Author Topic: Room measurements - done!  (Read 2426 times)

Offline flemo

  • Sr. Member
  • ****
  • Posts: 469
Room measurements - done!
« on: September 20, 2012, 07:22:59 PM »
Okay folks, well I have had my room measured and here's the results:

"Analysis of cumulative spectrum decay plots was performed with time domain slice and amplitude scaling to reveal primary room mode resonances.

Calculation of raw room modes was performed to derive basic room mode data and this was compared with the initial listening tests, and the cumulative spectral decay analysis.

There is an impression of LF bloom in the room and this was previously estimated to be dominant in the region of 60Hz.

Room mode calculations suggest likely modal resonances to be as follows:
Dominant primary mode = tangential at 56.6 Hz
Secondary mode = axial at 44 Hz
Note: Raw mode calculations assume an empty room, so the actual room response will be affected by furniture and surface treatments.

Cumulative spectral decay (waterfall plot) analysis shows the following as measured at the listening position:
Dominant primary mode = at 57.5 Hz
Secondary = at 61 Hz
Tertiary = 43 Hz

Additional resonances are noted around 205 Hz and 272 Hz which are likely to be functions of surface reflections and/or cavity resonances in portions of the oddly shaped room.

There is a good correlation between perceived sound, the calculated modal resonances and the measured data."

All this means very little to me but I am just waiting for my acoustic absorbers to be purpose designed and then I can build them.

I do have the waterfall plots but don't have a effing clue how to attach them to the thread!  I can email them and maybe somebody else can upload them.  ???

cheers, Pete.



   

Offline kajak12

  • Hero Member
  • *****
  • Posts: 2411
    • http://killerdac.com/forum/index.php
Re: Room measurements - done!
« Reply #1 on: September 20, 2012, 09:13:12 PM »
email me flemo
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline kajak12

  • Hero Member
  • *****
  • Posts: 2411
    • http://killerdac.com/forum/index.php
Re: Room measurements - done!
« Reply #2 on: September 20, 2012, 10:59:56 PM »



Figure 1.  listening position primary resonance 57.5 Hz
Band limited 20 Hz - 2000Hz
Time slices to 300 ms.



Figure 2 - view 1.
listening position secondary resonance 61 Hz
Band limited 20 Hz - 2000Hz
Time slices to 300 ms.
« Last Edit: September 20, 2012, 11:14:32 PM by kajak12 »
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline kajak12

  • Hero Member
  • *****
  • Posts: 2411
    • http://killerdac.com/forum/index.php
Re: Room measurements - done!
« Reply #3 on: September 20, 2012, 11:02:15 PM »


« Last Edit: September 20, 2012, 11:03:58 PM by kajak12 »
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline kajak12

  • Hero Member
  • *****
  • Posts: 2411
    • http://killerdac.com/forum/index.php
Re: Room measurements - done!
« Reply #4 on: September 20, 2012, 11:02:51 PM »




Figure 3 - view 1.
listening position tertiary resonance 43 Hz
Band limited 20 Hz - 2000Hz
Time slices to 300 ms.
« Last Edit: September 20, 2012, 11:16:54 PM by kajak12 »
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline Braddles

  • Newbie
  • *
  • Posts: 39
Re: Room measurements - done!
« Reply #5 on: September 21, 2012, 05:59:46 PM »
How did you get this organised Pete and how much did it cost?

Offline flemo

  • Sr. Member
  • ****
  • Posts: 469
Re: Room measurements - done!
« Reply #6 on: September 21, 2012, 11:24:22 PM »
  How did you get this organised Pete and how much did it cost?

Hi Brad,

My techie did it for me (at mates rates).  I discovered he has a very large involvement in professional sound studios and equipment. 

I can pm his details if you wish?

Pete

Offline Paul Spencer

  • Full Member
  • ***
  • Posts: 111
Re: Room measurements - done!
« Reply #7 on: November 16, 2012, 10:43:48 AM »
Looks like he used a Mac with Fuzz Measure. Unfortunately, for some reason waterfalls done with Fuzz are always a bit fuzzy and hard to read. The results appear buried in the noise floor, but having said that you can see clear room modes still. Did he explain the results and what to do with them?

That measurement is showing the bass running quite hot, elevated above the midrange.

You have quite a few modes in the middle of the bass range, meaning all bass notes will be strongly dominated by the room. Since they are spread all over the bass range, they are indicating that you need broadband absorption, unfortunately bad news as that means the bigggest kind of traps to fully fix the decay issues. If you have a few modes that have some space between them, then you can get narrow band traps made up that are less obtrusive. But if you have modes all over the place, then you need resistive traps. Kind of like a room full of zombies coming after you - you pull out the machine gun rather than the shot gun to get one at a time.


Offline flemo

  • Sr. Member
  • ****
  • Posts: 469
Re: Room measurements - done!
« Reply #8 on: November 16, 2012, 10:53:15 PM »
Looks like he used a Mac with Fuzz Measure. Unfortunately, for some reason waterfalls done with Fuzz are always a bit fuzzy and hard to read. The results appear buried in the noise floor, but having said that you can see clear room modes still. Did he explain the results and what to do with them?

That measurement is showing the bass running quite hot, elevated above the midrange.

You have quite a few modes in the middle of the bass range, meaning all bass notes will be strongly dominated by the room. Since they are spread all over the bass range, they are indicating that you need broadband absorption, unfortunately bad news as that means the bigggest kind of traps to fully fix the decay issues. If you have a few modes that have some space between them, then you can get narrow band traps made up that are less obtrusive. But if you have modes all over the place, then you need resistive traps. Kind of like a room full of zombies coming after you - you pull out the machine gun rather than the shot gun to get one at a time. 

Hi Paul

I cautioned him about going nuts with treatments and only wanted to treat the room in stages, starting with the most obvious and worst aspect which is the 58hz hump.  He designed me some 60hz Helmholtz absorbers as a starting point.

But since then, my system has come along leaps and bounds and the bass issues which really concerned me are no longer a significant problem. 

I had many people suggesting the room was the cause of the problem, and to a point it was, and still is.  But having optimised the system and being very delighted with the way its running I am not as motivated to treat the room.  My system produces phenomenal, clean, tight, dynamic bass.  The system has attack and pace without harshness or fatigue.  I find it quite outstanding in fact, and haven't heard anything like it before. 

I will build the absorbers in the near future because I don't think I have anything to lose, and who knows it may just take the system up another level, or two??

Cheers, Pete.
 

 

Offline kajak12

  • Hero Member
  • *****
  • Posts: 2411
    • http://killerdac.com/forum/index.php
Re: Room measurements - done!
« Reply #9 on: November 16, 2012, 11:35:56 PM »
Looks like he used a Mac with Fuzz Measure. Unfortunately, for some reason waterfalls done with Fuzz are always a bit fuzzy and hard to read. The results appear buried in the noise floor, but having said that you can see clear room modes still. Did he explain the results and what to do with them?

That measurement is showing the bass running quite hot, elevated above the midrange.

You have quite a few modes in the middle of the bass range, meaning all bass notes will be strongly dominated by the room. Since they are spread all over the bass range, they are indicating that you need broadband absorption, unfortunately bad news as that means the bigggest kind of traps to fully fix the decay issues. If you have a few modes that have some space between them, then you can get narrow band traps made up that are less obtrusive. But if you have modes all over the place, then you need resistive traps. Kind of like a room full of zombies coming after you - you pull out the machine gun rather than the shot gun to get one at a time.  


Hi Paul

I cautioned him about going nuts with treatments and only wanted to treat the room in stages, starting with the most obvious and worst aspect which is the 58hz hump.  He designed me some 60hz Helmholtz absorbers as a starting point.

But since then, my system has come along leaps and bounds and the bass issues which really concerned me are no longer a significant problem.  

I had many people suggesting the room was the cause of the problem, and to a point it was, and still is.  But having optimised the system and being very delighted with the way its running I am not as motivated to treat the room.  My system produces phenomenal, clean, tight, dynamic bass.  The system has attack and pace without harshness or fatigue.  I find it quite outstanding in fact, and haven't heard anything like it before.  

I will build the absorbers in the near future because I don't think I have anything to lose, and who knows it may just take the system up another level, or two??

Cheers, Pete.
 
Placebo oh sorry the right kind of amp :P
still discovering the link between electronics and audio reproduction.so much to learn and so little time