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Discussion Starter #1
I have a thread on-going over at the cult, but thought I'd share the details here.

Room is 14.75' Wide by 16.5' deep with 7.75' height.

Theater/Room details can be seen here:
http://www.hometheatershack.com/forums/home-theater-room-photos-finished-rooms-only/66830-scubasteves-theater-scuba-tank.html#post604692



The front of the theater is an exterior wall so the IB couldn't have gone there. I have a rather large storage section to the left of my theater. In fact the whole left and most of the backside of the theater is surrounded by storage/unfinished space. I did not calculate the VAS, as I knew I had way more than 10x.

I'm on limited funds. I already had a Behringer EP1500 and I've already ordered 2 of the 4 drivers. The other 2 can hopefully come later this summer. I will be planning to upgrade to an EP2500/EP4000 when I make that jump.

I've already built the manifold and have built it for the 4 drivers. Outer MDF and Inner Plywood. At this point I'm just waiting on the drivers. Today marks the 20th business day. In the meantime I'm working on the grill/cover and other details.

I also have ordered a UMM6 mic from Cross Spectrum Labs (yet to use it) and will be EQing the subs when the time comes with a miniDSP 2x4 balanced (advanced plug-in).

On to the images:

Cad mockup and sanity check


rough location, I actually ended up moving it up higher:


Sketchup Models for further sanity check. (I drew the boards one by one and then moved them into the assembly)




Manifold Outer


Inner screwed and glued to the outer:


Finding center with offset from center to allow for brace


Router Circle Jig Pivot(Milescraft tool from Home Depot/Lowes)




Recessed inset being machined




Finished Cutout


With my 2year old (hell be 3 next month) shown for reference. He's in the 95th percentile for height so he probably doesn't make a good reference.


Test fit into final resting spot. All of the boxes around will be relocated. Manifold won't be attached until I get the drivers.


What it currently looks like on the other end. I'm working on the grill this week.
 

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Discussion Starter #4
Got word that my drivers shipped and should be here Friday. Went ahead and placed the order for the 2nd pair. Fi ended up honoring the 4 driver discount. While waiting for the drivers I went ahead and finished up the grill aspect

I already had GOM fabric covered OC703 absorption on the first reflection, so I made a "panel" that is basically a frame with some left over fabric I had. Now, it basically looks as it did before, except there is a big hole in the drywall with the IB manifold behind it.

Low light iphone5 pictures inbound:

I initially planned to do some elaborate magnet feature with a hinge for "easy" access but was concerned about the IB blowing it off so after I already had the frame wrapped I ended up having to pull the fabric back to put some threaded bolts in. These bolts are held into the frame with a nut that serves double purpose as a slight standoff from the wall. Then I use simple wingnuts on the opposite side of the drywall to hold the panel in place. It's easily removeable for access and yet it's firm enough that it should withstand whatever the IB throws at it.















 

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! Are those 18 FOOT woofers? I can't even see your son in the 'for size reference' pic! JK, I'm sure you just got your pics mixed up.

Are those other sub woofers I see in your room? Will these be added to complement or replace? What do you have now?
 

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Discussion Starter #7
! Are those 18 FOOT woofers? I can't even see your son in the 'for size reference' pic! JK, I'm sure you just got your pics mixed up.

Are those other sub woofers I see in your room? Will these be added to complement or replace? What do you have now?
Here's the image, not sure what happened.



These are being added to replace. I don't really care much for the cheap-o sony's. Down the line I may compliment but one of the advantages for doing the IB was to take some of the box clutter out of the room.
 

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Awesome! I'm finding that the 2x4 wall needs additional cross bracing in my install to minimize vibration. In your case, that would mean installing 2x4 blocking between vertical members every couple feet or so floor to ceiling, at least for the studs adjacent to your manifold. Anyhow, something to do while you await delivery of your subs! :D
 

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Discussion Starter #9
Awesome! I'm finding that the 2x4 wall needs additional cross bracing in my install to minimize vibration. In your case, that would mean installing 2x4 blocking between vertical members every couple feet or so floor to ceiling, at least for the studs adjacent to your manifold. Anyhow, something to do while you await delivery of your subs! :D
Interesting, I haven't read many other people say that. It certainly an easy thing to do, but I wonder if that's more a consequence of your manifolds being completely supported by the wall whereas mine is mostly supported by the ground?
 

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Interesting, I haven't read many other people say that. It certainly an easy thing to do, but I wonder if that's more a consequence of your manifolds being completely supported by the wall whereas mine is mostly supported by the ground?
Could be. Plus, my wall has to be floating above the floor to meet code here in Denver
 

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Discussion Starter #12
So, I got the 2 drivers put in. At first I was very underwhelmed. I started off by listening to music as I wanted to bring the levels up slowly. The drivers were barely moving. I went to my AVR and put the Sub level at +10db. Still wasn't much output.

I then moved on to my demo disc and boom. There it is. I was listening to music via my AppleTV (gen3) that was playing tracks from my iPhone via Airplay. I'm guessing that maybe Apple puts a high pass filter in there or something. Either that or the cones were just really really stiff and it was coincidence that when I switched the Bluray movie soundtrack that it loosened up.

My initial thought is that it's quite a bit of output and it digs low. Which were project goals. In fact, in terms of output I don't even need the other 2 drivers. I'm still moving forward with them only because I have not measured the room yet and because I might need the headroom for EQ'ing.

I played a 10Hz and a 15Hz tone, albeit at about 10 to 12db down out of fear, and the drivers jumped plenty but did not make an audible sound. I was hearing plenty of sound because all sorts of things in my room and house were buzzing, but I have to say it was the first time I've heard a driver play below 20Hz and be virtually soundless. "Hear the bass, not the box", couldn't be any more accurate.

The downside
Because the sub system plays much lower than my previous system, and thus rumbles the house more I have to turn it down more than my previous subs. This will likely be alleviated when I EQ. Judging by my ears only, I would guess that I have dips in the 40 to 60Hz range and I'm definitely noticing the reduced output there since I have the entire sub system turned down.

I can't tell if it's just a sort of placebo effect or if it's truth but I think I can localize the LFE to the left side of the room (where my manifold is). I will need more time to know for sure.

I noticed when watching TV last night, my wife and I caught up on some episodes from earlier in the week of Big Bang Theory and stuff of the like, that I noticed very little sub presence. It might again be just because I have the system turned down because of the ultra low LFE range that I've lost some of the mid to upper LFE range that I had with my previous subs. Hopefully this will be solved by EQ. Either that, or I am hearing a more proper LFE for the first time without box flutter and confusing that with the absence of LFE.

The biggest downside is that I can't listen to it at the levels that I want to because it just beats the whole house to death. My Kids' toys, 2 floors up, start going off (the motion activated ones). The kitchen hardwood, 1 floor up, feels like it's literally lifting off the studs. Several interior doors rattle around in their door frame. All in all, I think my family is accommodating and I think as sleepless as my kids are (for other reasons) they are somewhat immune to the residual theater noise but this takes it to another level. I'm guessing when it's all said and done I won't be running the system even remotely hard on a daily basis.

I found a guitar center that had a used EP1500 for sale for $99 so I bought it and added their 1 year warranty. Too tempting to pass up and considering I doubt I'd drive it hard. I'm not set from an equipment standpoint. I just gotta wait for the other 2 drivers to show up and in the interim I'm going to start getting used to taking room measurements and applying EQ.



 

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Hey man, glad you are up and running. I feel your frustration as I have a 3 year old and an 8 week old, not to mention a wife that likes to go to bed early. I'm only able to go to around -25 dB on a nightly basis, which is not too bad but does not make me go :yikes: like I know this system can. If I can find 1 opportunity a week to turn it up I'm lucky.

Bummer about the localization issue. I hope you get used to it or forget about it or whatever. I had an issue like that in the past where I had a sub behind me and I could always tell it was there. Was always bugging me. When I switched to stereo subs that totally went away. That's one of the biggest reasons I went with a stereo manifold setup in my room.

Maybe you could incorporate one of your old subs on the other side of the room to help. I was also thinking maybe you'd want to incorporate a infrasonic filter that you could turn on when you didn't want to be so disruptive :innocent: Maybe then you could turn the system up a little louder...
 

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I know too well that feeling of dismay when something doesn't give the results you expected. I built a set of transmission line speakers in the mid 80's and thought I had done something wrong as the bass didn't appear to be there like my old speakers. After several weeks of listening I realised I was hearing the real bass and not the false bass generated by my old ported speakers.

Are you still going to install the second pair? Even if the localisation is purely in your mind a second set will remove that effect.
 

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Discussion Starter #15
My long winded post probably misconstrued my overall feeling. All in all, I'm certainly not dissatisfied. Sure I'm probably not going to get to play it as high a level as I'd like due to the house buzzing and rattling, but I can't really fault the sub or the install for that.

I'm also not completely sure it's localized. My brain knows those two 18s are hiding over there to the left and I might just be telling myself that. Will need more exposure and time for any of that perception thinking to ward away subjective perception.

I am still moving forward with the 2nd pair. Subs and second EP1500 already ordered. Even though I don't need them from an output standpoint, I think it will give me plenty of headroom for EQing, which should fix some of the issues I noted as well as help with any localization effects. Although the 2nd pair is gong to be installed right under the first pair.
 

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Discussion Starter #16
I received my 2nd EP1500 yesterday. I hooked it up right where my existing EP1500 was to make sure it works OK. It works great so far.

I also have been spending some nights the past week or so to get into taking measurements and then applying EQ.

I really like the MiniDSP product. So easy to add EQ, remeasure, tweak EQ, remeasure, ect. The only thing I don't like about it is needing to hack up a cable and attaching them with the supplied pheonix connectors. This is only required if you buy the balanced model. I bought the balanced model because the unbalanced has unusually low output levels. The balanced doesn't have this issue.

Here are some of my measurements from last night.

Subs with and without EQ (no smoothing)


Subs with and without EQ (1/6 smoothing)


I made the sub a little hot in the upper LFE region because I felt like it was lacking in that area. It's probably a memory thing from the color added from an entire life of listening to "box subs". Unfortunately since the tweaking last night I have not had a chance to do a higher volume audition because it was really late and the kids/wife were asleep. The lower level audition showed pretty dramatic improvement.

By taking multiple readings of the subwoofer and center playing together, you can focus on the cross over point (80Hz) while adjusting the subwoofer distance setting (delay) and phase to find the appropriate point for the subs/mains to be integrated. From what I understand you can do this with the left, right or center speaker. I choose the center speaker because it's what I had measured last before moving on the sub. I started with leaving the setting in the my Yamaha AVR at it's default of 1ft, I then started bumping up the delay in my MiniDSP subwoofer EQ. As I moved away from 0, the SPL at the crossover point continued to drop. I reset this back to 0mS and instead attempted to increase the distance in my Yamaha AVR. Like with the MiniDSP, as I moved to distances greater than 1ft, the SPL at the Xover frequency dropped and you could begin to see erratic phasing behavior. As I got really high in distance (approx 25ft) it started to get into phase again. I ended up settling on the default of 1ft and 0mS delay. The image below has many of the measurements turned off for clarity sake.


The subwoofer decay and waterfall tells me that there even though my frequency response is greatly improved, there is still significant ringing. (sub tones are lingering around too long). At these frequencies 14Hz, 22Hz, 36Hz I don't think there is any "bass trapping" I can do at these frequencies to make it go away. Some 14Hz ringing probably isn't to bad as it's mostly just tactile feeling. The 36Hz would be nice to do away with though.

 

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Perhaps some of this is the "beating to death" of your house...:hsd: :heehee:

Maybe you need to start upgrading that situation? Eliminating buzzes, rattles, etc...
 

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Discussion Starter #18
Perhaps some of this is the "beating to death" of your house...:hsd: :heehee:

Maybe you need to start upgrading that situation? Eliminating buzzes, rattles, etc...
While at high output it does excite the whole house, I don't actually have to much buzzing/rattles in the actual theater. I think it's mostly luck. I have one buzz where a side surround the shares the wall with my manifold starts rattling against the drywall, but it's only at really really low content (10Hz-ish) and I've only noticed it when playing tones where everything is otherwise silent.

Luckily the doors in the theater don't vibrate at all (that I've noticed), yet the guest bathroom one floor up can't be shut.

I think I'm almost done. I watched some content last night at higher output and after EQ its definitely better. Plus I'm sure the drivers are more broken in now.

I'm still waiting on the other 2 drivers, but I probably don't need them. I'm anticipating that they will make the in-room response smoother and hopefully clear up a null I have some so that my EQ on that frequency doesn't need as high a Q.
 

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Steve, how do you like that Milescraft jig? It looks pretty robust, is it fairly stable and steady when using? Have a good hold when working with MDF?

It seems like you built a pretty serious monster IB, considering its attacking your house 2 floors up. I hope you and the family get to enjoy it for a long time!
 

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Discussion Starter #20
Steve, how do you like that Milescraft jig? It looks pretty robust, is it fairly stable and steady when using? Have a good hold when working with MDF?

It seems like you built a pretty serious monster IB, considering its attacking your house 2 floors up. I hope you and the family get to enjoy it for a long time!
I'm not a woodworker by any stretch, and I found it easy enough to use. The only thing I don't like about is that the center pivot piece is attached to the routed board with a nail and after a few uses it's started to wear. They should probably sell additional ones.
 
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