Bass Trap / Acoustic Panel Experiences

[edward.ruthven]

I would like to gauge the general experiences of members with Bass Traps and Acoustic Panels. A friend and myself have now started building our own panels. We started with two bass traps in bottom corners of front wall in my friends lounge (5m * 5m * 3m high), and found little difference as soon as we added an additional 2 traps at back wall, we then noticed a huge difference in the bass (now not all over the place as well as more solid and controlled).

I will be putting up 6 mid / high panels in my place tonight. I am already using 4 think Pink rolls left in there packaging in my room corners (Will replace next month).

Comments please.

[audiomuze]

Appropriate room treatments are essential to getting the best out of your listening experience. No matter how good your system, if it is in an acoustically poor setting you're never going to get the benefits the system delivers.

Have a look at the thread I started about my listening space - there are quite a few good references in there as well as some good insights from members.

Rigid fiberglass panels are best for low frequency absorption, unfortunately though, it would seem they're not without potentially serious  health risks, so I'm not going further until I've sourced a suitable alternative.

[Rodney_gold]

It's actually a bit pointless designing room treatment in a shotgun manner , you can actually worsen the sound. What you really need to do is measure the room and find the nodes and QUANTIFY the issues you want to address and then construct accordingly.

[NoSnipeLimit]

I don't know much about this, but how do you measure the room?

[joel]

How do you measure the room?

That's an interesting question and not so easy to answer.

Been reading some white papers recently (Floyd Toole and a few other boffins) and it seems that traditional methods (RT60 and the like) are seriously flawed.

But back to the original post.

I do a simple test in my listening room whenever people ask about the effectiveness of the bass traps i have.

I get them to sit and listen to music while I move a trap.
Each time I've done this I've not had to move a trap more than half a metre before i get told that bass quality and quantity has changed for the worse.

In my room then bass traps work well.

I've also recently been chatting to some people about small room acoustics and what Ive been told (and this concurs with Rodney) is that while some of the solutions available do work, each room has to be treated on its merits. A one panel fits all solution is often not as effective as manufacturers of said panells claim them to be.

I used to think that I knew a little about acoustics, but the more I learn, the less I realise I actually know.

[DRNB]

It's actually a bit pointless designing room treatment in a shotgun manner , you can actually worsen the sound. What you really need to do is measure the room and find the nodes and QUANTIFY the issues you want to address and then construct accordingly.

I'm not an expert, but from what I've read and researched, one can never go wrong with bass traps. Yes in larger rooms one can build tuned traps for specific problems, but in the average listening room traps in as many as possible corners won't hurt.

Mid and high frequency treatmend is a different story. Too much will let the room sound very dead. There are a couple of "rule of thumbs" though. Treat the first reflections with mid/high frequency absorption panels. Diffusers behind the listeners sometimes create more speciousness, but if the listener sits too close tho the rear wall, I would treat that with some absorption panels as well. Be carefull not to overdo mid/high frequency treatment.

[Dolby]

Ironic this comes up now ... I asked about it the other day here >>>> http://www.avforums.co.za/index.php/topic,14312.0.html

There's a link from Music Lover on a local manufacturer - but I'd be interested in your pricing on this?

I contacted a hifi shop about this initially and they also recommended measuring the room and getting an acoustic signature. However - I think adding anything can't make the sound worse as I have ZERO on walls right now, ZERO curtains, ZERO carpets and the only thing in the room is pretty much my couches

The canvas wall art would cost me about R6,000.00+ though

[edward.ruthven]

In terms of mid / highs i am only going to put panels at the first reflection points. I have already noticed what broadband bass traps do and will be using them. I have built my own panels using u-therm 6 for bass panels and u-therm 3 for mid / high. These are isover products.

[Rodney_gold]

You can actually go wrong with bass traps , especially if there is a Null , or they do not cure a sharp  resonant peak that you may have. I have a + 8db peak at 50hz running from 40-60hz - tell me how to build a bass trap that will surgically excise this? If you have not even simply measured freq response at listening position , then you dickering around in the dark. You need to cure the gross anomolies before you can tackle the finer stuff. At the end of it all , a totally "corrected" flat room sounds like doo doo - even the makers like TACT/Lyngdorf  that do true time and frequency correction actually allow "preference" curves to be overlaid atop the correction. The first point to start at is correcting bass , which is not very problematic to do via eq. You can go up the freq range once that is done.
In the interim , a cheap unit like the KRK ergo which corrects sub500hz in the time and freq domain is a great buy , it has 2 corrections , one for sitting position (time and freq) and one for the whole room (freq) and is a damn good 24/96 dac to boot.. it's a great solution to those that dont want all manner of ugly constructions floating around the lounge/whatever.
Even something like a simple 4 band digital paprametric equaliser can do wonders without treating the room.
However , all of these gizmos are obviously much more effective if the room is good to start with. You wont get good sound in a lift shaft , no matter what you do.
There are other options , you can try put furniture , bushy pot plants , artworks etc in the areas you would put the traps and diffusors in , maybe not as effective , but aesthetic. You can also listen nearfield which almost takes the room out the equation.

There are also other considerations , what may work at one volume level may not as things get louder or softer , so you have various "corrections" based on SPL as higher SPL's might tend to excite nodes that arent as obtrusive at lower SPL's.
The other issue is that anytime you get new speakers/equipment/change listening or speaker position , your treatments have to change.
I have used a TACT, Behringer deq 24/96 , lyngdorf/krk ergo , Z-sys RDP-1 , and find that the Z-sys which is only a very good digital parametric works the best for ME.
If you want a reference as to the true tonality etc of the music , use a set of good headphones as they don't have any room interaction issues , you can "tune" to that reference if you want ...

[LAV]

Rigid fiberglass panels are best for low frequency absorption, unfortunately though, it would seem they're not without potentially serious  health risks, so I'm not going further until I've sourced a suitable alternative.

Tell me more - are the risks still as bad when they are inside a cover where the fibres cannot become loose / escape?

[edward.ruthven]

I stay in Krugersdorp Gauteng. Is there anyone available to do measurements at a reasonable cost.

[Rodney_gold]

Buy a cheap SPL meter and run a test disc thru your system , if you have a modern high quality android phone , it will have a spl meter built in , not particularily accurate , but adequate for gross measurements. Any amount of 20-20khz 1/3rd octave test tones available for download on the net , or you can generate your own with a freebie wav editor. I use an XTZ room analyser , which is good for me .. but isnt the cheapest option.
Despite me exhorting you to measure , don't get that hung up on measurements , cos if your treatments sound better to you , regardless of whether they "correct" , it is good for you..no universal truth in terms of what is the best hifi system , room sound etc. You only got you to please.

[Timber_MG]

REW and HOLMImpule are easy to use applications that will give you a relatively simple view of what goes on. If you want to see trends (such as identify room modes) then a cheap electret skype mic hooked up to a laptop/PC will give you a simple introduction to measurement.

I believe REW will measure the basic reverb parameters for which you don't need calibrated response. RT60 is not everything, but it's a starting point. Most small rooms do well with some diffusion to get rid of the worst slap echo and just about all small rooms have serious bass issues (CLD panel drywall systems with large coverage percentages need not apply)

[Dolby]

I wish they'd make an audio program where one could build a 3D room to scale, point out the materials, windows, doors and locations of the speakers - and it'd work out roughly what is going on with the saves

[Shonver]

I wish they'd make an audio program where one could build a 3D room to scale, point out the materials, windows, doors and locations of the speakers - and it'd work out roughly what is going on with the saves

They do.

SoundEasy has this functionality, but I'm sure that there are other programs available.