or Connect
AVS › AVS Forum › Audio › Audio theory, Setup and Chat › Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs
New Posts  All Forums:Forum Nav:

Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 201

post #6001 of 9577
Quote:
Originally Posted by jkasanic View Post

Also above my pay grade but I would've thought the opposite (i.e. you'd want an NRC of 1.0 to ensure none of the frequencies are reflected back into the room) See this article.  You didn't by chance mixup the NRC's?

No what I said was right. Their burlap has a 1.0 NRC rating, perfectly absorbent. While the black micro suede has a 0.8 rating which means it is 20% reflective. I still am not sure how a 80%absorbent and 20%reflective is better for bass like she said.

Gear mentioned in this thread:

post #6002 of 9577
Quote:
Originally Posted by LastButNotLeast View Post

I guess I learned something from the refrigerator episode, after all.
The tiles I was looking at have an NRC of .85. Someone suggested ceiling tiles with an NRC of .80. 
http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/5880#post_23891863

So if this cloth has an NRC of .80, it's anything but acoustically transparent, which your testing should confirm.
That doesn't mean you can't use it for your intended purpose. You just need to figure out what frequencies it's absorbing.

I think I see what you are saying. A NRC rating of 1.0 is opposite of acoustically transparent because it absorbs 100%. That is what you are saying correct?
post #6003 of 9577
Quote:
Originally Posted by jlpowell84 View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Work harder??  This is above my pay grade, but I thought the idea was that the sound waves passed through the gubbins and converted some of their energy into heat as they did so? That would seem to me to require that the sound wave first passed through the cloth so that it could actually get into the gubbins and convert the energy?

Personally, as it only takes a few seconds when you have the Mic out, I'd measure it and put my mind at rest. If ATS use the exact same cloth I'd assume they know what they are doing and that it is indeed AT.

Haha good one! I will indeed test it. 20% is not enough to make me search out another fabric if true.

I'm sure they wouldn’t use a material that impeded the panels from their designated purpose. I’d like to know for sure though ;)

post #6004 of 9577
Quote:
Originally Posted by jlpowell84 View Post
 
Quote:
Originally Posted by jkasanic View Post

Also above my pay grade but I would've thought the opposite (i.e. you'd want an NRC of 1.0 to ensure none of the frequencies are reflected back into the room) See this article.  You didn't by chance mixup the NRC's?

No what I said was right. Their burlap has a 1.0 NRC rating, perfectly absorbent. While the black micro suede has a 0.8 rating which means it is 20% reflective. I still am not sure how a 80%absorbent and 20%reflective is better for bass like she said.

 

All that matters is that it passes the frequencies you are trying to absorb., It doesn't have to be acoustically transparent in the same way as speaker grilles do. I think :)

post #6005 of 9577
Quote:
Originally Posted by jlpowell84 View Post


I think I see what you are saying. A NRC rating of 1.0 is opposite of acoustically transparent because it absorbs 100%. That is what you are saying correct?

Right. Just Google it (which you should do today anyway because they have a wonderful Halloween graphic).

http://en.wikipedia.org/wiki/Noise_reduction_coefficient

post #6006 of 9577
Quote:
Originally Posted by kbarnes701 View Post
 

 

All that matters is that it passes the frequencies you are trying to absorb., It doesn't have to be acoustically transparent in the same way as speaker grilles do. I think :)

How about if it absorbs the frequencies you're trying to absorb?

:D

post #6007 of 9577
Quote:
Originally Posted by kbarnes701 View Post

All that matters is that it passes the frequencies you are trying to absorb., It doesn't have to be acoustically transparent in the same way as speaker grilles do. I think smile.gif

Yes! So basically a successful measurement, for the cloth, would be to have the exact same eq line but just a certain amount of spl lower correct?
post #6008 of 9577
Quote:
Originally Posted by LastButNotLeast View Post

How about if it absorbs the frequencies you're trying to absorb?
biggrin.gif

Hmmm, I'm getting a little confused lol!
If it absorbed then it would aid the insulation inside the trap or panel right?
post #6009 of 9577
So then what will a successful measurement look like?

FYI I will do it tonight. Should I cover the subs too?
post #6010 of 9577
Quote:
Originally Posted by kbarnes701 View Post

Can you blow through it easily?
I almost passed out once trying to blow through microsuade (inherited a bunch of panels from Filmmixer). Re-wrapping them in speaker grill cloth did the trick.
post #6011 of 9577
Quote:
Originally Posted by sdurani View Post

I almost passed out once trying to blow through microsuade (inherited a bunch of panels from Filmmixer). Re-wrapping them in speaker grill cloth did the trick.

Are you saying to not use my micro suede from ATS acoustics?

Couldn't a small amount of reflection be good like a scatter plate from GIK? I think Jerry has one. Perhaps it wouldn't scatter correctly
Edited by jlpowell84 - 10/31/13 at 1:50pm
post #6012 of 9577
Is anyone interested in some Roxul AFB?
2x24x48 12 pack. Super cheap. PM if so
post #6013 of 9577
I think the point about the NRC value is that if you're building a "broadband" absorber then you don't want a reflective material covering your "gubbins"! If you only want to treat certain frequencies then you'll want a cover with some amount of reflectivity (like putting wax paper or a trash bag over a bass trap so as not to absorb the higher frequencies).

I just assumed jlpowell84 was building broadband absorbers so if that's not the case then he should be even more picky about what he uses to cover his treatments as AT material will allow those higher frequencies to also be absorbed by his gubbins!
post #6014 of 9577
Quote:
Originally Posted by jkasanic View Post

I think the point about the NRC value is that if you're building a "broadband" absorber then you don't want a reflective material covering your "gubbins"! If you only want to treat certain frequencies then you'll want a cover with some amount of reflectivity (like putting wax paper or a trash bag over a bass trap so as not to absorb the higher frequencies).

I just assumed jlpowell84 was building broadband absorbers so if that's not the case then he should be even more picky about what he uses to cover his treatments as AT material will allow those higher frequencies to also be absorbed by his gubbins!

Tell me about it JK! Now I am all worried! It didn't question if it was good enough for a professional acoustic company. But I want the best possible, that is my broad progressive goal in my system. I will build broadband panels for my walls and also square 17x17 soffit bass traps for front right and left ventricle corners, and some bass panels with open backs to set along the floor to wall junction wherever I can set one.

I will now use pink fluffy in my soffit traps per Jehovensah (spelling I know, have mercy on me. ). smile.gif
post #6015 of 9577
Quote:
Originally Posted by jlpowell84 View Post

Is anyone interested in some Roxul AFB?
2x24x48 12 pack. Super cheap. PM if so

 

I think you might be overreacting.  Why not build a trap with the materials you have and use it to evaluate various treatment locations?  At the very least you could measure the bare Roxul AFB as a comparison for whatever material you do decide to use.  This could at least help you start identifying areas that yield improvement in your space.  Worst case you get some experience building a trap which I think we all could use! ;)

post #6016 of 9577
Quote:
Originally Posted by jkasanic View Post

I think you might be overreacting.  Why not build a trap with the materials you have and use it to evaluate various treatment locations?  At the very least you could measure the bare Roxul AFB as a comparison for whatever material you do decide to use.  This could at least help you start identify areas that yield improvement in your space.

Yes I can tend to overreact wink.gif
That is my plan to set raw stuff all over and measure. I will have it tomorrow. It seems the corner soffit bass traps will be pink fluffy undoubtedly though now with J chiming in

I don't want to sell it all. Just with using pink fluffy for soffit traps that will leave me extra. I could build 24 panels of 4x24x48 with what I have ! I guess it will go fast, prob about 10 of those panels will go up, and then some either 4 or 6 inch 18x48 panels to set along the floor to wall junctions. I don't want 24 inches wide there because that sticks out to far into the room on the floor. 18 will give me proper performance I am sure
post #6017 of 9577

Ok, borderline OT given our recent discussion on DIY treatments so don't shoot me but I thought this was too cool not to share and might help those of us with two left thumbs or insufficient tools at our disposal:

 

http://www.irishacoustics.com/index.php/acoustics/diy-acoustic-traps/

 

Addresses the frame issue that Keith had building his traps and provides a very clean look for the more modern living space! ;)

post #6018 of 9577
I think our discussion falls on the ok side. We are not talking about how to construct but how we can use the optimal materials in rightly tackling our room issues. After all that's why me measure! It's good for us to know absorption properties and stuff like that smile.gif
post #6019 of 9577
Quote:
Originally Posted by jlpowell84 View Post

One other thing. My black micro suede fabric that I bought for wrapping my traps in doesn't seem to be acoustically transparent. If I hold up my mouth to it and talk it really muffles the sound. I thought the fabric was supposed to be acoustically transparent do I need to get different material? I sure hope this is okay because I really really like the look and I already spent money on it

I'll bet if you measure the frequency pass through (with REW, yet) you will find that the frequencies muffled are higher than those you would be trying to "catch" with a bass trap. So all is O.K.

People probably need so called acoustical transparency for mid and high frequencies only, and not then if the only purpose is to absorb (rather than attenuating a bass peak).

On the general concept of acoustical transparency, my dealer got off a good one: "Saying 'acoustically transparent' is like saying 'clean coal.' " That being said, I do have an 'acoustically transparent' front projection screen by Semour that probably comes close. I haven't measured it with instruments, just ears. Also Audyssey easily compensated for it, IMO. Only the center channel is behind the screen, and the one part of the curve in which the response of the Center, RF & LF is virtually identical is above about 8K, all the way up.
post #6020 of 9577
OK, a few things to address (that was a lot of posts between last night and now!):

Jerry, yes, I see from your posts that you have exactly the right idea. SPL = Sound PRESSURE Level, so yes, the best places to locate a pressure based bass trap is where you see the highest pressures at the specific frequencies.

Keith,
the same applies to you. I assume that you didn't mean stacking 4 Scopus traps in the window but that the window can accommodate 4 Scopus traps edge to edge? Use REW or Omnimic to measure those areas to see where the SPLs of the particular frequencies are the highest to see where the optimal placement positions would be (i.e. flat on the wall or on the corners (considering floor-wall and wall-ceiling intersections as corners as well as the floor+2 wall intersections).


jlpowell,
since you're making bass traps, at bass frequencies, just about any fabric material is fairly 'bass transparent'. When folks talk about acoustically transparent (as in AT projection screen material, they're talking about mid and high frequencies). Think about it, in the bass frequency region, heavy drapes do practically nothing (i.e. all the comments of, "I have some bass issues, I'm going to try putting some heavy drapes over the windows/walls" is always met by, "that isn't going to do squat for the bass frequencies. It will reduce reflections in the highs and mids, but not bass region").


Max
post #6021 of 9577
Ok Max, thanks. I am hoping to use the same fabric for my wall panels too. Although I don't have any really HF issues, major ones that is
post #6022 of 9577
Do you guys do distortion measurements?
post #6023 of 9577
Quote:
Originally Posted by jlpowell84 View Post

Ok Max, thanks. I am hoping to use the same fabric for my wall panels too. Although I don't have any really HF issues, major ones that is
Broadband wall panels? I'm not sure how that might affect their effectiveness if they aren't as acoustically transparent at higher frequencies.


Max
post #6024 of 9577
Quote:
Originally Posted by jlpowell84 View Post

Do you guys do distortion measurements?

Yes, but they (to me) are more relevant in the midrange and higher where your likely to hear it.
post #6025 of 9577
Quote:
Originally Posted by jim19611961 View Post

Yes, but they (to me) are more relevant in the midrange and higher where your likely to hear it.

Ok just hadn't seen any hear before and did in another thread smile.gif
post #6026 of 9577
Quote:
Originally Posted by djbluemax1 View Post

OK, a few things to address (that was a lot of posts between last night and now!):

Jerry, yes, I see from your posts that you have exactly the right idea. SPL = Sound PRESSURE Level, so yes, the best places to locate a pressure based bass trap is where you see the highest pressures at the specific frequencies.


Max

Nice to know I am on the right track. I talked to Bryan Pape at GIK today, and he is of the opinion that it is not that important whether the Scopus traps are on the width or length wall. At the target frequencies (40Hz +/- 5Hz), it doesn't matter.

The traps ship tomorrow, so sometime late next week I'll have measurements demonstrating their effectiveness.
post #6027 of 9577
Quote:
Originally Posted by AustinJerry View Post

Quote:
Originally Posted by djbluemax1 View Post

OK, a few things to address (that was a lot of posts between last night and now!):

Jerry, yes, I see from your posts that you have exactly the right idea. SPL = Sound PRESSURE Level, so yes, the best places to locate a pressure based bass trap is where you see the highest pressures at the specific frequencies.


Max

Nice to know I am on the right track. I talked to Bryan Pape at GIK today, and he is of the opinion that it is not that important whether the Scopus traps are on the width or length wall. At the target frequencies (40Hz +/- 5Hz), it doesn't matter.

The traps ship tomorrow, so sometime late next week I'll have measurements demonstrating their effectiveness.
Curious to see the results, and especially, to see what differences (if any) show up in the measurements around the MLP when placing the traps where REW measurements show the highest SPLs at the offending frequencies v in other locations if you don't mind taking the time to test different Scopus placements.


Max
post #6028 of 9577
Quote:
Originally Posted by djbluemax1 View Post

Curious to see the results, and especially, to see what differences (if any) show up in the measurements around the MLP when placing the traps where REW measurements show the highest SPLs at the offending frequencies v in other locations if you don't mind taking the time to test different Scopus placements.


Max

Max, I would like to accommodate, but it depends. The first placement will be at the intersection of the front wall and the floor, beneath my wall-mounted flat panel. Alternate locations are mounting on the side wall at the intersection with the ceiling, on either side of the room. The side wall mounting is more complex, so if the front wall placement yields measurable improvement, I will be reluctant to place nails in the wall to test a second location. Let's see how it goes.
post #6029 of 9577
Quote:
Originally Posted by AustinJerry View Post

Max, I would like to accommodate, but it depends. The first placement will be at the intersection of the front wall and the floor, beneath my wall-mounted flat panel. Alternate locations are mounting on the side wall at the intersection with the ceiling, on either side of the room. The side wall mounting is more complex, so if the front wall placement yields measurable improvement, I will be reluctant to place nails in the wall to test a second location. Let's see how it goes.

I will be anticipating the results as well. Curious at the effectiveness of a specific targeted frequency
post #6030 of 9577
Quote:
Originally Posted by jlpowell84 View Post

Are you saying to not use my micro suede from ATS acoustics?
Don't know about that ATS material specifically, was just commenting about my experience with microsuade from a few years ago.
Quote:
Originally Posted by jlpowell84 View Post

Is anyone interested in some Roxul AFB?
Since you already have it, why not just use it?
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Audio theory, Setup and Chat

Gear mentioned in this thread:

AVS › AVS Forum › Audio › Audio theory, Setup and Chat › Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs