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4xIB318" vs two ported monsters - Page 2

post #31 of 94
Quote:
Originally Posted by ChopShop1 View Post

If I place the sub at LP and then listen around the room for the best response, I pick the best position. If I use the 4 best areas of response, that would be optimal correct??

Not necessarily, as the net total output is not going to be the sum of the individual outputs, unless they're all symmetric relative to the room boundaries and listening position.

I think for four subs that means the listening position has to be in the center of the room.
post #32 of 94
Thread Starter 
Quote:
Originally Posted by FOH View Post

Are you referring to co-location?

I can appreciate your concern for ultimate output, however you'll have insane output at all but the lowest frequencies. And the lowest frequencies will sum acoustically in a manner that essentially renders them co-located. Their wavelengths are so big, (56.5 feet for a 20hz wave) you'll largely enjoy the benefits of collocation into the range of concern.

The benefits gained for theoretical co-location aren't an all or nothing proposition. The manner in which these acoustic gains occur don't merely begin at zero, and jump to 6db at full co-location. It's a gradual process whereby the two distinct sources operate entirely separate from one another, and slowly sum to the total +6db due to constructive superimposition at the LP.

When two sources, IB manifolds in your situation, are operational relatively close to each other (whereby their acoustical centers are approximately within 1/4 wavelength), the gains from mutual coupling exist. This sums their acoustic output and will combine and propagate as a single wavefront over the range involved (within 1/4 wavelength). The incremental nature of the constructive superimposition is due to the sources being increasingly in phase at the LP, then the acoustic output of the manifolds essentially act as a single, much more capable IB.


I'm going to link some superb reads for you. These are outstanding, there's much I could link for you, but this is the best;

Getting the Bass Right

Loudspeakers and Rooms

Those two papers will help you determine a great deal.

The following web page, and collection of links includes a significant amount of the above material, however it's presented somewhat differently;

Here


I'm guessing you've spent some time at The Cult?


Good luck and I appreciate the kind words,...it's a pleasure to help.



Best of luck

I have read a ton on the cult. I also read your links, thank you. They were very informative, and I am learning many things quickly, but am afraid my scientific reasoning and ability to understand is quite limited in comparison to those who can truly put this information to work. It seems if I place 4 manifold, 2 drivers each, in the following manner, I will have my best shot at optimum performance based on my limitations. The front wall is nearly 26 feet long. If I place a manifold beneath the floor in each fron corner to start and then on more, in around 9 feet from each respective sidewall(just inside the mains) I can: still reap the benefits of colocation to some extenet and drastically improve the response vs a single or even dual locations.

I have another question....If I get a couple of sealed subs and place them at various locations to find the best combo, the locations that yield the best output/response combo would also offer these results if IB manifolds were placed in the same location right??
post #33 of 94
Quote:
Originally Posted by ChopShop1 View Post

I have another question....If I get a couple of sealed subs and place them at various locations to find the best combo, the locations that yield the best output/response combo would also offer these results if IB manifolds were placed in the same location right??

Correct. And actually testing is key. All the fancy theories in the world don't amount to anything in comparison.
post #34 of 94
Thread Starter 
Quote:
Originally Posted by S_rangeBrew View Post

Correct. And actually testing is key. All the fancy theories in the world don't amount to anything in comparison.

Cool, I just wasn't sure if it would vary because the manifold mouth would be firing up through the floor.
post #35 of 94
Quote:
Originally Posted by ChopShop1 View Post

Cool, I just wasn't sure if it would vary because the manifold mouth would be firing up through the floor.

Doesn't matter.

Measurements trump everything, also, keep in mind that extensive bass traps really help minimize nulls as well.
post #36 of 94
Thread Starter 
Quote:
Originally Posted by FOH View Post

Doesn't matter.

Measurements trump everything, also, keep in mind that extensive bass traps really help minimize nulls as well.

Yeah, the bass traps are new to me. I know they need to be used, but am not sure I understand how to place them best and how exactly they accomplish what they do.
post #37 of 94
Quote:
Originally Posted by ChopShop1 View Post

Yeah, the bass traps are new to me. I know they need to be used, but am not sure I understand how to place them best and how exactly they accomplish what they do.

This one's easy, ...easy and cheap. There's two types of absorption, pressure based diaphragmatic (like wall movement), and velocity based like fiberglass. We'll focus on velocity based.



The above image illustrates how the need for spacing away from a room boundary is needed to effectively absorb the low frequencies. The bass wavelengths are huge in size. The velocity is greatest at the 1/4 wavelength point, so bass trap effectiveness is aided when spacing the material off the wall.

Bass traps primary need to exist in corners, and spaced off the walls.

You've got to get the energy when it's moving, the closer to the wall, the less the energy is moving so it needs to be thick, and spaced off the wall.

----------------

Here is Ethan Winer's superb paper on room treatment. Contained therein is bass traps etc.

There's a certain type of bass trap called the SSC, or Studio Tips Superchunk. Here that process is detailed.

----------------

Gearslutz is a fantastic place for acoustics related threads, the one I linked to is a nice bass trap summary. Here they have an entire board dedicated to bass traps and treatment.

--------------

I'd suggest the Ethan Winer paper first, it's really good.

Bass traps address the time domain, by damping excessive ringing in the bass octaves. This allows better note to note delineation of bass detail, tighter bass and fewer nulls,..smoother response. All small rooms need significant bass trapping. Oft cited, oft overlooked. Huge gains are to be had.

The latest info suggest cheap pink fluffy is best for thick bass traps. Cheap, very effective,...win-win!


Best of luck
LL
post #38 of 94
Quote:
Originally Posted by FOH View Post


There's a certain type of bass trap called the SSC, or Studio Tips Superchunk. Here

I just built some traps similar to these. I was too cheap to buy the high density fiberglass so I had to modify the process a bit.

Stack about 6 or 8 triangle shaped pieces of insulation in the corner. Compress these pieces with a plywood triangle, and while compressing the stack, screw the plywood triangle into the wall. Repeat until you reach the ceiling, or stop a little short and its a great place to hide surround speakers. I made covers by building a plywood frame and wrapping with cloth. Super easy, super effective. The insulation is incredibly dense by the time you reach the top.

My room has 6 corners. I have the rear 2 corners completed and it's made a huge difference in how the room sounds.

Enjoy!





post #39 of 94
Thread Starter 
Quote:
Originally Posted by gracey View Post

I just built some traps similar to these. I was too cheap to buy the high density fiberglass so I had to modify the process a bit.

Stack about 6 or 8 triangle shaped pieces of insulation in the corner. Compress these pieces with a plywood triangle, and while compressing the stack, screw the plywood triangle into the wall. Repeat until you reach the ceiling, or stop a little short and its a great place to hide surround speakers. I made covers by building a plywood frame and wrapping with cloth. Super easy, super effective. The insulation is incredibly dense by the time you reach the top.

My room has 6 corners. I have the rear 2 corners completed and it's made a huge difference in how the room sounds.

Enjoy!








Very cool, thanks for posting the pics!!
post #40 of 94
Quote:
Originally Posted by gracey View Post

I just built some traps similar to these. I was too cheap to buy the high density fiberglass so I had to modify the process a bit.

Stack about 6 or 8 triangle shaped pieces of insulation in the corner. Compress these pieces with a plywood triangle, and while compressing the stack, screw the plywood triangle into the wall. Repeat until you reach the ceiling, or stop a little short and its a great place to hide surround speakers. I made covers by building a plywood frame and wrapping with cloth. Super easy, super effective. The insulation is incredibly dense by the time you reach the top.

My room has 6 corners. I have the rear 2 corners completed and it's made a huge difference in how the room sounds.

Enjoy!






So, is it better to do the triangle thing, or build a panel that has some air space behind it? I've seen both ways, and am wondering if there's an advantage one way or the other.

Also, I was under the impression that for the corner traps it was more effective to stack them loosely instead of compressing them, even going so far as to add supports every few feet to keep the bottom layers from getting too compressed. Anyone have any light to shed on the matter? I'm planning on doing treatments soon and am trying to get as clear an understanding as my limited mental capacity allows.....
post #41 of 94
Thread Starter 
I tell you guys, just when my mind is made up, I change it again. In one moment, I feel like buying two ported subs and making it "easy" for myself. The next minute, I'm am 110% sure I am going with an IB build, and then back and forth again. I really wish I could get a good listen to a large IB setup near me...anyone near Connecticut??
post #42 of 94
Quote:
Originally Posted by ChopShop1 View Post

I tell you guys, just when my mind is made up, I change it again. In one moment, I feel like buying two ported subs and making it "easy" for myself. The next minute, I'm am 110% sure I am going with an IB build, and then back and forth again. I really wish I could get a good listen to a large IB setup near me...anyone near Connecticut??

You know, you could also build two 18" ported subs (or any combination of subs) for way less then $3300.
post #43 of 94
Quote:
Originally Posted by gracey View Post

I just built some traps similar to these. I was too cheap to buy the high density fiberglass so I had to modify the process a bit.

Stack about 6 or 8 triangle shaped pieces of insulation in the corner. Compress these pieces with a plywood triangle, and while compressing the stack, screw the plywood triangle into the wall. Repeat until you reach the ceiling, or stop a little short and its a great place to hide surround speakers. I made covers by building a plywood frame and wrapping with cloth. Super easy, super effective. The insulation is incredibly dense by the time you reach the top.

My room has 6 corners. I have the rear 2 corners completed and it's made a huge difference in how the room sounds.

Enjoy!

Fortunately for all of us, the loose fluffy works best for thick bass traps, and it's much cheaper than high density 703/705 products.





Quote:
Originally Posted by RyguyOK View Post

So, is it better to do the triangle thing, or build a panel that has some air space behind it? I've seen both ways, and am wondering if there's an advantage one way or the other.

Also, I was under the impression that for the corner traps it was more effective to stack them loosely instead of compressing them, even going so far as to add supports every few feet to keep the bottom layers from getting too compressed. Anyone have any light to shed on the matter? I'm planning on doing treatments soon and am trying to get as clear an understanding as my limited mental capacity allows.....


Those Gearslutz links I provided are quite comprehensive. Absolutely, loose outperforms 3lb density a bit. either way works wonders, however the pink fluffy is significantly cheaper so quite the bonus there. Yes, supporting them every couple of feet, so that their own weight doesn't compress the entire process much is preferred.

Regarding the airspace, the info I posted above, regarding the airspace and proper spacing of the material is self explanatory. You've got to place the material where the velocity is reasonably high for effectiveness.

Bass traps are remarkable in their effectiveness. Very few AVS contributions, and very few AVS contributors discuss bass traps and their bang for the buck is extraordinary. No room should be without bass trapping,...and utilizing the loose fluffy type, as cheap as it is, expense is of minimal concern as well.

The time domain is so important,....clean it up and the freq domain follows.



Good luck
post #44 of 94
Quote:
Originally Posted by ChopShop1 View Post

I tell you guys, just when my mind is made up, I change it again. In one moment, I feel like buying two ported subs and making it "easy" for myself. The next minute, I'm am 110% sure I am going with an IB build, and then back and forth again. I really wish I could get a good listen to a large IB setup near me...anyone near Connecticut??


I think someone said it earlier. 4 manifolds in the front, 8 ib3 18's, 2 amps. No big boxes taking up space. Don't look back.
post #45 of 94
Thread Starter 
So, I have this plan now for 8 IB3 18". I was going to grab two ep4000 , but have another idea. I would really like to keep the two amps up with the processor, but the fan noise will keep me from doing that. I can spend more than the cost of the ep's, so what are my options. What amp choices would work optimally and not have fan noise???
post #46 of 94
post #47 of 94
Thread Starter 
Thank you for the link gracey...is there nothing out there that is better and doesn't need a fan mod???
post #48 of 94
Quote:
Originally Posted by ChopShop1 View Post

Thank you for the link gracey...is there nothing out there that is better and doesn't need a fan mod???

There are alot that are better. Lab Gruppen, Qsc, Crown, Marathon etc. They too will have loud fans as they are built to survive when pushed in tough environments. You will not be stressing an amp with an IB, thus a quiet fan will still provide ample cooling. Fan mods are easy.

Now build it!
post #49 of 94
Thread Starter 
Quote:
Originally Posted by gracey View Post

There are alot that are better. Lab Gruppen, Qsc, Crown, Marathon etc. They too will have loud fans as they are built to survive when pushed in tough environments. You will not be stressing an amp with an IB, thus a quiet fan will still provide ample cooling. Fan mods are easy.

Now build it!

Not to be a wise a$$, but I was looking for a little more info than that. Which ones have the quietest operation, with or without fan mod...which have the grunt to put out enough power and run easy doing it??
post #50 of 94
This one's nice, has built in eq., rca inputs, and I don't think it has a fan.


http://www.parts-express.com/pe/show...number=300-811
post #51 of 94
You will notice that there is a trend towards pro amps here as power to price ratio is tilted in favour of them. But there are tradeoffs, noisy fans, cable adapting, no 12v trigger for turn on, etc. These things can be worked around by doing some mods. If you want an amp that is more user friendly, aesthetically pleasing and quiet you may want to look at consumer grade. An IB setup requires less power than some other alignments, if 1000 watts will do then maybe an Emotiva monoblock amp would fit the bill. Or something similar.

http://shop.emotiva.com/collections/.../products/xpa1

I hope you find what works for you.
post #52 of 94
Thread Starter 
Quote:
Originally Posted by ScooterX View Post

You will notice that there is a trend towards pro amps here as power to price ratio is tilted in favour of them. But there are tradeoffs, noisy fans, cable adapting, no 12v trigger for turn on, etc. These things can be worked around by doing some mods. If you want an amp that is more user friendly, aesthetically pleasing and quiet you may want to look at consumer grade. An IB setup requires less power than some other alignments, if 1000 watts will do then maybe an Emotiva monoblock amp would fit the bill. Or something similar.

http://shop.emotiva.com/collections/.../products/xpa1

I hope you find what works for you.

Also a good suggestion, I will look into some consumer amps. I just want to be sure that the amp I get is suited to LF response. What should I look out for??
post #53 of 94
Thread Starter 
I also like an idea that someone had in another thread..placing the sub amps in the room below with the back waves of the IB. Problem solved, no fan noise, can't see em, cheap power. Anyone see anything wrong with this??

Also, does anyone know anything about the differences between the ep and epx for berry??
post #54 of 94
Quote:
Originally Posted by ChopShop1 View Post

That is a very encouraging endorsement. Have you had the opportunity to take measurements?? What other sub systems di dyou have experience with? What type of placement are you utilizing in your room? Array or manifold? What are you running for power? Sorry for all the questions, just curious if this would work for me as well. Thanks

Sorry, been away a couple days. At the listening position I've hit 120 dB at 20 Hz and 110 dB at 10 Hz. The mouth of the IB is 14 feet from the main listening position. As stated, I have 3 openings (doorways) in the room. Before the IB, I had a small Infinity sub, then a 12" Klipsch sub, later, an SVS PB12+2 and then finally the PB12+2 AND a SVS PCU running together. My IB is an array on the front wall. I use a Behringer EP-2500 (now EP-4000) wired at 2 Ohms. My drivers are 18" Ascendant Audio Avalanche's.
post #55 of 94
Quote:
Originally Posted by ChopShop1 View Post

I also like an idea that someone had in another thread..placing the sub amps in the room below with the back waves of the IB. Problem solved, no fan noise, can't see em, cheap power. Anyone see anything wrong with this??

Also, does anyone know anything about the differences between the ep and epx for berry??

My amp is in the kitchen just for that very reason. I've never had to mod the fan and never had an overheating issue even wired at 2 Ohms/side. It's been running that way for 4 years or so.
post #56 of 94
Quote:
Originally Posted by ChopShop1 View Post

Not to be a wise a$$, but I was looking for a little more info than that. Which ones have the quietest operation, with or without fan mod...which have the grunt to put out enough power and run easy doing it??

You can easily swap the 24v fans out in the Behringers for quieter ones if need be. There's a thread at the cult with pics and part numbers.
post #57 of 94
post #58 of 94
Oops, can anyone re-size that monster? Sorry.
post #59 of 94
Thread Starter 
Thanks Cecaa. That is pretty encouraging. I am thinking of 8 18" fi IBs and two Behringers. I woud love to be able to do an array, but the front wall of my room is an outside room, so SOL on that one.

How drastically does your ib outperform the SVS subs you've had??
post #60 of 94
It's a COMPLETELY different sound. Initially you catch yourself turning the gain up to where you think it sounds right. You put your meter on it and WOW, you're running it REALLY hot. After you get used to it you realize how absolutely clean the bass is compared to a ported box. When you listen to thunder in a movie, you hear every crack and nuance of the clap. It's not just a rumble any more, it sounds real. Before the IB, I was always wanting to upgrade or find out what's better as far as bass is concerned. I haven't thought once about doing something different since I built it.
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