CuznEddy Cinema Project Begins - Page 45

I swear while reading this, that it came across to me like Charlie Browns Teacher talking to him.

To calibrate your rew setup bring up spl meter, play test tone, click calibrate button on on spl meter panel, measure actual spl
with other spl meter, enter measured reading into REW and it calibrates.

As far as your graph, change the y axis to reflect 60db span or in this case 110-170db. This gives those familiar with REW a graph theyre used to.....


Waterfall, those areas where the waterfall comes all the way out ie. 50hz and 80hz you have major ringing. Higher up you see waterfall disappears before the front edge of graph........

That 50hz ring is the largest correctable issue i see. Itll take some serious bass trapping to tame but evey little bit you tame will pay off big time as thats right in the slam department.

If you have correction software like audyssey it will even notch out that area to try to tame the ring but bad part is youll lose output and flat response characteristics........

Absorbent Bass trapping (more like midbass trapping) isn't going to help at 50Hz. Your best bet is to just put a little EQ on it. That will go a long way. Otherwise you're into tuned resonant chambers like Dennis E. puts into his risers.

No sleep to loose on the soffit decision.

What language are all of you speaking? Oh, never mind I forget that I'm a noob when it comes to this stuff. Don't worry, I'll catch up.

Regards,

RTROSE

I disagree with EQ being a better solution to ringing at 50 Hz and that bass trapping won't help that low. I'm basing this purely on my own measurements and experience.

BTW, I only believe half what I read over on the acoutic treatments master thread. That discussion gets fanatically derailed discussing highly technical debate which in our world of AT means little.

Exhaust treatment possibilities before you slap some EQ on it. EQ causes just as much problems as it corrects.

Cuz,

Are your measurements with or without Audyssey engaged? To see what EQ does to your response try this: With Audyssey engaged I'll bet you a beer every one of those modal ringing regions will coincide with a dip in your FR. Since your version doesnt cover the sub region. Look above the sub crossover with Audyssey dis-engaged. look for regions of higher ringing on the waterfall graph. Now look at the FR with Audyssey engaged whats happening in those areas of higher ringing? I'll bet Audyssey is cutting those regions to cure the Ring/Decay which reduces the ring by reducing your systems output in that region but now youve got a hole or dip in your FR.

Using the absorption approach ... adding enough to make a worthwhile difference at 50Hz you end up absorbing way too much elsewhere. Over treatment is a real thing and it's easy to end up with a lifeless room.

That said I agree that treatment first rather than generic EQ, however in the sub base territory in rooms as small as ours.. A quick parametric filter really is extremely effective and is very cost effective.

Z,

Your making the assumption that we're talking all broadband absorption. There are bass trapping solutions which do not over attenuate the higher frequencies and should be applied as needed.

However most rooms will never come close to over abosorbed unless you get really carried away trying to tame lower frequencies with broadband absorption. Broadband absorption is however generally effective for most rooms with mild to moderate application. Cuz's room is far from over treated judging by his graphs.

I'm not sure if by your post you mean applying PEQ to correct FR or Decay/Ringing. They are two different problems. Yes PEQ is absolutely effective for flattening FR but it cannot correct Decay/Ringing without negatively affecting FR.

All im saying is if you try a simple filter on that peak and it won't take much you'll clean up quite a bit. It'll improve what you hear the response graph and the waterfall since less energy is being added to the room.

Just taking the simple approach here. In a matter of moments you can get quite far improving and you didn't spend any time or money building anything. Not sure the SMS gets you focused enough as I haven't worked with it. Bottom line there are lots ways to skin a problem. Just offering some advise that is simple and very effective.

Cuz,

It looks like you have quite a bit of decor in that space and it looks very good. Like you mentioned any further substantial treatments will probably take away from the appearance......

Looks like a broadband absorber on back wall? What material/ thickness? Is there an air gap behind? You could add some deep bass traps to the back wall. Google ethan winer bass trap DIY. Deep bass trap panels are covered by 1/4" plywood with rigid fiberglass inside sealed to the wall. They could be used back wall or anywhere you have open wall space.

21" corner traps are certainly worthwile if you can make it work.

Also where the back wall meets ceiling corner traps would work, if you can fit into decor.

I your high frequencies get too damped in the process cover some traps outside face with kraft paper and theyll function more like mid/low traps reflecting most the high stuff.

Performance vs appearance is where it gets tricky.

Are all your other treatments like that? 2" with 1/2" gap? If so theyre doing virtually nothing below like 500hz. The air gap on the back is almost as important as material thickness. Double up for 4" thick and 2" air gap in back and you will easily double their performance from 500 down.

Maximize what you already have before adding more stuff to that beautiful room.....

Without reading all the history.... regarding your xover integration between the mains and sub. Have you adjusted the sub distance setting in your AVR in increments and run the REW measurement? What you'll find is you can't go by a measured distance for best sub to main integration and that Audessy won't get it right either (It makes a calculation but doesn't go back and check it's work in the real world). I'd start with 1 ft increments.. This is a great exercise regardless giving you a picture of what's actually happening between the 2. You may find that you can eliminate the dip entirely without any EQ boost and that the final sub distance setting may be far different than what intuition would expect.

Probably goes without saying .. save all your settings... The sub distance / integration setting is one of the 1st things you want to achieve so that needs to happen prior to any EQ being applied etc.. The easiest way is to run the sweep on the center via driving the L and R input at the same time and using PLII AVR setting. Getting the center to sub is the big one but if you really want to get fancy you can try to find the middle ground with the L and R as well. Of course this is all to some single mic location.

Ultimately, what you are going to stumble into is how good (or lack thereof) a system like Audessy really does compared to having your own measurment and EQ system. While adequate for 90% of users that go plug and play.... once you open this kimono it's all over.. Now that you are measuring the room it ends up being like the red pill blue pill analogy.. Did you really want to take it

By the way...... nice room response so far.. If I'm to believe that graph it's showing +/- 5dB for the response window.. Almost too good.

Happy listening

If you drive the L & R inputs equally only the center will produce sound in PLII. You shouldn't have to unplug anything. Typically use a Y cable to drive the L and R inputs from REW.

So with all of this scientific bantering back and forth the real question is, Does it sound any better? If it does is there still room for improvement? If not then what in the sam hill are you waiting for, get back to work you lazy bum!

Regards,

RTROSE

If your not gonna work on something at least cruise around others threads and prod them along.....

Hi Craig,

Thanks for the heads up to check out your drapes (if you weren't over in the media/games room section I'd stop in more often ). This is the kind of thing I'm thinking about in my theater but probably with a matching valance as well. What type of fabric did you use and is it single thickness or backed with a lining? Did you or your wife make it?

I'm enjoying catching up on your EQ journey -- I remember being one of the most tedious parts of my build.

Cheers.

Since you brought up E.W. I thought I'd share these if you haven't already seen them. Pay close attention to the deep bass traps which are covered by 1/4" ply so they just work on the bass more like a resonator than a absorber.......

Enjoy!

http://www.ethanwiner.com/BTPlans.gif