# bass traps location



## Tiki (Nov 24, 2014)

I'm new here and recently I set up a home theater from sony...My place is small and there are only limited options to place the speakers. This is the best position i have come up with. The subwoofer is beside the couch and above it is the right surround speaker coz thats the best bass sound from the couch (i used the crawling method). The problem is the bass is loud but its not crisp so I'm planning to place some bass traps. Can anyone help me where to place the bass traps here?


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## bpape (Sep 14, 2006)

First thing to do is get as much space behind you as you can manage. I'm sure it can't be a lot but the farther you get from the wall behind you (up to about 1/3 of the room length) the less boomy the bass will be. Won't fix anything but it's something to do that's free.

A couple of bass absorbers with damped membranes behind your seating would be a good start. Looks like the only place to symmetrically place corner treatments though would be the wall/ceiling junction. Could probably get away with the left rear corner given it's much closer to you than the other side.


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## Tiki (Nov 24, 2014)

Hi bpape, thank you for your advice but the option to move my couch forward is not possible. I would be too close on my TV already if will do that. Do you have any link where i can see how to DIY the bass traps that you recommend?


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## bpape (Sep 14, 2006)

That's a typical problem. People buy a screen and then the seating position suffers (and the bass response/clarity with it) when a smaller set would be brighter and sharper and you could sit in a better place and have the same viewing angles.

Not really hard to build - just use a perimeter frame, with 3lb fiberglass and a piece of pond liner on the front side floating against the fiberglass, and wrap with fabric.


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## Tiki (Nov 24, 2014)

I agree. I'm not really into acoustics before but now I'm very interested in learning about it now. Anyway, the fiberglass offers another problem for me because here in my region, it's not available but I have seen a type of foam that's heavier than the normal mattress foam. I don't know if it could give a closer result compared to fiber. Here is the image.


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## Tiki (Nov 24, 2014)

Thank you projectors rule. It seems that you are very knowledgeable about this stuff.  The sub under the TV is no longer an option because there is a drawer under it, placing the sub there means the drawer becomes unusable and its where the bluray player is placed. That leaves me to either place the sub at corners or hang it on the ceiling. Hope we could find a great solution for this problem. 

By the way I placed the sub in the couch, i need to redo the test tomorrow using what you recommend.

Thank you again.:wave:


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## bpape (Sep 14, 2006)

The foam is a rubberized closed cell type. Not suitable for acoustics. Can you get mineral wool instead of fiberglass? Not as easy to work with but it works. Also look for any sort of fiber insulation - cotton, etc.


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## vidiot33 (Dec 12, 2013)

ProjectorsRule said:


> Based on your layout, I would locate the sub under the tv, start closest to the right speaker and move incrementally towards the left. Or mentioned you used the crawling method, but did you use a hard chair to place the sub on and position the chair at the listening area? Or did you place the sub on the couch? If you placed it on the coach, you may want to try again with a hard wood or metal chair, then, crawl. But where you currently have it is not the best for sure, it's in a corner which is a big no no for accuracy and tight bass. I would place the sub under the tv and play with it from there. Also did you place the volume knob at half volume and turn the crossover all the way to the highest level? then run the tuning software? Set the crossover in the receiver to 80 and speakers should be small. Phase should be 0 or normal on the sub.


Although there is some debate about sub placement, a number of knowledgable acousticians 
do in fact recommend corner placement, but obviously this would depend on the room and the sub.


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## bpape (Sep 14, 2006)

Corner placement has pluses and minuses. Least SBIR, most gain, but also maximally excites the room modes. Every room is different.


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## bpape (Sep 14, 2006)

Where are you getting this information? Bass control deals with much more than just bass - imaging, dialog clarity, etc. You can limit the range of them if desired but if done correctly, you'll actually end up with more, deeper, tighter bass.

2x3 for reflections is great if all you want to do is get mids and highs and if you're only dealing with 1 speaker and 1 seat. For 3 speakers and 8 seats, 2x3 is not even close to enough. Even if only 1 row, there is more to reflections than just mids and highs. Bass also reflects off the walls and can cause a lot of response issues. That requires more surface and thicker treatments. It's called SBIR.


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## bpape (Sep 14, 2006)

You're welcome to your opinion but keep it civil. Not a great start at ingratiating yourself with the membership.

I asked where you got that information. Didn't get an answer. My recommendations are based on years of experience and treating everything from Grammy winning studios and mastering suites, to designing thousands of custom home theaters, to 6 figure audio rooms for manufacturers, dealers, and enthusiasts to churches and auditoriums, etc.

His reflections will be out in the kitchen and on the window. We're only talking about treating the right front corner (left front is the stairwell and takes care of itself. The left rear corner is much closer to the seating and will skew the response and imaging if not dealt with. 

The left wall needs to be addressed from a full range perspective if possible to minimize the vast difference in reflection times as well as the difference in SBIR.

Bass is omni-directional, not non-directional. Bass builds up at all boundaries. Bass waves require larger surface area as well as more thickness. Can't hit a 10' wave with a 2x3 panel. 

How much of that can be done in a residential environment with limited setup options is yet to be seen. Just laying out the optimal and then see what of it can be done.

The seating close to the rear wall is where all the bass builds up masking dialog, imaging cues, micro-dynamics, harmonic textures, etc. That needs range limited bass control also.


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## vidiot33 (Dec 12, 2013)

bpape said:


> You're welcome to your opinion but keep it civil. Not a great start at ingratiating yourself with the membership. I asked where you got that information. Didn't get an answer. My recommendations are based on years of experience and treating everything from Grammy winning studios and mastering suites, to designing thousands of custom home theaters, to 6 figure audio rooms for manufacturers, dealers, and enthusiasts to churches and auditoriums, etc. His reflections will be out in the kitchen and on the window. We're only talking about treating the right front corner (left front is the stairwell and takes care of itself. The left rear corner is much closer to the seating and will skew the response and imaging if not dealt with. The left wall needs to be addressed from a full range perspective if possible to minimize the vast difference in reflection times as well as the difference in SBIR. Bass is omni-directional, not non-directional. Bass builds up at all boundaries. Bass waves require larger surface area as well as more thickness. Can't hit a 10' wave with a 2x3 panel. How much of that can be done in a residential environment with limited setup options is yet to be seen. Just laying out the optimal and then see what of it can be done. The seating close to the rear wall is where all the bass builds up masking dialog, imaging cues, micro-dynamics, harmonic textures, etc. That needs range limited bass control also.


I have followed your insightful contributions for some time and appreciate all the free help you have given us. This poster is obviously uniformed.


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## mechman (Feb 8, 2007)

Attacking moderators publicly is a rules violation. And attacking Bryan is downright ridiculous! That poster is gone! :foottap:


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## lcaillo (May 2, 2006)

Absolutely. The only thing I would add is that attacking anyone the way he did is way over the line and we don't just look out for moderators. Had he done that to any user here he would have been gone. He can disagree with anyone, even someone expert in a particular area like Bryan, but it has to be done in a respectful way.


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## Tiki (Nov 24, 2014)

I've been trying to look for wools and fibers here in my location and even our ace hardware here has no insulation supply. I don't know other alternatives for bass traps. By the way I'm using sony's BDV-E690 home theater. I also downloaded REW but i don't know how to use it with my laptop 'coz it only has 1 jack for mic(in) and headphone(out) at the same time. I'm not also contented with the highs. Can I place a small piezo tweeter connected parallel with the fronts?


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## Tiki (Nov 24, 2014)

Thank you Bryan. I have just read your post. I'm very thankful for your explanation about the bass wave and its behavior. You are right, if I go to the left rear side close to the door, I can hear the bass resonating but if I listened from the table, the bass is good (i guess here is the location with the best bass response). Are you advising that I should place my bass trap (if I could find the materials) on the left rear corner-to-ceiling part only?


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## Tiki (Nov 24, 2014)

Thank you Bryan. I have just read your post. I'm very thankful for your explanation about the bass wave and its behavior. You are right, if I go to the left rear side close to the door, I can hear the bass resonating but if I listened from the table, the bass is good (i guess here is the location with the best bass response). Are you advising that I should place my bass trap (if I could find the materials) on the left rear corner-to-ceiling part only?


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## bpape (Sep 14, 2006)

The left rear is a good place to start. I would also look at the wall behind you due to proximity and then the left wall.


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## Tiki (Nov 24, 2014)

bpape said:


> The left rear is a good place to start. I would also look at the wall behind you due to proximity and then the left wall.



Am I correct in this picture?

What are your recommended dimensions for front left, rear left and back wall?


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## bpape (Sep 14, 2006)

Yes - my mistake on the stairs. I read the direction of travel wrong. Sorry. Both left corners would be good as well as thick panels on the wall behind you and then look at the early reflections on the left wall.


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## Tiki (Nov 24, 2014)

Thank you. How about the dimensions? Is it critical for the design?


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## Tiki (Nov 24, 2014)

Thank you. What are the dimensions you can recommend? Or maybe you can give me a link for the design. I've searched for it but there are so many different styles, some are hollow and some are not. I don't really know what is the best. Hope you could help me.:help:


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## bpape (Sep 14, 2006)

Solid chunks work best. The more thickness, the lower in frequency they will perform. For instance, our Soffit Traps (17" square and 47" tall) will go down to the upper 30's.


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## Tiki (Nov 24, 2014)

Good day Bryan.

I have found a supplier for fiberglass and rock wool here in my place at last but they only have 50mm thickness. I guess that's already better than nothing. What do you think should I choose, the fiber glass or the rock wool?

Thank you.


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## bpape (Sep 14, 2006)

what it the density? You can certainly use multiple layers.


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## Tiki (Nov 24, 2014)

60 for wool and 45 for fiber.


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## bpape (Sep 14, 2006)

The rockwool would be better for 50 or 100mm thick panels. For thicker, the fiberglass would be as good or better. Realistically, they're both decent densities so basically use what is cheaper and easier to work with. Unfortunately, the wool is likely cheaper but the fiberglass will be easier to cut and work with. 

Flip a coin I guess. I would use the fiberglass personally.


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## Tiki (Nov 24, 2014)

Thank you Bryan. I guess i'll go with the rockwool 'coz its denser and cheaper. Anyways, would it be ok if I'll replace the center speaker of my sony home theater with a bookshelf speaker like this http://ecx.images-amazon.com/images/I/61idb9W6MZL._SL1200_.jpg ? Would there be any issues?

The center speaker's impedance by the way is 6 ohms.


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## bpape (Sep 14, 2006)

As long as it's a pretty good voice match for the L and R, should be fine.


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## Tiki (Nov 24, 2014)

Thank you. Is it ok to use an 8-ohm speaker in replacement of the original 6 ohms? by the way my HT is sony BDV-E690, it's not for pros but that's the only thing within my budget and i want to really improve it.


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## bpape (Sep 14, 2006)

As long as the impedance is higher and not lower than the originals you'll be fine. I wouldn't use a 4 ohm speaker just to be safe.


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## GCG (Aug 22, 2013)

Bryan the front and surround channels are rated for 3 ohms. Low impedance designs on low end HTIB setups usually make for power supplies with limited voltage rail specs. 8 ohms would probably be OK but wouldn't the possibility of clipping be elevated, even at 8 ohms especially if they are pushed too hard?

Manual with specs on page 54


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## bpape (Sep 14, 2006)

Lower impedance pushes the amp harder. Higher impedance is more resistance to the amp modules. Think of the speakers pulling power - lower impedance will suck more out of the power supply.


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## GCG (Aug 22, 2013)

i'm aware of that and not contesting the current benefits however most amplifiers stipulate an impedance range of between 6 and 16 ohms. 6 ohms and you push the limits of current but with 16 you bump up against the voltage limits and a greater risk of clipping at higher volumes. That ratio 16/6 is 2.667 the same for the lower impedance design of 8/3. All I was saying was with the design he'd be in the same territory voltage limit-wise as on a standard design @ 16 ohms.


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## bpape (Sep 14, 2006)

Just saying that going from 6 ohm standard to 8 ohm is going to make little difference for 1 channel and you're at least going the right way.


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## Tiki (Nov 24, 2014)

Can I connect it like this? Two speakers in parallel with 3 ohms and 8 ohms into a 3-ohm speaker out?


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## GCG (Aug 22, 2013)

Strongly ill advised. Results in a very low impedance. (~2.2 ohm) to each channel. You'd be safer with just the 8 ohm, although I still think the low impedance design could be voltage limited. If you try just the 8's increase listening volume gradually and listen for degrading sound quality. This could be an indication of clipping.


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## phazewolf (Feb 5, 2012)

Any Sony amp I have ever had did NOT like even a simple 4 ohm load if you were to try 2.2 ohm I don't think your going to like the results. The unit I have said 6 ohm min and it did not even like that much and would over heat and shut down on me.


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## GCG (Aug 22, 2013)

Low impedance HTIB amps are a different beast. Most are designed for low impedance loads. This one is designed specifically to drive 3 ohm loads on all but the center which is rated for 6 according to the spec in the manual.


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## Tiki (Nov 24, 2014)

Which is a better bass trap? a bare rockwool or a rockwool with coated foil?


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## bpape (Sep 14, 2006)

Not a matter of better or worse. All else being the same, the faced one just limits the frequencies that can be absorbed. Generally most facings (FRK or FSK) will start to roll off absorption about 500Hz.


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