Corner Bass Traps - Always beneficial?

[edorr]

Empircal evidence - Bass traps work!

So I decided to do a little bass trapping expirement. First, I measured my room without bass traps. Next I left the entire measurement setup untouched, installed floor to bottom traps (an 8 feet stack of 24 x 24 x 34 triangular cut up corning 703 in each corner), and redid the measurement. The difference was so dramatic I first though I made a mistake in my setup. Doublechecked everything but the difference was real. I used the Trinnov for measurement. Since Trinnov only does one channel at a time, I split on channel with a Y-splitter and what shows at Left channel on the chart is actually left and right.

This chart is without the trap. I was a little shocked about the huge dip around 50Hz. Note that this was measured with only the botttom woofer on the Evolution Acoustics engaged.



Next, I dumped all this corning 703 in the corner (I will build a frame with fabric later):



Then I remeasured:



WOW, my 12 dB null is now 4 dB null! Easily correctable with DRC! My 3 dB peak has become a 7 dB peak, but keep in mind it had set the bass level on the spakers to + 6 dB. Very impressive. The entire low frequency response has been jacked up by 6-8 dB, all with a few hundred bucks worth of corning!

Finally, I did a regular calibration with the Trinnov, left and right channel separately, obviously with the traps in place. This is what i got:



Without DRC, I am +/- 7 dB, and with correction I am +/- 3 dB. Note that the 5 dB boost between 20 - 100 Hz and the drop off in high frequency is actually my defined response curve. Note that I did not move my speakers at all thoughout any of this. I decided to keep them where they are (30" from sidewall, 60" from back wall) for practical / aesthetic reasons.

Bottom line, $350 and 2 hours well spend! More improvement than I would have ever imagined.

 

[Bill Hart]

Impressive. I'm eventually gonna have to get some measurement software. I'm afraid of what it will show.

 

[Rutgar]

View attachment 4385

I personally find speakers moved very far into the room far more offensive to my asthetix sensibilities (especially large ones) than some panels on the wall / ceiling. I have not done any measurements yet, but unless moving the Evolutions Acoustics MM3 to far back into the corner completely destroys the LFE response curve, I am going to compromise a little on optimal placement for this reason.

This what my room looks like now - corner bass traps will be constructed this week end. Panels on ceiling probalby later.

I tried getting away with my MMThree's being further back towards the front wall. But, I could never get the performance I was looking for. I eventually ended up with them over 8 feet out in to the room (front of the speaker, from the front wall), in a nearly 23 foot long room.

I have no real bass trapping at this time. What is seen in the corner is just 2" thick Echo Busters. Under the screen are two RPG BAD Panels, angled across the wall and floor.

 

[NorthStar]

---Quite impressive indeed Ed. Those bass traps work great, and so is TRINNOV. :b

* Rutgar, those are gorgeous speakers!

 

[microstrip]

WOW, my 12 dB null is now 4 dB null! Easily correctable with DRC! My 3 dB peak has become a 7 dB peak, but keep in mind it had set the bass level on the spakers to + 6 dB. Very impressive. The entire low frequency response has been jacked up by 6-8 dB, all with a few hundred bucks worth of corning!

Edorr,

Your results are impressive - the 5 dB boost at 20 Hz using the traps is a real achievement. You refer that you only used the bottom woofer of the towers for the measurements - it is crossed at 2kHz with response up to 10kHz?

 

[Rutgar]

---

* Rutgar, those are gorgeous speakers!

Thank you! However, the credit really needs to go to Kevin M. and Jonathan T.

 

[Mike Lavigne]

Thank you! However, the credit really needs to go to Kevin M. and Jonathan T.

+1

 

[Ethan Winer]

You are saying that real improvement with fewer traps is still possible. As a start, how effective do you think that just 4 regular Mondo Traps, plus 4 (2x4) FAT Mondo Traps (totaling 8 traps), would be in pursuing effective bass trapping? I have been using standard 2" thick, 2x4' absorption panels for years across the corners, but I am way less than satisfied with the result.

The eight RealTraps you mentioned will definitely make a noticeable improvement in a room that size. Certainly better than 2-inch thick panels.

--Ethan

 

[Rutgar]

The eight RealTraps you mentioned will definitely make a noticeable improvement in a room that size. Certainly better than 2-inch thick panels.

--Ethan

That was my guess Ethan. Thank you for confirming.

 

[Rutgar]

• The speaker and listener initial locations should be carefully selected based on proper study of room dimensions and practicality. The left and right speakers should create a spread of 45 to 60 degrees from the center point of the listening position.
.

If I'm allowed to focus on this statement for just a moment...

I have always heard that 45 degrees or slightly less was recommended. 60 degrees sounds like a pretty wide spread, almost like putting the listening position between the speakers. However, I will admit, when I move My current listening position closer to my speakers, thus increasing the angle, I seem to move out of a null, because the bass gets much more robust.

 

[NorthStar]

If I'm allowed to focus on this statement for just a moment...

I have always heard that 45 degrees or slightly less was recommended. 60 degrees sounds like a pretty wide spread, almost like putting the listening position between the speakers. However, I will admit, when I move My current listening position closer to my speakers, thus increasing the angle, I seem to move out of a null, because the bass gets much more robust.

* 45 degrees is for movies.

* 60 degrees is for music.

...Generally, but not ultimately.

--> Moving your main listening chair forward and backward is a good way to experiment.
The peaks and nulls changed with each position. The preferred choice is ultimately yours.
And the more your experimentations the more calculated and wise your choice is, IMO.

By the way, for music some people like a 70 degree angle (Michael Fremer for example).

 

[Rutgar]

* 45 degrees is for movies.

* 60 degrees is for music.

...Generally, but not ultimately.

--> Moving your main listening chair forward and backward is a good way to experiment.
The peaks and nulls changed with each position. The preferred choice is ultimately yours.
And the more your experimentations the more calculated and wise your choice is, IMO.

By the way, for music some people like a 70 degree angle (Michael Fremer for example).

Interesting. I guess I've read too many books/papers that insist on the 'equal lateral triangle' when it comes to listening position and speakers. Every time I have ever moved in closer, I've always felt I was committing an audio faux paux.

 

[DonH50]

The equilateral triangle is a good starting point. Where you go from there is up to you. Generally a wider spacing provides a wider image but leads to a hole in the middle. Too close and stereo separation suffers. The actual point is highly dependent upon the speakers, room, and your preferences. I have used a few measurement techniques in the past to help positioning but it always seems to come down to listener preference.

 

[microstrip]

(...) Bottom line, $350 and 2 hours well spend! More improvement than I would have ever imagined.

Edorr,

Could you confirm if these two graphs taken from you post #141 were obtained without any change of placement of the speakers and microphone or equalization changes?

I have been playing with some specific room bass treatments in the corners of my room and can not approach anything close to your results.

 

[edorr]

Edorr,

Could you confirm if these two graphs taken from you post #141 were obtained without any change of placement of the speakers and microphone or equalization changes?

I have been playing with some specific room bass treatments in the corners of my room and can not approach anything close to your results.

I did not touch a thing between these two measurements, just dumped a bunch of Corning 703 in the corners. I even kept the microphone turned on to avoid moving it slightly when pulling the switch. I was absolutely shocked by the results myself.

 

[rockitman]

Bass trapping works. It was a huge improvement for my system. I am fully RealTrapped.

 

[microstrip]

I did not touch a thing between these two measurements, just dumped a bunch of Corning 703 in the corners. I even kept the microphone turned on to avoid moving it slightly when pulling the switch. I was absolutely shocked by the results myself.

Thanks. Could you tell me the exact dimensions of your room and the distance from the speaker front to the front wall? I am carrying some simulations and would like to cross it using your data. My room nulls seems to be more resistant than yours!

 

[DonH50]

Low-frequency room nulls tend to be very difficult to counteract with room treatment, and their depth depends upon not only dimensions but the type of walls and such. I have a very heavily treated room and the nulls live on, though not as bad.

 

[microstrip]

Bass trapping works. It was a huge improvement for my system. I am fully RealTrapped.

Christian,
Not only RealTrapped - I have found the secret reason of your good sound in your pictures!

 

[edorr]

Thanks. Could you tell me the exact dimensions of your room and the distance from the speaker front to the front wall? I am carrying some simulations and would like to cross it using your data. My room nulls seems to be more resistant than yours!

Room is 13' wide. Speakers are 6-" from front wall, 30" from side wall (center of woofer). The room is about 25' deep, but the back of the room is not a sematrical square. There is a hall behind it, an open door to adjacent space and a diagonal wall. This asymetry may be beneficial.