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treating room for vintage Infinty dipole speaks
- Thread starter randy4354
- Start date
bharper
tube junkie...
I am not currently using the felt, but have it ready to try, and a friend with a recording studio uses it on planar speakers with good success, at my recommendation.
I, as you see in the avatar, have rs4.5's, and unless you tow them in a lot, the rear reflection is very destructive in my setting, with bare wall and glass behind them. Really messes with the center image.
I, as you see in the avatar, have rs4.5's, and unless you tow them in a lot, the rear reflection is very destructive in my setting, with bare wall and glass behind them. Really messes with the center image.
AngelRa
Active Member
There is plenty of reliable information on the web. If you ask in a forum like AK you are going to get a lot of myths mixed with real info.
From Galen Carol Audio "The single most important and influential link in the audio reproduction chain is also the least understood and most neglected - the listening room itself."
Reliable acoustics web sites:
http://www.auralex.com/
http://www.sonex-online.com/
http://www.rpginc.com/
http://www.acousticsciences.com/
http://www.ethanwiner.com/acoustics.html
http://www.silcom.com/~aludwig/Room_acoustics.html
http://www.silcom.com/~aludwig/My_Music_Room.htm#Wall_treatments
http://www.gcaudio.com/resources/howtos/roomacoustics.html
Good read:
http://www.ethanwiner.com/believe.html
From Galen Carol Audio "The single most important and influential link in the audio reproduction chain is also the least understood and most neglected - the listening room itself."
Reliable acoustics web sites:
http://www.auralex.com/
http://www.sonex-online.com/
http://www.rpginc.com/
http://www.acousticsciences.com/
http://www.ethanwiner.com/acoustics.html
http://www.silcom.com/~aludwig/Room_acoustics.html
http://www.silcom.com/~aludwig/My_Music_Room.htm#Wall_treatments
http://www.gcaudio.com/resources/howtos/roomacoustics.html
Good read:
http://www.ethanwiner.com/believe.html
Hey bharper, toeing-in the 2b's helped alot with the center image,thanks!The one thing I'm finding this is, that I need to add defraction behind the speakers because I have the same arrangement, the speakers and the same 50" projection TV between them.The 2 entertainment "shelving" tower units are the only thing changed and they were the same depth as the TV.With that setup I had no toe-in and the center image was very good.I think I need to add some defraction to about the depth from the front wall as the TV?Thoughts?
Randy
Randy
AngelRa
Active Member
http://www.tubetrap.com
The diameter is related to the lowest effective frequency. The wider the lower. You need to know where are your room modes pile up before making or buying these traps.
Hi AngelRa,thanks for the web sites.To find my room modes,what do I need?Also I have the materials to build some acoustic panels(OC 703 1" thick) and I think what I need to control first is the is the first reflections.With that in mind I believe the panels only require 2" of the 703 to absorbe the mid to high frequencies,correct?Or should I build them 4" thick for more of a broad band trap?Thanks for the input!
Randy
Randy
AngelRa
Active Member
Check previous posts on this forum.
To find your room modes you need to measure your room. Then use the following page:
http://www.mcsquared.com/modecalc.htm
Take note of the axial modes below 100Hz. The rest are not as powerful. Organize the modes from lowest frequency to highest. Note any groupings or frequency regions where modes concentrate. The lower the frequency of the grouping the more damaging the mode pile up is. If your modes are nicely spaced then forget about them, you are lucky. Otherwise you have a lot of work ahead. But we look at that only if you need it.
First reflection panels. I assume you read my previous posts about locating first reflection spots with a mirror, if not look back in this thread. There are some DIY examples on the net. Check this one out: http://structbio.vanderbilt.edu/~jsmith/ht/703-panels.html
Panel thickness, as a general rule a 4" thick panel have similar absorption coefficient as a 2" panel with a 2" enclosed air gap to the wall. That should save you some $.
OK AngelRa, I'm going to measure and use the web page to figure out the modes and hopefully I don't screw it up.I'm looking at getting a friends camera to get some pics,would this help for this help to get some recommendations?I just finished the first acoustic panel, and hoping to get 3 more done tonight.
Randy
Randy
AngelRa
Active Member
Can you post your measurements? + Photo?
bharper
tube junkie...
hey angelra,
that speaker under the tv is a custom made sub, a couple of ev 18" woofers, rounded top front edge to match the 4.5's, made from solid oak. obviously ported, and displaces 20 cubic feet... yep, it thumps..
up top is a eminent technology center, with four lft planar panels....
a quick test to surpress the rear emission a bit is use some masking tape, and tape some packing bubble rap to the back sides of the emims, and see where you stand.
need to tow in most emim/emit speakers, the horizontal dispertion is not very good, really bad over 10khz on the emits.
brian
that speaker under the tv is a custom made sub, a couple of ev 18" woofers, rounded top front edge to match the 4.5's, made from solid oak. obviously ported, and displaces 20 cubic feet... yep, it thumps..
up top is a eminent technology center, with four lft planar panels....
a quick test to surpress the rear emission a bit is use some masking tape, and tape some packing bubble rap to the back sides of the emims, and see where you stand.
need to tow in most emim/emit speakers, the horizontal dispertion is not very good, really bad over 10khz on the emits.
brian
AngelRa
Active Member
Wow, I bet it can play Telarc 1812 cannons!
For some reason my camera won't take indoor pics in low light areas so I still have to wait for my friend's unit.As far as measurements go,are you asking about room dimensions?I finished four of the panels and placed the first 2 at the first reflection areas on the side walls and didn't really find any change.Not sure where to put the next 2 because I believe you shouldn't put absorbtion panels behind dipoles,right?One other thing I've noticed is there is a big null between the speakers right in front of the projection tv.The tv is about 24"deep against the wall and the speakers are about 44" from the wall.I believe the tv is screwing with the center image.
Randy
Randy
AngelRa
Active Member
Room dimensions.
All first reflection spots need absorption regardless of speakers used.
I believe many Infinity speakers benefit more from covering the wall behind the speakers and behind the chair/sofa than the side walls.
The effect of the first reflection spot being cover is only evident in the listening area. Missing panels may void any gains from the other panels.
You covered 2 out of 6 spots. The best analogy I can think is: Imagine a room with six lamps on. How many should be turn off to make the room totally dark? The same is true for 1st reflections, how many does it takes to blur sound?
Place a panel in front of the TV to check your suspicions.
Room acoustics is not easy, but it the way to best possible sound. Do not give up.
For many years I used, still have, Infinity dipole speakers. I placed them where the rear wave came out, bounced from the rear wall and then the side wall to emerge next to the speakers.
What I'm saying is that I used it all. It didn't harm the imaging at all.
YMMV!
What I'm saying is that I used it all. It didn't harm the imaging at all.
YMMV!
AngelRa
Active Member
You are right. It is related to the research of Olive and Toole. They researched the effect of controlling but not eliminating the left and right wall early reflections. They found out that these side reflections basically controls the perceived spaciousness of the sound.
But the recommend to do so after an initial evaluation with all primary reflections eliminated. If the desired result is attained with all primary reflections eliminated they recommend to stop. If the image is not wide enough then they recommend to gradually use weaker absorbers on the side walls until the desired effect is attained.
Reference: The Master Handbook of Acoustics, 3rd edition, Chapter 19.
Now, since you already got it setup, can you help randy, he could use some of your settings. Can you provide your room dimensions and the exact location of the speakers and the angle. How busy is your room? Paintings, bookshelves, heavy furniture? Rugs? Carpet? Maybe a photo?
Thanks.
These speakers were designed with a rear wave. Eliminating it defeats the design! Embrace the openness and the rear firing drivers (sounds like me, rear firing).
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Randy, you have the option of "hard room end/soft room end" here. The wall behind the dipoles can be smooth with no treatment. The opposite end behind the listener can be softened to soften standing waves.
By the way, these speakers should be 3 feet from the rear wall and at least 1.5 feet from the side walls. I should have said that earlier.