front Center no TT...



Front Center w/TT...



Overlayed...



Rear Center no TT...



Rear Center w/TT...



Overlayed...



WOOHOO!!

Now, I still have some funkiness going on above 80hz, any ideas?

I did try a few different crossovers, 60hz/80hz, 80hz80hz, 100hz/100hz, 120hz/120hz. Out of all the above, 120hz/120hz worked best, is this odd?

Thanks for the breakdown, I didn't know that. It makes more sense to me now

I would love to post some waterfalls and ETC graphs, I just need to run some better sweeps. I tried to run a few full range sweeps last night but each channel had a different starting point. The right channel showed the main jump at about 26ms, then all looks ok from there but why did it start so late? Also, my other channel had a curvy wave untill about 40ms, never seen that before. I think I deleted those graph so we'll see what I can come up with tomorrow. As for the waterfalls, should I be posting full range waterfalls or just up to 300hz or 500hz?


Thanks Spaceman, I'm sure I'll get through them, some light has been shed so there's more to come!

The panels were joined with no special technique, just 90 deg cuts with a little bit of glue and a few brad nails


True, moving the LCR's is not a possibility, might not even experiment because of the difficulty in that and the fact that it can't be implemented permanently

Thanks for keeping up with me FOH

I believe the poly between layers of fiberglass aids in LF absorption. The poly acts as a membrane, it vibrates with certain frequencies and then the fiberglass absorbs the energy. If the poly was in front of the fiberglass, that would reflect the UHF to help keep the room from becoming too dead.

Not much of an update for me though, over the last few days I've been making new frames for my wall panels to accept 3" fiberglass for broadband absorption. What a pain in the butt process that I wish I knew was so important in the beginning

I've also been fighting with LFE treatment/sub placement, I'm awaiting on a friend to borrow his Klipsch 12" powered box so I can test placement much easier than with the 200lb table tuba

I've also been messing with my Econowave LCR's, I seems to have bad rolloff in the UF department, especially after the screen goes up, theres not much I can do about that though I don't think

I'm also trying to figure out my front wall situation. I'd like to treat the front wall completely behind the screen with 2"-3" of fiberglass but I'm not sure if the fiberglass can stick past the LCR baffles and if so, how much is too much? Dennis mentioned that it was ok but he didn't tell me how much not to stick past as I'm sure there is a logical limit. As is, if I do 3" on the wall, the fiberglass will protrude about 2" past the LCR baffles, I don't know if that's acceptable or not. I can also peel some FG from the panels and make them 2" thick, not sure what to do there though.

For first reflection panels, how much area on the wall per reflection, per seat should be covered? I'm guessing I want to treat first reflections for all seats, but I'm just afraid of making the room too dead. Although, I forgot ataht Dennis mentioned that I can place strips of poly or carpet plastic over my fiberglass panels to help reflect some of the energy but not all of it, this is if my room does end up being a bit dead from sidewall treatments. Hmm, thoughts?
Edited by Digital_Chris - 6/7/12 at 2:11am

Thanks a lot for your replies, I like the way you think

I have done a little bit of work with that calculator, that's how I came up with 30hz for my long axial mode, front to back. Nto sure how to treat for this though. Either way, I cannot wait to get the subs and room tuned so I can experience what I've ben missing, I want to feel those ULF notes!!!!! I watched The Hulk and I'm still waiting to here those nasty foot steps ppl talk about

Thank you also for your comment on the side wall treatment, I will do panels 3-4 feet high, 1.5 - 2 feet above and below my head, along the wall down to the last reflection point for the last seat. I also need to take some sweeps and figure out this ETC tool and how to read it.

A side note, I decided to build a shallow false wall, even though it will hide my front can lights, I might be able to work around that. I'm going to do the 'minimalist approach" design. I'll post pics in the next few days when that comes together. I'm doing this so I can toe in my speakers as recommended and to fit the 3" fiberglass on the whole wall, not just behind the screen as originally planned.

Like always, buy some wood, change design, return wood, buy different wood, change design slightly, buy more wood

Haha, such a simple piece of woodwork takes so many turns, tomorrow it should be finished, and maybe painted

Pictures to come!

Ok ok ok, pictures will be delivered tonight :P

EDIT: No, they won't be

The weekends kill me at night, well sundays anyway. I work midnight to 7am so on the weekends I try to stay somewhat on schedule but that doesn't work too out well sometimes, therefor, when sunday evening comes, I'm tired when I need to be awake for work

So, bottom line is, my plan tonight was to watch a movie at 8, eat some food after and then work downstairs by taking a few REW measurements along with posting pictures of my almost complete false wall, but, I needed to lay down aftert I ate, I was beat... Plus, when I was down there before the movie, I was getting irritated working on the theater because I'm just at a stand still even though I'm working my butt off down there. The last few months, I've just been picking away at re-doing things that were already done, and the theater isn't even complete yet!!

So, instead of pictures for now, I will just write down what I did in a nut shell...

Finished painting the 2x8's and 2x4 black for the false wall, started modifying the LCR cabinets AGAIN! Since I am no longer doing total flush mount, I removed the lips I added to seal the cabs to the wall and am now "pushing" the speakers out of the wall a bit so the front wall can be covered with insulation without sticking past the speakers. I also learned that the Econowave's are to be toed in, so I made room for that as well. Pictures will show more than my words can describe so hopefully I can post a few over the next couple of days.

I still have to paint my re-worked wall panels that will house the 3" fiberglass at reflection points, which I still have to decide, ETC the whole thing or mirror trick it? Aye yi yi. I tell ya, this isn't fun right now...
Edited by Digital_Chris - 6/17/12 at 9:56pm

Ok, finally, a few pictures of my "progress" from the past few weeks, just excuse the blurriness of any shots, it's dark in the room and camera was being bitchy with the focus

Here are the new frames I was working on to accomodate the 3" thick fg for reflection panels...





Temporarily hung on wall for bracket mock-up...





Said brackets...



Front false wall framing, should be roughly 8" space between false wall and actual wall, this will leave room to toe-in the LCR's and stick them out a bit to fit the 3" fiberglass around them and on the whole wall...







Unfortunately the new false wall will hide the front can lights, although I think that when the screen is up, the lights will shine behind and illuminate the speakers a bit and might look neat, we'll see...



And here are the speaker pieces I cut tonight, they will allow me to seal the speaker onto the front wall while being toed in...








That's all for now, questions or comments are welcome. Time for work!!

Night!

What do you mean? Why did I toe them in or how did I know how much to toe them in?

Guess work

Haha, actually, it's the opposite for me, I was never having "fun" watching movies in my unfinished/untreated room, I think it sounded pretty blah, either too low in volume or to high and just missing fullness overall. I haven''t found a happy medium yet so I'm hoping treatments will help out. I mean, I know I CAN be a perfectionist sometimes but this is getting out of hand, it seems that everyone else can be happy with just throwing up the PJ and a quick setup of speakers but nooo, not me, i just feel like I haven't heard what I'm expecting yet, ya know?

I also need to figure out how to paint my new frames, NOT looking forward to that

Wozers, I finally got downstairs in the past few days to get my panels and speakers done. The panels are finally painted and the speakers are 80% modified. I'm just waiting for my X-Over board to return. I sent them out to a guy in NY to look them over for me. These guys are very knowledgeable with the Econowave speakers, my graphs didn't look right so after as much testing as I could do, I sent out my boards to make sure they are not the problem.

Anyway, here are some pics of the progress...



















Hopefully in the next few weeks I can have more progress to show

Time for a small update, but not really much of an update because technically, I haven't done anything since my last "official" update so this is more of a post on what my next step(s) will be

I should have my x-over boards back tomorrow and I can get my cabs buttoned back up. The boards tested out fine and so did my mic even though my current cal file was affecting my graphs more than I thought so Skywave sent me his cal file which made my mic read much closer to his, that's a start in figuring out this high frequency roll off! 2nd is that I forgot that I had a "pure direct" button on my receiver which apparently disables ANY type of EQ. I will press that button and re-do some measurements to see if my upper frequencies improve, hopefully all of this will happen over the next few days...

Stay tuned!

Thanks Andreas, it's killing me but you guys keep me chuggin' along :P

True that

Ok, I think I just confirmed something. The front row seems like it would benefit from side wall treatment much more than the back row. I have my speakers back together and hung the screen for a little movie demo for myself

I put on The Incredible HULK because I really want to feel those footsteps put down by Abomination, still not impressed yet, tweaking of the subs is still needed. I sat in the back row where the bass is very strong although a bit boomy, the front row is so weak compared to the back row, as I've already mentioned a billion times so far

Anyway, as I was sitting in the back row, I watched the last fight scene between the HULK and Abomination and was like wow! this already sounds great, besides the slightly boomy bass and the lack of ULF, it sounds pretty darn good. Very rich, dynamic and clear. This film is a bit on the loud side I must say so I think I had the demo up a bit more than my regular volume but it still sounded awesome, and that means a lot coming from a guy who never seems happy

Then I replay the same scene in the front row but the bass is now almost non existent, a lot of the sounds blend together and the surrounds are not nearly as envelolping. I'm thinking the surround issue could be because I technically have two sets of side surrounds for the rear row and only one set for the front but regardless, I'm unimpressed by the front row surround effects at the moment. I now see that my front row needs improvement not only in the LF but everywhere else as well. If all else fails for the LF department, I hope I can at least get both rows sounding the same in the mid and upper frequencies.
Edited by Digital_Chris - 7/18/12 at 2:48am