Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 359 - AVS Forum
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post #10741 of 10754 Old 07-09-2014, 03:23 AM
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Quote:
Originally Posted by Audionut11 View Post
Thanks Markus. Between that and the link 3ll3d00d shared earlier, I have some good reading to do.
I remember reading that thread (linked by JohnM) at the time & finding it confusing (IIRC it meanders through some measurement errors). FWIW you can see the 1st example of me doing thisstarting at this post in this thread which might be useful as a summary/starter guide.
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post #10742 of 10754 Old 07-14-2014, 02:14 PM
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This is the thread to start with REW, and it has 10,741 posts.

I have read many at the beginning and end. What I need is a primer on basic how-to analyse your current audio performance.

I am considering doing this and testing with REW prior to adding ANY acoustical treatments in the room.

Can anybody point me to a thread or post that gives some beginning instruction as to how to tackle this in a DIY perspective; not just "hire some professional to do it" answer?

I really truly appreciate everyone's contribution in this thread.

Kyle
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post #10743 of 10754 Old 07-14-2014, 02:26 PM
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Kyle, I can't tell from your post whether you are a already familiar with REW, and are looking for guidance on how to interpret your measurements, or whether you are seeking advice on how to use REW. If it is the latter, then have you looked at the REW beginner's guide? There is a link in my sig. If you are looking for advice on existing measurements, post them here, and you will get plenty of feedback.
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post #10744 of 10754 Old 07-14-2014, 07:24 PM
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Quote:
Originally Posted by skipford View Post
Can anybody point me to a thread or post that gives some beginning instruction as to how to tackle this in a DIY perspective; not just "hire some professional to do it" answer?

The acoustical master thread and the DIY movie poster acoustic panel threads helped me the most.
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post #10745 of 10754 Old Yesterday, 11:14 AM
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Help with nasty null?

I was shocked running REW with my new sub (empty room) to find a nasty nasty null. I've moved both my MLP and sub around to a number of positions and could use some guidance. My room's dimensions aren't THAT far off a recommended ratio--or so I thought.

Is this my room--or my sub? Would love an expert opinion--especially what is happening when I add Roxul in the corners. I would like to keep my MLP as centered (width) as possible for imaging.

Anyhow:

Room is 120" by 196.5" by 88". The room is sealed--double walled--double solid core doors. The "room layout.jpg" below doesn't show the window on the top wall, the door on the bottom wall left, or the closet for the equipment rack on the bottom right. I'm working on it.

Running REW I found the best height for my MLP was around 39" from the floor. Got steadily worse until 50" was abysmal. Moving the MLP forward and backward "move MLP depth.png" I found 64" from the back wall (top green) to be the smoothest. Then weeks later I continued my testing at 74" (38% rule perhaps?) though I'm now not sure why as 64" was superior...

"Move Sub along wall" had me running the sub toward me along the right wall until it was comically close to the MLP--perhaps not doable. It ended up looking the flattest at 64" off the front wall "sub along side wall right".

Fearing this didn't seem a very viable placement I found the flattest response along the front wall placing the sub at about 31.5" off the left wall, and 48-52" into the room "best along front wall".

Finally I temporarily placed 3 bags of Roxul safe n sound in the corners. Front left and right and back left "adding roxul".

Adding the Roxul did some pretty funky stuff from 60Hz upward that I don't understand. I've also included a waterfall comparison "adding roxul waterfall".

Gear:
UMIK-1 with horizontal orientation and calibration file
Onkyo 805 with audyssey disengaged and crossover at 120Hz (highest it will go)
SVS PB-2000 at 75dB, phase at 0, input on LFE

So.....what insight does any of this provide--if any? How close could I get this response to flat without a second sub and just using placement and a miniDSP do you think? Would dual subs in such a small room (damn you ceiling!!!) even be beneficial?

I wish I hadn't blown my budget on a single sub! Doh!

Edit: Apologies in advance--it appears I had my graphs end at 120Hz--not 200Hz as instructed...
Attached Images
File Type: jpg room layout.jpg (131.9 KB, 25 views)
File Type: png move sub along wall.png (182.8 KB, 25 views)
File Type: png move mlp depth.png (96.6 KB, 22 views)
File Type: png best along front wall.png (49.7 KB, 25 views)
File Type: png adding roxul.png (57.4 KB, 25 views)
File Type: png adding roxul waterfall.png (574.8 KB, 25 views)
File Type: png sub on right wall.png (40.6 KB, 19 views)

Last edited by HDgaming42; Yesterday at 01:05 PM.
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post #10746 of 10754 Old Yesterday, 06:45 PM
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Had Dan AKA SmithandWEsson over my house to run REW on my system. But we got these strange readings with my KEF Q900 fronts taking a nose dive around 2k.
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File Type: jpg kef.jpg (123.7 KB, 20 views)


Last edited by jsil; Today at 01:17 AM.
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post #10747 of 10754 Old Yesterday, 07:54 PM
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post #10748 of 10754 Old Yesterday, 08:11 PM
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Quote:
Originally Posted by HDgaming42 View Post

Is this my room--or my sub?
RoomSim

Using your measurements as near as I could guess, to simulate your room, with 1/12 octave smoothing:



I guess "Room".


RoomSim at Sourceforge

There may be better simulators, don't know. Maybe you already have one.

I'll be back later...

equitech -> various digital sources > benchmark > krell pre and monoblocks > reQuest
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post #10749 of 10754 Old Today, 01:00 AM
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Hi AustinJerry,

His a forum member and he was showing me how REW works. We ran REW in my room and we got those readings. Need help understanding what is going on.


Last edited by jsil; Today at 10:23 AM.
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post #10750 of 10754 Old Today, 05:04 AM
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Quote:
Originally Posted by HDgaming42 View Post
How close could I get this response to flat without a second sub and just using placement and a miniDSP do you think?
Place the sub VERY close to your head behind the listening position, about 1' from your ears. This puts you in the direct field of the sub where SPL is very high compared to what is sent into the room. You'll hear a lot more direct sound and way less detrimental room effects.
The only drawback of this setup is that it's highly listening position dependent.

Quote:
Originally Posted by HDgaming42 View Post
Would dual subs in such a small room (damn you ceiling!!!) even be beneficial?
Yes, if you place them correctly.

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole

Last edited by markus767; Today at 05:41 AM.
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post #10751 of 10754 Old Today, 08:41 AM
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Quote:
Originally Posted by RayDunzl View Post
RoomSim

Using your measurements as near as I could guess, to simulate your room, with 1/12 octave smoothing:



I guess "Room".


RoomSim at Sourceforge

There may be better simulators, don't know. Maybe you already have one.
Oddly enough, I think I've run every damned calculator under the sun...but a room simulator. Completely ignorant of their existence. Room mode calculators didn't (at least to me) predict this mess as clearly as what RoomSim seems to have done. Thanks for this.

Quote:
Originally Posted by markus767 View Post
Place the sub VERY close to your head behind the listening position, about 1' from your ears. This puts you in the direct field of the sub where SPL is very high compared to what is sent into the room. You'll hear a lot more direct sound and way less detrimental room effects.
The only drawback of this setup is that it's highly listening position dependent.
Initially I read that as "one inch". The room is already skirting the outer boundaries of WAF; I think that would be the final straw!
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post #10752 of 10754 Old Today, 08:54 AM
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Originally Posted by HDgaming42 View Post
Initially I read that as "one inch". The room is already skirting the outer boundaries of WAF; I think that would be the final straw!
A sub at about shoulder height is probably more WAF friendly then a sub out in the room where it can be seen all the time.

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole
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post #10753 of 10754 Old Today, 08:59 AM
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Quote:
Originally Posted by HDgaming42 View Post
Oddly enough, I think I've run every damned calculator under the sun...but a room simulator. Completely ignorant of their existence. Room mode calculators didn't (at least to me) predict this mess as clearly as what RoomSim seems to have done. Thanks for this.
Your measurements are a good example why I keep telling people to use room simulators ONLY for educational purposes and NOT for planning a real setup.
If you plug dimensions and locations of your room into REW's room simulator then you'll see a very different picture than the actual situation as shown by your measurements. Only in-room measurements tell the truth.

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole

Last edited by markus767; Today at 09:44 AM.
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post #10754 of 10754 Old Today, 12:53 PM
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Quote:
Originally Posted by markus767 View Post
Your measurements are a good example why I keep telling people to use room simulators ONLY for educational purposes and NOT for planning a real setup.
If you plug dimensions and locations of your room into REW's room simulator then you'll see a very different picture than the actual situation as shown by your measurements. Only in-room measurements tell the truth.
Can you comment as to why adding Roxul seems to raise up one null slightly, while creating (moving forward?) a new, much deeper null?
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