Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multiple subs vs. bass traps
Multiple subs vs. bass traps
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th December 2015, 07:58 PM   #11
youknowyou is offline youknowyou  Canada
diyAudio Member
 
youknowyou's Avatar
 
Join Date: Jun 2014
Quote:
Originally Posted by djn View Post
So is it correct to say multiple subwoofers level sub signals around the room and traps reduce decay time?

Are the end results the same?
Subwoofer may very well ''smooth the FR'', but any Professional acoustician will tell you that the FR is much less important the the ETC response. You need to reduce decay time in LF and thats where bass traps cannot be replaced by subwoofers. the only way to reduce decay time is by absorbing the LF bouncing around the room.

Earl method of adding multiple subs may very well help for comb filtering, but id personally like to see the ETC. Low Freq must be absorbed and without bass traps, it seems that adding subwoofer will help the FR response but the ETC will show a very different story. Bass traps is absolutely necessary to reduce decay and since you have many subwoofer, bass traps is even more critical.
it seem that while smoothing the FR, earl method (multiple subwoofer) do not address decay time. I know that acoustician find ETC much more informative about the room response then the FR especially in LF

Do you have the ETC measurements at the listening position?

In any room, you must have as low decay time below the Schroeder area as the rest of the frequency range. Basically, you need many bass traps no matter the room if you want to have even decay across the frequency range. This is where most hobbyist give up but theres no replacement for absorption of LF.

If you want to build bass traps, go to gearslutz in the studio forums. many pro will tell you how to build ect. I suggest to front the bass traps with FRK to not make your space to ''dead''. I recommend to use safe n sound and try to make them as thick as possible, ideally at least 14 inch thick and the thicker the better.
__________________
Dad's speakers: Amphion one18/ Genelec 1037b/ ESL57/ Altec604/ Tannoy RED 15 inch/
Mine: Harbeth SHL5+

Last edited by youknowyou; 27th December 2015 at 08:18 PM.
  Reply With Quote
Old 27th December 2015, 08:01 PM   #12
youknowyou is offline youknowyou  Canada
diyAudio Member
 
youknowyou's Avatar
 
Join Date: Jun 2014
Quote:
Originally Posted by chris661 View Post
By exciting the room more evenly, the multiple distributed subs approach means you ought to end up with a flat LF response anywhere in the room.

I don't know much about LF room treatment, but would guess the aim is similar. I do know that absorbers have to be huge to be effective at LF. Of the two, I'd probably go for multiple subs.

Chris
yes Broadband bass traps needs to be huge. you can however built pressure based bass traps which takes less place.

Acheiving a flat LF response is far from resolving bass problems in a room. the ETC is as important and many will say that its even more important the Flat response.

More subwoofer means more LF resonance bouncing in the room. Resonance needs to be absorbed via absorption.
I also highly recommend treating the first reflection points.
__________________
Dad's speakers: Amphion one18/ Genelec 1037b/ ESL57/ Altec604/ Tannoy RED 15 inch/
Mine: Harbeth SHL5+

Last edited by youknowyou; 27th December 2015 at 08:20 PM.
  Reply With Quote
Old 27th December 2015, 10:26 PM   #13
djn is offline djn  United States
diyAudio Member
 
djn's Avatar
 
Join Date: Oct 2004
Location: Albuquerque, New Mexico
Thanks You. Looks like we may be moving so and I want to get a house with a dedicated room so I am in the planning stage.

I Google "ETC response" but could not find anything audio related.
  Reply With Quote
Old 27th December 2015, 10:43 PM   #14
youknowyou is offline youknowyou  Canada
diyAudio Member
 
youknowyou's Avatar
 
Join Date: Jun 2014
Quote:
Originally Posted by djn View Post
Thanks You. Looks like we may be moving so and I want to get a house with a dedicated room so I am in the planning stage.

I Google "ETC response" but could not find anything audio related.
ETC is the waterfalls graph that show your decay times: http://www.gikacoustics.com/understanding-decay-times/ the aim is to have even decay times across all the frequency range: within -10db to -15db at 15ms ideally.

You also have to spend the time to find you ideal listening position and speaker placement http://www.gikacoustics.com/monitor-positioning/. You also should read about rooms modes. http://www.gikacoustics.com/what-are-room-modes/

To find your ideal listening position, the 38% rule is a good starting point and it really helps for the bass response.
''
THE 38 PERCENT RULE
The placement method used here is based on the "38 percent rule" which theorizes that the best listening position is 38 percent into the length of the room, when measured from either the front or rear wall. This offers the best compromise of peaks versus nulls for any given room size. For 2-channel listening you'll get the flattest low frequency response by sitting 38 percent of the way back from the front wall. However, this is not practical in many home theaters, especially those with large screens, because that puts you too close to the screen. Fortunately, you can get the same benefit by sitting 38 percent of the room length when measured from the rear wall.
Please understand that 38% is one theoretical best location to begin measurements, but it may not end up the best place to sit due to other factors - wall properties, speaker location, speaker type, furnishings in the room, and a host of other conditions that can affect frequency response. The only way to know which location really is flattest is to measure the low frequency response at high resolution as explained in our Room Measuring Primer article.
Once you know the ideal listening position from the front or rear wall, the next step is to place the loudspeakers. The speakers and listening position should be at the points of an equilateral triangle, as shown in Figures 1 and 2. Again, loudspeakers should be aimed at the listener's head in the prime seat. Note that the theoretical point of the triangle is just behind your head, with the axis lines grazing your ears.
If you have suitable software, or the RealTraps Test Tone CD, or another way to accurately measure your room's low frequency response, you can experiment with different speaker distances by sliding both speakers along each axis while you measure the response. Otherwise, put them along the axis at a distance that is convenient and makes sense for the size and layout of your room. Too often people obsess over minute details that matter only a little, while ignoring ergonomic concerns that matter much more.''
http://realtraps.com/art_room-setup.htm


here's more information
https://www.gearslutz.com/board/8206233-post13.html
https://www.gearslutz.com/board/so-m...9-38-rule.html

''All else being equal, 38% back from the front wall is better than 38% from the rear wall, only because you are then further from the rear wall, which means rear reflections will have less energy when they reach your ears (since they have to travel a bit further). So the smearing that comes from first reflections will be a bit less intense.

Generally, 38% is a good starting point, as Glenn says, because there are likely to be few/no nulls or peaks in that area. This is a good theoretical starting point; your ears should always be the judge.

As far as speaker placement, the speakers should make an equilateral triangle with your head, ideally with the tweeters at the same height as your ears. As far as how widely they are spaced, it really depends on what else is going on in the room. I don't know if this is intentional, but in many rooms I've noticed that the speakers are approximately the same distance from the center line of the room (ie, a line from the front to the rear, going through the mix position) as they are from the front wall. In other words, if the speakers are 6' apart (3' each from the center line, have them be 3' from the front wall. These numbers are round; by far I think it is more important to make the equilateral triangle between the speakers and your head, such that the speakers fit comfortably into your space.

I'm sure there is a theoretical optimum, but if you keep things symmetrical, make the equilateral triangle, and add bass traps and absorbers for a RFZ you should be doing just fine. ''
__________________
Dad's speakers: Amphion one18/ Genelec 1037b/ ESL57/ Altec604/ Tannoy RED 15 inch/
Mine: Harbeth SHL5+

Last edited by youknowyou; 27th December 2015 at 11:06 PM.
  Reply With Quote
Old 27th December 2015, 11:00 PM   #15
youknowyou is offline youknowyou  Canada
diyAudio Member
 
youknowyou's Avatar
 
Join Date: Jun 2014
for speaker placement, once you have determine the right listening position making sure you understand room modes and that your Listening position is not in a major room mode.


always measure one speaker at a time. once one speaker measure well, try to place it symetrically and at the same distance from the back wall and side wall then the other.

For example:

Place the mic at listening position.
place your speaker 1 feet from back wall:

measure at 1.5 feet from side wall, then try 2 feet from side wall, then 2.5 from side wall, then 3. and always keeping the speaker 1 feet away from back wall and just move your speakers vertically

repeat:
place your speaker 2 feet from back wall:
measure at 1.5 feet from side wall, then try 2 feet from side wall, then 2.5, then 3.
always keeping the speaker 2 feet away from back wall and just move your speakers vertically

place your speaker 3 feet from back wall:

measure at 1.5 feet from side wall, then try 2 feet from side wall, then 2.5 from side wall, then 3.
always keeping the speaker 3 feet away from back wall and just move your speakers vertically

ECT

you will see a pattern emerging, where no matter how far from back wall, the response will be bad. this is because you are in a room mode and you need to also look at how far you place your speaker from the side walls. so the distance from the side wall is as important as from the back wall.
You will clearly see a pattern emerging and be able to understand where are your room modes: if you place your speaker in a room modes, you will excite too many freq and it will be evident in your bass response: peaks and dips will be sometime very severe. then you move your speaker only 1 feet and then boum, response is MUCH better.

For example, the response will always be decent at 2 feet away from side wall and always look bad at 3 feet away from side walls.
for example, you will see that when your 1.5 feet away from back wall, it always measure good, but 2.5 feet away from back wall looks terrible.

Was I clear? Im french...

anyways, this takes a while, but you will be able to determine your room modes clearly. ITs very easy and very understainable once you get the hang of it. read about room modes to understand a bit about it. very simple but you need to know!

Note: the listening position must stay the same.



After you determine the best listening position and speaker placement, its time to add room treatment. Bass traps and first reflection treatment is needed. for bass traps, you have two main option: velocity based or rpessure based bass traps. for dealing with early reflection, you have many option and it dépends on how far your willing to go.

good luck!
__________________
Dad's speakers: Amphion one18/ Genelec 1037b/ ESL57/ Altec604/ Tannoy RED 15 inch/
Mine: Harbeth SHL5+

Last edited by youknowyou; 27th December 2015 at 11:05 PM.
  Reply With Quote
Old 27th December 2015, 11:01 PM   #16
thunk303 is offline thunk303  Australia
diyAudio Member
 
thunk303's Avatar
 
Join Date: Mar 2005
Location: Eltham, Melbourne, Australia
Almost on topic but this site/company has some good 101 papers and some free diy goodness.

Arqen: Acoustic Design, Recording Studio Acoustics

Another reference is all.
__________________
http://nomadessentials.com.au
  Reply With Quote
Old 27th December 2015, 11:20 PM   #17
youknowyou is offline youknowyou  Canada
diyAudio Member
 
youknowyou's Avatar
 
Join Date: Jun 2014
Quote:
Originally Posted by thunk303 View Post
Almost on topic but this site/company has some good 101 papers and some free diy goodness.

Arqen: Acoustic Design, Recording Studio Acoustics

Another reference is all.
this is a very complete guide and every points he talks about in the article must be addressed.
the rear wall must be treated as well as side wall reflection to ensure a free reflective zone.
the more corners with thick bass traps the better!
__________________
Dad's speakers: Amphion one18/ Genelec 1037b/ ESL57/ Altec604/ Tannoy RED 15 inch/
Mine: Harbeth SHL5+
  Reply With Quote
Old 28th December 2015, 01:02 AM   #18
AllenB is offline AllenB  Australia
diyAudio Member
 
Join Date: Oct 2008
Quote:
Originally Posted by djn View Post
So is it correct to say multiple subwoofers level sub signals around the room and traps reduce decay time?

Are the end results the same?
Distributed subs are active bass traps. This is the other side of the phase coin.
  Reply With Quote
Old 28th December 2015, 02:32 AM   #19
youknowyou is offline youknowyou  Canada
diyAudio Member
 
youknowyou's Avatar
 
Join Date: Jun 2014
Quote:
Originally Posted by AllenB View Post
Distributed subs are active bass traps. This is the other side of the phase coin.
bass traps absorbs.
even if multiple subwoofer smooth the FR, it doesnt do anything to absorbs the LF resonance in the room.
__________________
Dad's speakers: Amphion one18/ Genelec 1037b/ ESL57/ Altec604/ Tannoy RED 15 inch/
Mine: Harbeth SHL5+
  Reply With Quote
Old 28th December 2015, 03:00 AM   #20
Mindsource is offline Mindsource  Canada
diyAudio Member
 
Join Date: Aug 2015
Location: Winnipeg
A short presentation on the topic by Dr. Geddes.

https://www.youtube.com/watch?v=SCWL-zusyqw

He addresses 'bass traps' in there.
  Reply With Quote

Reply


Multiple subs vs. bass trapsHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
What is the diff between distributed subs and lots of bass traps??? djn Subwoofers 22 27th December 2015 08:57 PM
Bass traps? simpleacoustic Subwoofers 7 30th November 2011 11:29 PM
When and how to use bass traps MalJ Multi-Way 5 15th September 2010 12:40 PM
DBA (dual bass arrays) and active bass traps capslock Subwoofers 3 20th August 2006 12:52 PM
bass traps? bostonswoop Subwoofers 3 30th March 2006 02:03 PM


New To Site? Need Help?

All times are GMT. The time now is 01:13 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki