Acoustic Treatment Phase one (1)

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

sry,

here are the pics...

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

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].



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"

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?

Bumping up, because there was a date issue on the above post.