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Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 123

post #3661 of 9491
Quote:
Originally Posted by markus767 View Post

Quote:
Originally Posted by jkasanic View Post

I did some extensive experimentation on my single sub placement.

Could you try one more configuration? Put the sub very close to your ears (<2') behind your listening seat (put it on a chair with the driver pointing at your head). Then run MultEQ again. I'd like to hear how this sounds to you and see a measurement at the listening position (e.g. sub + L would be enough).

When I'm able to move the sub from its current location then I'll take this measurement as well.  Thanks.


Edited by jkasanic - 6/17/13 at 12:41pm

Gear mentioned in this thread:

post #3662 of 9491
Quote:
Originally Posted by jkasanic View Post


Having recently tested a new laptop and ASIO4ALL, I can clearly confirm that you're not in the minority when it comes to head scratching why this doesn't seem to work?!  FWIW, I would stick with the HDMI cable and just use the java driver in REW for mains plus sub measurements (i.e. L, C, R with and without sub and L+R with and without) as these will be the most meaningful anyway.  You'll be giving up discrete 8 channel measurements but still be able to use your HDMI cable and avoid a lot of the pitfalls that still exist with ASIO drivers.

 

From there, it's exactly as Keith described.  Follow the guide and see if you can get your graphs to resemble something similar to what Jerry posted.  Most likely, you're missing sub output and your levels are not calibrated correctly showing much higher than actual output readings.

 

Again, more directed @Mark than at you, Joe... I agree that the LCR with and without sub and L+R with and without are basically all we really need. Although I am using the ASIO driver with no problems with my cheap Windows 7 laptop, I have never measured, and probably never will measure, anything other than the speakers and combinations you mention. I would just add that measuring the subs on their own (each sub) and together (both subs) is also important, but you know that anyway.

 

Mark, are you with us on this?  That is to measure the following:

 

  1. Left speaker on its own (subs physically switched off or disconnected)
  2. Right speaker on its own (ditto)
  3. Centre speaker on its own (ditto)
  4. Sub 1 on its own
  5. Sub 2 on its own
  6. Subs 1 and 2 together
  7. L+R + Subs

 

In the REW pane where you select the speakers, these correspond to:

 

  1. Left drop down box - channel 1, Right drop down box blank
  2. Left drop down box - channel 2, Right drop down box blank
  3. Left drop down box - channel 3, Right drop down box blank
  4. Left drop down box - channel 4, Right drop down box blank (Sub 2 physically switched off or disconnected)
  5. Left drop down box - channel 4, Right drop down box blank (Sub 1 physically switched off or disconnected)
  6. Left drop down box - channel 4, Right drop down box blank (Both subs switched on/connected)
  7. Left drop down box - channel 1, Right drop down box - channel 2 (Both subs switched on/connected)

 

I found the above a little confusing at first - are you sure you are measuring the correct channels, as designated by the channel numbers above?

 

In the Limits box in REW, set it like this for all your measurements:

 

 

 

 

When you produce your graphs, use 15-300Hz for bass, with no smoothing and 15-20000Hz for everything else, with 1/6th smoothing.

 

For waterfalls, follow the advice already given.

 

Edited by kbarnes701 - 6/17/13 at 1:03pm
post #3663 of 9491
Quote:
Originally Posted by jkasanic View Post

When I'm able to move the sub from its current location then I'll take this measurement as well.  Thanks.

Will be interesting. By the way, is your room documented somewhere?
post #3664 of 9491
Quote:
Originally Posted by mark_anderson_u View Post

LEAD Technologies Inc. V1.01

I originally thought that at the 1st axial mode of the width (8.75ft) would be best. Got no bass whatsoever. I then read a great article on blu-ray forum about room modes and sub placement and it said to try and put it between the 1st and 2nd modes. So I located it about 6.75ft and difference was dramatic


If you look at the middle (width) panel of the mode calculator chart above, you'll see that the location of your subwoofer (6 3/4 ft) is where the room's 3rd width mode (drawn in red) is peaking. That is, you've placed your pressure generator (subwoofer) where pressure is already highest (peak).

If you follow that red line to the left a bit, you'll see that your 3rd width mode (also written in red) is 96Hz. Rather than cancel a mode, you've re-inforced your 3rd width mode peak to make it ring like a mutha... well, just look at your measurement above and see what's happening around 96Hz.

Could you move your sub back to the midpoint of room width and re-measure? I know you feel that you got no bass whatsoever, but try that location again and raise the subwoofer level until you get a measurement.
post #3665 of 9491
Quote:
Originally Posted by mark_anderson_u View Post


This is certainly not the in-room response of a subwoofer. Did I read your post wrong?
post #3666 of 9491
Quote:
Originally Posted by jevansoh View Post

Quote:
Originally Posted by jkasanic View Post
 
Well, let me be the first case then!  At first, I was planning to use R30 Roxul insulation panels in the corners behind my false wall as well as at the floor and ceiling joints.  Then it was suggested that I consider covering the entire wall.  In this case, I believe I've gone from just bass trapping to absorbing across the entire stage.  You mention that you can never have too much bass trapping...does this still apply?  The floor plan below shows the basic elements of my listening space:
 



 I'm willing to treat areas outside of the false wall but these obviously require a little more WAF which means I'll likely be buying panels that either blend in with the decor (so as to be invisible) or add to it (e.g. decorative panels).  Either way, I've lost my low cost DIY approach being applied behind the false wall!  Suggestions?

Although it is very possible to design for "too much bass trapping" in implementation, I've yet to see it done.

However, if you are using broadband velocity based trapping (fuzzy insulation) then you aren't really using true "bass trapping" at all and as you are taming the bass you are also sucking all the life out of the room as it's having an even more pronounced effect on the higher frequencies.

To keep it cheap and simple, if you have enough room, you can do what I did and treat the whole front wall (behind my false screen wall - all hidden) with R30 insulation and depending on how much room you have back there and how much trapping you need, you can orient it so that it is 9.5" thick or 15" thick. Then simply cover it with plastic so you don't over absorb the mids and highs and now you are using it strictly as a bass trap. You may want to do even more in the corners (double up the layers, for instance, which is exactly what I did).

Unfortunately, due to the design of my pre-existing room and an HVAC duct that is running the width of the room approx. 22" in depth, I'm only left with about 10" from the edge of my L & R speakers (toed-in) to the drywall:

 

 

I was planning to use R30 Roxul panels which are only 7-1/4" deep.  Are these not thick enough to address my specific issues (room mode at 30Hz)?

Quote:

Originally Posted by jevansoh View Post
 

In small rooms and rooms where you aren't able to alter the construction by creating splayed walls, you can easily use large reflectors (Mine are simply 5/8" Drywall which is cheap at under $10.00 for a 4x8' panel and very massive so they make a perfect specular reflector) cut, sized, and placed to create an ISD Gap and then put bass trapping IE: R30 insulation behind the reflector without overdamping the highs. Two birds. One stone. wink.gif

 

Do you have any pictures of these you could post?

post #3667 of 9491
Quote:
Originally Posted by kbarnes701 View Post

Quote:
Originally Posted by jkasanic View Post


Having recently tested a new laptop and ASIO4ALL, I can clearly confirm that you're not in the minority when it comes to head scratching why this doesn't seem to work?!  FWIW, I would stick with the HDMI cable and just use the java driver in REW for mains plus sub measurements (i.e. L, C, R with and without sub and L+R with and without) as these will be the most meaningful anyway.  You'll be giving up discrete 8 channel measurements but still be able to use your HDMI cable and avoid a lot of the pitfalls that still exist with ASIO drivers.

 

From there, it's exactly as Keith described.  Follow the guide and see if you can get your graphs to resemble something similar to what Jerry posted.  Most likely, you're missing sub output and your levels are not calibrated correctly showing much higher than actual output readings.

 

Again, more directed @Mark than at you, Joe... I agree that the LCR with and without sub and L+R with and without are basically all we really need. Although I am using the ASIO driver with no problems with my cheap Windows 7 laptop, I have never measured, and probably never will measure, anything other than the speakers and combinations you mention. I would just add that measuring the subs on their own (each sub) and together (both subs) is also important, but you know that anyway.

Good point and one that us schleps with only a single sub that can't play to 15Hz tend to forget!  If I pull the trigger on that Submersive upgrade then I guess I'll have to figure out ASIO afterall! biggrin.gif

post #3668 of 9491
Quote:
Originally Posted by sdurani View Post
Quote:
Originally Posted by jkasanic View Post

Does this method of speaker placement work for both gains and nulls?
Sure, because they're manifestations of the same resonance (you'll hear it as a peak or dip depending on whether you're in a location where those reflections reinforce each other or cancel each other, respectively). If you keep the resonance from being excited, then you won't hear the peaks & nulls associated with that resonance.

I'll give you a real world example. Your room's first width mode is 40Hz, and its second width mode is around 80Hz. If you put your sub in its old corner location, played a 80Hz tone and walked across your room, you would hear what your mode calculator chart shows: at the side wall the 80Hz tone would be loud, at the one-quarter point it would quiet, at the half-way point it would be loud again, then quiet at the three-quarter point, and loud at the opposite wall. Place a pair of subs at the quarter points of room width, and that same 80Hz tone would sound relatively the same level as you walked across the room.

You've measure as much when you moved your sub from the corner to the midpoint of room width. Since you were measuring from the middle of room width, your first width mode (40Hz) was a null at that location. If you had been measuring closer to either side wall, that same frequency would have looked like a peak. When you moved your sub, it prevented the mode from being excited, and your 40Hz problem became inaudible (and the peaks & dips associated with it).

 

Thanks for the lesson.  I keep forgetting that our response measurements are single point. rolleyes.gif

 

Quote:

Originally Posted by sdurani View Post

Quote:

Originally Posted by jkasanic View Post

Did you end up just tacking pink fluffy stuff to your drywall? 

I used 4" OC703 a few inches from the wall. It started because I was thinking about what reflections (i.e., from which direction) I didn't want to hear. To see if theory translated to practice, I had a friend walk a hand mirror across the front wall, marking locations where I saw the reflections of my side and rear speakers, and placed 2'x4' absorbers there. It worked, allowing me to hear more details floating between my L/C/R speakers. Experimented outward from there.

See my post above on the R30 Roxul.  I'm wondering if I can even do anything about the 30Hz room mode (besides adding a 2nd sub and experminenting with placement)?

Quote:

Originally Posted by sdurani View Post
 

Originally Posted by jkasanic View Post

I also think I might fall into the category of someone that prefers some localization in the surrounds. Heck, it could be that I prefer an NE model but since Jason confirmed my understanding about the order in which we should be dealing with issues (e.g. worrying about LF absorption/diffusion and terminating high gain early reflections before worrying about the things that differentiate the models), I can start addressing some of these areas.

Joe, before you put any absorption on your front wall, understand the studio model you've chosen to emulate:

What exactly is your concern wrt using absorption on the front wall?  I thought taming the LF for ringing was still a requirement of an NE model and isn't the reflective nature of the front wall more focused on higher frequencies anyway (i.e. I could treat the outer layer with a thin sheet of plastic to prevent absorbing these higher frequencies)?  TBH, I'm not sure I'm "committed" to following any one model hard and fast at this point.  I'd just like some good direction on addressing my LF issues with room treatments (if even possible) and then move on to the high gain early reflections.  Once I've spent some time listening to my room with these areas improved, I may decide to go further.  At this point though, I'm struggling enough with these two things.

post #3669 of 9491
the monitors are soffit mounted into the front wall in NE and LEDE/RFZ.

you're not constructing a NE or LEDE room. you're simply emulating the time-domain specular response (if you choose to do so).

in either or ANY of those studio models, it is understood the LF/modal region issues are addressed - this can be accomplished in a myriad of ways.
post #3670 of 9491
Shift key anyone?
post #3671 of 9491
Quote:
Originally Posted by markus767 View Post

This is certainly not the in-room response of a subwoofer. Did I read your post wrong?

Nope. It's what I measured, but clearly there's something wrong with either what I'm sending (sounds Ok to me) or what I'm getting at the Mic/REW. Will have to try and figure out what the issue is. The sub is working: I literally feel it when the system is playing reasonably loud.

One thing that is strange (I think) is that when I start the sine wave sweep in REW the red bars on the level bars go from top to bottom, then I hear the sweep and the green bars go up. Not sure if that's normal or not
post #3672 of 9491
Quote:
Originally Posted by markus767 View Post

Quote:
Originally Posted by jkasanic View Post

When I'm able to move the sub from its current location then I'll take this measurement as well.  Thanks.

Will be interesting. By the way, is your room documented somewhere?

 

First, if you could respond to my post on the ringing below 100Hz in waterfall plots that would be great!

 

As for my room, I didn't do a build thread as the room was just retrofitted with a false wall mainly for aesthetic purposes (although, I'm beginning to think the audio and video rabbit hole I've jumped down has me heading down a more dedicated room path and soon I'll be blacking out walls and ceiling, replacing the in-ceiling surrounds and redoing my seating (WAF permitting of course)!  These layouts pretty much show the room in its entirety.  One exterior wall (back wall) has a sliding glass door with a black out shade, the left wall (not shown) is a common wall with a neighbor, the right wall is completely interior with two openings for a hallway near the screen and a stairwell at the back of the room and the screen wall is concrete behind the studs and drywall.  Floor is concrete with carpet and ceiling is drywall with air gap to floor joists above.

 

 

Actual photo with masking panels shown:

post #3673 of 9491
Quote:
Originally Posted by mark_anderson_u View Post

Quote:
Originally Posted by markus767 View Post

This is certainly not the in-room response of a subwoofer. Did I read your post wrong?

Nope. It's what I measured, but clearly there's something wrong with either what I'm sending (sounds Ok to me) or what I'm getting at the Mic/REW. Will have to try and figure out what the issue is. The sub is working: I literally feel it when the system is playing reasonably loud.

One thing that is strange (I think) is that when I start the sine wave sweep in REW the red bars on the level bars go from top to bottom, then I hear the sweep and the green bars go up. Not sure if that's normal or not

 

It's one thing to hear the sub playing with normal content but a completely other thing when playing test signals via HDMI through REW.  Follow Keith's recommendations to ensure you have the proper channels activated (assuming you even get ASIO working?).  If not, try using the java driver to reduce the number of variables (i.e. source of errors) in your setup.

post #3674 of 9491
Quote:
Originally Posted by localhost127 View Post

the monitors are soffit mounted into the front wall in NE and LEDE/RFZ.

you're not constructing a NE or LEDE room. you're simply emulating the time-domain specular response (if you choose to do so).

in either or ANY of those studio models, it is understood the LF/modal region issues are addressed - this can be accomplished in a myriad of ways.

 

Thanks for reiterating the point about "emulating" as I'm sure it could be lost on the casual follower of this thread. It's for this very reason (i.e. the assumption that LF/modal issues have already been addressed) that I'd like to discuss the myriad of ways to accomplish this in more detail. It feels like we keep going round and round on this issue. If the thread is taking on a logical progression of the steps involved to treat an "existing" room (per the OP's first few threads and not necessarily the title of the thread), then all of the discussion on the various models is somewhat premature (unless of course we're back to saying that treatment of the LF issues will depend on the model you are attempting to emulate)?! I'm basing this on the premise purported by the OP that he's never seen "too much bass trapping" implemented in practice. I'd like for us to discuss in more detail the finer points of bass trapping vs. absorption and whether or not it's a worthwhile endeavor to deal with sub 40Hz issues passively?
post #3675 of 9491
Quote:
Originally Posted by jkasanic View Post

I'm wondering if I can even do anything about the 30Hz room mode (besides adding a 2nd sub and experminenting with placement)?
I doubt you'll be able to tame a 30Hz peak with treatment. If placing a sub at the midpoint of room length is not an option, then try nearfield bass (as Markus suggested).
Quote:
Originally Posted by jkasanic View Post

What exactly is your concern wrt using absorption on the front wall?
Just pointing out that it conflicts with the posted description of the studio model you've chosen. If you do decide to reflect mid and high frequencies off the front wall, using a thin sheet of plastic, then understand that you'll be reflecting content from your surround speakers from the same direction as your front soundstage. If you're OK with that, then I have no concerns.
post #3676 of 9491
Quote:
Originally Posted by sdurani View Post

Quote:
Originally Posted by jkasanic View Post

I'm wondering if I can even do anything about the 30Hz room mode (besides adding a 2nd sub and experminenting with placement)?
I doubt you'll be able to tame a 30Hz peak with treatment. If placing a sub at the midpoint of room length is not an option, then try nearfield bass (as Markus suggested).

 

Geez, all those suggestions about covering the front wall with Rockwool and this is what you thought originally?! tongue.gif

post #3677 of 9491
Quote:
Originally Posted by jkasanic View Post

Geez, all those suggestions about covering the front wall with Rockwool and this is what you thought originally?! tongue.gif
Heh, if I'd known that you wanted to absorb down to 30Hz, I would have suggest absorbers a few feet deep.
post #3678 of 9491
Seriously, very little music has content at 30Hz. What impact does ringing at that low a frequency really have? Does it really matter for cinema content? Given the difficulty of treating for very low frequencies, I think it is a valid question.

Or, to ask it a different way, the expert opinion is that before addressing the specular region, it is assumed that the modal region is under control. Down to what frequency does "in control" mean?
post #3679 of 9491
The only limit is your sub(s) and content. There's a lot of low frequency content in movies, even down to single-digit frequencies. If such low frequencies can't be controlled then high-passing the subs is the only option. On the other hand I don't see why applying a simple PEQ wouldn't be feasible.
post #3680 of 9491
Quote:
Originally Posted by jkasanic View Post

Quote:
Originally Posted by kbarnes701 View Post

Quote:
Originally Posted by jkasanic View Post


Having recently tested a new laptop and ASIO4ALL, I can clearly confirm that you're not in the minority when it comes to head scratching why this doesn't seem to work?!  FWIW, I would stick with the HDMI cable and just use the java driver in REW for mains plus sub measurements (i.e. L, C, R with and without sub and L+R with and without) as these will be the most meaningful anyway.  You'll be giving up discrete 8 channel measurements but still be able to use your HDMI cable and avoid a lot of the pitfalls that still exist with ASIO drivers.

 

From there, it's exactly as Keith described.  Follow the guide and see if you can get your graphs to resemble something similar to what Jerry posted.  Most likely, you're missing sub output and your levels are not calibrated correctly showing much higher than actual output readings.

 

Again, more directed @Mark than at you, Joe... I agree that the LCR with and without sub and L+R with and without are basically all we really need. Although I am using the ASIO driver with no problems with my cheap Windows 7 laptop, I have never measured, and probably never will measure, anything other than the speakers and combinations you mention. I would just add that measuring the subs on their own (each sub) and together (both subs) is also important, but you know that anyway.

Good point and one that us schleps with only a single sub that can't play to 15Hz tend to forget!  If I pull the trigger on that Submersive upgrade then I guess I'll have to figure out ASIO afterall! biggrin.gif

 

LOL!  

post #3681 of 9491
Quote:
Originally Posted by markus767 View Post

The only limit is your sub(s) and content. There's a lot of low frequency content in movies, even down to single-digit frequencies. If such low frequencies can't be controlled then high-passing the subs is the only option. On the other hand I don't see why applying a simple PEQ wouldn't be feasible.

 

Markus,

 

I think you missed the point of my question.  We know that excessive bass ringing in the 40-80Hz range can result in bloated, one-note bass, which can make music quite unpleasant.  But what does ringing below 40Hz sound like?  Is the ringing really unpleasant when all it affects is movie sound track effects?

 

I am at a decision point.  My bass ringing is reasonably controlled down to 40Hz.  Can I move on to work on taming specular reflections, or must I exert more effort on the below 40Hz modal region?

post #3682 of 9491
Quote:
Originally Posted by AustinJerry View Post

Quote:
Originally Posted by markus767 View Post

The only limit is your sub(s) and content. There's a lot of low frequency content in movies, even down to single-digit frequencies. If such low frequencies can't be controlled then high-passing the subs is the only option. On the other hand I don't see why applying a simple PEQ wouldn't be feasible.

 

Markus,

 

I think you missed the point of my question.  We know that excessive bass ringing in the 40-80Hz range can result in bloated, one-note bass, which can make music quite unpleasant.  But what does ringing below 40Hz sound like?  Is the ringing really unpleasant when all it affects is movie sound track effects?

 

I am at a decision point.  My bass ringing is reasonably controlled down to 40Hz.  Can I move on to work on taming specular reflections, or must I exert more effort on the below 40Hz modal region?

 

+1  A very eloquent way of asking what I've been trying to for the past few days...thanks Jerry! 

post #3683 of 9491
Quote:
Originally Posted by AustinJerry View Post

Quote:
Originally Posted by markus767 View Post

The only limit is your sub(s) and content. There's a lot of low frequency content in movies, even down to single-digit frequencies. If such low frequencies can't be controlled then high-passing the subs is the only option. On the other hand I don't see why applying a simple PEQ wouldn't be feasible.

 

Markus,

 

I think you missed the point of my question.  We know that excessive bass ringing in the 40-80Hz range can result in bloated, one-note bass, which can make music quite unpleasant.  But what does ringing below 40Hz sound like?  Is the ringing really unpleasant when all it affects is movie sound track effects?

 

I am at a decision point.  My bass ringing is reasonably controlled down to 40Hz.  Can I move on to work on taming specular reflections, or must I exert more effort on the below 40Hz modal region?

 

I look at it like this - but fully accept that I might be wrong, and welcome being told so if I am. Really low bass isn’t very easy to hear is it? I don't mean ringing, I mean the initial impulse.  Look how the Audyssey test tones sound at 75dB - you can barely hear them. So if the initial impulse between 15Hz and 30Hz isn't all that easy to hear, then how much will hear of the 'secondary' bass that is being bounced around the room, when we have dropped it in level by 30dB, for example?

 

I'm not saying we should just ignore ringing below 30Hz of course. Just that we may be getting obsessed with it when the reality of what we hear isn't the same as the reality of what we see on a graph.

 

Here is my latest waterfall (made since I effected Sanjay's suggestions. I still have some more work to do as I need to remeasure and probably re-run Audyssey after the PJ and screen go in tomorrow). 

 

Should I expend a lot more effort on the 15-30Hz region, and if I do, will the audible result be worthwhile?  IOW, same question as yours, Jerry.

 

 

 

Graph is L+R+Subs, Audyssey ON.

 

For comparison, here is the graph of Subs only, Audyssey ON.

 

 

When I ran Audyssey, I forgot that I had the Submersives in 'Pgm 2' mode (which boosts the level of the bass below 30Hz by about 3dB). My usual practice is to run the subs in Pgm 1 for Audyssey calibration and then switch to Pgm 2 afterwards, thus preserving the boost from Audyssey's clutches. I expect that when I re-run Audyssey in Pgm1 mode and then change to Pgm2 I will see a deterioration in the waterfall wrt to the ringing, simply because I will be pumping a lot more energy into the room below 30Hz. 

 

The question is, if I do, what should I do?  Ignore it?  Make an effort to control it (very hard)? Or simply revert back to Pgm1, which might possibly show a better waterfall than those above?

 

Any and all comments welcome.

 

Incidentally, if I had followed my 'preflight manual' I wouldn't have forgotten to reset the subs to Pgm1. This shows the value of consistent preflight checks (and explains why airline pilots do them). But I became cocky, and thought I would do it based on my 'experience'. Ha!


Edited by kbarnes701 - 6/18/13 at 5:46am
post #3684 of 9491

^^^^Keith, can you post before and after you changed the sub locations?  Did you change anything else?  I could be wrong but that appears to be a noticeable improvement below 40Hz from where you were??

 

EDIT:  Ok, that's more like what I remembered.  I believe that ringing below 20Hz was the spawning of the "Graphitis Nervosa" comment!


Edited by jkasanic - 6/18/13 at 6:00am
post #3685 of 9491
Quote:
Originally Posted by sdurani View Post

Quote:
Originally Posted by jkasanic View Post

Geez, all those suggestions about covering the front wall with Rockwool and this is what you thought originally?! tongue.gif
Heh, if I'd known that you wanted to absorb down to 30Hz, I would have suggest absorbers a few feet deep.

 

I guess I just expected more from the room mode guru! biggrin.gif

 

post #3686 of 9491
Quote:
Originally Posted by jkasanic View Post

I guess I just expected more from the room mode guru! biggrin.gif
Doh! Sorry to disappoint, but I don't get to choose effective subwoofer locations (your charts do).
post #3687 of 9491
@Keith,

What advice did you receive from Sanjay WRT sub placement that resulted in the improvement?
post #3688 of 9491
Quote:
Originally Posted by AustinJerry View Post

what does ringing below 40Hz sound like?  Is the ringing really unpleasant

Yes.
post #3689 of 9491
Quote:
Originally Posted by jkasanic View Post

^^^^Keith, can you post before and after you changed the sub locations?  Did you change anything else?  I could be wrong but that appears to be a noticeable improvement below 40Hz from where you were??

 

EDIT:  Ok, that's more like what I remembered.  I believe that ringing below 20Hz was the spawning of the "Graphitis Nervosa" comment!

 

There is a noticeable improvement since I adopted Sanjay's advice. I have changed so many things in the HT recently, in preparation for PJ and screen installation tomorrow, that I think any 'before' graphs would be less than helpful TBH.

 

The difference between what I have now and what you remember is entirely due to speaker and sub placement, which shows how very important that is.

post #3690 of 9491
Quote:
Originally Posted by AustinJerry View Post

@Keith,

What advice did you receive from Sanjay WRT sub placement that resulted in the improvement?

 

I gave Sanjay mty room dimensions and some photos showing the limitations of what options I have or don't have. Sanjay kindly suggested that I move the subs from their contemporary locations and experiment moving them a foot at a time and then 6 inches at a time, using REW as my guide as I went along. This enabled me to find some alternative locations that helped smooth the bass quite a bit. (Incidentally, the locations have only been made possible by the ever-angelic Mrs Keith consenting to my permanently blocking one of the two doors into the room). 

 

The subs were originally: Sub 1 in right hand corner, Sub 2 just off halfway along the left side wall. They are now both along their respective side walls, facing each other, about 1/4 of the distance (guessing) from the front wall (1/4 of the side wall length I mean).  I was also able to make some changes to the bass traps once the sub had been moved out of the corner but this would probably have had only a minor effect.

 

Once that was done, Sanjay suggested that it would be possible now to move the L and R speakers to 21 inches from the side walls (measured to the centre of the woofers). The combination of these suggestions has resulted in the L+R+Subs waterfall I just posted. I am a very happy bunny. And these improvements came at a cost of precisely $0 too!  

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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