Corner Base Trap Completed Project

[RobinKidderminster]

At the moment I have a 4in 4x2 trap on the wall behind. Starting as an ezperiment I will make it a bit more wife friendly before posting pix. My design however is very light and I am very happy to hang it up as and when needed. I may try first reflexion but it may get a bit ott. Playing Warhorse last night was an absolute thrill. I totally agree that money is wasted on cables etc unless the room has some modest treatment. I will be very interested to see your hc setup but I am sure it will benefit enormously from our recently discovered knowledge. It would be nice to see the whf listening rooms wrt acoustic treatment. I also hope that lots of forumites join in to share their experiences. Can I pop round for a cuppa when you are done? I'll bring the rubber gloves.

Cheers

 

[sheggs]

Hi Robin,

Have you thought about art panels for those first reflection points in your living room? You can choose a image of your own choice. Most acoustic companies sell them or you could find somewhere who does dye sublimination printing (pricey but the only type of acoustic printing) and make your own panels.The panels will only need to be thin to tackle those first relfection points

I also agree with chewy be great to see what the difference it has made to your room. We have a handy video that helps you use the free REW software - http://www.youtube.com/watch?v=e4uSR3cUUSY&feature=relmfu

If you don't already own an omni directional mi then the Behringer as in the video is cheap but very effective (about £45 from Amazon)

 

[Chewy]

Hi Sheggs,

Is the Behringer better/more accurate than the RadioShack SPL meter? I'm just just wondering of I should get one, but already have the SPL meter?

Also, on first reflection points, am I right in thinking you should be aiming to treat any first reflections that are within 20ms (approx 20ft reflection path)? The only reason I ask, is because that means for me, in my room which is 18.5ft x 11ft, to treat all first reflection points from the front three speakers (all of which would be less than 20ft) I end up covering about two thirds of the side walls, plus a good third of the ceiling.

Plus then if I treat all four corners, all eight tri-corners and all ceiling soffits with bass traps, and the whole of the front wall with broadband absorption (which seems standard practice) - I worry that I will be over treating the room and end up deadening the room? What do you recommend?

(Rob, I hope you don't mind me posing these questions on your thread?)

 

[VoodooDoctor]

http://www.youtube.com/watch?v=B9u7k2V4YPw

Gik's video on First Reflection Points.

 

[RobinKidderminster]

Hya Chewy Sheggs. +1 for new forum and no probs with highjacking thread! Good to find a discussion. As a Physics grad I should be happy to try the measurements and thanks for the video which should be very helpful. Having said that, I am so happy with my results so far I really dont care about the graphs. Would be fun tho' so must give it a try! Side treatment is a difficult one for me since on one side I have a window bay and the other side is open. Asymetric tho' I have never found an obvious imballance. Another question .... should I angle a rear panel trap up or down or flat against the wall .... is slight angled up going to help with ceiling reflelctions? I am convinced that more treatment would make more huge improvements but limited to a difficult room and a lounge/non hc room I think I am as far down the road as I can go. Not disappointed BUT if only ! ! !

Cheers

 

[RobinKidderminster]

Finished the corner traps. If I did them again I would probably make them taller but they do 'disappear' quite well. The rear panel is 'temporary' but very light so can be removed when we have visitors. I would like to replace the mirror with a proper panel/picture but still experimenting. Blimey Warhorse was amazing!

Latest pix http://s1051.photobucket.com/albums/s421/robinkidderminster/Latest%20Bass%20Traps/

 

[chrisup]

Robin a really interesting project well done from another in Kidder. I am in my flat in Kent having my ceilings replaced after a flood from the balcony above (asbestos removed) my lounge into bay is 7.5 m x 4.7 x 3.3 Ceiling and I have huge windows with sea views. I use a Nytech receiver Rega Planar 3 and Celestion 3s. I also have a 1970s Rotel reciever (RX202) Rank Domus Speakers and an old Philips CD60. I am hoping 2 layers of Plasterboard on the ceiling will help with accoustics plus carpet tiles (need replacing), curtains and furniture.

Best Wishes

Chris

 

[sheggs]

Hi Sheggs,

Is the Behringer better/more accurate than the RadioShack SPL meter? I'm just just wondering of I should get one, but already have the SPL meter?

Also, on first reflection points, am I right in thinking you should be aiming to treat any first reflections that are within 20ms (approx 20ft reflection path)? The only reason I ask, is because that means for me, in my room which is 18.5ft x 11ft, to treat all first reflection points from the front three speakers (all of which would be less than 20ft) I end up covering about two thirds of the side walls, plus a good third of the ceiling.

Plus then if I treat all four corners, all eight tri-corners and all ceiling soffits with bass traps, and the whole of the front wall with broadband absorption (which seems standard practice) - I worry that I will be over treating the room and end up deadening the room? What do you recommend?

(Rob, I hope you don't mind me posing these questions on your thread?)

Hi chewy,

The Radio Shack metre is pretty good for tackling certain generic problems. The full room measurment software just takes it to that next level. It basically -

Will show your nulls and peaks in db's for all the different hz so you can identify problem areas

Produce waterfall graphs which basically show the decay time of these hertz (basically how long does it take for the sound wave to stop ringing)

Can identify not just hertz but exactly where it is coming from if you have (you'll be surprised how much people in studios have problems with reflections off the mixing desk) a specific problem

What a lot of people use it for as well is to trial different listening positons because sometimes the low cost solution to the problem can just be as easy as where you sit. (Hence the sitting on the floor thread LOL)

As the video demonstrates (thanks Voodoodoctor) is first reflection points are basically the first place that these sound waves hit when they leave your speakers. so this would generally (but not exclusively) be to the side of each speaker, the floor and the ceiling.

On the sides you only need to tackle those immediate spots one thin panel about one metre tall should generally cover it (unless you have floor to ceiling speakers) and these should be placed in line height wise with the speakers.

Ceiling clouds are more regularly used in studios and then you would cover the listening position and two or three panels would be required.

Just remeber the symetrial rule if you can though, to treat both speakers the same

 

[sheggs]

This look safer than Zalan's video :type:

 

[sheggs]

Hi Robin,

If its in the middle of the wall flat but if you wanting to dela with the bass that collects where the wall meets the floor or ceiling than angled into the corner

You should def do some testing if you are a phsyics grad, you'll love that stuff. You'll soon be telling us, how are you on the room modal calculations?

 

[RobinKidderminster]

I have yet to calculate my modals but hey, why not? Cheers for advice & hope WHF team respond to forum addition.

 

[Chewy]

Hi chewy,

The Radio Shack metre is pretty good for tackling certain generic problems. The full room measurment software just takes it to that next level. It basically -

Will show your nulls and peaks in db's for all the different hz so you can identify problem areas

Produce waterfall graphs which basically show the decay time of these hertz (basically how long does it take for the sound wave to stop ringing)

Can identify not just hertz but exactly where it is coming from if you have (you'll be surprised how much people in studios have problems with reflections off the mixing desk) a specific problem

What a lot of people use it for as well is to trial different listening positons because sometimes the low cost solution to the problem can just be as easy as where you sit. (Hence the sitting on the floor thread LOL)

As the video demonstrates (thanks Voodoodoctor) is first reflection points are basically the first place that these sound waves hit when they leave your speakers. so this would generally (but not exclusively) be to the side of each speaker, the floor and the ceiling.

On the sides you only need to tackle those immediate spots one thin panel about one metre tall should generally cover it (unless you have floor to ceiling speakers) and these should be placed in line height wise with the speakers.

Ceiling clouds are more regularly used in studios and then you would cover the listening position and two or three panels would be required.

Just remeber the symetrial rule if you can though, to treat both speakers the same

Thanks for coming back to me,

Sorry, I probably didn't make it clear in my post, I already have and use REW, but use it currently with the Radioshack SPL meter as the mircophone. My question was, will the Behringer produce more accurate measurements with REW?

Regarding panels for the first reflection points, yes, my plan was to make 1200 x 600 panels, since these are the size of the Rockwool boards I believe. I would then be placing these on the walls around 200mm off the floor, and hence they would finish a little above seated ear height.

Still, there is a heck of a lot of wall coverage to cover all first reflection points for two seating position, from all three front speakers, with a 20ms or less delay time. See below:

http://www.flickr.com/photos/dsmstainlessproducts/7703932164/in/photostream/lightbox/

(Can't get the damn image to appear on the face of the post?!?)

 

[mykspence]

You frequently see on forums, pictures of people's set-ups with a rack load of high end kit, and top quality speakers, all housed in a plain room with wood floor and leather sofas, not a single absorptive surface in sight, but they insist on changing this speaker cable or that power lead to try and improve the sound they are clearly not content with, without a single thought for the room which is no doubt dramatically limiting the potential of their system.

Sad but oh so true.

 

[RobinKidderminster]

Think with GSB thats +2 then . . . to open a new forum topic.

 

[sheggs]

Hi chewy,

The Radio Shack metre is pretty good for tackling certain generic problems. The full room measurment software just takes it to that next level. It basically -

Will show your nulls and peaks in db's for all the different hz so you can identify problem areas

Produce waterfall graphs which basically show the decay time of these hertz (basically how long does it take for the sound wave to stop ringing)

Can identify not just hertz but exactly where it is coming from if you have (you'll be surprised how much people in studios have problems with reflections off the mixing desk) a specific problem

What a lot of people use it for as well is to trial different listening positons because sometimes the low cost solution to the problem can just be as easy as where you sit. (Hence the sitting on the floor thread LOL)

As the video demonstrates (thanks Voodoodoctor) is first reflection points are basically the first place that these sound waves hit when they leave your speakers. so this would generally (but not exclusively) be to the side of each speaker, the floor and the ceiling.

On the sides you only need to tackle those immediate spots one thin panel about one metre tall should generally cover it (unless you have floor to ceiling speakers) and these should be placed in line height wise with the speakers.

Ceiling clouds are more regularly used in studios and then you would cover the listening position and two or three panels would be required.

Just remeber the symetrial rule if you can though, to treat both speakers the same

Thanks for coming back to me,

Sorry, I probably didn't make it clear in my post, I already have and use REW, but use it currently with the Radioshack SPL meter as the mircophone. My question was, will the Behringer produce more accurate measurements with REW?

Regarding panels for the first reflection points, yes, my plan was to make 1200 x 600 panels, since these are the size of the Rockwool boards I believe. I would then be placing these on the walls around 200mm off the floor, and hence they would finish a little above seated ear height.

Still, there is a heck of a lot of wall coverage to cover all first reflection points for two seating position, from all three front speakers, with a 20ms or less delay time. See below:

http://www.flickr.com/photos/dsmstainlessproducts/7703932164/in/photostream/lightbox/

(Can't get the damn image to appear on the face of the post?!?)

Hi chewy,

Sorry I think I did misunderstand you there, I presume the metre is omnidirectional? How do you position it? There's a lot of debate about how this should be done but at about listening height pointing at the ceiling and your results should come out the same. The Behringer is just a good omnidirectional mic that comes pre calibrated.

With regards to the reflection points. I would definately deal with the early ones first, basically those ones that are hitting the wall directly in front of the speakers. The mirror trick really does work. Those are the ones that will cause oyou problems in the 125 - 250hz range and can quite often be identfied by a buzzing/ humming sound in your listening environment. Obviously soundwaves are 360 degrees and they hit everywhere in the room at some point. If you tried to deal with all reflection points it would competely deaden the room and no sounds would travel anywhere which would give a dry and completely unrealistic enviroment. Radio stations use this technique for their interview suites etc.

Def go for the immediate first reflection points and go from there. There is a way after that and you are still encountering problems that we can look at your REW data and pretty much measure specifically where the other problems are coming from.

 

[RobinKidderminster]

Ain't it great to listen to music and not to kit.

 

[RobinKidderminster]

Ain't it great to listen to music and not to kit.

 

[RobinKidderminster]

New speakers? Room treatment? Biamping? Not sure which has made the most difference now but its so refreshing to listen again to old recordings and enjoy them again yet for the first time.

 

[RobinKidderminster]

And finally ....

As mentioned in Vol2: Ch4: Para46 ... in the far end of the room where my PC is sited there was a huge base boom which has now gone completely. This proves nothing in terms of improvement except it really demonstrates what a little ol' base trapping does.

ELO now souning much sweeter ..

 

[RobinKidderminster]

Just a likkul comment. My Mezzos are tall brutes, the tweeter somewhat higher than the listening position. I tried raising the back, pointing the tweeter exactly at ear level. Maybe the angle also directs the bass 'into' the setee? Quite pleased after careful alignment with a laser.
My point? Always worth experimenting with toe in etc and dont forget the horizontal axis.
More focussed? Better soundstage? Midrange improvement? Maybe expect bias but always worth a free tweak.

 

[BenLaw]

These changes have a scientific grounding in why they will change the sound. Moving speakers or listening position should always be the first port of call for tweaking (or more) the sound.

 

[RobinKidderminster]

Yes Ben. My flagon of snake oil dried up a while back so its science, science, science. :cheers:

 

[BenLaw]

I haven't had a chance to watch the video, but I have read the comments about it on this link:

http://www.recordingreview.com/blog/recording-studio-construction-acoustics/why-your-bass-traps-dont-work/

If it's right, a 4" trap with 4" space will absorb 423Hz frequencies and a 6" trap with 6" of space will absorb 282Hz frequencies. Doesn't sound good. What are anyone's thoughts?

 

[RobinKidderminster]

Certainly proper room measurements are important before claiming 'provable' gains. I 'know' my corner traps have had a huge effect on the room since the significant boom outside my listening area disappeared completely. Exactly what frequencies were absorbed or how significant the changes made in the listening area is entirely subjective until I buy a decent mic.
At least its science and not snake oil!

 

[sheggs]

If you are going to buy acoustic treatment rather than build it yourself than ask to see the test results. The results will either be in sabins and absorption coefficients.
If in Sabins the higher the number the better. Basically you divide the surface area by the sabins to get the coefficient.
A coefficient of 0 means it does not absorb anything at that frequency and 1 means 100%

Basic of bass trapping is that the more area you cover and the deeper (not denser) you make them the better they perform. Tri traps with no airgap perform best.(down to abut 45hz) If making panels to straddle a corner they need to be at least 8 inches thick to really tame those lows

If you get a chance go and check out our education pages on our site, has loads of short articles and videos explaining how it all works