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Discussion Starter #81 (Edited)
Construction is 95% completed. I have some sealing around the door and ceiling to do yet.

I have not truly fired this thing up yet as I have a serious gain issue with the MiniDSP. I have purchased a Samson S-convert to handle that problem. I currently have it setup just to do some test tones and sweeps from the computer. Taking things slow.....I don't really want to start listening to this thing until I have it tuned because I know how bad things can sound without at least minimal tuning. Surprisingly, I get absolutely no vibrations from the baffle even during loudest test sweeps(Unlike the rest of the house). The baffle being effectively 11" thick helped but what turned it into a rock was it being anchored directly to the concrete. So 11" baffle may have been overkill :) duh.
The entire house does indeed shake on slow sweeps and I have only managed to put the EP4000 amp up to 50%. At this point I cannot imagine ever having the amp at 100%. With my old sub, I had just had some vibrations at various places in the HT ceiling during very loud passages, with the IB, the walls and things are vibrating in other rooms through the HT walls. I have yet to find a wall surface in the house where at least some vibrations cannot be felt. I do not fear of this damaging the house though. My ears would die long before my house shakes loose. Example, the bathroom mirror 2 levels up makes noise. I am going to have to better secure the trim along the HT doors/walls/floors, because it is vibrating between where the nails are. One wall is like jelly to the left of the sub - need to beef that wall up or else my REW waterfall plot will look like a ski-jump because it continues to flex "long" after sound has stopped.

When a slow sweep is still subsonic, you hear nothing but the whole house vibrating and you feel very strange. There is no indication that sound is coming from the IB - just the house starts to shake as if it has nothing to do with what you are doing. Like a perfect simulation of an earthquake. During the first sweep it freaked me out (there was quite a loud vibration from behind me somewhere before I heard anything else). I am sure it's my imagination, but your vision seems to blur a bit.

Sweeps, especially slow sweeps, and single frequency size waves do create much more vibrations in objects than movies/music because they build up fundamental frequencies in all physical things, but it is a good test to see what may audibly vibrate from time to time during playback.

I may have some time this weekend to post some baseline sweeps and start that whole process.

Initial lesson learned, one of the design goals of this subwoofer turned out to be unnecessary. The funny thing was that I was expecting the baffle to vibrate and impart unwanted mechanical energy to the wall if I coupled it to the wall. So if you look close at the pictures - there is a 1/4" gap between the sub baffle and the wall that is currently filled with spray in foam. Well, turns out this was completely unnecessary given how much I overbuilt. The baffle is solid as a rock and the baffle wall moves quite a bit with the air pressure of the subs. Hard to believe, but the baffle is about the only thing NOT vibrating in the house. I am now considering coupling the wall directly to the baffle to stabilize the wall. Something will need to be done to stabilize that wall and the other walls in the basement.




 

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Discussion Starter #83
Thanks!

Here are some quick AND PROBABLY COMPLETELY INVALID measurements. I have read up on REW and I think I have things right but this is where I lose all confidence in my abilities and need the help fellow Shacksters.

What I have done below is to do a baseline and then compare that with what Audyssey did. I am waiting on my line gain for the MiniDSP so I can really do some EQ'ing, but I thought this may have some value.

***Volume non-sense*** I am using the EP4000 at 50% and the volume on the receiver is set 10-15db below the level I used to watch movies at before the IB. Also, Audyssey put the subwoofer level down an additional -12db when leveling the IB. So, the volume in the graphs is WAY down where it would be without all the reduction in sub levels. Does all this invalidate these sweeps?

I am using the MiniDSP UMIK1 USB mic connected directly to my computer and then using the SPDIF from the computer directly into the receiver.

The Red is the baseline, the green is what Audyssey did.

Any thoughts/help/advice on these would be great. My room is mapped out earlier in the thread. It is 5400 square feet in an L shape with NO current room tuning except for some owens corning 702 behind the screen, thick carpet, and a sectional at mid room.

I have also attached the REW file with the 2 sweeps.

 

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Firstly, awesome build. I'm getting a little scared to build my own. The wife might freak.

Second, response seems to fall off a cliff at 15 Hz, which seems a bit strange. Looks like a ported box response.

Third, looks like you have a giant mode at 25Hz but otherwise looks like auydessy(sp?) did a pretty good job with the eq.

After a little practice you will find RoomEQ Wizard to be a very easy program to work with. You seem like a smart guy so I'm sure you'll get used to it soon.

So baffle wall is just hung from ceiling now huh? Yeah, sounds like coupling it to the baffle is a good idea.
 

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Discussion Starter #85
Firstly, awesome build. I'm getting a little scared to build my own. The wife might freak.

Second, response seems to fall off a cliff at 15 Hz, which seems a bit strange. Looks like a ported box response.

Third, looks like you have a giant mode at 25Hz but otherwise looks like auydessy(sp?) did a pretty good job with the eq.

After a little practice you will find RoomEQ Wizard to be a very easy program to work with. You seem like a smart guy so I'm sure you'll get used to it soon.

So baffle wall is just hung from ceiling now huh? Yeah, sounds like coupling it to the baffle is a good idea.
Thanks for the thumbs up! Well, maybe it's the last 5% of the build that I am procrastinating on - that would be finishing up the sealing of the room. Maybe it is behaving like a ported box to some degree with the small air leaks I have, but I doubt it. Just for kicks I did a sweep with the door open and it did not affect the sounds as much as I thought it would - strange. Maybe I will try pumping up the volume soon, but I have got 500 watts going to each driver which can bottom them out under 15hz. So I am proceeding with caution until I can put in a SSF.
 

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Looking great, blitzer! That manifold looks amazing from the rear, the structural details give it an industrial feel, and I'm sure it's very very stable. Looks nice and clean from the front too, but you need to show us a wider angle of the finished (almost) baffle!
 

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Discussion Starter #87
Firstly, awesome build. I'm getting a little scared to build my own. The wife might freak.

Second, response seems to fall off a cliff at 15 Hz, which seems a bit strange. Looks like a ported box response.

Third, looks like you have a giant mode at 25Hz but otherwise looks like auydessy(sp?) did a pretty good job with the eq.

After a little practice you will find RoomEQ Wizard to be a very easy program to work with. You seem like a smart guy so I'm sure you'll get used to it soon.

So baffle wall is just hung from ceiling now huh? Yeah, sounds like coupling it to the baffle is a good idea.
I think I have figured out the issue with the response falling off rapidly below 15Hz. I believe it is the microphone. I bought a UMIK-1 Microphone from MiniDSP and they have had issues with the response. It is a big controversy, but originally the mic was supposed to have response much further down than 15Hz. Now, they have changed the published response to be just down to 15hz and changed all the correction files for the microphones to not include any correction below 20Hz. The original correction files had entries down to 4.9Hz..... Dissapointing. I am going to have to get another mic to accurately plot the response below 15hz
 

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Wow. I don't know if I could concentrate on the movie if I had speakers like that in front of me. Those things are amazing.
 

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Discussion Starter #97
LOL. Thanks guys. It has been 13 years of swapping, trading up and hiding how much they cost from the wife somehow. I have gravitated completely away from boxes. If unfamiliar with these speakers(Legacy Whispers), they are mostly dipoles. The 15" cones each have another cone behind it, but they are open to the air in the back. I now go to high end audio shows and hear $30K speakers and just hate the boxy sound. I guess I am a dipole snob now.

I have now entered the crazy phase with my wife and friends. Most of them can't tell the difference between a clock radio and high end speakers and just think I am nuts. But they like the demo with the IB sub. But I assume you guys are all similarly nuts?
 
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