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May I Try With A Fresh Slate: Room Analysis Suggestions
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ritelec
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1st March 2011
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May I Try With A Fresh Slate: Room Analysis Suggestions

Hi it's me. again,

Please check out graphs sent and pic's for your consideration and suggestions for room treatment. I used a AT4050 (in omni) with FuzzMeasure. I will start laying out for new work surface area, and building 2'x4' frames for 6" roxul AFB. (3" dbl).
Please let me know of your suggestions or any other analysis views you may need. Enclosed please find L&R speakers & waterfall of jbl's with rmc correction. And, L&R speakers & waterfall of jbl's without rmc correction. AT4050 freq. response for omni.


Thank you for baring with me on this.

Rich.
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May I Try With A Fresh Slate: Room Analysis Suggestions-left-rmc.gif   May I Try With A Fresh Slate: Room Analysis Suggestions-right-rmc.gif   May I Try With A Fresh Slate: Room Analysis Suggestions-waterfall-l-r-rmc.gif   May I Try With A Fresh Slate: Room Analysis Suggestions-left-no-rmc.gif   May I Try With A Fresh Slate: Room Analysis Suggestions-right-no-rmc.gif  

May I Try With A Fresh Slate: Room Analysis Suggestions-waterfall-no-rmc.gif  
ritelec
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Here is the at4050 spec.
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Room Pic's.
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I wouldn't be surprised if JBL's room correction only corrects the bass. Keep n mid that EQ won't fix acoustic problems at all. It can only help bass at the listening position. Getting rid of all early reflections is a must to improve ITDG. The speakers should be good. JBL practically wrote the book on loudspeaker performance interpretation--actually the head of research there did.

This post should help:
audio blog: Tightening The Loudspeaker, Recording and Room Connection

Dan
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Rich,

Can you export the IRs as wav or aiff and post them instead? That way anyone can look at them the way they prefer. It’s hard to read with the scale set like it is (waterfall) and there’s no ETC graphs.
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sorry for the OT, but whoa! what are those mother horn loaded speakers in the corner? do you use them?
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Quote:
Originally Posted by audiothings View Post
sorry for the OT, but whoa! what are those mother horn loaded speakers in the corner?
JBL 4560s with JBL 2345 of Emilar high frequency horns?

Andre
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1st March 2011
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sorry for the OT, but whoa! what is that plastic sheeting covering every boundary? And what is behind it? Just curious.
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Quote:
Originally Posted by fitZ View Post
And what is behind it? Just curious.
Please don't say concrete.
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lol... concrete.....lol And on the walls is not plastic wrap, it's inverted thin carpet painted.

The bins are for playing live in the room (which virtually doesn't happen anymore).

I don't want to write much right now and turn this post into a mess like I did the other, so... I am currently trying to figure out how to send a wav or aiff impulse response file over as suggested. Waterfall, what should I put the setting at for sending? Is this the proper ETC requested?

Thank you.
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May I Try With A Fresh Slate: Room Analysis Suggestions-etc-left.gif   May I Try With A Fresh Slate: Room Analysis Suggestions-etc-rt.gif   May I Try With A Fresh Slate: Room Analysis Suggestions-edc-lft.gif   May I Try With A Fresh Slate: Room Analysis Suggestions-edc-rt.gif  
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Quote:
Originally Posted by ritelec View Post
Is this the proper ETC requested?
The ETC is good, but we only need the first 30ms or so. If you stretch things out we'll be able to see the early reflections clearly within this interval. You want the reflections occuring before 20ms or so to be as weak as possible.
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Sorry for the delay, 10 hrs later, here I am trying to create a impulse responses in logic impulse response utility (this 003 is killing me... or maybe I'm killing me). Trying to create one with pro tools and waves IR, Trying FM and logic in tandem.... OH MY... I started looking more in FuzzMeasure and found export impulse response. (boy I suk). Is this what you were asking for and will it work for you?

Thank you.
Rich
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Is this better Paul? You can really tell something from this?

Rich
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Thanks Dan!!! Good Reading. Trying to absorb here (no pun intended)......
Rich
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Here is a very cursory look at the ETC providing a few issues of note that one can gain from its viewing.

Also, I would love(sic) to hear the rationale for the carpet on the wall! Remove it. If you need treatment, do it properly with dedicated broadband panels placed strategically (in other words, only where the ETC helps you to identify if and where they are needed!)
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File Type: pdf ETC.GSForum.Annot..3.1.11.pdf (170.3 KB, 191 views)
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Thank you SO!!! much SAC,

Wow, thats amazing! I'm been reading around and will continue to do so. What is considered the "early" and "later" part of the interval? I located a post from Dec 10' that you went into great detail which I have to really get into. (got to call it a day for now though). But I just had to write you back and thank you. You helped make a bit more sense of it for me, and again....amazing!!!

I took the tape measure out. Your 17ft 8in. looks like the left speaker to the right wall. The hot to the right of it in the same red box looks like the left speaker to left wall. The center red box looks like it may be from that angled ceiling part in figure 3 of 5 pic's I sent..... and yes, the 32ft 4in is the back wall. Amazing! I got a bit of work to do.
So that back wall would be a defuse? Center red block? First red block and green....GET RID OF DESK!! lol. amazing.

Thanks again.
Rich
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"+1" thanks SAC. your contributions to this forum are often much appreciated.
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Thank you Dan!

I went thru it, and will again, and probably again,and again.

Where I am right now is, and your opinions welcome.
I will let the insulation and lumber sit in the shed until I relocate work surface and speakers.

I intend to move the monitors to 3' out from wall (front of woofer not driver).

I have a direction for the work surface if you would look at the 2nd image I sent for reference (will also try to post it here so you don't have to scroll)..

The monitors will be out the 3' to front which would put them alittle in front of the large PA speaker (about 5").

Straight down from the front of the monitor (in that vertical plane), I will slide that single rack back to be even with that plane.

The larger rack underneath it thats on the floor that the desk is sitting on will be slid back so the front is on the same plane as the top rack and front of speaker.

This will be done for both sides.

If you look at the 2nd picture (or here if it worked). There is a pad for the mouse on the left side of control surface.

I intend to remove the section of the wood table so vertically it's in line with the speaker front and the front of the two racks. Horizontally, the wood would be gone from the left of the table to the beginning of the black mouse pad. This section of table will also be removed on the right side to be in the vertical plane of that speaker and a piece left to the right of control surface the same measurement as left mouse pad area. (if you were looked just at the piece of plywood it would be "T" shaped).

The visual monitors support table will be slid back, and those monitors slid forward as not to go past front speaker plane (although if the speakers are angled, not sure how that is possible,but...)

I was considering modifying the table that was left, so please give me feed back on this also.
On the wood that is left for work station, I was considering drilling holes in it. Kind of making it look like peg board... and instead of drilling perpendicular to the wood, to even drill those holes on an angle from monitors toward my feet at the sitting position. Then, to install a layer of 3.5" Roxul AFB underneath that drilled area.


The speakers for now will be placed on the top rack as in the pic. (I will measure, to see affects)
I picked up some tubular steal to support the desk for the new design.

I will be seeing the steal man next week with a design to get the speakers off the racks.
Basically it's going to be a right angle support from the back wall (back of the speakers) to position them over the racks but not touching them. Probably designed as a TV holder that will pivot by the wall and pivot at the speaker location.

Am I spinning my wheels? Or does this direction sound good?


Thank you.
Rich
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Quote:
I intend to move the monitors to 3' out from wall (front of woofer not driver).
94 Hz dip/start of comb. That will require at least a ft of fluffy insulation to significantly squash--may be not sufficiently. I'm not sure how well the correction in those monitors will deal with it, but it can't hurt unless the boost is too much for the amp or drivers to handle at your preferred volume. An undamped dip can't really be fixed by EQ. Both of the first front wall dips and bumps are psychoacoustically significant in the frequency domain, but maybe not in the time(I'm researching this now). Closer to the wall with the same absorption should actually be a better situation b/c the smaller wavelengths are easier to absorb. This will excite the modes a bit more however and give you some free power d/t loading.

Do you need to have the PA speakers in there? My idea--essentially what I have is a nearly anechoic front end and diffusion on the rear and sides with nothing in between you and the monitors. Having a lot of close, hard, reflective surfaces near the monitors is not a good idea in both time and frequency domains. I'm having a bit of trouble imagining your future room(I'm tired as hell), but that would be my suggestion.

Those JBL's may have a tight enough pattern to essentially crossfire them and have the first horizontal reflection points off the contralateral walls and thus heard by that contralateral ear of the original. IOW, the first reflection from the right speaker will be heard by the Left ear and will be uncorrelated and of significant delay. IACC Glossary: Interaural Cross Correlation (IACC) | Sweetwater.com will be improved as well as envelopment and a sense of space. You'll still get the recorded environment, but it won't sound dry.

Don't know if that makes sense, but I'm trying.

Dan
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yes and no.... Thinking of putting speakers closer than 3.5' or 3'now?? ..... fill with fluffy pink stuff? (I"m still thinking that's regular insulation) was considering doing all corners with the roxol afb superchunck style (16" triangle). top ceiling corners maybe 8 or 10"x 3 or 4' panels in corners, 2'x4' hanging panels on 4 walls. laying roxol on top of the rugs that are hanging from the ceiling . Go rest up. thank you. So many questions,.


I'll go read some more, thats all I've been doing now for two weeks and I'm still confused.
I'll give thought about the PA speakers.
Hopefully I get an answer back about cutting the table.

Thanks again .
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5th March 2011
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I've actually got a coffee table in my LR that I cut and stuffed. Still haven't recovered it. Maybe that's why the GF always wants to stay at her place? :facepalm :

Roxul is better than pink and fluffy for sure. Sorry, I'm forgetting which thread I'm posting in. Work has been nuts. The super chunk corner is not the most effective use of the stuff. This might get me flamed here, but it's an undeniable fact. The corner has very little particle movement in the modal region.

Check this out for a bit of proof: hunecke.de | Room Eigenmodes Calculator
Enter your dimensions. The white areas are where porous absorbers are most effective and where you won't hear the offending frequency clearly. Walking around your room and placing huge porous absorbers where you actually don't hear the offending frequencies will smooth out your bass.

Making CLD walls or actually tuning them to the resonance will get you a better damped bass. In areas of high pressure--the dark areas on calculator-- a diaphragmatic absorber is most effective. IOW, where you hear the offending frequency is where something other than a porous absorber if maximum effectiveness is in order. Mix these facts with a good parametric EQ, and you'll have a room with great bass an nearly perfect bass when in the listening position.

Dan
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Thats a cool one....Thanks......


These frequencies are all over.


Man -Oh- Man.


babysteps.



Tomorrow the saw!!!
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6th March 2011
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Any pics from that saw work?

I ended up posting what I wrote on the bass/perception topic so that the 'why' could be accessible. audio blog: Hearing Beyond Haas It's certainly not complete, but I'm trying to keep it brief.

Dan
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Hi Dan,

No pics today, sorry. The "boys" decided to come down and jam (my head) for a few hours. I took apart rack, table area. Marked for cutting.(I'm on a different computer so bare with me). It's always best to to measure and place panels and treatment, but, is there any type of "rule of thumb" for treatment behind speaker area wall?(for clarity sake, I'll call this the back wall (back of speakers)). While things are disconnected and gone, it would be easier to address that area. At this point I was thinking of hanging a 2'x4'(or 6')x7"deep (2-3.5" deep roxul afb) horizontally on that wall. Or, 2-2'x4' vertically...(3.5" or 7" deep??? with or without a gap between them so they would be more behind the speakers ???)(or make them 4'x4'...no gap???).. Also to put a 10"x6' (3.5" or 7" deep???) across the top corner where the wall meets the ceiling. (should something go down low where wall meets floor too???).
Rain here today, Design metal bracket for speaker mounting. Surf. Read alot more.

Thank you for the interest and support!!

Rich
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Thanks for the reading material Dan,

Pretty involved stuff.
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I've decided to move the right PA speaker and place it where the conga is in the pics supplied. Then center the work station in that area (right under that light behind the visual monitors that's not on).

Where the drop down ceiling drop down is on the left, I'm thinking about a gobo or partition wall to continue that plain to the floor. That area would be 11' 9"wide. The speakers would be about 2' 6" to back wall from back of speaker and about 2' 3" from right side wall and new left wall to side of speaker. Should that be better than it's the way it sits now?

Dan... in literature you sent this way. axis line of ear level to speaker seems to be at top of woofer. My current ear position on the jbl's is about there or between woofer and tweeter. Just checked jbl literature and they recommend center of high transducer (tweeter). Go for it? Or stick to current level.
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7th March 2011
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What is the purpose of the JBLs? For mixdown or simply as a PA while practicing?

If as a PA, you are simply creating a comb filtering lab with e spaced mono sources - regardless of what most still think is the proper SR configuration due to the fact that they did it at Woodstock.

You would be better off placing them in a corner, which will minimize the mid and high frequency reflections off the side walls due to the controlled dispersion of the horns and then invert the top speaker (placing mid horns together) and stack and splay them to cover the area needed if you actually need the volume of two (which I seriously doubt).

IF you need the additional volume (I defy anyone to justify this), inverting them and aligning them vertically per their acoustic centers will allow the corresponding drivers to couple and will minimize the horizontal polar lobing and subsequent comb filtering.

This same technique will dramatically improve any live performance where folks erroneously employ split stacks for mono sources.

Oh, and in split stacks, lowering the gain of one stack by 3dB SPL relative to the other stack will result in an apparent 10 dB SPL increase in the total sound field. (This SHOULD raise a few eyebrows and leave more than a few scratching their heads; but it is nevertheless a researched, proven and documented technique.)
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As far as listening height, I'd go with the JBL literature. I was just basing my remark on the cheaper line of JBL that I measured--theirs is directly between the drivers by measurement.

As far as the rule of thumb--none that I now of. The more gap, the thicker the absorber, the more area of coverage, the better. More area is more important than more depth according to Ethan's data. I'd trust it. According to the Roxul site, you need 4" thick, but that doesn't take in account for gap and area.

Dan
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