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Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 169

post #5041 of 9566
Quote:
Originally Posted by jlpowell84 View Post


What about the bass sounding "muddy," as being too close to a wall. I don't know if it's true or myth but I remember reading too close to a wall thickens and makes the bass sound muddy as opposed to tight. I would like to have my Submersives as close to the wall as possible for the simple fact that they intrude less physically on the room.



Muddy can mean different things. Using this chart, it refers to frequencies in the 250-450hz range.

Regardless of the frequency range you mean, I would look for peaks, elevated response over a wide area or very slow decays in the region in question.
Edited by jim19611961 - 10/8/13 at 2:42pm

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post #5042 of 9566
What Jim said.

Boundary reinforcement due to placement near a reflection plane and especially in corners (where 2 or more intersecting planes like the floor and 1 or 2 walls) increases bass reinforcement, meaning you're getting free headroom, but potentially more bass SPLs also tend to mean potentially longer ringing.

It's usually bass peaks overwhelming and masking other frequencies, or ringing (bass that continually bounces around and decays too slowly) that also masks other frequencies that causes the perception of 'muddiness'.

Proper placement to allow the EQ to minimize peaks plus bass traps to minimize ringing are great ways to get tight bass that doesn't sound 'muddy'.


Max
post #5043 of 9566
Nice! I plan on getting the triangular corner bass traps for the right front and right rear (left side of room is open). And like 8 of the 4 inch bass traps, 24x48's. Probably go with AST acoustics since I like the black micro suede and beveled edges look.
post #5044 of 9566
OK
Original design was each sub sat next to the front spkrs like in my gallery.
Yesterday and today, I moved the sub that was next to front right spkr all the way to be behind MLP so now the subs are on opposite walls.
I made sure the rear of both subs were 12" from their respective wall.
I did a bunch of moving and measuring, picked the best spots using SPL vs freq and then ran a close pattern 5 point XT32 and am a bit disappointed. frown.gif
It seems 20 to 40 Hz is a tiny bit better but then it falls apart.
I think i will just enjoy the spkrs for awhile smile.gif

post #5045 of 9566
Quote:
Originally Posted by jkasanic View Post

Quote:

Originally Posted by bao01 View Post

 
Quote:

Originally Posted by djbluemax1 View Post

For practical purposes, folks tend to slide the subs along the walls, both because no one wants a random monolith sitting in the middle of the room, and because the boundary reinforcement from being close to the corners (where intersecting planes like a wall and the floor is considered a corner) increases the bass.

Max


So how do you decide on the distance from wall to rear of sub? 3", 6", 9", 12"

Does this distance make a big difference?

thanks

Depends on your room configuration and the standing waves.  I think you already got some excellent advice from a highly respected member of AVS (sdurani aka Sanjay or as Keith likes to call him the speaker placment guru).  I would start there and put the subs as close to the wall as you have room for the reasons mentioned above.  You can always experiment with moving them out from the wall when you take measurements.

Quote:
Originally Posted by AustinJerry View Post

You fine-tune sub placement by using REW measurements, either measurement sweeps, or the RTA method discussed recently. Once you have found a position along the wall that seems to be the best position, you can experiment with adjusting the distance away from the wall, again taking measurements. In my experience, adjusting the distance away from the wall did not produce significant changes. In my current configuration, the subs are 12" from the wall.

Quote:
Originally Posted by djbluemax1 View Post

Yep. The variance between 3" - 12" from the wall generally tends to make less difference than the placement along the wall. Of course, measurements will determine if it makes a significant difference in your own room as some factors can change things. For instance, there are some downward firing subs that may work better slightly further from the walls, but for most sealed or front ported designs, the difference in distances away from the wall won't be too significant.

Measure the best locations along the wall first, then, if you like, try measuring the differences with different distances away from the wall.

Max

I tried 12" and 18" and it didn't really change the SPL graph so i picked 12".

thanks guys
post #5046 of 9566
Quote:
Originally Posted by bao01 View Post

OK
Original design was each sub sat next to the front spkrs like in my gallery.
Yesterday and today, I moved the sub that was next to front right spkr all the way to be behind MLP so now the subs are on opposite walls.
I made sure the rear of both subs were 12" from their respective wall.
I did a bunch of moving and measuring, picked the best spots using SPL vs freq and then ran a close pattern 5 point XT32 and am a bit disappointed. frown.gif
It seems 20 to 40 Hz is a tiny bit better but then it falls apart.
I think i will just enjoy the spkrs for awhile smile.gif


Do you have the responses of each individual sub without Audyssey? After reviewing all of your posts, I think there has been some confusion over what you posted previously. I think it might help to see the individual responses as well as the combined response before any EQ is applied BICBW.
post #5047 of 9566
Ok. I will post pre xt32 graph for each sub. Standby

At least with the new layout of opposing walls, I can maintain 80 db down to 15 hz. YAY!
Should be good when I buy Pacific Rim BD smile.gif
Edited by bao01 - 10/8/13 at 7:00pm
post #5048 of 9566
Quote:
Originally Posted by bao01 View Post

OK
Original design was each sub sat next to the front spkrs like in my gallery.
Yesterday and today, I moved the sub that was next to front right spkr all the way to be behind MLP so now the subs are on opposite walls.
I made sure the rear of both subs were 12" from their respective wall.
I did a bunch of moving and measuring, picked the best spots using SPL vs freq and then ran a close pattern 5 point XT32 and am a bit disappointed. frown.gif
It seems 20 to 40 Hz is a tiny bit better but then it falls apart.
I think i will just enjoy the spkrs for awhile smile.gif


Observation here. In my short time in this hobby any general response graph observation...It seems nearly everyone has the classic 60hz null. Is this a widespread null or perhaps a unique sample of graphs I have laid eyes on? If it is a problem at 60hz that is common, do we know why?

Quote:
Originally Posted by bao01 View Post

Ok. I will post pre xt32 graph for each sub. Standby

At least with the new layout of opposing walls, I can maintain 80 db down to 15 hz. YAY!
Should be good when I buy Pacific Rim BD smile.gif

I read on the bass list movie forum it has a filter that neutered from 25 hz and below...
post #5049 of 9566
CSL says the UMIK-1 are sold out. Are the UMM-6 just as good or should I wait?

Which of you are hoarding the UMIK-1s? wink.gif
post #5050 of 9566
I have both and cannot see any difference between the two.
post #5051 of 9566
Quote:
Originally Posted by jlpowell84 View Post

Observation here. In my short time in this hobby any general response graph observation...It seems nearly everyone has the classic 60hz null. Is this a widespread null or perhaps a unique sample of graphs I have laid eyes on? If it is a problem at 60hz that is common, do we know why?
I read on the bass list movie forum it has a filter that neutered from 25 hz and below...

Some said my 66 Hz null is too narrow to be audible. I need to read up on what is audible and what isn't.

Re the neutering of Pacific Rim - that sucks - i guess 25 hz will have to do.
post #5052 of 9566
Quote:
Originally Posted by bao01 View Post

Some said my 66 Hz null is too narrow to be audible. I need to read up on what is audible and what isn't.

Re the neutering of Pacific Rim - that sucks - i guess 25 hz will have to do.

I just ordered Olympus has Fallen. The monument scene apparently has an extremely intense scene thick right along the 20hz line with stuff down into the single digits.
post #5053 of 9566
Quote:
Originally Posted by jlpowell84 View Post

Observation here. In my short time in this hobby any general response graph observation...It seems nearly everyone has the classic 60hz null. Is this a widespread null or perhaps a unique sample of graphs I have laid eyes on? If it is a problem at 60hz that is common, do we know why?

Maybe there are many folks with null around 64 to 67 Hz because many of us have 8 or 9 ft ceilings. It is a tangential room mode, not axial. Hard to remove just by sliding subs around on floor. You'd have to start raising the subs off the floor. eek.gif
post #5054 of 9566
Quote:
Originally Posted by bao01 View Post

Maybe there are many folks with null around 64 to 67 Hz because many of us have 8 or 9 ft ceilings. It is a tangential room mode, not axial. Hard to remove just by sliding subs around on floor. You'd have to start raising the subs off the floor. eek.gif

Really! That makes sense as that is a very common ceiling height. Hmm, raising my two submersives wouldn't be too far fetched if it offered a lot.
post #5055 of 9566
Quote:
Originally Posted by bao01 View Post

You'd have to start raising the subs off the floor. eek.gif

..., delay the rear subs and you have a double bass array:


Edited by markus767 - 10/9/13 at 8:30am
post #5056 of 9566
Markus is probably right. There is probably a way to fix nulls due to ceiling height. I am still learning smile.gif
Thanks Markus.
Edited by bao01 - 10/9/13 at 8:00am
post #5057 of 9566
A DBA does not only "fix nulls due to ceiling height" but "removes" the room completely. It doesn't get better than that.
post #5058 of 9566
So how does it become a DBA. Simply subs in the front and rear?
post #5059 of 9566

@jlpowell84:  Did you read the link that Markus posted?  It's pretty well described there and there's an additional link that you could probably use Google translate to read.  Basically, it is an array on the front and rear walls.

post #5060 of 9566
I read a little of the DBA thread. I think you have to place the subs up on the wall. They can't just sit on the floor. They have to be arranged symmetrically with each other ON the wall, taking height of the room into consideration.

I shall bolt my 130 lb Fathom f113 subs to the drywall now - standby for pics. smile.gif
post #5061 of 9566
Yea I've read through that thread before. Was just curious what the minimum requirement to be a DBA would be. Or do they have to be smaller multiple drivers mounted in a flat, skinny box all over the front and back walls. It seems the bass would react the same if some boxes were set up against the walls right?

If I put a Submersive up front and then one behind the couch would that classify as a DBA?
post #5062 of 9566

No need for bolts.  Picture hooks should do it.  :D

post #5063 of 9566

Yeah, probably don't even need the ones with nails, just the sticky back glue type... :p

post #5064 of 9566
Nah, use the bolts.

Haven't you always wanted an open floor plan?
post #5065 of 9566
You guys should have bought subs for good sound not for max weight smile.gif
post #5066 of 9566


ok this seems terrible...this is L,R,SW x-over at 70
why is the output at 20hz and up so low?!? we are talking 25db difference...luckily the projected EQ is much nicer but still...
post #5067 of 9566

Brian, something is wrong with that measurement.  Let's go through a few presentation basics, and then you can re-post the graphs.

 

- First, click the "All SPL" button at the top.  You should always use this mode when displaying frequency sweeps.

 

- Second, adjust the vertical scale to read 50-100dB.  We need to see the lower end of the measurement.

 

 

 

- Third, when measuring L+R+Sub(s), it is usual to measure 15-20,000Hz, and include a second graph that shows the full range, with 1/6 smoothing.  So, you should post two graphs as follows:

 

 

 

 

Now, if you look at the graph above titled "Low Frequencies", notice that it is relatively flat out to 300Hz.  Your graph takes a nose dive above 80Hz, as if the left and right speakers were not emitting the test tone.  Please measure left+right+sub(s), 15-20,000Hz, and publish the results with 1/6 smoothing so we can see what is going on.

post #5068 of 9566
well right now i am only concerned about measuring my sub...so I reran with sub only...here is the result:

post #5069 of 9566
Quote:
Originally Posted by Brian Fineberg View Post

well right now i am only concerned about measuring my sub...so I reran with sub only...here is the result:


I'm a rookie myself, but that doesn't look so good frown.gif
post #5070 of 9566
Sorry to have to say this, but that is a terrible graph. I still think you are doing something wrong with taking the measurements, because your sub response can't be that bad.

Back to the previous graph. It didn't look right either. We need to zero in on what is wrong with your REW measurement technique or we won't make any forward progress. Did you read the Guide, and are you following it step-by-step when you are setting up REW and taking your measurements?
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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