or Connect
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
New Posts  All Forums:Forum Nav:

Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How... - Page 84

post #2491 of 9576

I believe the OP is still using an Oppo player as a pre-pro, and is not using an AVR.  This suggests that there may be something different with how the Oppo handles bass re-direction.

Gear mentioned in this thread:

post #2492 of 9576
Hi guys,

Decided to jump into REW rabbit hole. Got my Dayton umm yesterday. As I was setting it up, I dropped on the floor. Two feet onto the carpet. Snaped at the neck. WTF.

I taped it and it looks alright, I guess.
I haven't tried it yet. Plan to set up my system this wkend. My question to you guys is this, what do I need to look for to see if the mic is broken or messed up.

And can I trust it?
post #2493 of 9576
Quote:
Originally Posted by mp5475 View Post

Hi guys,

Decided to jump into REW rabbit hole. Got my Dayton umm yesterday. As I was setting it up, I dropped on the floor. Two feet onto the carpet. Snaped at the neck. WTF.

I taped it and it looks alright, I guess.
I haven't tried it yet. Plan to set up my system this wkend. My question to you guys is this, what do I need to look for to see if the mic is broken or messed up.

And can I trust it?

 

I did the same thing.  Used gaffer tape to hold the two pieces together.  As long as the wires were not severed, you should be OK.  Make sure you tape it so you can orient the mic to point directly at the ceiling.

post #2494 of 9576
Quote:
Originally Posted by AustinJerry View Post

I did the same thing.  Used gaffer tape to hold the two pieces together.  As long as the wires were not severed, you should be OK.  Make sure you tape it so you can orient the mic to point directly at the ceiling.
Thanks! Hope to be posting my curves soon. I am at page 69 of this thread. Few more pages to go to catch up.
post #2495 of 9576
Quote:
Originally Posted by sdurani View Post

Quote:
Originally Posted by jkasanic View Post

I could get something like a GIK 242 panel for both of those openings or would you suggest something thicker like a 244 panel?
Not familiar with those, but 4 inches of OC703 placed 4 inches from the wall would do the trick. Put it in a frame shaped like the opening on the opposite side, wrap the frame in cheap speaker grill cloth. Don't use a plastic or paper membrane in front of the rigid fiberglass to reflect the higher frequencies. You want a broadband absorber, not a bass trap. Those openings aren't going to reflect back higher frequencies, so the absorbtion on the opposite side shouldn't either.
Quote:
Originally Posted by jkasanic View Post

The false wall is actually 25" deep but the backs of the LCR speakers are less than 9" to the back wall
Speaking of bass traps, consider taking advantage of that 9" gap by draping pink fluffy fiberglass down your entire front wall. Bass trapping doesn't get much cheaper. That much surface area will likely be more effective than a couple of corner traps.

If that's a little radical for your room, then you can use 6" or 7" Rockwool, convering as much of the front wall as possible. It is lower density than rigid fiberglass, so will do a better job at absorbing lower frequencies.

 

Thanks for the suggestion.  I had thought about doing something crude like that to see what benefits I could realize.  I wouldn't mind spending a little more for Rockwool just because it seems a little easier to handle BICBW.  I'll need to see if I can find some locally.

post #2496 of 9576
Quote:
Originally Posted by jkasanic View Post

I'll need to see if I can find some locally.
Is there a Lowes hardware store near you?

http://www.lowes.com/pd_122333-1278-RXCB3023_?productId=3693532
post #2497 of 9576
Quote:
Originally Posted by sdurani View Post

Maybe it's a reflection that is cancelling the direct sound at 400Hz.

1130 ÷ 400 = 2.8 feet (wavelength of 400Hz)

Which means the path of the reflected sound is 1.4 feet (half-wavelength) longer than path of the direct sound from your centre speaker, and they're combining out of phase at the measuring mic.

Whenever you've measured a dip at 400Hz, has there been a boundry (wall, ceiling, floor) or reflective surface (coffee table, television) less than a foot away from the centre speaker?

1) My original layout utilized a center channel speaker above my sceen, behind GOM in an overhead soffit (but angled slightly down). In this configuration I was suspecting a ceiling reflection as dip was the worst.
2) For my latest configuration I have a different center channel speaker positioned below my screen angled up about 12 degrees to the MLP. In this case theseverity of the "dip" is less, and the frequency shifted slightly lower.

I really do need to quit working from memory and need to post some fresh REW comparison graphs here, with an image of my layout.
post #2498 of 9576
Quote:
Originally Posted by sdurani View Post

Quote:
Originally Posted by jkasanic View Post

I'll need to see if I can find some locally.
Is there a Lowes hardware store near you?

http://www.lowes.com/pd_122333-1278-RXCB3023_?productId=3693532

 

Haha...do I detect a hint of sarcasm? tongue.gif  I wasn't really familiar with "Rockwool" and everything I found online implied I needed to find an industrial supply company to order it.  Of course, most of that info dated back to 2007!  After some further internet sleuthing, I also came across Roxul and was in the process of trying to determine which was the best when I saw your post...so you've beat me to it once again! wink.gif  This would be a relatively inexpensive solution even if I end up having to build a frame to hold the sheets.  The construction of my false wall is such that I can easily tear it down and no one would ever know it was there.  On the flip side, it's custom size means it will probably end up going with the house if/when I decide to move!

post #2499 of 9576
Quote:
Originally Posted by Pres2play View Post

I'll try selecting sub alone tomorrow. I got so caught up trying to get a full range measurement, I forgot to do that.

This is the graph with 4 (sub) selected in the output box and no smoothing...base level seems normal. (BTW, I'm alone using one of the two subs right now).


and here is a full-range measurement with 1 selected in the output box (blue trace) and the sub overlay from the pic above


both were measured at same volume setting, but full range graph shows a reduced signal in the bass region. I can set the volume higher in the sub to match the mains, but the volume knob on the back of the sub is already set to 12 o'clock, which seems rather high as it is.

The sub trim control in the player is set at 0.0dB. Setting it higher could introduce distortion. In either case, shouldn't the sub trace and the full-range curve matchup at the bottom?

I've been messing with the sound panel on the laptop, setting and resetting speaker size in the surround configuration window, and even selecting bass management option here...but no success.



The problem must be with the player. I will post in the Oppo thread and see if anyone there can help.
post #2500 of 9576
^ I still think there is something wrong with how the Oppo is doing bass management. If you look at the graphs I posted yesterday evening, you will see a distinct roll-off in the sub response above the crossover point (80Hz). When measuring in REW, the signal is sent to the satellite audio channel, and by virtue of bass management, frequencies below the crossover are sent to the sub. In your measurement, it looks like the full measurement sweep is being sent to the sub, which would account for continued response by the sub above the crossover. I could understand this if you were sending a 15-300Hz test tone to the LFE channel, but this should not be happening if you are sending the test signal to a satellite speaker with proper bass management.

Am I making any sense? I would be interested in hearing what you find out in the Oppo thread. Ask there if anyone is using the Oppo as a pre-pro like you are.
post #2501 of 9576
Quote:
Originally Posted by jkasanic View Post

Quote:
Originally Posted by kbarnes701 View Post

Hey Joe!

 

It was Bryan Pape who worked with me - a very patient guy. We did it all via email. I sent him a 3D model of my room and he used that as the starting point.

 

I wouldn't neglect all those other corners - you have the ceiling/wall corners and the floor/wall corners too. AIUI the more corners you can do the better the result.  Also don't forget the ceiling reflections.

 

I think the 244s are the best choice for angling across the corners - that is how I use them anyway. I then use 242s on the wall/ceiling for taming the reflections shown in my ETCs. I used string and mirrors in combination.

 

Can you use any  244s on the floor in front of the screen?  I assume you have thick drapes over that window on the back wall?

 

I am far from an expert on room treatments but AIUI the more corners you treat, the better, using measurements and your ears as guides for both the 244s and the 242s. At some stage you reach diminishing returns and after that it's more Graphitis Nervosa setting in than significant benefits. But it's surprising how much treatment you can get into a room if you try!

 

Yeah, I should've mentioned that AJ commented about the ceiling corners as well.  How exactly do you treat the floor corners?  Same as the ceiling...seems like they would be in the way most places or risk being damaged?  As for the ceiling, I think I'll take Jerry's advice to Pres2Play about treating the first reflection.  I plan to trig everything out (finally get to use angle of incidence = angle of reflection!) so I can place the panels precisely in the right locations.  Are you suggesting using the GIK 244's instead of the tricorner traps?

 

The floor/wall is a corner like any other corner. Use the tricorner traps - just lay them down on the floor - easiest install ever! :)  The tricorners are great for most corners but are not really practical for ceiling/wall corners. There, the 244s at a 45 degree angle across the corner are an easy install. I use two hooks in the ceiling and two in the wall and my trusty cable ties.

 

Quote:

When you say use panels on the floor do you mean the same as you would on the ceiling?  There's no real reason to have to walk in front of the screen except the bathroom is located off the opening to the right of the screen.  The large opening at the back is a sliding glass door.  It has a pretty decent shade for blocking out light but no idea on the sound absorption characteristics?!  I've been looking at my decay plots and waterfalls and I still have several issues that need to be addressed with room treatments.  Thanks for your input!

 

EDIT:  I saw on the GIK website a tri-trap being used on the floor-wall corners.  I think I'm already reaching in terms of WAF with the layout I proposed (although I might be able to squeeze in a white ceiling panel as well)!

 

WAF permitting, I don't think you can do too much!  (As ever, my comments are wrt to a HT used for movies. I know nada about using the room for music).

post #2502 of 9576
Quote:
Originally Posted by Pres2play View Post

After several hours testing the new sub, here's a before and after with left speaker in small mode. Green is before; blue is after, with 1/6 smoothing. The result is barely noticable.





Then I tried the right speaker and the result was even worse, which left me thinking there's either a problem with the sub or REW is not routing the full bass signal to the speaker. To test this, I went into the preference window and selected output 4 in the timing box which is the sub, and got this...


Red is the new trace


This explains the 50 Hz drop in all my previous graphs, the sub was never engaged. We shouldn't have to select the sub separately, right guys, unless only the sub is being tested? I'll have to check my player and REW guide to see what I missed.

Edit: no smoothing

Something odd there. You are correct - you do not have to select the sub when testing L or R or C with sub because the bass redirection automatically routes to the sub. IOW, if testing the L + Sub you select Output 1 in the left box and nothing in the right box. If you want to test L only, you physically turn off or disconnect the sub. If you want to measure the sub only, you select Output 4 in the left dropdown box.

 

If yours is not working that way, it suggests that the Oppo is not handling bass redirection in the usually understood way, or you have not set it up correctly to do so.

 

Although I have an Oppo it is the 93 which does not have the same facility as yours so I cannot check it out. Maybe a question in the Oppo thread for your model would be a good idea?

 

Is there a reason you don't have a prepro or an AVR? (Other than the obvious additional cost).

post #2503 of 9576
Quote:
Originally Posted by AustinJerry View Post

Sanjay,

Can you clarify: if a speaker is pointed away from a wall, how can sound be radiating 180 degrees to the rear and reflecting off a rear boundary? Are we talking about sound coming out of the ducted port facing the rear wall?

 

Sound comes out of the speakers all around them if you think about it (at some frequencies at least) - when you stand directly behind a speaker, you still hear sound from it don't you?

post #2504 of 9576
Quote:
Originally Posted by AustinJerry View Post

^ I still think there is something wrong with how the Oppo is doing bass management. If you look at the graphs I posted yesterday evening, you will see a distinct roll-off in the sub response above the crossover point (80Hz). When measuring in REW, the signal is sent to the satellite audio channel, and by virtue of bass management, frequencies below the crossover are sent to the sub. In your measurement, it looks like the full measurement sweep is being sent to the sub, which would account for continued response by the sub above the crossover. I could understand this if you were sending a 15-300Hz test tone to the LFE channel, but this should not be happening if you are sending the test signal to a satellite speaker with proper bass management.

Am I making any sense? I would be interested in hearing what you find out in the Oppo thread. Ask there if anyone is using the Oppo as a pre-pro like you are.

Thank you, Jerry. I have the XO set to 100 Hz, but completely agree, the bass is not dropping off the way it should. I can test out the bass management on my old Yamaha receiver to confirm what's happening. I may drag it out if I have time today. Also, posted in 105 thread. Will get back to you later.
post #2505 of 9576
Quote:
Originally Posted by mp5475 View Post

Hi guys,

Decided to jump into REW rabbit hole. Got my Dayton umm yesterday. As I was setting it up, I dropped on the floor. Two feet onto the carpet. Snaped at the neck. WTF.

I taped it and it looks alright, I guess.
I haven't tried it yet. Plan to set up my system this wkend. My question to you guys is this, what do I need to look for to see if the mic is broken or messed up.

And can I trust it?

 

They seem to be really fragile don't they?  You are not the first to have snapped it off at the neck. I suspect it will still function perfectly normally. You could probably test it with a disc of test tones of known frequencies or something - play a selection of them and see if the REW response corresponds?  There may be better ways. One consolation is that if the mic is now taped up with gaffer tape, it will definitely have that 'professional' look about it ;)

post #2506 of 9576
Quote:
Originally Posted by kbarnes701 View Post

Sound comes out of the speakers all around them if you think about it (at some frequencies at least) - when you stand directly behind a speaker, you still hear sound from it don't you?

Just a minute, Keith, I'm going to take my speaker out into an open field to test out your theory... tongue.gif
post #2507 of 9576
Quote:
Originally Posted by Pres2play View Post

Thank you, Jerry. I have the XO set to 100 Hz, but completely agree, the bass is not dropping off the way it should. I can test out the bass management on my old Yamaha receiver to confirm what's happening. I may drag it out if I have time today. Also, posted in 105 thread. Will get back to you later.

Now that I think about it, even passing a 15-300Hz test tone to the LFE channel should exhibit a sharp roll-off above 120Hz. Definitely something fishy going on.
post #2508 of 9576
Quote:
Originally Posted by kbarnes701 View Post

Something odd there. You are correct - you do not have to select the sub when testing L or R or C with sub because the bass redirection automatically routes to the sub. IOW, if testing the L + Sub you select Output 1 in the left box and nothing in the right box. If you want to test L only, you physically turn off or disconnect the sub. If you want to measure the sub only, you select Output 4 in the left dropdown box.

If yours is not working that way, it suggests that the Oppo is not handling bass redirection in the usually understood way, or you have not set it up correctly to do so.

Although I have an Oppo it is the 93 which does not have the same facility as yours so I cannot check it out. Maybe a question in the Oppo thread for your model would be a good idea?

Is there a reason you don't have a prepro or an AVR? (Other than the obvious additional cost).

Thanks, Keith. If REW didn't work the way you described, it would certainly limit its usefulness. If the Oppo is responsible, we may have discovered a problem with the Oppo's internal bass management using the player's HDMI input. I have posted the issue in the owner's thread.

A new receiver is in the works, just trying to get the best deal.
post #2509 of 9576
Quote:
Originally Posted by AustinJerry View Post

Quote:
Originally Posted by kbarnes701 View Post

Sound comes out of the speakers all around them if you think about it (at some frequencies at least) - when you stand directly behind a speaker, you still hear sound from it don't you?

Just a minute, Keith, I'm going to take my speaker out into an open field to test out your theory... tongue.gif

 

When you get back, I bet you will tell me that you could still hear sound from it when you stood behind it :)

post #2510 of 9576
Quote:
Originally Posted by kbarnes701 View Post

When you get back, I bet you will tell me that you could still hear sound from it when you stood behind it smile.gif

I'll never know--the cable didn't reach that far.
post #2511 of 9576
Quote:
Originally Posted by jkasanic View Post

Haha...do I detect a hint of sarcasm? tongue.gif
Nope, since your location isn't listed under your avatar, I didn't know whether there was a Lowe's near you.
Quote:
Originally Posted by jkasanic View Post

This would be a relatively inexpensive solution even if I end up having to build a frame to hold the sheets.
Since you already have a false wall, you can just tack the rockwool batts to front wall. Who's going to see it? Since it is relatively inexpensive, keep in mind that the more surface area you cover (as a percentage of room boundries), the more effectively you'll absorb bass.
post #2512 of 9576
Quote:
Originally Posted by AustinJerry View Post

Quote:
Originally Posted by kbarnes701 View Post

When you get back, I bet you will tell me that you could still hear sound from it when you stood behind it smile.gif

I'll never know--the cable didn't reach that far.

 

Haha!  If it had, I am sure you would find the speakers omnidirectional, especially at the lower end of the spectrum :)

post #2513 of 9576
Quote:
Originally Posted by kbarnes701 View Post

Quote:
Originally Posted by AustinJerry View Post

Quote:
Originally Posted by kbarnes701 View Post

When you get back, I bet you will tell me that you could still hear sound from it when you stood behind it smile.gif


I'll never know--the cable didn't reach that far.

Haha!  If it had, I am sure you would find the speakers omnidirectional, especially at the lower end of the spectrum smile.gif

Omni-directional implies the same sound level in all directions. That's certainly not the case, especially for tweeters in sealed speakers, which tend to quite directional. THX certified speakers even restrict the vertical dispersion to minimize reflections off the ceiling and floor. Granted you can hear something, but the sound levels are substantially reduced from the on-axis sound levels.
post #2514 of 9576
Quote:
Originally Posted by Pres2play View Post

I've been messing with the sound panel on the laptop, setting and resetting speaker size in the surround configuration window, and even selecting bass management option here...but no success.



The problem must be with the player. I will post in the Oppo thread and see if anyone there can help.

 

Have you tried unchecking the Bass Management (or checking Disable all enhancements) in this Windows menu?  I'm wondering if this is causing an issue with how your test tones are being played through REW?  I don't have HDMI working so I skimmed through the guide on this part but I seem to recall not wanting any ehancements enabled on other connections?!  Just a thought...

 

EDIT:  Nevermind, I just saw where you said you tried checking this option (presumably you already had the problem before you checked it).

post #2515 of 9576
For those who have JavaScript enabled, see animated gif below.

Radiation pattern of a typical loudspeaker.



Keep an eye on the changing frequency and compare it to the directivity balloon.

Easy to spot which direction is the front of the speaker, since the directivity in that direction doesn't change.
post #2516 of 9576
Quote:
Originally Posted by jkasanic View Post

Have you tried unchecking the Bass Management (or checking Disable all enhancements) in this Windows menu?  I'm wondering if this is causing an issue with how your test tones are being played through REW?  I don't have HDMI working so I skimmed through the guide on this part but I seem to recall not wanting any ehancements enabled on other connections?!  Just a thought...

EDIT:  Nevermind, I just saw where you said you tried checking this option (presumably you already had the problem before you checked it).

Hi. The problem has been there from the beginning. I guess I only noticed it now thanks to my growing familiarity with REW.

No one has answered my post about the HDMI input on the Oppo player. I may have to resort to pulling out my receiver to see if it's the player, the laptop or REW setup.
post #2517 of 9576
Quote:
Originally Posted by Selden Ball View Post

Quote:
Originally Posted by kbarnes701 View Post

Quote:
Originally Posted by AustinJerry View Post

Quote:
Originally Posted by kbarnes701 View Post

When you get back, I bet you will tell me that you could still hear sound from it when you stood behind it smile.gif


I'll never know--the cable didn't reach that far.

Haha!  If it had, I am sure you would find the speakers omnidirectional, especially at the lower end of the spectrum smile.gif

Omni-directional implies the same sound level in all directions. That's certainly not the case, especially for tweeters in sealed speakers, which tend to quite directional. THX certified speakers even restrict the vertical dispersion to minimize reflections off the ceiling and floor. Granted you can hear something, but the sound levels are substantially reduced from the on-axis sound levels.

 

Hmmm... not sure about that definition of 'omni-directional'. It seems to me that it means the sound (or whatever) will radiate in, or come from, all directions. I don't seen any implication of the sound being the same in all directions. As you know, omni comes from the Latin meaning 'every'. I think we would be seeking a word with the Greek for 'same' in it - homo - as in, for example ,homobaric (having the same weight). But this is semantics and not all that relevant I grant you. In the context of acoustics 'onmidirectional' may well have the usage you describe. :)  But I did carefully say to Jerry that the sound radiating from the rear was only evident at certain frequencies, but it is nontheless still there. Now whether the amount of sound below, say, 400Hz, that is heard from behind the speaker is sufficient to cause reflective issues due to SBIR I have no idea. Sanjay seems convinced it does (I think) and he is the go-to guy on this topic (for me anyway).

 

Edit: just saw Sanjay's neat animated GIF.... that seems to settle it :)

 

EDIT again: thinking some more about this, when I am outside in a huge open space or field, as I am every day, if someone is standing in front of me, with their back turned towards me, and they speak, I can still hear them. Not as clearly of course, but I can definitely still hear them.

post #2518 of 9576
Quote:
Originally Posted by sdurani View Post

For those who have JavaScript enabled, see animated gif below.

Radiation pattern of a typical loudspeaker.



Keep an eye on the changing frequency and compare it to the directivity balloon.

Easy to spot which direction is the front of the speaker, since the directivity in that direction doesn't change.

Can you explain exactly what we're seeing?
post #2519 of 9576
Quote:
Originally Posted by sdurani View Post

Quote:
Originally Posted by jkasanic View Post

Haha...do I detect a hint of sarcasm? tongue.gif
Nope, since your location isn't listed under your avatar, I didn't know whether there was a Lowe's near you.
Quote:
Originally Posted by jkasanic View Post

This would be a relatively inexpensive solution even if I end up having to build a frame to hold the sheets.
Since you already have a false wall, you can just tack the rockwool batts to front wall. Who's going to see it? Since it is relatively inexpensive, keep in mind that the more surface area you cover (as a percentage of room boundries), the more effectively you'll absorb bass.

 

Sorry, I just noticed that my location wasn't included in my avatar.  Thanks!

 

I suppose I could just tack it to the wall but I was trying to avoid touching the painted drywall surface.  Here's a view with 14 panels (upper panels have to be cut 10" in height):

 

 

And here's another view showing the two panels you suggested on the wall opposite the two door openings.  I've tried to show the edge of the panels lining up with the openings (that's the two guide lines running through the doorways just to confirm this is what you meant?):

 

post #2520 of 9576
Quote:

Originally Posted by kbarnes701 View Post



 

 

EDIT again: thinking some more about this, when I am outside in a huge open space or field, as I am every day, if someone is standing in front of me, with their back turned towards me, and they speak, I can still hear them. Not as clearly of course, but I can definitely still hear them.

 

Are you sure it isn't just sound coming out the port in the rear?   eek.gif

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Audio theory, Setup and Chat

Gear mentioned in this thread:

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