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Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 186

post #5551 of 9539
Quote:
Originally Posted by jlpowell84 View Post

i need help. Why is my sub measurement cutting off so soon? I have my speakers unplugged to measure just raw sub response. I have the LPF for LFE in my Denon set to the highest of 250hz as well as the crossover at 250hz the highest.

help!



eek.gif

Why am i cutting off at 80hz?

Everything is off. I ran a one mic mlp just to set sub distance/delay. ave straight to subs, audyssey off, etc

Maybe the subs don't go any higher? Or there is a high-pass filter? Are you measuring the LFE channel, which has a HPF of 120Hz?

Gear mentioned in this thread:

post #5552 of 9539
Quote:
Originally Posted by markus767 View Post

i dont know what that means
Then you are looking at different graphs than I do.

Could you post the .mdat of your measurements?

I dont know what this means

And the sub is reading 85db which is simply the level i measured at:
post #5553 of 9539
Quote:
Originally Posted by Brian Fineberg View Post

I dont know what this means

And the sub is reading 85db which is simply the level i measured at:

The MDAT is the saved REW file with the measurements. Markus wants to be able to analyze the file using his own instance of REW. You can zip up the MDAT file and either upload it here as an attachment or, if it is too big, then use a file-sharing site such as DropBox. Are you a DropBox subscriber?
post #5554 of 9539
Quote:
Originally Posted by AustinJerry View Post

Maybe the subs don't go any higher? Or there is a high-pass filter? Are you measuring the LFE channel, which has a HPF of 120Hz?

I set higher in the ave, perhaps a seaton feature? its not of a permanent importance type thing though. I measured all along the front wall and literally the same exact looking graph. besides up against the tv stand which was closer in than the 1/4 and 3/4 points. That one had a deeper 59 hz dip. But otherwise the 1/4 & 3/4 points look nearly identical to the corners. So I am going to settle with the corners 10 inches from each wall in anticipation of triangular bass traps. I will pull down the peaks, run Audyssey and implement a house curve with PGM 2 on the Submersive which gives a +3db below 40 hz.

here is the final resting place, in the corners 10 inches from each wall.
post #5555 of 9539


better?
post #5556 of 9539
Yes. Quite a bit of ringing below 40Hz, but this is not uncommon. The presentation is much better, agreed?
post #5557 of 9539
Quote:
Originally Posted by AustinJerry View Post

Yes. Quite a bit of ringing below 40Hz, but this is not uncommon. The presentation is much better, agreed?

Yes i agree. Im a noob and admit it haha

Only way to stop that ringing is thick bass traps correct? (Which wont happen in my current room)
post #5558 of 9539
Quote:
Originally Posted by Brian Fineberg View Post

Yes i agree. Im a noob and admit it haha

Only way to stop that ringing is thick bass traps correct? (Which wont happen in my current room)

Let's see if anyone else has anyone else has any suggestions.
post #5559 of 9539
well I am all done! This is it.







PGM 2


biggrin.gif
post #5560 of 9539
Your gonna get yelled at. The y axis should be in increments of 5
post #5561 of 9539
Ah crap, too much too remember!
post #5562 of 9539
Quote:
Originally Posted by jlpowell84 View Post

Ah crap, too much too remember!
Tell me about it lol!!
post #5563 of 9539
Quote:
Originally Posted by jlpowell84 View Post

well I am all done! This is it.


biggrin.gif

Why isn't the vertical axis in increments of 5???? wink.gif

Seriously, that response is looking good. Where is the waterfall of L+R+subs?
post #5564 of 9539
Quote:
Originally Posted by AustinJerry View Post

Why isn't the vertical axis in increments of 5???? wink.gif

Seriously, that response is looking good. Where is the waterfall of L+R+subs?

Yea my bad Jerry, I totally forgot! I feel I am getting to know the software more though. I will adjust it correctly, that was all with minor cuts and boosts. Nothing crazy. I did do the 100 and 30hz sine wave comparison and I don't feel I am there yet. I read the most basic assessment of a good house curve is those two frequencies sounding the same volume. I was using the mini dsp software more and realized how to install a low shelf filter to help this more. I can get it all set with the low shelf filter (looks like a 8-10db increase slant from 100hz to 30hz) then the minor cuts and boosts strategically placed for flatness. I can then bypass the shelf filter, run Audyssey, and then un bypass the shelf filter. I will see how that goes. I may try to let the shelf filter ride before Audyssey as well just to see how it does. It's all fun, in having good time!
post #5565 of 9539
Waterfall, please. Frequency response is one thing, how well modal ringing is controlled is the real test. You don't need to run a new measurement--just generate the waterfall from the measurements you have.
post #5566 of 9539
Quote:
Originally Posted by AustinJerry View Post

Waterfall, please. Frequency response is one thing, how well modal ringing is controlled is the real test. You don't need to run a new measurement--just generate the waterfall from the measurements you have.

Yes I will when I get back. I'm watching the Oregon game. Can you kindly remind me the parameters for the waterfall. It skipped my mind. I will need a lot of MS as I know it's not good
Edited by jlpowell84 - 10/19/13 at 8:57pm
post #5567 of 9539
Thread Starter 
Quote:
Originally Posted by kbarnes701 View Post

Following Jason's advice, I have ordered a load of absorption material, which will be here next Wednesday and will be used to augment the existing acoustic panels. Each panel currently across a corner will have its depth of insulation at least doubled - ie they will become 8 inches of absorber (minimum) as compared to the current 4 inches. This will be achieved by filling the 'air gap' which is currently there with the traps placed across the corners, as per J's advice. I have also found space for two more (non-standard size) traps on the floor/wall corner under the screen area - I am going to build these traps myself as I am fed up with paying a fortune for what is effectively a slab of insulation, a bit of wood and a metre or two of fabric. Visually the home-made panels will be identical to the GIK ones I am currently using. 

I should have them in place by the end of next week all being well. I will re-measure and report back of course.

Happy to save you some money since I cost you so much on the projector/screen idea. wink.gif

Now I just need some pics of your room!

--J
post #5568 of 9539
Quote:
Originally Posted by AustinJerry View Post

I thought you would follow the Guide, Brian. A waterfall measures modal ringing, and really does't show much of anything of value above 300Hz.

We have been using 15-300Hz on the horizontal scale, 40/50 -100dB on the vertical scale, and between 450ms and 600ms for the time window. Your waterfall doesn't look good from 100Hz down. Perhaps it is just the graph. Please repost a waterfall using the L+R+subs with Audyssey on, and using the guidelines I just mentioned. That will give us a better view. I would start with 600ms.

I thought we were aiming for 450 ms as "silver" and 300 ms as "gold"? What would 600 ms be - a "bare minimum" for an untreated room (like mine)?

BTW if Jason's right about REW somehow measuring slightly below the noise floor by about 10 db, the difference between using 45 and 50 db as the lower range of the vertical scale sure makes a difference for me. At 50 db, I fall about 2-3 db from the lower extreme. OTOH, at 45 db I have a ringing problem between 50 and about 90 Hz, as the waterfall decays to the very bottom of the chart. That's at 450 ms. At 600 ms, my entire range from about 50 hz on, except for an artifact at 200 Hz, is also 2-3 db minimum from the bottom, but there's consistently more room above the bottom of the chart. Same data, different presentation.
post #5569 of 9539
Thread Starter 
Quote:
Originally Posted by kbarnes701 View Post

Quote:
Originally Posted by jkasanic View Post

Keith, would be great if you could document your process for building the custom panels? I know there are a ton of DIY treatment threads already but for those of us following your specific journey it would be great to see the detail as well as the measured results.

Well I can tell you now how I intend to build the panels. Take 4 pieces of planed smooth timber - two will be 48 inches in length and two will be 24 inches. Width of each piece will be 120mm, which IIRC is just short of 5 inches and thickness will be 18mm which is just over half of one of your American inches. Butt joint (ooher) and glue and screw them. Leave for 24 hours for the glue to dry. Take sufficient Camira Cara Black fabric to cover the frame and lay on floor. Place frame on top. Place slab of acoustic absorber gubbins inside frame. Draw back the fabric tightly and staple to the frame, in the back. Take one piece of any old acoustically transparent cloth of size 50 inches by 26 inches and fit inside the rear of the frame (in that approx 1 inch gap - frame = 5 ins, acoustic gubbins = 4 ins) and staple to frame. That step is to hold the gubbins into the frame, and to make the back look neat as well as concealing the gubbins itself. Turn acoustic panel over, admire handiwork, drink beer.

Each panel (I am making three - the full size one described above and two custom sizes which will fit in the screen wall/floor corner) should take about 30 minutes max to make from start to finish (with 24 hours in the middle for the wood glue to dry). Total cost I am guessing is about $25 each full size panel including all materials, but excluding beer. Or $200 if you factor in my time and the beer smile.gif

After installation, each panel will have an additional thickness of gubbins shoved behind it, which will be invisible to bystanders. I am not making the panels double thickness to accommodate two slabs of gubbins as I want all the panels to appear the same, and of course my existing panels are single thickness only. 

Once complete I will have to run Audyssey again and then I will remeasure with REW and we can compare the difference between the waterfall J commented on when he gave me this idea and the new waterfall incorporating Double Thickness Gubbins™. Remember this is solely aimed at improving the bit of ringing at 60Hz. If it  doesn’t improve it, J will have much to answer for LOL.

Great plan!

Since it's my fault if it doesn't work well though, I must suggest one minor alteration.

I always take a hole saw and cut holes all around the frame. This does a few things.

First, it makes the panel lighter. Secondly, and most importantly, it exposes more of the insulation so it can work better (absorb more) and cuts down on reflections from the frame itself which of course is what we're trying to get rid of in the first place.

I just modified 16 2'x4'x4" panels (was changing the fabric to black anyway) and used a 2.5" hole saw.

HINT: If I had it to do over though, I'd just use a jig saw and cut most of the inner part of the frame away, keeping just enough to keep it structurally sound as that would be much faster.

Good luck and congratulations on a very wise choice.

Where are those pics? biggrin.gif

--J
post #5570 of 9539
Thread Starter 
Quote:
Originally Posted by AustinJerry View Post

Quote:
Originally Posted by kbarnes701 View Post

Well I can tell you now how I intend to build the panels.


Keith, how are you going to augment the existing corner-mounted panels? Are you going to simply fill the triangular air space? Will you cover the ends? And what material will you be using, R-30 "pink fluffy"? I have a number of spots that I could do something similar, but am concerned with the resulting appearance.

If you put more insulation "behind" your existing panels, you won't see it at all and it won't change the appearance.

However, if using R-30 (or any type of pink/fluffy which measures about 5000 rayl/s) in the simulations I've done, it works better if the more dense (don't confuse with thickness) material is against the wall and the fluffy stuff is in front.

No matter what though, insulation is better than airspace although airspace is better than nothing.

It definitely doesn't have to look bad or be expensive though.

--J
post #5571 of 9539
Thread Starter 
Quote:
Originally Posted by jkasanic View Post

Quote:
Originally Posted by kbarnes701 View Post

 
Quote:
Originally Posted by jkasanic View Post

 
Quote:
Originally Posted by kbarnes701 View Post

Well I can tell you now how I intend to build the panels.


You know what they say...a pic is worth a 1k words! Good news is that no long exposures will be required! tongue.gif

I figured someone would say that smile.gif  Surely no pics are required for such a simple description of how to build these things?  We're already OT for this thread and I don't think I’d be doing the thread any good by uploading a dozen OT pics!

BTW, if a picture is worth a thousand words, why do people always use words to get that across? wink.gif

Well, with words like "gubbins" a pic would leave little to the imagination! wink.gif

On a serious note, I don't think treatments are any more OT than discussions of minidsp's or Audyssey for that matter.  They're all attempts to improve overall SQ and considering we're well past the "how do I get my mic setup" stage, the thread as two choices - either die or evolve.  I vote for the latter or we start a new thread that is the next phase of using REW, HDMI and USB Mics and that is more in depth on how to use REW to apply room treatments?

Truthfully, I've always hoped this thread would evolve past how to use REW, generate the graphs, and understanding them into how to IMPROVE the results.

You cannot do that without proper acoustical treatments, so in my opinion, it is very much on topic to discuss home made (or even store bought) treatments and how we use them to improve our results.

I just ran out of title length for the thread, that's all. tongue.gif
post #5572 of 9539
Thread Starter 
Quote:
Originally Posted by sdrucker View Post

Quote:
Originally Posted by AustinJerry View Post

I thought you would follow the Guide, Brian. A waterfall measures modal ringing, and really does't show much of anything of value above 300Hz.

We have been using 15-300Hz on the horizontal scale, 40/50 -100dB on the vertical scale, and between 450ms and 600ms for the time window. Your waterfall doesn't look good from 100Hz down. Perhaps it is just the graph. Please repost a waterfall using the L+R+subs with Audyssey on, and using the guidelines I just mentioned. That will give us a better view. I would start with 600ms.

I thought we were aiming for 450 ms as "silver" and 300 ms as "gold"? What would 600 ms be - a "bare minimum" for an untreated room (like mine)?

BTW if Jason's right about REW somehow measuring slightly below the noise floor by about 10 db, the difference between using 45 and 50 db as the lower range of the vertical scale sure makes a difference for me. At 50 db, I fall about 2-3 db from the lower extreme. OTOH, at 45 db I have a ringing problem between 50 and about 90 Hz, as the waterfall decays to the very bottom of the chart. That's at 450 ms. At 600 ms, my entire range from about 50 hz on, except for an artifact at 200 Hz, is also 2-3 db minimum from the bottom, but there's consistently more room above the bottom of the chart. Same data, different presentation.

The goal is to be able to see everything decay (by 60db) within 300ms for the whole range 20hz to 20khz but since that is very difficult, for the modal range (15hz or 5hz or whatever to 300hz) this goal is relaxed to 450ms.

However, if with your graph set to show 450ms you still cannot see the tail fall below the floor then you need to increase it to whatever it takes to see it disappear which could mean 500ms, 600ms, 800ms, etc.

Compare this with the Spectogram to see where the tail ends to make sure the graphs agree.

So everyone's display before treatment or as they are working on it will be different. We want to see all the way to the end though and not just have the "mountain" hit us in the face.

Only when we are finished with the treatment will the window fit within 300ms to 450ms and the tail truly fall below the noise floor.

If we limit the graph to 300ms or 450ms and it doesn't show everything, then how do we know how bad it is or how much more work we have to do??

I'm glad this got brought up because it appears everyone is setting the limit to 450ms or so which is really only appropriate if you can see 50-60db fall into the noise floor within 450ms and for the most part, I'm not seeing that and cannot get a grasp as to how bad things are (how long they TRULY ring) because the limit stops too soon. Does that mean there is ringing to 650ms, 870ms, etc? Who knows.

And what do you mean, "If I'm right!!" cool.gifwink.gif
post #5573 of 9539
Quote:
Originally Posted by jevansoh View Post

Truthfully, I've always hoped this thread would evolve past how to use REW, generate the graphs, and understanding them into how to IMPROVE the results.

You cannot do that without proper acoustical treatments, so in my opinion, it is very much on topic to discuss home made (or even store bought) treatments and how we use them to improve our results.

I just ran out of title length for the thread, that's all. tongue.gif

Saweet! Thats what I want to do. I like the look of the AST black micro suede with the beveled edges. But I could surely make some myself.
post #5574 of 9539
post #5575 of 9539
Quote:
Originally Posted by AustinJerry View Post
 
Quote:
Originally Posted by Brian Fineberg View Post


Thanks. Yeah. After this rerun of audyssey I have decided to keep audyssey engaged. Thanks for all the help. I think I'm in a good place right now until A. I can get treatments B.i build a dedicated room

 

Judicious use of treatments can improve things.  I wish I could build a dedicated room.  That would be an opportunity to avoid a lot of the same mistakes, and make a few new ones.

 

Oh yes. If we ever move from this house, one of the essential requirements of the next house is that it will have a suitable room for dedication to a HT. I’d love to have a go at that, using the knowledge that I have slowly accumulated with my current room. IDK if we will ever move - we like it here, it is horse-friendly, and moving house in the UK is a very expensive business with transaction taxes running at 5% of sale price etc, plus all the associated costs of redecoration, new carpets, remodelling of kitchens and bathrooms etc etc etc.

post #5576 of 9539
Quote:
Originally Posted by Brian Fineberg View Post



better?

 

Considerable ringing low down. Difficult to fix with treatments. Optimising sub placement can help a lot. If your FR was a little flatter it might help too.

post #5577 of 9539
Quote:
Originally Posted by Brian Fineberg View Post
 
Quote:
Originally Posted by AustinJerry View Post

Yes. Quite a bit of ringing below 40Hz, but this is not uncommon. The presentation is much better, agreed?

Yes i agree. Im a noob and admit it haha

Only way to stop that ringing is thick bass traps correct? (Which wont happen in my current room)

 

They'd have to be too thick to be practical. 1/4 wavelength thickness is needed. The wavelength of 30Hz is 38 feet, so the traps would need to be 9 feet thick!  Optimising sub and speaker placement is the way to ameliorate this ringing. And using multiple subs.

post #5578 of 9539
Quote:
Originally Posted by jevansoh View Post
 
Quote:
Originally Posted by kbarnes701 View Post

Following Jason's advice, I have ordered a load of absorption material, which will be here next Wednesday and will be used to augment the existing acoustic panels. Each panel currently across a corner will have its depth of insulation at least doubled - ie they will become 8 inches of absorber (minimum) as compared to the current 4 inches. This will be achieved by filling the 'air gap' which is currently there with the traps placed across the corners, as per J's advice. I have also found space for two more (non-standard size) traps on the floor/wall corner under the screen area - I am going to build these traps myself as I am fed up with paying a fortune for what is effectively a slab of insulation, a bit of wood and a metre or two of fabric. Visually the home-made panels will be identical to the GIK ones I am currently using. 

I should have them in place by the end of next week all being well. I will re-measure and report back of course.

Happy to save you some money since I cost you so much on the projector/screen idea. wink.gif

Now I just need some pics of your room!

--J

 

Haha!  Yeah, I am about $5,000 lighter since you first gave me the notion that I could squeeze a PJ in here!  But it was one of the very best things I have done, so I am grateful to you. My new Epson 5030 arrives any day now... 

 

I'll try pics again.

post #5579 of 9539
Quote:
Originally Posted by jevansoh View Post
 
Quote:
Originally Posted by kbarnes701 View Post
 
Quote:
Originally Posted by jkasanic View Post

Keith, would be great if you could document your process for building the custom panels? I know there are a ton of DIY treatment threads already but for those of us following your specific journey it would be great to see the detail as well as the measured results.

Well I can tell you now how I intend to build the panels. Take 4 pieces of planed smooth timber - two will be 48 inches in length and two will be 24 inches. Width of each piece will be 120mm, which IIRC is just short of 5 inches and thickness will be 18mm which is just over half of one of your American inches. Butt joint (ooher) and glue and screw them. Leave for 24 hours for the glue to dry. Take sufficient Camira Cara Black fabric to cover the frame and lay on floor. Place frame on top. Place slab of acoustic absorber gubbins inside frame. Draw back the fabric tightly and staple to the frame, in the back. Take one piece of any old acoustically transparent cloth of size 50 inches by 26 inches and fit inside the rear of the frame (in that approx 1 inch gap - frame = 5 ins, acoustic gubbins = 4 ins) and staple to frame. That step is to hold the gubbins into the frame, and to make the back look neat as well as concealing the gubbins itself. Turn acoustic panel over, admire handiwork, drink beer.

Each panel (I am making three - the full size one described above and two custom sizes which will fit in the screen wall/floor corner) should take about 30 minutes max to make from start to finish (with 24 hours in the middle for the wood glue to dry). Total cost I am guessing is about $25 each full size panel including all materials, but excluding beer. Or $200 if you factor in my time and the beer smile.gif

After installation, each panel will have an additional thickness of gubbins shoved behind it, which will be invisible to bystanders. I am not making the panels double thickness to accommodate two slabs of gubbins as I want all the panels to appear the same, and of course my existing panels are single thickness only. 

Once complete I will have to run Audyssey again and then I will remeasure with REW and we can compare the difference between the waterfall J commented on when he gave me this idea and the new waterfall incorporating Double Thickness Gubbins™. Remember this is solely aimed at improving the bit of ringing at 60Hz. If it  doesn’t improve it, J will have much to answer for LOL.

Great plan!

Since it's my fault if it doesn't work well though, I must suggest one minor alteration.

I always take a hole saw and cut holes all around the frame. This does a few things.

First, it makes the panel lighter. Secondly, and most importantly, it exposes more of the insulation so it can work better (absorb more) and cuts down on reflections from the frame itself which of course is what we're trying to get rid of in the first place.

I just modified 16 2'x4'x4" panels (was changing the fabric to black anyway) and used a 2.5" hole saw.

HINT: If I had it to do over though, I'd just use a jig saw and cut most of the inner part of the frame away, keeping just enough to keep it structurally sound as that would be much faster.

Good luck and congratulations on a very wise choice.

Where are those pics? biggrin.gif

--J

 

Great info - thanks J. That hole saw idea is a great suggestion. 

 

Pics... yeah. At the moment they look like pictures of a black cat sitting on a pile of coal during a total eclipse.

post #5580 of 9539
Quote:
Originally Posted by kbarnes701 View Post

 
Quote:
Originally Posted by AustinJerry View Post

I think discussion of treatments used to improve room acoustics is on-topic for this thread, especially when coupled with measurements to show a particular type of treatment's effectiveness.
 
OK guys, if that's the consensus it's fine by me. But there's a difference between that and building the traps isn't there?  Using them is on topic, but surely building them isn't?  
Quote:
Originally Posted by kbarnes701 View Post

Quote:
Originally Posted by jevansoh View Post

 
Quote:
Originally Posted by kbarnes701 View Post

 Great plan!

Since it's my fault if it doesn't work well though, I must suggest one minor alteration.

I always take a hole saw and cut holes all around the frame. This does a few things.

First, it makes the panel lighter. Secondly, and most importantly, it exposes more of the insulation so it can work better (absorb more) and cuts down on reflections from the frame itself which of course is what we're trying to get rid of in the first place.

I just modified 16 2'x4'x4" panels (was changing the fabric to black anyway) and used a 2.5" hole saw.

HINT: If I had it to do over though, I'd just use a jig saw and cut most of the inner part of the frame away, keeping just enough to keep it structurally sound as that would be much faster.

Good luck and congratulations on a very wise choice.

Where are those pics? biggrin.gif

--J

Great info - thanks J. That hole saw idea is a great suggestion. 

Pics... yeah. At the moment they look like pictures of a black cat sitting on a pile of coal during a total eclipse.

Whoa, whoa...I think this falls under the building category!! biggrin.gif

This is why I do think it's a good idea to discuss ideas for our DIY treatments as well. I've read a ton of those other threads recently and there never seems to be a shortage of good ideas like the one J posted! wink.gif
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