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post #1621 of 2004 Old 07-11-2014, 07:02 PM - Thread Starter
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Quote:
Originally Posted by Mfusick View Post
How much max depth do you have to work with? (JPA)

If you build 4 Gjallerhorns you might not end up needing smoothing subs. You certainly would NOT need more bass One Ghorn alone already has more output than 4 sealed UXL18's at 16hz. Multiple subs in different locations have a way of smoothing themselves too.

If you could fit them the infinity 1260 would make a really nice smoothing sub. $60 each. Good quality with harman technologies. They are almost a proper bass solution unto themselves. You don't need much low or ULF output for smoothing subs, most of the trouble is between 30hz-90hz. You have a big room too.
I could probably swing 16" for the column depth if I had to. I'm actually considering some mid-build changes that may give me a little more flexibility in column depth.

WIth regard to the subs, my issue is going to be room modes. It looks like both rows of seating fall in a null at 38 Hz and 76 Hz. No amount of extra output will fix that. So I'm looking at adding smoothing subs to help eliminate modes, not increase output. The question I have is, if my horn subs are giving me 115 dB at the LP, but I have a 9 db null at 38 Hz, does the smoothing sub have to be able to output 115 dB to smooth out the response. I'm guessing it does not, but I can't think of why the physics would support that.

Another option I have, recommended by Toole, is a single sub at the front wall midpoint and another at the rear wall midpoint. This is supposedly an optimal configuration for a rectangular room with the seats within a 6' square at the middle of the room.

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post #1622 of 2004 Old 07-12-2014, 06:52 AM
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Is the change you're considering in treatment depth? I think 6" for treatments would be pretty close to ideal. Then a 16" deep column would stand out 10" and look right. Of course, there's no rule about that - the column could end up flush with the treatment and still look very good, IMO.

Regarding the output from smoothing subs: I have a few thoughts here, which might be half-baked, so prepare a few grains of salt. In a room with perfect walls (zero transmission - perfect reflection) the null from a single driver located at a room boundary would be a perfect notch, where SPL goes to zero at one line across the room. If an additional sub is at the opposite wall, the measured SPL at that location should be equal to every other position ( I think, but again, this might be half baked), assuming the subs are identical. If the second sub were good for half the output of the first, I think the notch should be reduced to being only -3dB - so that's pretty good. Obviously a theoretical perfect room doesn't exist, so expect some smearing in space, time, and frequency. (Speaking of that, can you put a small sub in there and check out your modal response as is? There's lots to learn at this stage, with the basic shell complete.)

I just don't see why anything other than identical subs should be considered, when flexibility, phase, and output are all taken into account. I'm sure I haven't supported that statement enough to be persuasive, but there you have it: I favor symmetry in all aspects of subwoofer system design. Maybe that's naive or ill-informed, but that's what I'm doing - but sealed, which I think will be a lot more forgiving that horns.
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post #1623 of 2004 Old 07-12-2014, 07:34 AM
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Originally Posted by HopefulFred View Post
Is the change you're considering in treatment depth? I think 6" for treatments would be pretty close to ideal. Then a 16" deep column would stand out 10" and look right. Of course, there's no rule about that - the column could end up flush with the treatment and still look very good, IMO.

Regarding the output from smoothing subs: I have a few thoughts here, which might be half-baked, so prepare a few grains of salt. In a room with perfect walls (zero transmission - perfect reflection) the null from a single driver located at a room boundary would be a perfect notch, where SPL goes to zero at one line across the room. If an additional sub is at the opposite wall, the measured SPL at that location should be equal to every other position ( I think, but again, this might be half baked), assuming the subs are identical. If the second sub were good for half the output of the first, I think the notch should be reduced to being only -3dB - so that's pretty good. Obviously a theoretical perfect room doesn't exist, so expect some smearing in space, time, and frequency. (Speaking of that, can you put a small sub in there and check out your modal response as is? There's lots to learn at this stage, with the basic shell complete.)

I just don't see why anything other than identical subs should be considered, when flexibility, phase, and output are all taken into account. I'm sure I haven't supported that statement enough to be persuasive, but there you have it: I favor symmetry in all aspects of subwoofer system design. Maybe that's naive or ill-informed, but that's what I'm doing - but sealed, which I think will be a lot more forgiving that horns.
Half baked thoughts? No!

A sub systems limiting factor is the weakest link........ie. the lesser capable drivers limits system's overall ability. Had this fact given to me by an expert from Triad.

So I dropped leveling subs in columns which were designed in my system......and went to 4 identical drivers. Level and gain matching was easy! I do suppose in the hands of an expert with appropriate equipment anything is possible.
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post #1624 of 2004 Old 07-12-2014, 07:42 AM
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Are you looking for the column to be the same depth for it's full height? If not, you could have a deeper column base up to your chair rail height for the smoothing sub and then keep a thinner upper column.
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post #1625 of 2004 Old 07-12-2014, 09:15 AM
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Quote:
Originally Posted by TMcG View Post
Are you looking for the column to be the same depth for it's full height? If not, you could have a deeper column base up to your chair rail height for the smoothing sub and then keep a thinner upper column.

This is a good idea. If you needed a little extra depth this could work and look good.


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Originally Posted by HopefulFred View Post
Is the change you're considering in treatment depth? I think 6" for treatments would be pretty close to ideal. Then a 16" deep column would stand out 10" and look right. Of course, there's no rule about that - the column could end up flush with the treatment and still look very good, IMO.

Regarding the output from smoothing subs: I have a few thoughts here, which might be half-baked, so prepare a few grains of salt. In a room with perfect walls (zero transmission - perfect reflection) the null from a single driver located at a room boundary would be a perfect notch, where SPL goes to zero at one line across the room. If an additional sub is at the opposite wall, the measured SPL at that location should be equal to every other position ( I think, but again, this might be half baked), assuming the subs are identical. If the second sub were good for half the output of the first, I think the notch should be reduced to being only -3dB - so that's pretty good. Obviously a theoretical perfect room doesn't exist, so expect some smearing in space, time, and frequency. (Speaking of that, can you put a small sub in there and check out your modal response as is? There's lots to learn at this stage, with the basic shell complete.)

I just don't see why anything other than identical subs should be considered, when flexibility, phase, and output are all taken into account. I'm sure I haven't supported that statement enough to be persuasive, but there you have it: I favor symmetry in all aspects of subwoofer system design. Maybe that's naive or ill-informed, but that's what I'm doing - but sealed, which I think will be a lot more forgiving that horns.

A local friend of mine I know in real life is HAA, ISF, Cedia, THX, ..etc.. Certified and has taken Dennis Classes and also traveled out to the THX ranch for some trainings; He explained this to me once: In an ideal scenario you'd actually have 4 subs, one in each corner, and two on the floor and two on the ceiling. This would produce the best result.

Placement of subs can fix a lot of issues, so can a properly designed room. Smoothing subs are a good tool to use for sure, but not a requirement. And with a properly designed bass horn you won't necessarily have better or worse response at the LP than a sealed sub. The only certain is you would have more bass and lower distortion within the design intentions assuming it was designed right. You'd also need a lot less watts to get that. I think around here there is a prevailing assumption that sealed is better simply because they are easy to calibrate, have good extension, easiest to build, and take the least amount of space. This is all true, and obviously has some serious benefits too. But, the one thing sealed isn't great at is output so while they are a great solution for a smaller space they become much worse solution for bigger spaces.

There is a reason why Metallica uses bass horns at their show and not sealed subs. There is a reason why most of the IMAX theaters have Danely bass horns installed in them. It's because in bigger spaces they work better, and in situation where you want good output they are the best choice. The problem with bass horns isn't that they are hard to calibrate really, it's more just the WAF factor they are big, and difficult and expensive to build and design. Ported subs are out of phase 180 degrees at port tune, sealed are not- and horns are 90 degrees out of phase. Mixing them can be a tad bit tricky but it's not impossible. There is a bunch of guys in the DIY section running mixes with good results validated with measurements and I have read a couple threads where even Dennis calibrated some sealed smoothing subs with some ported cabs and said the results were very good.

Room nodes and response are tough to really account for 100% in the design phase because just moving the sub off the wall or closer can change things, and it's not always as perfect as it seems in theory when you actually measure the room. Things can be different so really the best way is to plan the room the best you can according to theory and then measure the final results to calibrate. I'm not sure JPA would know the full importance of some of this stuff until he has subs in his room, but either way it's all fixable for a great result with any kind of sub and even a mix of them.

I think that an 80Hz null would occur if the radiating plane is 3.5 feet from the wall. With most subs that wouldn't be a problem. If a sub was so large that the baffle was that far away from the wall the simple cure is to aim it at the wall I think. More subs in more locations has a natural effect of smoothing response so probably the best solution is to have more than just one subwoofer and to locate the subwoofers properly. If you can get some subs on the side of the room and back of the room that will do a great job at evening out the response. The way subwoofers interact with a room are usually dependent on their placement in the room, and moving them or placing them in a different spot can get a different result. But having a bunch in different spots has a way of averaging out things. JPA can you do a sub in the back to counteract the sub in the front ? That's a great option for you. It won't necessarily alleviate your need to calibrate but my guess is it would minimize it and have a positive effect at your bass response at LP.

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post #1626 of 2004 Old 07-12-2014, 09:33 AM
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Quote:
Originally Posted by doublewing11 View Post
Half baked thoughts? No!

A sub systems limiting factor is the weakest link........ie. the lesser capable drivers limits system's overall ability. Had this fact given to me by an expert from Triad.

So I dropped leveling subs in columns which were designed in my system......and went to 4 identical drivers. Level and gain matching was easy! I do suppose in the hands of an expert with appropriate equipment anything is possible.
I don't think so. Shawn Byrne explained to me in a PM:

" You don't need to go that low in frequency for the balancing sub. It isn't necessary due to the nature of the modal fundamental frequency in the room. Your problems don't begin till you hit those frequencies which are usually around 30 Hz or above, which is why bass thumping subs are not needed for a balancing sub. "

This was within what I was already told by others too, and so I trust his advice.

It's not about being the "weakest link" for a smoothing sub, it's just about providing enough balance for a smooth response and being properly integrated. Triad is good stuff and certainly using good stuff helps make things easier, but I think any modest but decent quality sub woofer has the ability to be a smoothing sub. It doesn't have to be an ULF thumber or keep up with your main bass solution.

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post #1627 of 2004 Old 07-12-2014, 10:16 AM
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Quote:
Originally Posted by Mfusick View Post
It's not about being the "weakest link" for a smoothing sub, it's just about providing enough balance for a smooth response and being properly integrated. Triad is good stuff and certainly using good stuff helps make things easier, but I think any modest but decent quality sub woofer has the ability to be a smoothing sub. It doesn't have to be an ULF thumber or keep up with your main bass solution.
I hope you are correct. I am planning two 15" ported subs up front, and 3 10" sealed balancing subs in the columns around the room. We shall see--stay tuned.
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post #1628 of 2004 Old 07-12-2014, 10:20 AM
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I hope you are correct. I am planning two 15" ported subs up front, and 3 10" sealed balancing subs in the columns around the room. We shall see--stay tuned.
Are you porting the 10" at the same tune as the 15"? That's probably smart to keep it simple.

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post #1629 of 2004 Old 07-12-2014, 10:25 AM
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Actually, the 10" subs will sealed Procella P10si (smaller, so they'll fit in the columns). The ported 15" subs are JBL Project Array 1500 which I already have, and am very happy with.
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post #1630 of 2004 Old 07-12-2014, 12:56 PM
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Actually, the 10" subs will sealed Procella P10si (smaller, so they'll fit in the columns). The ported 15" subs are JBL Project Array 1500 which I already have, and am very happy with.
Dennis quoted me two P10si for my room for balancing subs, but every other room I've ever seen from him has had 3 balancing subs. Maybe I'll ping Dennis to take a look at things again FWIW. What is the planned position of these balancing subs? I have one to the side of the front seating and one on the back wall at the opposite side of the side sub. Not sure where the third would go....maybe behind the seating on the same side as the side sub?? Dunno...

EDIT: JPA - Can't a DSP assist you with addressing some of the room nulls by flattening the response curve through EQ? I'm asking because I don't know and I thought you were entertaining the notion of installing a MiniDSP (or similar) to handle all of the additional output channels and to easily deal with timing, comb filtering, nulls and other frequency issues.

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post #1631 of 2004 Old 07-12-2014, 01:34 PM
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Yes minidsp would be good idea, especially if mixing ported and sealed ( or horns)

Ported and sealed are the most problematic to integrate. It would be smarter and easier to stay all ported or all sealed, but ported are bigger usually which is tough to WAF factor as smoothing subs.

I'm playing with folding 8 horns in my room design. 6 under a big riser, two behind screen wall. Perhaps 4 behind screen and 4 in back IDK... I might abandon the idea it's a lot of ply and hassle but I think results could be good.

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post #1632 of 2004 Old 07-12-2014, 01:39 PM
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...What is the planned position of these balancing subs? I have one to the side of the front seating and one on the back wall at the opposite side of the side sub. Not sure where the third would go....maybe behind the seating on the same side as the side sub?? Dunno...
Dennis has shown the P10si subs in the front side column on the left, the right side rear column, and on the back wall left column. I will be using a QSC DSP-922az to eq/balance the subs.
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post #1633 of 2004 Old 07-12-2014, 02:20 PM - Thread Starter
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I messed up my plots earlier (plotted sin instead of cos), so my nulls are distributed differently than I thought, but problematic none the less.

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Originally Posted by HopefulFred View Post
…..Regarding the output from smoothing subs: I have a few thoughts here, which might be half-baked, so prepare a few grains of salt. In a room with perfect walls (zero transmission - perfect reflection) the null from a single driver located at a room boundary would be a perfect notch, where SPL goes to zero at one line across the room. If an additional sub is at the opposite wall, the measured SPL at that location should be equal to every other position ( I think, but again, this might be half baked), assuming the subs are identical. If the second sub were good for half the output of the first, I think the notch should be reduced to being only -3dB - so that's pretty good. Obviously a theoretical perfect room doesn't exist, so expect some smearing in space, time, and frequency. (Speaking of that, can you put a small sub in there and check out your modal response as is? There's lots to learn at this stage, with the basic shell complete.)

I just don't see why anything other than identical subs should be considered, when flexibility, phase, and output are all taken into account. I'm sure I haven't supported that statement enough to be persuasive, but there you have it: I favor symmetry in all aspects of subwoofer system design. Maybe that's naive or ill-informed, but that's what I'm doing - but sealed, which I think will be a lot more forgiving that horns.
As always, quite insightful, HF. The fundamental issue that I'm working around is my seats are 14' from the subs. In 14', I'll lose a little over 12 dB between the sub and the seating. As a result, I need a LOT of output. A horn(s) will allow me to get the output I need while keeping amp costs low. Unfortunately, there's no fitting a horn in a column, so I'm looking at how I can provide smoothing without breaking the budget on drivers and amps. This is a somewhat Rube Goldberg approach, but the goal is to keep costs of drivers and amps as low as I can while maintaining output and good seat-to-seat variation.

The 19 Hz null at my seating is less likely to be an issue than the others (I think), because the boundaries in my room are flexible. While there will be a dip, I think it will be less prominent, and there is at least some scientific basis for my hopes (Toole, p 210).


Quote:
Originally Posted by TMcG View Post
Dennis quoted me two P10si for my room for balancing subs, but every other room I've ever seen from him has had 3 balancing subs. Maybe I'll ping Dennis to take a look at things again FWIW. What is the planned position of these balancing subs? I have one to the side of the front seating and one on the back wall at the opposite side of the side sub. Not sure where the third would go....maybe behind the seating on the same side as the side sub?? Dunno...

EDIT: JPA - Can't a DSP assist you with addressing some of the room nulls by flattening the response curve through EQ? I'm asking because I don't know and I thought you were entertaining the notion of installing a MiniDSP (or similar) to handle all of the additional output channels and to easily deal with timing, comb filtering, nulls and other frequency issues.
My layout has three smoothing subs plus two in the front. However, I did not request a sub analysis, so I have no confidence that the number of subs or their locations has been optimized in any way.

With regard to EQ, you can certainly cut a peak or push up a null in the response, but this will be across all seats. So if the front seats have a peak at 70 Hz and the back seats have a null at 70 Hz, if we boost 70 Hz to fix the front row, we've just worsened already boomy bass for the second row. The goal is to limit the seat-to-seat variability so that global EQ affects all the seats in the same way.

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post #1634 of 2004 Old 07-12-2014, 02:32 PM - Thread Starter
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In case anyone is interested, this is the plot of the first three length modes that I've been puzzling over. Feel free to correct me if my understanding of how this works is wrong! The vertical black lines are my seating positions.


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post #1635 of 2004 Old 07-12-2014, 02:36 PM
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...I did not request a sub analysis, so I have no confidence that the number of subs or their locations has been optimized in any way.
I wouldn't go that far; I'm sure Dennis (and Shawn) know quite well at a glance which modes are in the subwoofer passband and where the nulls will be, and if they don't know off the top of their heads which subs assist which modal cancellations - both in phase and inverted - I'm sure they can scribble it out in a moment. It's one of those things like feng shui; you just see it after you've done it enough.

Also, I think you might be too quick to say you can't fit a horn in a column. Depending on the passband and maybe a little ingenuity with regards to shape and the way it interfaces with the soffit or riser, you might get away with a lot. I've never done it, but I bet a simple horn could be made. I'm sure it wouldn't compare with the most popular designs, but it might get you what you need. It would be an interesting intellectual exercise in any case.

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post #1636 of 2004 Old 07-12-2014, 02:42 PM - Thread Starter
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I wouldn't go that far; I'm sure Dennis (and Shawn) know quite well at a glance which modes are in the subwoofer passband and where the nulls will be, and if they don't know off the top of their heads which subs assist which modal cancellations - both in phase and inverted - I'm sure they can scribble it out in a moment. It's one of those things like feng shui; you just see it after you've done it enough.

Also, I think you might be too quick to say you can't fit a horn in a column. Depending on the passband and maybe a little enginuity with regards to shape and the way it interfaces with the soffit or riser, you might get away with a lot. I've never done it, but I bet a simple horn could be made. I'm sure it wouldn't compare with the most popular designs, but it might get you what you need. It would be an interesting intellectual exercise in any case.
Good point! I should remember that the way things sound in my head does not necessarily communicate well on the internets. I didn't mean that the subs were just put on the drawing randomly, only that I don't know that they applied any sort of sub optimization algorithms to optimize placement. I'm with you in that I'm sure Dennis and Shawn have done this enough that they can grab the low-hanging fruit at a glance.

It's interesting that you mention building a horn for the columns, I would think it would need to be tuned quite high (relatively speaking), but I have been wondering if I could build smoothing subs tuned to my identified nulls in order to get extra output. I'm not sure if it would get me anything other than wasting output below the tune, though.

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post #1637 of 2004 Old 07-12-2014, 02:49 PM
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The extra challenge you'll encounter there is the extra phase wrapping near tune for any alignment other than sealed. With DSP of course you can change the phase but with multiple tunes in play, it will get complicated and difficult in a hurry.

If pursuing a variety of subs (not just positions), I do like the idea of deliberately limiting their bandwidth, so that you can optimize specific output (that is, output per dollar or output per cubic foot) within the design range.
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post #1638 of 2004 Old 07-12-2014, 04:21 PM
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I still think infinity 1260 subs in the bottom base of a column have potential as smoothing subs. They can fit and accommodate small box volume, and perform way above budget. $60 per speaker do it I'm every column, run them all off a single iNUKE.

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post #1639 of 2004 Old 07-12-2014, 04:42 PM
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Quote:
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I don't think so. Shawn Byrne explained to me in a PM:

" You don't need to go that low in frequency for the balancing sub. It isn't necessary due to the nature of the modal fundamental frequency in the room. Your problems don't begin till you hit those frequencies which are usually around 30 Hz or above, which is why bass thumping subs are not needed for a balancing sub. "

This was within what I was already told by others too, and so I trust his advice.

It's not about being the "weakest link" for a smoothing sub, it's just about providing enough balance for a smooth response and being properly integrated. Triad is good stuff and certainly using good stuff helps make things easier, but I think any modest but decent quality sub woofer has the ability to be a smoothing sub. It doesn't have to be an ULF thumber or keep up with your main bass solution.

All well and good.........balancing subs are better than nothing at all and I agree with most parts of your rebuttal. Premise is, the balancing subs are not broadband as you noted in post. For greater broadband integration, using same capable drivers across room is a much better alternative. What's great about smaller subs spread across room is their relatively small size and can be hidden inconspicuously.......but still, integration is much better across a wider frequency spectrum with similarly capable drivers.
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post #1640 of 2004 Old 07-12-2014, 10:02 PM
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Originally Posted by doublewing11 View Post
All well and good.........balancing subs are better than nothing at all and I agree with most parts of your rebuttal. Premise is, the balancing subs are not broadband as you noted in post. For greater broadband integration, using same capable drivers across room is a much better alternative. What's great about smaller subs spread across room is their relatively small size and can be hidden inconspicuously.......but still, integration is much better across a wider frequency spectrum with similarly capable drivers.
I think that if you have all 5 subs on separate channels with separate EQ, you will be able to smooth out the bass response pretty well, unless your room has major problems. So that's my story, and I'm stickin' to it...
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post #1641 of 2004 Old 07-12-2014, 10:23 PM
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Time for another update. Earlier in the week I got another chance to work in the theater. I got quite a bit done all things considered.
Very nice job. Another big step accomplished!
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http://www.avsforum.com/forum/61-are...l#post26079610
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post #1642 of 2004 Old 07-12-2014, 11:03 PM
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Originally Posted by LeBon View Post
I think that if you have all 5 subs on separate channels with separate EQ, you will be able to smooth out the bass response pretty well, unless your room has major problems. So that's my story, and I'm stickin' to it...
I see no problem with that........

An expert calibrator with a little time can do wonders given the right tools. If I had to personally eq five different subs.........

Not happening......
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post #1643 of 2004 Old 07-13-2014, 05:56 AM
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AFA the modes diagram, the only modes of concern are the low pressure ones(valleys). The high pressure modes are peaks in response easily Eqed out. Modal dips(low pressure modal regions)are normally impossible to overcome with EQ. This assumes the generator is in a high pressure region of the modal distribution.

If you want to MEASURE potential sub positions quickly:

Place sub at listening position

Play Pink noise through sub

Place Mic at potential sub positions and measure with RTA, that will give you a snapshot of what each sub position is capable of independently relative to seating position.

Smoothing subs are a good idea IMHO if your using 2 subs or less. Unless you have a serious room issue you wont need smoothing subs with 3 or more strategically placed subs. This allows more budget and focus for the main subs. Three subs + EQ gets 99% for 99% of rooms.

Identical subs is the only safe bet at integration. Ive fought sealed and ported before and its no fun. If your not concerned about response below tuning then it works ok but below tuning all bets on predictability are off.

I recommend you measure the room with RTA as i suggested and see what the task is before you select the tool.
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post #1644 of 2004 Old 07-13-2014, 06:17 AM
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Originally Posted by doublewing11 View Post
I see no problem with that........

An expert calibrator with a little time can do wonders given the right tools. If I had to personally eq five different subs.........

Not happening......
One of the side effects of having lots of subs (4 or more) is you don't need to calibrate and EQ them as much; the multiples have a way of doing what you want on their own.

With 4 subs, and a few "smoothing" subs I wouldn't be surprised if there wasn't much needed calibration wise. This is of coarse assuming you have them strategically placed in different locations for good response. Stack them all in a single corner and all bets are off.

In my opinion EQ and "calibration" should be an absolute last resort. Properly designed subwoofer solution in a properly designed room and properly set up shouldn't need much. The goal would be to avoid heavy EQ and calibration corrections up front with proper planning and execution. WAF factor is often the main problem because a lot of people don't want a huge sub visible in their beautiful theater and the proper location in a room might not be aesthetically pleasing. If you remove WAF factor you can ideally get a set up that doesn't need too much help and performs well simply because it's executed well. You can also design into your room theoretically ideal bass solution set up so WAF factor isn't lost. Usually this is as simple as subs on multiple different walls, or subs in the back and not a bunch stacked behind the screen in a single location. If you can't do that then smaller "smoothing" subs are a tool you can use too. I'd rather not have to do extensive calibration and EQ correction if I could avoid it.
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post #1645 of 2004 Old 07-13-2014, 07:44 AM
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Red face

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Originally Posted by Mfusick View Post
One of the side effects of having lots of subs (4 or more) is you don't need to calibrate and EQ them as much; the multiples have a way of doing what you want on their own.

With 4 subs, and a few "smoothing" subs I wouldn't be surprised if there wasn't much needed calibration wise. This is of coarse assuming you have them strategically placed in different locations for good response. Stack them all in a single corner and all bets are off.

In my opinion EQ and "calibration" should be an absolute last resort. Properly designed subwoofer solution in a properly designed room and properly set up shouldn't need much. The goal would be to avoid heavy EQ and calibration corrections up front with proper planning and execution. WAF factor is often the main problem because a lot of people don't want a huge sub visible in their beautiful theater and the proper location in a room might not be aesthetically pleasing. If you remove WAF factor you can ideally get a set up that doesn't need too much help and performs well simply because it's executed well. You can also design into your room theoretically ideal bass solution set up so WAF factor isn't lost. Usually this is as simple as subs on multiple different walls, or subs in the back and not a bunch stacked behind the screen in a single location. If you can't do that then smaller "smoothing" subs are a tool you can use too. I'd rather not have to do extensive calibration and EQ correction if I could avoid it.

Well stated........

And you just proved my original point!
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post #1646 of 2004 Old 07-13-2014, 08:14 AM
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If I'm taking a first stab at this, I want four subs: two on each side wall. Symmetrical left to right, so one right and one left at 7 feet, and the same at 22 feet. Run the front two out of phase from the rear two. Four matching. Anyone know how this mapped out according to Harman? Their research stipulated "coherent" operation - does that mean they did not manipulate phase?

I know you're concerned about output, and the space is big I'll grant you, but I bet this can be done pretty reasonably.

Does this look right to you, JPA (how about you, Nick)?
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post #1647 of 2004 Old 07-13-2014, 11:44 AM - Thread Starter
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Quote:
Originally Posted by NicksHitachi View Post
……..
Smoothing subs are a good idea IMHO if your using 2 subs or less. Unless you have a serious room issue you wont need smoothing subs with 3 or more strategically placed subs. This allows more budget and focus for the main subs. Three subs + EQ gets 99% for 99% of rooms.
…....
Unfortunately, I'm not sure I'll be able to get four subs uniformly placed in the room. I've got space for two big subs up front, and one big sub in the back right half of the room. After that, subs will need to go in the columns unless I put one under the bar or beside the first row of seats. Which, BTW, I'm seriously considering changing to a row of three up front which might make that feasible. But I don't want to plan on that at this point.

As I understand it, even numbers of subs is more attractive for lowering seat-to-seat variation. Is that still the general consensus?


Quote:
Originally Posted by HopefulFred View Post
…..
If I'm taking a first stab at this, I want four subs: two on each side wall. Symmetrical left to right, so one right and one left at 7 feet, and the same at 22 feet. Run the front two out of phase from the rear two. Four matching. Anyone know how this mapped out according to Harman? Their research stipulated "coherent" operation - does that mean they did not manipulate phase?

I know you're concerned about output, and the space is big I'll grant you, but I bet this can be done pretty reasonably.

Does this look right to you, JPA (how about you, Nick)?
This sounds reasonable. I can see where subs at 7' and 22' would address the (2,0,0) mode, although I'm not sure about why we would want the second set out of phase with the first. We're placing the subs so that we drive a null, wouldn't we want them in phase? I could see changing the phase if we were at a boundary with a pressure max that was out of phase with the other sub. I'm not sure about this, though.

I take it you don't have an issue with the (1,0,0) mode? Flexible room boundaries will certainly impact this, but I'm not sure if it will just reduce the dip, or if it will lower the frequency of the dip, or maybe both. The more I think about it, the less I know for sure

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post #1648 of 2004 Old 07-13-2014, 12:28 PM
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JPA ,

Two great sub and another in the back is a decent plan. I don't see huge problem with that. Some smoothing subs might help, but you might be ok without too.

Would you do a DIY solution for smoothing subs or a commercial drop in model ?

Is the cost the primary concern ? Or the WAF factor and aesthetics ?

You could always speaker wire each column then retrofit with smoothing subs later if you really needed them.
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post #1649 of 2004 Old 07-13-2014, 12:32 PM - Thread Starter
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I'm planning to DIY all the subs/speakers in the room. There's just no budget for commercial units. I've prewired most of the columns for smoothing subs (all if I decide to use one set of the 12/4 for a smoothing sub), so I should be able to hide all of the subs without issue as long as I can fit them in a 17.5" wide column (depth to be determined ).

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post #1650 of 2004 Old 07-13-2014, 01:07 PM
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Infinity 1260 one per column, sealed. 10" deep. $60 each.

That's my final answer.

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