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16 x 18's in a 1500ft^3 Space - Popalock's Sub Build - Page 27

post #781 of 943
Quote:
Originally Posted by popalock View Post

So, I got a new toy yesterday...

Looking forward to some epic DIY with the occasional epic slow-mo of me making saw dust...Maybe to the beat some of the newest dubstep out.

Video editing will be done by my daughter of course...lol


I hate to say it but the new Hero 3+ cameras just came out yesterday! I hope you got that one for less then $399.
post #782 of 943
Thread Starter 
Quote:
Originally Posted by gpmbc View Post

Nice work man! I know mine would look like Fisher Price my first grill set.

Thanks! Trust me...mine did too. This is the 4th grill set I've started, but only the 2nd that I've completed.

The amount of experience I gain with each grill I make is crazy. Just making the grill in the pic was a huge learning experience with about a handful lessons learned that I'll take with me moving forward.
post #783 of 943
Thread Starter 
Quote:
Originally Posted by mtg90 View Post

I hate to say it but the new Hero 3+ cameras just came out yesterday! I hope you got that one for less then $399.

This one was $329. Had no idea a new one was coming out. I can bring this one back tomorrow. Is the 3+ worth the upgrade?
post #784 of 943
Well you got it for the sale price. The 3+ is not a huge upgrade, it's a bit smaller and lighter, supposed to be 33% sharper and I know they said it the built in mic can handle an extra 10dB's before distorting. It has a few other small advantages too but I would not pay extra for it unless you wanted those features.
post #785 of 943
Great job on those grills man!!
post #786 of 943
Thread Starter 
Quote:
Originally Posted by mtg90 View Post

Well you got it for the sale price. The 3+ is not a huge upgrade, it's a bit smaller and lighter, supposed to be 33% sharper and I know they said it the built in mic can handle an extra 10dB's before distorting. It has a few other small advantages too but I would not pay extra for it unless you wanted those features.

Thanks for turning me on to this Matt. I looked into it. I dig those features... Will be returning the 3 for the 3+ within the next few days.

Quote:
Originally Posted by Reddig View Post

Great job on those grills man!!

Thanks man! Labor of love for sure.
post #787 of 943
Quote:
Originally Posted by popalock View Post

Oh yeah! Threw the wifey a surprise B-Day party this past weekend and had some family down. We watched several movies and it sounded great.

No complaints from the AT screen at all from an audio perspective. I did find that having my speakers out of view some how gave me more courage with the volume control...lol That said, I am still looking forward to picking up the FP10K from you as soon as I can get around to making the trip.

With that little gap between the subs and the screen, I was able to peek behind the screen and noticed a lot of light was bleeding through, but I honestly won't know if that has any effect on the brightness of my Panasonic PJ because I had an Epson on loan all weekend.

Running some sweeps is on my radar when I get the chance, but I have a few other priorities this week.

On other thing of note is... As with any new construction, or changes you make to your space, comes the possibility of more "rattles." Discovered a few nasty ones during some movie playback. I'll need to pin point the source and deal with it. You know how it is though, I would venture to say that no one else but me could careless or even tell that there was a rattle anyway.

More impressions to come soon.

If you have a frequency generator it could help you to pinpoint rattles while making sweeps with a sine wave waveform ...
post #788 of 943
Thread Starter 
Quote:
Originally Posted by maxserg View Post

If you have a frequency generator it could help you to pinpoint rattles while making sweeps with a sine wave waveform ...

I don't have a frequency generator, but I do have a ton of sine waves that I've downloaded. When I get the chance I'll try to go through to pinpoint my problem areas.

Sounds fun... rolleyes.gif
post #789 of 943
Quote:
Originally Posted by popalock View Post

I don't have a frequency generator, but I do have a ton of sine waves that I've downloaded. When I get the chance I'll try to go through to pinpoint my problem areas.

Sounds fun... rolleyes.gif

Use your blu ray demo disc, the tools section. Lots of fun. biggrin.gif
post #790 of 943
Quote:
Originally Posted by popalock View Post

I don't have a frequency generator, but I do have a ton of sine waves that I've downloaded. When I get the chance I'll try to go through to pinpoint my problem areas.

Sounds fun... rolleyes.gif

or REW dog!!!
post #791 of 943
I don't know how I missed all the updates this last month, but things look great.
post #792 of 943
Quote:
Originally Posted by NathanJ View Post

I don't know how I missed all the updates this last month, but things look great.

I'll agree with that! I'm still struggling to keep up with the latest on here but looking good!
post #793 of 943
Austin - I really like the makeover. What's your secret with the panels? I'll be starting mine in the next few weeks.
post #794 of 943
Thread Starter 
Quote:
Originally Posted by Gorilla83 View Post

I'll agree with that! I'm still struggling to keep up with the latest on here but looking good!

Thanks man.

Quote:
Originally Posted by Wahoo_envy View Post

Austin - I really like the makeover. What's your secret with the panels? I'll be starting mine in the next few weeks.

I plan on starting the write up this weekend. Hopefully that will answer any questions.
post #795 of 943
popa...truly awesome!
I too am on to making grilles...but you have done a buttload more with your theater than mine and you have a double quadruple buttload more speakers to cover with grilles than me.

I used Erich's flat-packs for my four DA 18s and am not sure how deep to make the grille covers to clear drivers while they are being used.eek.gif

Looking forward to your write-up so that I may shamelessly glean hints and tips!tongue.gif
Fantastic work, sir!!
Edited by blah450 - 10/8/13 at 3:12am
post #796 of 943
Nice grills

Been a while since I've caught up in this thread, nice progress overall.

Enjoyable and thought provoking comments reading both the subjective comments about the characteristic sound of the subs, and the Bl non-linearity impact on the issue.

Even though many multiples helps significantly in minimizing all sorts of non-linearities, at any given level, those big cone excursions that accompany the deepest effects still has the potential to position all 16 drivers out at the weaker ends of the curve. With any driver, attempting to resolve the remaining upper spectrum of LFE/RB riding atop the big demanding waves, is a tall order.

There can be a lot of things at play, but maybe this is one component of the subjective difference experienced.

Quote:
Originally Posted by LTD02 View Post

...and now that the screen is in place, a little absorption next to the speakers to minimize rear wall reflection will smooth frequency response just that little bit more...

+1

I'd fill as much of the area as possible with your material of choice. Anything from 703 rigid, Rockwool Safe-N-Sound, to the fluffy stuff, I'd cover as much of that entire behind the screen area as you can. Treating this area is helps in multiple ways;

1.) Overall bass damping, ... any amount of LF decay time attenuation you can provide is helpful for note-to-note detail and delineation, and there's absolutely no downside to placing it behind the mains/screen (excessive bass damping out in the room can minimize late returns if not executed properly, thus lowering spaciousness).

2.) As LTD mentioned, attenuating the omnidirectional energy radiating from the loudspeakers smoothes response irregularities resulting from reflected wave interactions with the direct sound. Whether it's the wall behind the mains, or an adjacent sidewall (or wall sized sub towers eek.gif ), these boundaries mimic an acoustical mirror, summing the energy, increasing or canceling the direct sound, depending on the phase difference.

3.) Lessening the reflected energy from the surrounds encountering the front wall and bouncing back toward the LP.

I read you're considering some new mains sometime in the near future, so thought I'd throw the above out there for anyone in such a position. Love that sub system, keep it up!

Quote:
Originally Posted by maxserg View Post

If you have a frequency generator it could help you to pinpoint rattles while making sweeps with a sine wave waveform ...

Good idea, you gotta sort out all those annoyances.
There's several such software based generators, but before everyone had computers, there was The Rattler. This was a corded hand held, remote sized tone generator with a freq knob, ... so one could sweep until the offending resonance could be found.


Good luck moving forward
post #797 of 943
Thread Starter 
FOH,

Thanks very much for the in depth response on the importance of addressing the area behind my AT screen. I definitely plan on doing some preliminary treatments to see if I can make improvements temporarily. At this point I don't want to go all out given the glimmer of hope that I will be able to upgrade my LCR.

IF (and it's a big if) I am able to get the LCR I am gunning for, I might end up making a few more updates that could effectively eliminate the need for treatments behind my screen all together. I still have quite a ways to go in order to get a firm grasp on SIBR, but my preliminary research indicates that the preverbal "wall of sound" would effectively eliminate the need for treatments behind the screen, correct?

By wall of sound, I am thinking adding a few more bass arrays and a LCR Noesis. Then I will address whatever gaps above/below the LCR as my attempt at a "wall of sound."

I'm got my fingers crossed that I'm not just pipe dreaming and this is something that will be able to come to fruition sooner than later... Time will tell.
post #798 of 943
filling in the gaps around your speakers with fiberglass is what foh was talking about as that will kill off the reflection from the wall behind the speakers.

with respect to an array of bass to project a wall of sound, that is a good idea. the trouble with your room is that you sit right on the rear wall and the energy from the wall of sound needs to be absorbed somewhere. so while you won't have any side/height modes, you will still have the rear wall to deal with. eq may work since, at least in theory, all seats would see the same wall of sound so long as they are all the same distance from the screen.
post #799 of 943
Austin was kind enough to give me a demo and the theater looks great and sounds even better! The pics of his theater really don't do this thing justice, you can't help but laugh (in a good way) when you see the huge towers of subs in front of you and behind you. I haven't experienced bass like that since I used to be into car audio, it was really cool to feel that in a home install!

The wife is already rolling her eyes that I have a sudden renewed interest in doing a more formal theater in the basement smile.gif
post #800 of 943
Quote:
Originally Posted by z0dVA View Post

Austin was kind enough to give me a demo and the theater looks great and sounds even better! The pics of his theater really don't do this thing justice, you can't help but laugh (in a good way) when you see the huge towers of subs in front of you and behind you. I haven't experienced bass like that since I used to be into car audio, it was really cool to feel that in a home install!

The wife is already rolling her eyes that I have a sudden renewed interest in doing a more formal theater in the basement smile.gif
If she likes it now, she'll love it when it's done. She'll be fine.
post #801 of 943
Quote:
Originally Posted by popalock View Post

FOH,

Thanks very much for the in depth response on the importance of addressing the area behind my AT screen. I definitely plan on doing some preliminary treatments to see if I can make improvements temporarily. At this point I don't want to go all out given the glimmer of hope that I will be able to upgrade my LCR.

IF (and it's a big if) I am able to get the LCR I am gunning for, I might end up making a few more updates that could effectively eliminate the need for treatments behind my screen all together. I still have quite a ways to go in order to get a firm grasp on SIBR, but my preliminary research indicates that the preverbal "wall of sound" would effectively eliminate the need for treatments behind the screen, correct?

By wall of sound, I am thinking adding a few more bass arrays and a LCR Noesis. Then I will address whatever gaps above/below the LCR as my attempt at a "wall of sound."

I'm got my fingers crossed that I'm not just pipe dreaming and this is something that will be able to come to fruition sooner than later... Time will tell.

Absorption on the front wall is key to improving dialogue and imaging. Chunk style traps (which you might be able to squeeze in there) will improve/smooth LF response. Roxul Safe N Sound is available at your HD right up the road. Its one of the few HD's that carry it in our area.

Can't wait to see the tutorial on the grills ... they look awesome!! how are they going to attach?

Also picked up a goPro Hero to use behind my boat .. I got the 3 (not the +) for $280 so I'm keeping it. tongue.gif
post #802 of 943
Thread Starter 
Quote:
Originally Posted by pauleyc View Post

Absorption on the front wall is key to improving dialogue and imaging. Chunk style traps (which you might be able to squeeze in there) will improve/smooth LF response. Roxul Safe N Sound is available at your HD right up the road. Its one of the few HD's that carry it in our area.

I have three extra pieces of some 2" Corning 703 laying around.
http://www.atsacoustics.com/item--Owens-Corning-703-Case-of-6--1004.html?d=GPGEN01&kw=1004-703-2

I know it's not ideally as thick as I need it to be, but I had a thought I wanted to run by you guys really quick. If I take those three pieces and literally hang them from my ceiling right behind my screen, about 10" from the wall itself, would that provide more absorbsion vs. simply hanging them directly on my walls like I did for my rear treatments?

I mean, if reflections (whatever frequencies) easily pass through the 2" 703, would hanging the absorbsion away from the wall force those frequencies to effectively pass through the 703 twice in order for it to reach the LP?

Does that make sense?

Don't worry gents, I fully plan to watch that Acoustics 101 video when I get home today... Hope I'm not asking a question Anthony answers in the video.

Quote:
Originally Posted by pauleyc View Post

Can't wait to see the tutorial on the grills ... they look awesome!! how are they going to attach?

Yeah man, I'll try to whip something up this weekend. Might be hard with everything we have going on... This will be my first official weekend with the new gopro, so I might get inundated with it...lol

Quote:
Originally Posted by pauleyc View Post

Also picked up a goPro Hero to use behind my boat .. I got the 3 (not the +) for $280 so I'm keeping it. tongue.gif

Nice! I ended up picking up the 3+ Black Edition on Monday. They don't even have it on the floor yet. Man, the gopro itself seems like it can get really expensive quick! All of the attachments, adapters, carrying cases, etc... Crazy... I blinked and was down like $600!
post #803 of 943
"I know it's not ideally as thick as I need it to be, but I had a thought I wanted to run by you guys really quick. If I take those three pieces and literally hang them from my ceiling right behind my screen, about 10" from the wall itself, would that provide more absorbsion vs. simply hanging them directly on my walls like I did for my rear treatments?"

yes. absorbers like that will work in the "velocity zone" of the wavelength, which occurs at roughly 1/4 and 3/4 of the wavelength. there is no particle velocity at the wall itself, so absorbers like that do almost nothing right on the wall except for very high frequencies.
post #804 of 943
Glad to help
Quote:
Originally Posted by popalock View Post

IF (and it's a big if) I am able to get the LCR I am gunning for, I might end up making a few more updates that could effectively eliminate the need for treatments behind my screen all together.

I understand, work in progress ....

The only way to eliminate the need for acoustic treatment up on the front boundary of the room is to implement a baffle wall. A baffle wall has many theoretical advantages to any other loudspeaker placement approach. However, unfortunately a baffle wall also heightens the importance of rear wall treatment because all front sources are placed at the pressure maximum. If all the pressure sources are located in the same plane and at the pressure maximum, all modal resonances front-to-back are maximally excited. Hence the concern for rear wall damping.

Studios employ flush mounted mains for a very simple reason; optimal wave-launch. First the boost gained from all the energy that otherwise would radiate omni-directionally is focused forward and not smeared in time from the bounce off the surface behind the speakers. So increased image focus, and significant smoothing to the frequency response. Also any slight disturbances or very early reflections or re-radiations (diffraction) of the wave-launch are lessened. Again smoothing the FR and retaining the wave-launch as un-corrupted as possible.


Quote:
Originally Posted by popalock View Post

I still have quite a ways to go in order to get a firm grasp on SIBR, but my preliminary research indicates that the preverbal "wall of sound" would effectively eliminate the need for treatments behind the screen, correct?

Not necessarily. Even if you employed the Noesis LCRs, and some other sub cabs, etc, you could still benefit from LF damping, modal damping of the front-to-back axial modes. This helps in both FR smoothing and lowering LF decay times.

In battling room modes in small rooms, in any of the three axis with absorption type treatment, one needs to use one boundary or the other, or ideally both. That said, if you went with your wall of sound, you could still benefit from a bunch of fluffy/rigid up higher etc., or wherever you could place it. Also, be mindful, many surface irregularities up front, could be detrimental to the image throw. Yes, constant directivity or any measure of directivity helps remove some of these issues, but just be mindful of several cabs up front somewhat incongruously set up.

I know, splitting hairs, .. ate up, anal retentive, just throwing items out there. Please don't misunderstand, merely trying to help. Poorly executed front of the room speaker set up is so pervasive around here. I see so many fantastically time consuming builds, yet it's easy to disregard some crucial fundamentals. If that initial wave launch is corrupted, being thrown at you smeared from multiple path lengths, the image detail, vocal intelligibility, and all the smaller nuances that the engineers tried so hard to capture, no amount of treatment, EQ, DSP can make up for it.

We love our big bombastic bass effects that accompany out favorite material. But our hearing acuity is most sensitive to the critical mid-band. Examining and addressing any potential issues in the mid-band is a force multiplier for our systems akin to nothing else we can do. Fortunately, psychoacoustics allows us to "hear past" many of the common issues we encounter. But any attempts lessening these acoustic distortions pays off huge in subjective contexts like smoothness, ease, image coherence, detail.

I know many hate such terminology, but subjectively we do attempt to describe the changes to the playback experience, as we move forward addressing the lowest hanging fruit we encounter.

Anyway, this turned into a mega response, my apologies. After the launch and direct sound, the remaining elements of the room's acoustic comes into play. That's an entire discussion into itself. But the most important component is bass trapping. Reducing the LF decay times, monumentally important, as increased clarity and detail, note-to-note delineation. As much effective bass trapping as you can aesthetically stand.




Regarding your sub system, .. from the first time I saw this group of (16)18"s, and knowing what all I discovered wrt multi-sub optimizing, I envisioned an opportunity for time delay attenuation of whatever modal issues arise front-to-back.

A variety of acoustic components at play;

It would appear the height and width modes are dealt with adequately via spreading of the sources as you have them, .. so we'll examine what could be done elsewhere, ie front-to-back.

1.) The seating is so close to the rear boundary, the listener is in a high pressure region (peaky response). Typically in this situation, you apply as much absorption thickness as possible behind the LP.

2.) It's not often achieved in practice, but ideally, one wants as many dedicated amp channels and corresponding DSP channels to provide differing amounts of time delay to manipulate acoustic summation of all the disparate sources. Individual EQ isn't an absolute necessity (individual low pass can help), global EQ (all the subs as one) is generally fine to tune the final response. But having the ability to tune via time delay specific groups of LF sources really is a powerful tool.

3.) In your system, the listener is (relatively speaking in 1/4 wavelengths) very close to some of the drivers, and significantly farther to other groups of drivers. If you could optimize the way the rear drivers sum at the listening position (time delay), and then take that group and align them with the front sub towers, I'd bet you could elicit even more smoothness in the freq domain.

4.) A final step is global EQ, knocking down whatever peaky response issues remain. Nulls are typically acoustic interference, peaks are typically modal excitation. As I mentioned above, if you have the ability to vary each groups low pass (the upper roll off), that too is a good tool to manipulate the FR smoothing. Any way you can manipulate the way the drivers sum is another arrow in your quiver.


Yeah, this post got away from me a bit. You may find the existing FR not too bad. That doesn't mean the subs are all playing nicely. The path lengths are all so dramatically different, and that's the genesis of the point I was trying to make. As good as it is right now, I'm thinking there's a lot left on the table.


Hope this helps,
All the best


Here's Genelec's take on some aspects of what I was discussing.
post #805 of 943
Quote:
Originally Posted by popalock View Post


I know it's not ideally as thick as I need it to be, but I had a thought I wanted to run by you guys really quick. If I take those three pieces and literally hang them from my ceiling right behind my screen, about 10" from the wall itself, would that provide more absorbsion vs. simply hanging them directly on my walls like I did for my rear treatments?

I mean, if reflections (whatever frequencies) easily pass through the 2" 703, would hanging the absorbsion away from the wall force those frequencies to effectively pass through the 703 twice in order for it to reach the LP?

It's not that it goes thru it twice, as LTD mentioned, it's the distance off the boundary that helps.

ATS Acoustics, or any company for that matter is great. But buying and making them yourself can save you huge. Not only markups, but the problem is shipping, hence purchased treatments cost a bundle.

Go to a local SPI, they'll sell rigid, rockwool, whatever you likely need. It's an insulation supply house, they're nationwide.

As a rule, fluffy rules unless you don't have the thickness to give up, problem is compression of the material, so steps must be taken to minimize this, like bird-netting. But, based upon the space you have to work with, 4" use the dense stuff.. 703 or equiv., @6-9" use Safe-N-Sound Rockwool.

If it's an area whereby you want returns, craft paper facing will start to reflect maybe around 1k, vinyl pool liner stuff around 500hz, 1/2lb MLV will return around 250hz.
post #806 of 943
so effectively you are saying that all acoustic panels should be suspended off the walls by at least a few inch gap? I have found for modal smoothing that just the simple (although plentiful) 2 inch 2x4 panels from ATS has worked wonders. well, and 4 inchers on the back wall.
post #807 of 943
Heck, my .5 inch sound board does wonders for echo but for low frequencies nothing will stop them except concrete. I have not decided on what I want to use for my baffle wall yet.
post #808 of 943
Quote:
Originally Posted by beastaudio View Post

so effectively you are saying that all acoustic panels should be suspended off the walls by at least a few inch gap? I have found for modal smoothing that just the simple (although plentiful) 2 inch 2x4 panels from ATS has worked wonders. well, and 4 inchers on the back wall.

A 4" panel is more effective than a 2" panel and 2" gap, but maybe not as much as one would think.

At a given panel thickness, the gap multiplies the effectiveness in the lower octaves.

As we go up in panel thickness, the situation transitions, ideally one needs to change to less dense material for better effectiveness.


4" rigid, with 4" gap, offers superb attenuation for both trapping, and first reflections. Remember, ideally ... if you absorb, you absorb it all. IOW, if you opt for absorption at sidewall reflection points, you implement as full of a broadband solution as possible.

After 4" w/4" gap, move to full thickness (all the way to the boundary) Safe-N-Sound Rockwool.

After that, move to fluffy. Problem is fluffy can be tough to deal with, whereas Safe-N-Sound is more stackable like rigid. These are the ideal, there's nothing stopping someone from going 8" thick of Owens Corning 703. That'll still work great. It's just that you could cover twice the area with 4" w/4" gap, and achieve almost as good performance.




This image is a comparo of 2" rigid mounted on the wall, 4" w/4" gap, 12" fluffy, 24" fluffy

post #809 of 943
Thread Starter 
Quote:
Originally Posted by z0dVA View Post

Austin was kind enough to give me a demo and the theater looks great and sounds even better! The pics of his theater really don't do this thing justice, you can't help but laugh (in a good way) when you see the huge towers of subs in front of you and behind you. I haven't experienced bass like that since I used to be into car audio, it was really cool to feel that in a home install!

The wife is already rolling her eyes that I have a sudden renewed interest in doing a more formal theater in the basement smile.gif

Thanks man. It was great to meet you. I've come to expect the typical "WTF Chuckle" as soon as people round the corner and spot the 18's...

Hell, sometimes I even look at them and can't hold back the same response...haha.

Worse thing about demoing other people's gear is the potential for the upgrade bug. It's a risk we all have to live with though.

I'm looking forward to making it up to your place in the near future.
post #810 of 943
Thread Starter 
Quote:
Originally Posted by FOH View Post

A 4" panel is more effective than a 2" panel and 2" gap, but maybe not as much as one would think.

At a given panel thickness, the gap multiplies the effectiveness in the lower octaves.

As we go up in panel thickness, the situation transitions, ideally one needs to change to less dense material for better effectiveness.


4" rigid, with 4" gap, offers superb attenuation for both trapping, and first reflections. Remember, ideally ... if you absorb, you absorb it all. IOW, if you opt for absorption at sidewall reflection points, you implement as full of a broadband solution as possible.

After 4" w/4" gap, move to full thickness (all the way to the boundary) Safe-N-Sound Rockwool.

After that, move to fluffy. Problem is fluffy can be tough to deal with, whereas Safe-N-Sound is more stackable like rigid. These are the ideal, there's nothing stopping someone from going 8" thick of Owens Corning 703. That'll still work great. It's just that you could cover twice the area with 4" w/4" gap, and achieve almost as good performance.




This image is a comparo of 2" rigid mounted on the wall, 4" w/4" gap, 12" fluffy, 24" fluffy


Outstanding info FOH. Very much appreciated.
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