Weird corner shape bass trap question

This might be the kind of thing that's so trivial it'll elicit eye rolls, or it might start a debate. My intuitive grasp on reflections is sorely lacking.

So I'm fitting my listening room with new acoustic treatments. I'm fortunate in that it's an L shaped room that branches to the left, with a doorway/hallway in the other left corner. That leaves the two corners on the right, tops and bottoms.

Three of those are standard corners. The fourth looks like this:



It's behind the listener on the right. That extra surface is about a foot wide.

So the question is: Does the rounding make bass less of a problem? Basically, does this corner need a bass trap more, or less than the other three? These things are expensive.

TIA

 

I would like to know this as well....

 

Is that corner in front of or behind the speakers? If it's a fair distance in front of the speaker (behind the listening position) it may not be worth addressing. The idea is that corners are pressure nodes and I think you're right that the odd shape offsets some of the detrimental effects particularly by creating some more random scattering of higher frequencies. More bass muddiness would occur if this corner is behind the speaker and probably would benefit from a bass trap. Just my 2 cents.

 

I was told that straight corners are the worst for bass, especially between wall and ceiling. We have these moldings all around the living room between wall and ceiling, comparable to what you have. I thought about getting them out because I don't like them, bit apparently they help with bass nodes ?!

 

Yeah, it's about as far from the speaker as it can get in this room. I've already got a healthy sized bass trap behind it.

I suppose I could always get a fourth later if the others don't handle everything. I've got a minor but annoying ringing in the lower highs/upper mids that's keeping me from properly hearing anything with significant presence in that range, like Roxy Music's Avalon. Driving me nuts

 

No. Non parallel surfaces and irregular shapes can break up flutter echoes and effect the specific frequencies were there are problems and make it so one place in the room vs another is more of a high sound pressure area compared to a purely rectangular room. But no, basically the issues of bass modes and standing waves are going to be substantially the same.

 

Another great way to eliminate or greatly reduce standing waves, is to not fully-enclose the room.

In my main HT (see link below) most of the back of the room opens to the rest of the house - which acts much the same as a very effective bass trap. Unless you are literally right beside one of the multiple subs in that room, you feel no increase or decrease in bass level / pressure, throughout the room. Measured in-room response is essentially flat from 15Hz on up. And while I have active control capability (Audyssey MultEQ XT in the pre/pro, and Velodyne SMS-1 Room Correction) neither is being used as the passive design features (layout, spacing, room treatments...) alone are sufficient to yield a flat in-room response.

Jeff

 

You may benefit from using some diffusers in your room to scatter the higher frequencies.

 

I have quite a few of those as well, and they've helped, but my bass treatments aren't nearly as far along, so here's hoping some full range bass traps can pick up the slack.

 

Which bass traps and diffusers are you using?

 

I have a few ATS Acoustics panels, one of which is 4" thick that I'm using as a combination absorption panel/bass trap in a corner that's basically a 2'x3' echo chamber. From hell. That was a big improvement.

Diffusers...I have a few homemade wooden panels and a bunch of reclaimed studio foam panels. Ugly, but made a big difference.

 

The term 'bass traps' seems to cover a range of frequencies. A bass trap panel 4" thick will effectively only absorb down to around 80Hz. See GIK 244 panel test results - these are just over 4" thick:

https://gikacoustics.co.uk/product/gik-acoustics-244-bass-trap-flexrange-technology/

Compare that to their Soffit Bass Trap which goes down to around 60Hz. In other words the larger the trap the lower it goes. Foam products generally don't seem to go down much below 125Hz.

It's possible placing the 4" panel diagonally across a corner may improve things.

Generally the more bass traps the better the bass, and the better the bass the better the rest of the frequencies. Some argue you can over do it.

To really understand what you are doing you need to measure, especially for bass. The most sophisticated way is to use a microphone and software like Room EQ Wizard. The simplest would be to get some test tones and listen. Here is a free download of bass test tones:

'+picTitle+' CLICK TO CLOSE<\/title><\/head>') newWindow.document.write('<body background="'+picURL+'" onFocusOut="self.close()" onClick="self.close()" \/body><\/html>') newWindow.resizeBy(picWidth-newWindow.document.body.clientWidth, picHeight-newWindow.document.body.clientHeight) newWindow.focus() } //--> </script> <title>RealTraps - Test Tone CD