avatar

luc

Tin Man

Posts: 32 Member Since: 04/02/2011

Lead

Jan 31 14 10:44 AM

Tags : :

greetings prw

we need to adress certain room modes in our controllroom, around 32 hz and 64 hz. we do have two quite big bumps there. the guy doing the measuring told us about the e-trap, http://www.bagend.com/ETrap.htm

do any of you have experience with these or similar devices?

any input is appreciated!
thank you

luc
Quote    Reply   
avatar

maarvold

Aqua Marine

Posts: 2,936 Member Since:23/01/2011

#1 [url]

Jan 31 14 11:39 PM

I scanned the webpage, but didn't read every word.  It seems like a variation of an idea that's become somewhat popular in Germany where you mount a mirror image of your front wall-mounted subs on the rear wall.  Then you phase flop the rear wall, delay the output to it by the travel time of the front wall's wave and the rear wall 'sucks up' the low end produced by the front wall so you only [theoretically] hear it once.  Seems like it should work to some extent at least.  I remember one of the more credible audiophile reviewers--Anthony Cordesman--raving about the performance of a Bag End sub system; it impressed me so much, I based my own dual sub setup on their concept.  Meaning that their removal device is probably also good (imo).  

Quote    Reply   
avatar

luc

Tin Man

Posts: 32 Member Since:04/02/2011

#2 [url]

Feb 2 14 9:23 AM

cheers maarvold, thanks for your reply. doesn't seem to be too popular in the "room-building-guild" :-)

we might give it a try, i'll report back!

luc

Quote    Reply   
avatar

achaiss

Tin Man

Posts: 11 Member Since:13/11/2012

#3 [url]

Feb 3 14 7:08 AM

Walter Storyk uses this one in critical cases and for the last solution when space does not allow huge acoustic bass treatment.
It's always a compromise. It's quite expensive.
If you have space, for the price... DIY acoustic treatment.

Quote    Reply   
avatar

maarvold

Aqua Marine

Posts: 2,936 Member Since:23/01/2011

#4 [url]

Feb 3 14 11:59 PM

achaiss wrote:

If you have space, for the price... DIY acoustic treatment.

I use digital room correction in my room.  The better I got the physical room treatment, the better everything sounded--I think because the room correction had to do less and in a less radical way.  It's probably good advice to try to treat in a physical way first.  There's a forum topic about VPR low frequency absorbers--might be worth exploring that.  Or maybe RPG Modex Plates (I think they're pretty similar).  

http://prorecordingworkshop.lefora.com/topic/19395482/Delving-deeper-into-Fraunhofers-VPR#.UvBzlRb0SFU
http://www.rpginc.com/ProductDocs/MDXP_Modex%20Plate/Modex%20Plate_2%20Page%20Brochure.pdf

Quote    Reply   
avatar

luc

Tin Man

Posts: 32 Member Since:04/02/2011

#5 [url]

Feb 4 14 6:52 AM

thank you both! our room was designed by WSDGe (for europe). and room unfortunatly is an issue!

we'll discuss everything, and i'll report back what route we chose!

thanks again
luc

Quote    Reply   
avatar

achaiss

Tin Man

Posts: 11 Member Since:13/11/2012

#6 [url]

Feb 5 14 6:33 AM

the room is an issue with a WSDGe design ???!!!
What is the issue? low end?

WSDGe are real professionals, if you have an issue they probably can work on it and fix it (if the space in your room and your budget allow it of course).
If WSDGe ask you to use an Etrap, it's probably because they can't fix a big modal problem in the low end and your room is small.

Am I wrong?
Good luck.

Quote    Reply   
avatar

luc

Tin Man

Posts: 32 Member Since:04/02/2011

#7 [url]

Feb 15 14 1:20 PM

yes, its a wsdge design. it's not a life and death situation, the room sounds great, but we do have 2 modes which we want to address!

Quote    Reply   
avatar

mauriciogargel

Tin Man

Posts: 25 Member Since:19/09/2013

#8 [url]

Oct 3 15 10:13 AM

I ve been playing with an etrap and it works.
The attached picture shows (in red) the room response with the etrap and (in blue) without. I was able to dial the response of two frequencies (30 and 53Hz).
Unfortunately the 60 Hz bump is physically located in another place in the room and I was not able to attack that one. Would need another etrap for that.image

Quote    Reply   
avatar

John Eppstein

Platinum Blonde

Posts: 1,150 Member Since:31/05/2015

#9 [url]

Oct 3 15 4:17 PM

I saw them at AES a few years back. Each unit can only cover 2 modes but that sounds like what you need. They're quite compact and the principle is sound, (Pun unintended)

I'd been interested in that principle back in the late '70s/early 80s for noise suppression systems but couldn't raise the capital investment to follow through on the idea.

Quote    Reply   
avatar

John Eppstein

Platinum Blonde

Posts: 1,150 Member Since:31/05/2015

#11 [url]

Oct 6 15 4:53 AM

maarvold wrote:

achaiss wrote:

If you have space, for the price... DIY acoustic treatment.

I use digital room correction in my room.  The better I got the physical room treatment, the better everything sounded--I think because the room correction had to do less and in a less radical way.  It's probably good advice to try to treat in a physical way first.  There's a forum topic about VPR low frequency absorbers--might be worth exploring that.  Or maybe RPG Modex Plates (I think they're pretty similar).  

http://prorecordingworkshop.lefora.com/topic/19395482/Delving-deeper-into-Fraunhofers-VPR#.UvBzlRb0SFU
http://www.rpginc.com/ProductDocs/MDXP_Modex%20Plate/Modex%20Plate_2%20Page%20Brochure.pdf

I'm not convinced that "digital room correction" has much, if anything to do with active bass trap technology. To start, does this "digital room correction incorporate an active, always on microphone t sense what's going on with the room modes?

Quote    Reply   
avatar

thomas northward

Silverado

Posts: 138 Member Since:10/02/2011

#12 [url]

Oct 6 15 5:50 AM

luc wrote:
thank you both! our room was designed by WSDGe (for europe). and room unfortunatly is an issue!

we'll discuss everything, and i'll report back what route we chose!

thanks again
luc

Aren't they supposed to fix that problem for you?

When your new car has issues, there's a guarantee.

Quote    Reply   
avatar

maarvold

Aqua Marine

Posts: 2,936 Member Since:23/01/2011

#13 [url]

Oct 8 15 9:16 AM

John Eppstein wrote:

maarvold wrote:

achaiss wrote:

If you have space, for the price... DIY acoustic treatment.

I use digital room correction in my room.  The better I got the physical room treatment, the better everything sounded--I think because the room correction had to do less and in a less radical way.  It's probably good advice to try to treat in a physical way first.  There's a forum topic about VPR low frequency absorbers--might be worth exploring that.  Or maybe RPG Modex Plates (I think they're pretty similar).  

http://prorecordingworkshop.lefora.com/topic/19395482/Delving-deeper-into-Fraunhofers-VPR#.UvBzlRb0SFU
http://www.rpginc.com/ProductDocs/MDXP_Modex%20Plate/Modex%20Plate_2%20Page%20Brochure.pdf

I'm not convinced that "digital room correction" has much, if anything to do with active bass trap technology. To start, does this "digital room correction incorporate an active, always on microphone t sense what's going on with the room modes?

Wow--I posted that in the beginning of February--maybe my point was that this is a different way to apply a subtractive process to deal with low end problems.  So, without rereading the description of the unit, I will at least say this: my advice is to solve the low end problems by any means necessary; in the months and years after you have done this, I predict you will look back and think, "I'm really glad I did that".  

Quote    Reply   
avatar

ericb

Gold Finger

Posts: 663 Member Since:01/02/2011

#14 [url]

Oct 8 15 12:03 PM

I've been considering activated carbon diaphragmatic low frequency absorbers from Acoustic Fields. Any experiences with these?

http://www.acousticfields.com/product/acda-12-activated-carbon-diaphragmatic-absorber/

Quite heavy, but they don't take up a lot of space, considering what is being attempted. 32Hz and even 64Hz are into some long, challenging wavelengths.

Might be worth a look if the eTrap doesn't pan out.

Quote    Reply   
avatar

zmix

Aqua Marine

Posts: 3,893 Member Since:20/01/2011

#18 [url]

Nov 18 16 10:11 AM

ruairi wrote:
zmix wrote:
Yes, my pal Barry Rudolph has a pair in his room, and has run some tests, I've examined the test data and the waterfall plot is impressive.

http://w.barryrudolph.com/mix/psi_audio_avaa_c20.html


Chuck,

Can you describe what it is that you are seeing that's impressive?

Cheers,
Ruairi

 
I downloaded his REW data and the waterfall response showed a dramatic decrease in LF resonance.  That is the only meaningful measurement in acoustical treatment.



Quote    Reply   
avatar

maarvold

Aqua Marine

Posts: 2,936 Member Since:23/01/2011

#19 [url]

Dec 10 16 11:07 AM

Although I treated the low end problems in my room in a different way, Barry Rudolph's comments mirror how I feel about the results of fixing the bottom end reproduction problems:

"I arrive at a mixes faster with much less of a struggle to get the low and low midrange frequencies correct for bass, kick and drum sounds. Mixes translate even better now..."

Quote    Reply   
Add Reply

Quick Reply

bbcode help