R/E/P Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 [2]  All   Go Down

Author Topic: huge nul at 70hz and 250hz  (Read 5438 times)

brett

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1114
Re: huge nul at 70hz and 250hz
« Reply #15 on: December 04, 2008, 03:39:00 pm »

Ethan Winer wrote on Thu, 04 December 2008 17:00

brett wrote on Wed, 03 December 2008 18:56

I said front wall ceiling? Is that what you meant too?


Sorry, I must have been on crack, I have no explanation for this.  Very Happy

In the grand scheme of things, it's not possible to have too much bass trapping in a room this size. You could line every single surface with 705 two feet thick and it still won't be perfectly flat. (Though you'd get pretty close!)

Quote:

I read on RPG's web site, no matter how thick you go there isbn't enough air movement in the corners to absorb the energy using fiber panels at these freq. And tuned is the only way to do it. Your thoughts?


I would not used tuned absorption in a room that size. Tuned traps are also more expensive and much more difficult to implement. The main problems you have are due to close proximity to the room boundaries. This means that small changes in placement - loudspeakers, instruments, your ears - changes the frequencies of the peaks and nulls. This is why you need broadband absorption more than tuned. The problem is not one low frequency that can be targeted, but many low frequencies.

--Ethan


true ethan, I have a very small sweet spot and usually use just one ear to hear it when making critical balance changes. I appreciate your input, but to deal with these low modal issues broadband absorbtion only would need to be much thicker than I have space to afford.  
Logged

Thomas Jouanjean

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 342
Re: huge nul at 70hz and 250hz
« Reply #16 on: December 06, 2008, 05:26:09 am »

Got any pics or detailed drawings (elevated and cut views) of your room?
Logged
Thomas Jouanjean
Northward Acoustics - Engineering and Designs
http://www.northwardacoustics.com
http://www.facebook.com/pages/Northward-Acoustics/1062876633 71

Pro Audio Partners:
ATC Loudspeakers
FOCAL Professional Speakers

brett

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1114
Re: huge nul at 70hz and 250hz
« Reply #17 on: December 06, 2008, 04:03:48 pm »

I can do a google shetchup in a few days if I need to but here is a floor diagram. thanks for taking a look.
index.php/fa/10613/0/
Logged

brett

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1114
Re: huge nul at 70hz and 250hz
« Reply #18 on: December 11, 2008, 04:44:48 pm »

thought I would bump this. No one wanted to take a stab at the tuned trap question.

I found plenty of info on tunning a helmhotz and even found a calculator. Have read ethans stuff on it as well but found no detailed instructions on calculatiing volume and membrane density thickness etc and how dense to fill the device with insulation. If you know of a DIY web site or book on how to create and tune these I would apreciate your help.

I am not looking to tune the entire room. meaning, not looking to have a perefectly balanced space, but rather employ some strategicly placed tuned traps to deal with the 70-80hz null at my mix position without having to employ eq's which add other issues with headroom and phase.

2' thick broad band in my room is not an option. Trying to avoid spending thousands on RPG modex devices.
Logged

andrebrito

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 60
Re: huge nul at 70hz and 250hz
« Reply #19 on: December 11, 2008, 06:14:46 pm »

problem with those calculators is that they dont work.. they may give you and idea but you actually need to go trial and error.

Quote:

I read on RPG's web site, no matter how thick you go there isbn't enough air movement in the corners to absorb the energy using fiber panels at these freq. And tuned is the only way to do it. Your thoughts?


Where is that written in the RPG site ?
Logged
--------------
Acoustician and Musician

http://www.onlineacoustics.com - Projects and Products (RGP and Green Glue)

http://www.sonicflames.com - my crazy label

brett

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1114
Re: huge nul at 70hz and 250hz
« Reply #20 on: December 11, 2008, 07:09:12 pm »

http://www.silentsource.com/diffusors-modex-plate.html

it is stated by the resellers

"Porous surface absorption is ineffective at these modal frequencies, because the air motion near walls and in corners is essentially zero , resulting in very low absorption efficiency. RPG developed its Modex™ line to address these problems..."

but it is also in the RPG  product material for the modex plate

http://www.rpginc.com/products/modexplate/Modex-Plate.pdf
Logged

Thomas Jouanjean

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 342
Re: huge nul at 70hz and 250hz
« Reply #21 on: December 12, 2008, 12:46:24 pm »

Brett,

I'll try and help in the next few days - it's been a crazy week here.

Hang in there Smile
Logged
Thomas Jouanjean
Northward Acoustics - Engineering and Designs
http://www.northwardacoustics.com
http://www.facebook.com/pages/Northward-Acoustics/1062876633 71

Pro Audio Partners:
ATC Loudspeakers
FOCAL Professional Speakers

brett

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1114
Re: huge nul at 70hz and 250hz
« Reply #22 on: December 12, 2008, 02:16:16 pm »

Thomas take your time, I am going to have to wait until after new years to build or buy anything.

Regards,
Brett
Logged
Pages: 1 [2]  All   Go Up