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 227

post #6781 of 9585
Q for you guys:
Is there any validity in looking at subs only vs. L/R+subs spectrograms? It seems to me naively to be telling me something about issues to address with my mains, either placement or with bass traps at the moment.


L/R+Subs (no Audyssey, mains crossed at 80 Hz)


Subs only (no Audyssey):


L/R+Subs with Audyssey, for completion


Is it fair to conclude that I have less ringing issues with the subs only than with the mains as part of the mix, over 40 Hz?. Ironically, the marginal improvement with Audyssey plays up the artificial nature of a fixed standard. When I drew the 450 ms line (accidentally missing on the capture, but the laptop's shut down due to baby), the w/o Audyssey L/R+subs plot had 60 and 70 Hz sections that just missed the 450 ms cutoff, while adding Audyssey to the mix had them just clearing it. They're still problems, but it depends on your rigor...and you still want to address 40-45 Hz, I'd think.
Edited by sdrucker - 11/12/13 at 9:36pm

Gear mentioned in this thread:

post #6782 of 9585

The subs only measurement is ever so slightly better above 40Hz, but the third spectrogram looks better over all frequencies than the first two, IMO.  I think it is OK to look at subs only if the purpose is to understand how the subs are performing.  But if the objective is to assess overall bass performance, left+right+subs should be measured.

post #6783 of 9585
Quote:
Originally Posted by AustinJerry View Post

The subs only measurement is ever so slightly better above 40Hz, but the third spectrogram looks better over all frequencies than the first two, IMO.  I think it is OK to look at subs only if the purpose is to understand how the subs are performing.  But if the objective is to assess overall bass performance, left+right+subs should be measured.

Agreed. FYI I moved my mains out another foot or so, which improved things over this plot from about 10 days ago, possibly:


This is the same subs placement and MV/db level, BTW. The other difference is IIRC ULS=50 now vs. ULS=16 before.
post #6784 of 9585
Quote:
Originally Posted by sdrucker View Post

Is it fair to conclude that I have less ringing issues with the subs only than with the mains as part of the mix, over 40 Hz?

No. Look at the energy around t=0. There's a difference in total energy between the graphs. Does one decay faster than the other? Hard to tell in a spectrogram. Look at the waterfall.

A spectrogram could tell the whole story if it could be normalized. But I've said that before...
Edited by markus767 - 11/13/13 at 1:40am
post #6785 of 9585
Quote:
Originally Posted by jkasanic View Post
 
Quote:
Originally Posted by jlpowell84 View Post
 
Deleted

Deleted OP's post since he edited it himself however, I think this still applies:

 

Dude...chillax!  I don't think anybody is purposefully ignoring you.  Keep in mind that what you are doing is not considered "normal" wrt the thread topic.  We're all trying to improve SQ but most of us in THIS thread are trying to figure out how to use less EQ!  I'm not saying what you're doing doesn't belong here but when you cross post in 3 different threads on the same site, you can expect a few people might decide not to respond.  It's just poor forum etiquette to keep posting the same stuff in different threads unless you aren't getting an answer (and then it's normal to inform everyone that you are cross-posting).  In this case, I think you're enthusiasm has gotten the better of you since you did get two responses from different members (myself and audionut11) and we both came to the same conclusion that your waterfalls were hard to read.  Heck, even Mark Seaton said as much in the SubM thread...so try to calm down and take a little more time to post your results.  Don't take this the wrong way but based on your posts it's pretty clear you can be impulsive (e.g. buying your gubbins before you even really knew what kind of treatments you wanted to make).  So blasting others in this thread for not immediately responding like you've discovered the Holy Grail is a little OTTIYAM (that's over the top if you ask me).

 

I saw jlp's now-deleted post and as it was directed at me, I have a couple of observations. First off, Joe, I agree entirely with your post above.

 

Second, @jlp, I think you will agree that it is up to any individual whether they choose to reply to a post of not. There is no implied right of a response in these threads, and if someone chooses not to respond for any reason at all, then it is his right. In my own case, I have chosen not to respond to people who repeatedly post graphs that are not to the agreed standard or illegible and I came to this conclusion for the reasons I gave before. Others will have a different opinion and may well decide to reply, asking continually for the agreed standards to be adhered to. I just got fed up with it - Jerry has gone to great lengths to produce a wonderful guide and we always ask everyone to read it and to adhere to the standards for presentation of graphs. It has become, if you like, a de facto 'thread rule'. Many threads have such rules.

 

I did specifically say, jlp, that I was NOT singling you out when I made my comments, and I am not. And, of course, I will continue to try to assist you wherever I can, but what I won't do is spend time trying to figure out graphs that are presented to all manner of different parameters. It's my personal choice and it is not the official standpoint of the thread in any way, as I think I made clear.  It isn’t hard to read the Guide and to make sure that the parameters of the posted graphs comply - most of the settings are 'sticky' in REW so once set they apply to all graphs subsequently produced. This is not a vendetta against you, jlp - just a choice of my own.

post #6786 of 9585
Quote:
Originally Posted by JohnPM View Post

Herb stopped shipping the UMM-6 outside the US because too many were breaking during shipping. See this post. Bear in mind that Cross Spectrum is a very small acoustics consultancy, as part of which Herb offers a mic calibration service. eCommerce web site design is not likely to be his speciality or priority, I suspect the setup he uses doesn't allow per-product selection of allowed destinations.

 

Thanks, John. I have deleted my posts on the subject. It's a pet grievance of mine that e-commerce companies need to have web sites that work for their customers. My own company used to design web sites and we went to huge lengths to ensure they were customer-friendly, even employing professional 'web site breakers' to find problems with them prior to launch. I would suggest that Herb adds a very prominent caveat to his site asking overseas customers to not order calibrated mics - perhaps on the first page. There is no need for him to change the ecommerce engine he uses then as people would hardly miss such a bold announcement. Any web  site designer could make that change for him in a few minutes. It will surely frustrate people if they go right through the ordering process only to be later told they cannot purchase, despite the sales engine telling them they could. Thanks for adding perspective to this for me.

post #6787 of 9585
Quote:
Originally Posted by arnyk View Post
 
Quote:
Originally Posted by djbluemax1 View Post
 
Quote:
Originally Posted by kbarnes701 View Post

If I buy from the US Amazon site (which I do very frequently since prices are often substantially better, even allowing for shipping and taxes) it tells me at checkout if the item I picked isn't available in my country (no rhyme nor reason to it I can figure - usually everything I seem to ever want is available but occasionally not).

Incidentally, to bring this back on topic, I know of nowhere in Europe which sells the calibrated UMM-6 mic, so what non-US guys will do from hereon in I have NFI. (Polite version of that is 'Not the Faintest Idea). wink.gif
Some manufacturers limit international sales of certain items to prevent cannibalizing the local sales market from overseas sales where prices may be lower. I know of several companies that do that. If you sell/ship their product overseas, your dealer status gets revoked. Heck, I know of some audio equipment companies in the US that mandate no Out-Of-State or online sales to prevent online price competition. You have to buy from a local supplier/dealer.

If you participate in international conferences you have the opportunity to set up whatever private arrangements you wish to establish. When no laws are broken, and only vendor marketing preferences are at stake, it is possible to find private individuals may be receptive to arrangements that are favorable to them, that also end up placing the equipment you wish into your hands. I know of people who have bought say 4 microphones locally and quite legally sent 3 of them to somewhere else, if you catch my drift. ;-)

 

Yes, thanks Arny... I catch your drift and have indeed used such methods in the past, with the help of 'forum friends'. :)

post #6788 of 9585
Quote:
Originally Posted by djbluemax1 View Post
 
Quote:
Originally Posted by kbarnes701 View Post

If I buy from the US Amazon site (which I do very frequently since prices are often substantially better, even allowing for shipping and taxes) it tells me at checkout if the item I picked isn't available in my country (no rhyme nor reason to it I can figure - usually everything I seem to ever want is available but occasionally not).

Incidentally, to bring this back on topic, I know of nowhere in Europe which sells the calibrated UMM-6 mic, so what non-US guys will do from hereon in I have NFI. (Polite version of that is 'Not the Faintest Idea). wink.gif
Some manufacturers limit international sales of certain items to prevent cannibalizing the local sales market from overseas sales where prices may be lower. I know of several companies that do that. If you sell/ship their product overseas, your dealer status gets revoked. Heck, I know of some audio equipment companies in the US that mandate no Out-Of-State or online sales to prevent online price competition. You have to buy from a local supplier/dealer.


Max

 

Hey Max - thanks. I was out of order and posted impulsively on a 'pet' topic of mine. I have deleted my posts. 

post #6789 of 9585
Quote:
Originally Posted by AustinJerry View Post
 
@Keith,

Perhaps you should voice your concern directly to Herb. In my dealings with him, he has been nothing but helpful and professional, and I think we owe him an opportunity to explain why the web site is set up the way it is.

 

I will email Herb and suggest he makes the 'no international sales' notice much more prominent. It caught me at a bad time I think - I've removed my posts.

post #6790 of 9585
Quote:
Originally Posted by sdrucker View Post

Consider this crazy kid, who (as I teased him in a PM) once said last summer:
"That's the bit I don't get. I am sure that most enthusiasts are aware of the need to optimism sub location and the room itself - if possible - before using an electronic EQ like Audyssey. Finding the best place in the room for the sub is fairly easy if you have only one sub and not all that difficult if you have two subs and some sort of measuring gear. There's no need to understand the theory behind it to get a good result any more than I need to know the theory behind cellular communication technology to make a phone call. And wrt to traps and treatments, there are plenty of sites that offer all sorts of advice and help. I just can't see what benefits I would gain by doing all this measuring and graphing over and above what I have already done. I have extremely limited options in my room for sub placement and treatments anyway - as do many others - so knowing that a series of measurements shows that my subs should be elsewhere frustrates rather than illuminates."

That was a few tuned membrane traps ago...biggrin.gif
 

 

Crazy is right. How could anyone think that??  

post #6791 of 9585
Quote:
Originally Posted by markus767 View Post

No. Look at the energy around t=0. There's a difference in total energy between the graphs. Does one decay faster than the other? Hard to tell in a spectrogram. Look at the waterfall.

A spectrogram could tell the whole story if it could be normalized. But I've said that before...

That's why I said 'fair to conclude' rather than 'I found'. I thought that seemed too easy...which means that to compare spectrograms for accessing rates of decay is invalid unless the energy on the two charts is a constant or on a standard scale accounting for the energy variation (like a Z score)?

Hmmm...I had thought that maybe the energy was just more evened out across the frequency range. Back to (the top of) waterfalls....
post #6792 of 9585
Quote:
Originally Posted by kbarnes701 View Post
 
Quote:
Originally Posted by sdrucker View Post

Consider this crazy kid, who (as I teased him in a PM) once said last summer:
"That's the bit I don't get. I am sure that most enthusiasts are aware of the need to optimism sub location and the room itself - if possible - before using an electronic EQ like Audyssey. Finding the best place in the room for the sub is fairly easy if you have only one sub and not all that difficult if you have two subs and some sort of measuring gear. There's no need to understand the theory behind it to get a good result any more than I need to know the theory behind cellular communication technology to make a phone call. And wrt to traps and treatments, there are plenty of sites that offer all sorts of advice and help. I just can't see what benefits I would gain by doing all this measuring and graphing over and above what I have already done. I have extremely limited options in my room for sub placement and treatments anyway - as do many others - so knowing that a series of measurements shows that my subs should be elsewhere frustrates rather than illuminates."

That was a few tuned membrane traps ago...biggrin.gif
 

 

Crazy is right. How could anyone think that??

Unless I'm mistaken, the bolded 'bits' tipped your hand as to the identity of the 'crazy kid'...and if that wasn't enough, then the reply sealed the deal AFAIAC! :D

post #6793 of 9585
Quote:
Originally Posted by sdrucker View Post
 
Quote:
Originally Posted by markus767 View Post

A spectrogram could tell the whole story if it could be normalized. But I've said that before...

Hmmm...I had thought that maybe the energy was just more evened out across the frequency range. Back to (the top of) waterfalls....

 

Hmmm, I might have to start reading Markus' posts more carefully as I always get distracted by the pretty gifs and lengthy links to verbiage way over my head! :D  As Jim so eloquently stated in another post, this is worth repeating.

post #6794 of 9585
Quote:
Originally Posted by jkasanic View Post

Hmmm, I might have to start reading Markus' posts more carefully

I have to agree smile.gif More reading and less writing can help a lot.
post #6795 of 9585
I realize that this thread seems to be for owners of the USB Mic with HDMI connection but there are a lot of knowledgeable people here that I would very much appreciate their input, so I hope that my EMM-6 setup doesn’t exclude me from the thread.

I do have a room construction link below for a much more detailed overview of my room.

The biggest problems that I had with my room are:
1. The HVAC was too noisy and cooled the room far too fast.
2. No amount of mid-range EQ tweaking using Audyssey Pro seemed to satisfactorily fix the “hard” vocal upper range.
3. The LF decays were slightly worse than I had expected.

HVAC

Please see my link below (page 2) for those interested in my HVAC solution and noise floor measurements. It’s not really relevant to this thread.

ACOUSTICS

The room revised elevations are shown below:



Revised Room Elevations and First Reflections

Revised Room Elevations and First Reflections.pdf 776k .pdf file

The changes from the original design are summarized below:

•Added first point refection absorption for the height, left, center and right speakers to the ceiling and door area.
•Changed the absorption thickness on the left and right walls next to the speakers to an average of 5+”.
•Modified all the speaker grills to remove/reduce edge refraction issues.
•Added front sub isolators
.

Ceiling Absorbers


Door, Wall & Speaker Absorbers

The room is loosely based upon a LEDE concept. I realize that it does not meet several criteria for such a room, in particular the Kicker delay. The original delay was designed to be just over 10mS and I wanted at least a 20dB level drop by 1mS extending to 10mS. I originally had the 10+mS delay but found I needed to move my MLP backwards by over 6”which caused the primary reflection from the rear QRD to move to 9.5mS. The good news was that after exhaustive testing this earlier arrival has absolutely no effect on the sound stage and its removal makes the room feel too dead.

The biggest issue by far was the over bright upper mid-range particularly on female vocals. The Genelecs are known for being a little bright but what I had was not fixable this with EQ via Audyssey Pro.

I need to point out that the original Audyssey XT32 Sub EQ and AVP XT32 EQ have never been changed during any tests; it just takes too long (WAF) to frequently run the full 11.1 tests and then Pro re-EQ on top of that.

What I eventually discovered was based mainly upon the ETC measurements. The primary reflections from the ceiling/walls and the non-linear reflections from the 1” fiber glass absorption next to the left and right speakers were significantly affecting the frequency response, or at least what I heard, which Audyssey seemed to either ignore or incorrectly try to fix. I also had two primary reflections from the door area from the Center and RHS speakers that needed to be removed.


Original ETC


Latest ETC

Once this absorption was installed there was a dramatic improvement to what was already a respectable sound stage and the upper mid-range improved significantly but was still too strident. I specifically did not use diffusion as I could not predict what it would do and wanted to maintain the front of the room as being dead with minimal reflections; so as I have “gobs” of SPL and headroom from the 1038 Genelecs, driving them a dB or two harder is of no consequence.

As can be seen from the latest ETC there is still a single very strong primary reflection around 1.2mS with a lot of “clutter” around it. This L/R symmetrical reflection, believe it or not, is from my suspended wooden floor, which is covered with 5/16” felt and 5/16” carpet. I have to assume that as these products are both made from synthetic fiber that they have very little acoustic absorption and will now have to be replaced with pure wool ½” acoustic felt underlay and ½” wool looped carpet; I have samples on the way to test.

The lack of absorption was confirmed by placing a small piece of 1” thick fiberglass batting at the primary floor reflection point and as can be seen below…the reflection is greatly improved.


Latest ETC with Floor Absorber

I can see no way for me to modify the room layout in any way to remove these floor reflections so any advice here to help me get rid of them would be gratefully received. Short of replacing the carpet or adding a REALLY thick rug across the front of my room!

Once I reduced the level of these floor L/R reflections I again noted a further slight reduction in the upper mid-range vocal “hardness” to an acceptable point. So much for Audyssey dealing with the impulse time domain, maybe it isn’t supposed to but their site seems to indicate that it does, not too sure how though.

The graphs below show the rooms’ current overall response.


Current Frequency Response

I originally introduced the “suck out” between 500Hz and 3.5 KHz using Pro in order to compensate for the overly bright response, it also includes the Audyssey crossover correction. I have no idea where the 322Hz dip came from but once the rear ceiling 2D Skyline diffusers are mounted I will re-run the full Audyssey EQ and re-publish.

The LF response 15Hz to 300Hz is flat enough for me and I have no desire to improve it. However I hope that when I re-run Audyssey and remove my Pro EQ the remainder of the response will match it.


Current Waterfall 1 – 15-20Khz (1/6 octave smoothing)


Current Waterfall 2 – 15-200Hz (1/48 octave smoothing)

I do not usually use data much below 60dB as the mic pre-amp LF noise floor is too high there (see my link), and below 32Hz most people’s threshold of hearing cannot detect that level. I will try to tame the response slightly at 27 Hz using Pro, hopefully that will pull the 27Hz decay back a little to.


Current Spectrogram

The Spectrogam seems to confirm the waterfall showing a maximum decay time of 450 mS for a 40dB decay for frequencies below 40Hz. There are no irregular decay patterns above this frequency. If the group delay of the subs, shown below, is taken into account then most of the LF decay relative to its peak is within 400mS.


Current Group Delay

Whilst I am basically happy with the LF response in terms of extension and clarity etc., I would still like to improve the decay below 40Hz if at all possible. I have therefore just updated the room to handle a pair of rear subs (either SVS SB12-NSD or PB-1000 as I have a space restriction) in the hope that if I reduce/cancel the level of the primary length mode I may see an improvement in this bottom end decay. However if this decay is strictly limited by the amount of LF absorption in the room (of which I can add no more due to lack of space) then I may see either no improvement or it may get worse depending upon how the additional subs interact with the existing rooms acoustics. Unfortunately the sub locations are really fixed per the attached room layout. I will update the thread once I get them installed and measured.

Comments on any of my graphs/room would be gratefully received and as to whether or not the addition of these additional subs will be of ANY acoustic value to the reduction of the LF decay, ignoring the obvious benefits to LF headroom and possibly flatter LF response, neither of which I am looking for.

If any additional graphs etc. are needed to help with any comments/analysis please let me know.

One final comment; what is very noticeable regarding the “hard” upper vocal register is that it very rarely reveals itself on high bit rate stereo or multi-channel DVDA, SACD or Blu Ray recordings but is very prevalent on many stereo 16 bit 44.1K CD’s. It does not matter whether I am using analog, HDMI or DL3/4 for the connection. It is almost as if during the mastering process they are compressing and pushing forward the upper mid-range. It does however become less noticable on these CD’s if I disable Audyssey but then the room doesn’t sound as pleasing.
post #6796 of 9585
Paul, I don't think you can improve <40Hz without major structural changes. You could experiment with Helmholtz absorbers though.
post #6797 of 9585
I did some measurements of FL/R only and noticed something I can't explain. I'm hoping that someone else can tell me what's going on here.

This graph is my FL/R speakers only, 1/6 smoothing, Audyssey off, crossover at 80hz. Why am I getting any significant output from my FL/R speakers below 80hz, specifically that giant spike around 34hz??


post #6798 of 9585
Jkasonic, I certainly didn't mean to incite any further and i understand what you are saying with the cart before the horse smile.gif

As far as cross posting. I don't think there is anything wrong if let's say I develop a great graph and then share it with the Submersive guys as well to show what that amazing sub is doing. Anyway, more thought out approach in the future smile.gif
post #6799 of 9585
Quote:
Originally Posted by kbarnes701 View Post

I saw jlp's now-deleted post and as it was directed at me, I have a couple of observations. First off, Joe, I agree entirely with your post above.

Second, @jlp, I think you will agree that it is up to any individual whether they choose to reply to a post of not. There is no implied right of a response in these threads, and if someone chooses not to respond for any reason at all, then it is his right. In my own case, I have chosen not to respond to people who repeatedly post graphs that are not to the agreed standard or illegible and I came to this conclusion for the reasons I gave before. Others will have a different opinion and may well decide to reply, asking continually for the agreed standards to be adhered to. I just got fed up with it - Jerry has gone to great lengths to produce a wonderful guide and we always ask everyone to read it and to adhere to the standards for presentation of graphs. It has become, if you like, a de facto 'thread rule'. Many threads have such rules.

I did specifically say, jlp, that I was NOT singling you out when I made my comments, and I am not. And, of course, I will continue to try to assist you wherever I can, but what I won't do is spend time trying to figure out graphs that are presented to all manner of different parameters. It's my personal choice and it is not the official standpoint of the thread in any way, as I think I made clear.  It isn’t hard to read the Guide and to make sure that the parameters of the posted graphs comply - most of the settings are 'sticky' in REW so once set they apply to all graphs subsequently produced. This is not a vendetta against you, jlp - just a choice of my own.

I understand why much more now than 48 hours ago. I won't post anymore on this to take up thread space. I will create a sticky note on my desktop with correct graph parameters. Once again I admit my mistakes and try and move forward smile.gif. More thought before posting smile.gif
post #6800 of 9585
Quote:
Originally Posted by Alan P View Post

I did some measurements of FL/R only and noticed something I can't explain. I'm hoping that someone else can tell me what's going on here.

This graph is my FL/R speakers only, 1/6 smoothing, Audyssey off, crossover at 80hz. Why am I getting any significant output from my FL/R speakers below 80hz, specifically that giant spike around 34hz??

Well, a typical filter looks like this:



The peak is probably caused by the room. By the way, more interesting is the dip at 60Hz.
post #6801 of 9585
Quote:
Originally Posted by jlpowell84 View Post

Jkasonic, I certainly didn't mean to incite any further and i understand what you are saying with the cart before the horse smile.gif

As far as cross posting. I don't think there is anything wrong if let's say I develop a great graph and then share it with the Submersive guys as well to show what that amazing sub is doing. Anyway, more thought out approach in the future smile.gif

 

No problem...all is forgotten so let's move onto the gubbins!  I'm in the process now of designing my soffits so I'll be interested to see what you come up with in your room!

post #6802 of 9585
Quote:
Originally Posted by markus767 View Post

Paul, I don't think you can improve <40Hz without major structural changes. You could experiment with Helmholtz absorbers though.

Markus,

I had a horrible feeling that would be the case. When I get a little more spare time I will build a couple and see if I can improve things. I will however try the additional subs as SVS has a very generous return policy if they don't improve things or make them worse.

Any advice or comments on the waterfalls or ETC?
post #6803 of 9585
Quote:
Originally Posted by jkasanic View Post
 
Quote:
Originally Posted by kbarnes701 View Post
 
Quote:
Originally Posted by sdrucker View Post

Consider this crazy kid, who (as I teased him in a PM) once said last summer:
"That's the bit I don't get. I am sure that most enthusiasts are aware of the need to optimism sub location and the room itself - if possible - before using an electronic EQ like Audyssey. Finding the best place in the room for the sub is fairly easy if you have only one sub and not all that difficult if you have two subs and some sort of measuring gear. There's no need to understand the theory behind it to get a good result any more than I need to know the theory behind cellular communication technology to make a phone call. And wrt to traps and treatments, there are plenty of sites that offer all sorts of advice and help. I just can't see what benefits I would gain by doing all this measuring and graphing over and above what I have already done. I have extremely limited options in my room for sub placement and treatments anyway - as do many others - so knowing that a series of measurements shows that my subs should be elsewhere frustrates rather than illuminates."

That was a few tuned membrane traps ago...biggrin.gif
 

 

Crazy is right. How could anyone think that??

Unless I'm mistaken, the bolded 'bits' tipped your hand as to the identity of the 'crazy kid'...and if that wasn't enough, then the reply sealed the deal AFAIAC! :D

 

I find it hard to believe anyone would take such a Luddite attitude TBH ;)

post #6804 of 9585
Quote:
Originally Posted by kbarnes701 View Post

I find it hard to believe anyone would take such a Luddite attitude TBH wink.gif

Six more months on this thread and you may lose the smiley emoticon...we're moving into less well-lit regions of the rabbit hole...
post #6805 of 9585
Quote:
Originally Posted by Alan P View Post

I did some measurements of FL/R only and noticed something I can't explain. I'm hoping that someone else can tell me what's going on here.

This graph is my FL/R speakers only, 1/6 smoothing, Audyssey off, crossover at 80hz. Why am I getting any significant output from my FL/R speakers below 80hz, specifically that giant spike around 34hz??


 

Do you have a graph of the front R and front L playing on their own, instead of as a pair?  I'd be more concerned about that huge and wide dip centred on 300Hz TBH. What does the graph look like when you add th sub(s)?

post #6806 of 9585
Quote:
Originally Posted by Digione View Post

The graphs below show the rooms’ current overall response.


Current Frequency Response

I originally introduced the “suck out” between 500Hz and 3.5 KHz using Pro in order to compensate for the overly bright response, it also includes the Audyssey crossover correction. I have no idea where the 322Hz dip came from but once the rear ceiling 2D Skyline diffusers are mounted I will re-run the full Audyssey EQ and re-publish.

The LF response 15Hz to 300Hz is flat enough for me and I have no desire to improve it. However I hope that when I re-run Audyssey and remove my Pro EQ the remainder of the response will match it.


Current Waterfall 1 – 15-20Khz (1/6 octave smoothing)


Current Waterfall 2 – 15-200Hz (1/48 octave smoothing)

I do not usually use data much below 60dB as the mic pre-amp LF noise floor is too high there (see my link), and below 32Hz most people’s threshold of hearing cannot detect that level. I will try to tame the response slightly at 27 Hz using Pro, hopefully that will pull the 27Hz decay back a little to.


Current Spectrogram

The Spectrogam seems to confirm the waterfall showing a maximum decay time of 450 mS for a 40dB decay for frequencies below 40Hz. There are no irregular decay patterns above this frequency. If the group delay of the subs, shown below, is taken into account then most of the LF decay relative to its peak is within 400mS.

Comments on any of my graphs/room would be gratefully received and as to whether or not the addition of these additional subs will be of ANY acoustic value to the reduction of the LF decay, ignoring the obvious benefits to LF headroom and possibly flatter LF response, neither of which I am looking for.

 

Welcome Digione and congrats on what appears to be a very nice room design both aesthetically and acoustically!  It's nice to see a build where acoustics is being tackled with objective measurements and balanced against what you are actually hearing in the room.

 

I think I speak for most here when I say that your bass decay/waterfalls are some of the best we've seen and you've obviously done a great job to control ringing.  HST, I think it's tough to predict what effect if any the changes you proposed will have on the sub 40Hz response/decay.  Seems to be an area where LOTS of pink fluffy is required or something more targeted to a specific frequency (e.g. Helmholz as Markus already suggested or dare I mention Scopus Traps :eek:).  In any case, please keep us posted with your results, one way or the other!


Edited by jkasanic - 11/13/13 at 11:34am
post #6807 of 9585
Quote:
Originally Posted by sdrucker View Post
 
Quote:
Originally Posted by kbarnes701 View Post

I find it hard to believe anyone would take such a Luddite attitude TBH wink.gif

Six more months on this thread and you may lose the smiley emoticon...we're moving into less well-lit regions of the rabbit hole...

 

TBH I don't see how I can do much more in this room..... ;)

post #6808 of 9585


Given the recent focus on Spectrograms, thought id show a view of what they look like from an Omnimic point of view.



"/width/1000/height/2000[/IMG]"

On another note, if you need your images bigger than the typical 500x1000 option allows, you can go into edit mode and change width and height values and resubmit to make it larger (see bolded).
post #6809 of 9585
Quote:
Originally Posted by jkasanic View Post

Welcome Digione and congrats on what appears to be a very nice room design both aesthetically and acoustically!  It's nice to see a build where acoustics is being tackled with objective measurements and balanced against what you are actually hearing in the room.

I think I speak for most here when I say that your bass decay/waterfalls are some of the best we've seen and you've obviously done a great job to control ringing.  HST, I think it's tough to predict what effect if any the changes you proposed will have on the sub 40Hz response/decay.  Seems to be an area where LOTS of pink fluffy is required or something more targeted to a specific frequency (e.g. Helmholz as Markus already suggested or dare I mention Scopus Traps eek.gif).  In any case, please keep us posted with your results, one way or the other!

Thank you for the compliment. I spent a LOT of time doing the acoustic modeling of the room including the design of the electronic, power and grounding systems. However, as you can see I didn't predict the floor primary reflection as being a problem. eek.gif

It's just a never ending process, funds, time and wife permitting. As soon as I have installed the rear 2D diffusers and fixed the floor refection's I will re-run the entire Audyssey process and post the results. Hopefully I will be able to accomplish this while I have the rear subs to see if they are worth keeping.

If I go with the resonators I will design and build them myself, its a lot less expensive. Originally I designed the room with panel membrane absorbers and even though they all seemed to "perform" as expected I just didn't have enough area to support their deployment so I resorted to a particular design of " bass trap" that I have used on a much larger scale in several control rooms and studios that I have built. They take up a lot of room but seem to be quite effective and broad band.
post #6810 of 9585
Quote:
Originally Posted by kbarnes701 View Post

Do you have a graph of the front R and front L playing on their own, instead of as a pair?  I'd be more concerned about that huge and wide dip centred on 300Hz TBH. What does the graph look like when you add th sub(s)?

I don't have a graph saved of each front, but I did run them - looks pretty much the same as the combined response.

That huge dip at 300hz is what it is - not getting a new room or new mains anytime soon...but, Audyssey does a fairly good job of flattening it out.

When I add the subs, the low end of course flattens out, but I have a pretty good hump (and excessive ringing) centered around 30hz which I'm guessing is a combination of my room and the extra output of my mains ~30hz.

Any idea why I would be getting such significant output below the XO? I'm assuming the one to blame would be my AVR...
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