Acoustic Treatment Phase one (1)

 

New member
Username: Mike_l

Post Number: 1
Registered: Oct-06
Hello everyone.
First of, I would like to thank many of you for the incredibly valuable information
Shared in this forum. I have spent hours reading before sending my first post.

I was completely ignorant in the subject of acoustic treatment, now...well...I know
Just a bit.

In browsing and looking at various posts I was able to decide to first go with the
Acoustic panels. It looks like I will use 24x48x2 Owens Corning 703 fiberglass boards with some type of wood frame.

The questions are:
1 is that the correct choice for my needs
2 where and how many will I need
3 is there a type of fabric I should use over another

I hope to get some leads from you boys.

Here is what I would like to accomplish as phase 1

Media room objectives:

1 re-arrange furniture
2 loosely setup components
3 install window treatment
4 build/install acoustic panels on walls
(where do I get the rigid board and where to put them)
5 build/install acoustic panels on ceiling (pfff...that will be fun)

steps 1,2 and 3 are all done. And let me tell you that the window treatment improved the
acoustic at a rate of at least 20%!!! Unheard of. (no point intended)

I have attached some pics of the layout of the room (office/media room) I have.
I would love some "sound advice" from all of you.
(You will notice that on the front side of the room the ceiling is much higher ( guess 15ft) than the rear)

Thanks.

Michele




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Gold Member
Username: Mixneffect

Orangevale, Ca. USA

Post Number: 1109
Registered: Apr-05
Thanks for the pictures.

This really helps diagnose problems, and facilitate a resolution.

First of all I would have to say that your strongest feature is also your weakest link.

I am talking about the shape of the room. It is great that the room is not square or rectangular (which causes boxy and/or tunneling effects). By having a somewhat of a trapezoid, you help eliminate some acoustic problems, but you also have a few things to worry about prior to investing in acoustic treatments to your walls and/or ceiling.

The con is that the room has a high ceiling on the end where the sound is focusing from. You are sitting in sort of a cornered listening position which is somewhat crammed because of the limited distance from your focal point (the front speakers). This may be a problem with certain bass frequencies. The distance between the speakers and you ear affects some larger wavelengths since you may not be at 1/4, 1/3, 1/2, and/or full wavelengths. Your ear will pick up peaks and dips, due to the distance between your ear and the front speakers.
Another problem is that you are experiencing a bass loss problem due to the high ceiling. A lot of bass is trapped in the corners above the front speakers.

Another problem is the height of the focal point of your front speakers. It seems that the tweeter and/or its focal point may be too low. I suggest that you get taller stands to help improve your imaging and/or phasing to at least ear level, sitting on the couch in the "sweet spot".

You would be amazed at the difference of how phasing and imaging is affected just due to improperly positioned speakers vertically and horizontally. Off-axis is also a big loser, so keep that in mind as well. The best image is in the sweet spot, and it diminishes from there...

May I strongly suggest that you see what you may improve by trying to abide by these hyper physics from this site. I am confident that you will hear a big difference if you use these guidelines before you spend money on wall and ceiling teratments.

http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/auditcon.html#c1

Obviously you may still need some treatment, but that may not solve your real problem.

Just my .02 :-)
 

New member
Username: Mike_l

Post Number: 3
Registered: Oct-06
Mix,
thanks for your informative post. I am to do even more thinking than I had originaly thought in order to exploit what I have.
(altough I am not looking for perfection)

I have begun working on the easiest possible improvement however as per your comment.

I have gradually rased the speakers to an ear hight then built a box with a bottom 1in off the floor so only the edges are in contact with the floor. (it made more sense to me)

I will later fill those up with some sort of bricks for added stability. (see pics)

Should I avoid wood to wood contact (box/speakers) and add a layer of somthing or is that fine?

Thanks
Michele
 

New member
Username: Mike_l

Post Number: 4
Registered: Oct-06
sry,

here are the pics...
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Gold Member
Username: Mixneffect

Orangevale, Ca. USA

Post Number: 1115
Registered: Apr-05
Here are some spikes you may use in order to reduce vibration and minimize unwanted noise. These speaker spikes just screw in to the bottom of your speaker box and/or stand.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=240-717

You may also want to consider in some better speaker stands.

http://www.partsexpress.com/webpage.cfm?&WebPage_ID=227&CFID=5614936&CFTOKEN=29032511

Yes you should avoid wood to wood contact and/or anything that may add unwanted vibration or noise.

Idealy you want the tweeter to be at ear level when SITTING in the "sweet spot". Also point the speakers inwards so that the tweeters are pointing directly at your ears. These simple adjustments will make probably the biggest noticable difference.

Your next step should be accoustic treatments, but not until you identify what bass loss you have due to the high ceiling away from your listening spot. That high ceiling may also add certain midrange reverbrations or echos.
 

New member
Username: Mike_l

Post Number: 5
Registered: Oct-06
mix,

I really like those stands (see pic) the problem is my speakers (made in 1974) are aproximately 14in wide 13in deep and 24in high. The weight is 45lbs.

Now the bottom base on the speaker stand is substantialy smaller as well as the top plate.

This is why I have built those boxes to the correct hight, and wide enough to avoid
wobble caused by all that weight on top.

However, I am wondering what is more stable (in my case)

1- A wide heavy box on top of carpeting or
2- A smaller stand with spikes going down through
the carpeting to the solid (wood) floor.

What do you think?

As far as the angle for the speakers I have always
used the manual for guidline. (see pic)

I will give it a try anyway to see if there is an improvement.

Any input/comments are welcome.

Thanks

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Gold Member
Username: Mixneffect

Orangevale, Ca. USA

Post Number: 1118
Registered: Apr-05
Use the separate screw in spikes on the bottom of your wooden stands. This way you have the height, satbility, and you can dress them up anyway you want.

http://www.partsexpress.com/pe/s howdetl.cfm?&DID=7&Partnumber=240-717

As far as the 40* angle is concerned, I believe that is just a generic factory recommendation. It is definetly not written in stone. That configuration limits you to how far apart the speakers are from each other, as well as how far the "sweet spot" is from them. Unfortunately you may not have that comfort.

I just place my speakers symmetrically in conjunction with the TV and the room, then direct them to my ears as needed.

Just remember to keep the speakers at least 12" from the wall. This will give a better bass response.
 

New member
Username: Scott_r_foster

Jacksonville, FL US

Post Number: 1
Registered: Nov-06
michele:

You asked:

"It looks like I will use 24x48x2 Owens Corning 703 fiberglass boards with some type of wood frame.

The questions are:
1 is that the correct choice for my needs
2 where and how many will I need
3 is there a type of fabric I should use over another"


1) 2" panels are too thin to work as broadband absorbers [on lows as well as highs] - use panels at least 4" thick. Owens Corning 703 is an excellent choice, but the brand name is not important. There are many folks making 3 lbs per cubic foot density semi-rigid fiberglass insulation board, and all of them will just work fine [CertainTeed and Johns Manville also make them] or rockwool boards of about twice that density are also a good choice. Shop for price in your local market at commercial construction suppliers such as these guys:

http://www.spi-co.com/servicecenterdirectory.cfm

http://www.lwsupply.com/centerloc/4_0_centerloc.asp

You can get information of the general absorptive characteristics of many standard materials here:

http://www.bobgolds.com/AbsorptionCoefficients.htm

2) Per our prior discussions from when you emailed me at readyacoustics.com, I suggest:

a) A pair of panels stacked vertically and mounted across each of the rear corners = 4 panels

b) A panel mounted high in each of the front corners = 2 panels

c) A pair of panels low on the front wall at the corners = 2 panels

d) A trio of panels on the ceiling reflection point = 3 panels

e) A panel on the right wall -- horizontal - at the reflection point = 1 panel [keep the drapes to handle the left side wall reflection point].

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This treatment plan will work whether you use our products, or "roll your own".

3) Anything you can breath through will be fine acoustically - though you may wish to consider fire resistance.

These articles on DIY bass traps may be helpful:

http://forum.studiotips.com/viewforum.php?f=8&sid=3df787e70821b342952f67ec4a9a474d

As to speaker placement, as explained above, placement is critical. There are many ways to estimate good locations, but there is no substitute for actual measurement - which is not a trivial exercise. Here is a link to an ongoing discussion of treatment, placement, and measurement and how they can be used in concert to refine the quality of a small room listening environment. If you skim over the evolution of this discussion, you can see how all these factors interact... but, take it with a grain of salt... these guys are chasing perfection in a very small room and verge on hair splitting IMO. Nonetheless, the discussion and processes are illuminating of the all the various challenges.

http://forum.studiotips.com/viewtopic.php?t=2597

Here are a pair of nice programs that can help you calculate placement:

http://www.rpginc.com/products/roomoptimizer/index.htm

http://www.harman.com/about_harman/technology_leadership.aspx

then left hand menu "White Papers"
then "Calculators"
then "Room Mode Calculator"
 

Silver Member
Username: Nency

Post Number: 231
Registered: May-09
Hello,
Thanks for sharing information.nice information.
 

New member
Username: Dave54321

Post Number: 1
Registered: Mar-12
Is it feasible to re-arrange things so you don't have a speaker stuck right in the corner like that? If not, then probably some kind of acoustic treatment is necessary there.

Don't go overboard with ordering loads of expensive wallboards and traps. Remember that a degree of room reverb is completely normal and our brains expect it. It only becomes a problem if the sound of your music is being noticeably adversely affected.

One thing which amazingly no one appears to have asked you, and is the most important factor of all, is: what are the symptoms of your room's (and speaker-position's) sound? Too boomy? Too bright? Too echoey? Too muddy? Or what?
 

Platinum Member
Username: Project6

Post Number: 16182
Registered: Dec-03
Yes it is feasible to re-arrange things. But it has been six years since the OP, so who knows what he could have done during that time.
 

Moderator
Username: Admin

Post Number: 10983
Registered: Dec-03
Bumping up, because there was a date issue on the above post.
 

Platinum Member
Username: Project6

Post Number: 16190
Registered: Dec-03
Time travel IS possible?!?!

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