bass traps added echo?

[inwardheel]

i have a room that is 12'10"x12'11" with 8'4" ceilings, it was built in the sixties i guess that's why it has weird dimensions. i am at the optimal listening position and i have my monitors decoupled from the desk.

i recently added 8, 4" 2'X4' bass traps that i made out of 8lb fibrex rockwool.
i put them in the four side corners of the room.

what i would like to know is why after doing this i seem to get an echo when i clap my hands in the center of the room, no where else but the center, it sounds like im in a racketball court but not as bad or as long of a decay. it didnt happen before the bass traps. flutter echo? would diffusion help?
also this is kinda a dumb question because i know that, "mattresses are only good for entertaining young ladies" but what about tempur pedic ones, they are pretty dense?

[AudioWonderland]

Originally Posted by inwardheel

i have a room that is 12'10"x12'11" with 8'4" ceilings, it was built in the sixties i guess that's why it has weird dimensions. i am at the optimal listening position and i have my monitors decoupled from the desk.

i recently added 8, 4" 2'X4' bass traps that i made out of 8lb fibrex rockwool.
i put them in the four side corners of the room.

what i would like to know is why after doing this i seem to get an echo when i clap my hands in the center of the room, no where else but the center, it sounds like im in a racketball court but not as bad or as long of a decay. it didnt happen before the bass traps. flutter echo? would diffusion help?
also this is kinda a dumb question because i know that, "mattresses are only good for entertaining young ladies" but what about tempur pedic ones, they are pretty dense?

The bass traps are a nice addition but you still have to address reflection points etc to deal with the flutter echo in the room.

[inwardheel]

thanks man i wasn't sure if that's what flutter echo was, personally do you prefer absorption or diffusion to fix flutter echo?

...

[bass man]

Originally Posted by Victor_Stoian

in such a small room diffusion will hardly work.
Go with absorbtion.

+1 for that,check the first reflections spots and then ...well kill them

[Glenn Kuras]

Originally Posted by inwardheel

what i would like to know is why after doing this i seem to get an echo when i clap my hands in the center of the room, no where else but the center, it sounds like im in a racketball court but not as bad or as long of a decay. it didnt happen before the bass traps. flutter echo? would diffusion help?

The flutter was there all along but now that you have tamed the low end you can REALLY hear how bag the flutter is in the room. For the early reflection points you want to use absorption but for the other areas mixing up absorption and diffusion is just fine.

[Weasel9992]

Originally Posted by Glenn Kuras

The flutter was there all along but now that you have tamed the low end you can REALLY hear how bag the flutter is in the room. For the early reflection points you want to use absorption but for the other areas mixing up absorption and diffusion is just fine.

Exactly.

Frank

[speerchucker]

Originally Posted by Glenn Kuras

The flutter was there all along but now that you have tamed the low end you can REALLY hear how bag the flutter is in the room. .

Yep.


Also, with those room dimensions, you probably have one HECKUVA LF node, at just one frequency. I don't have my charts handy, but whatever frequency has a dominant node at around 13'. Maybe 75-80 HZ, IIRC.

8" of Rockwool won't tame that.

(and you may have a doozy of a dip where the second overtone of that node aligns with the first overtone of your floor-to-ceiling node. Probably around 230-260 hz. I can't quite figure it in my head, and I'm way too lazy to go work it out for you. Your dimensions are almost perfectly incorrect.)

I highly suggest you buy some analysis software and get to work building tuned traps. Or, at least pump really short, single-octave flutter tones at high volume, and listen for ringing.

[Glenn Kuras]

Hey I LOVE tuned traps but I really would do as much with Broad Band first and follow up with tune if need be.

As far as software, here is one that is FREE!!
Room EQ Wizard Home Page

[Weasel9992]

Originally Posted by speerchucker

8" of Rockwool won't tame that.

It most certainly will. A 4" panel will be effective at 100Hz, and a 6" panel will be effect significantly lower than that. You'll need more than one of course...the amount of surface area you cover has a lot to do with how good the room sounds in the end.

Frank

[speerchucker]

Originally Posted by Weasel9992

It most certainly will. A 4" panel will be effective at 100Hz, and a 6" panel will be effect significantly lower than that

Where do people get this misinformation?

Look up the actual sabine charts, not info on some retailer's website. Look at the AMOUNT of absoption at those frequencies. Egads.....

[Glenn Kuras]

Originally Posted by speerchucker

Where do people get this misinformation?

Look up the actual sabine charts, not info on some retailer's website. Look at the AMOUNT of absoption at those frequencies. Egads.....

We get them from the LAB that WE TEST at.

[Weasel9992]

Originally Posted by speerchucker

Where do people get this misinformation?

Look up the actual sabine charts, not info on some retailer's website. Look at the AMOUNT of absoption at those frequencies. Egads.....

Egads indeed. Since I have to answer you in two places here's some RAL testing so you don't even have to go looking for it. The Tri Trap is still at 12 Sabins/unit at 100Hz, where the test ends. You have to extrapolate, but it's very clear that it's still working just fine well down below 100Hz. Unless you're accusing anyone of falsifying the data...?

Frank

[Glenn Kuras]

Originally Posted by Weasel9992

It most certainly will. A 4" panel will be effective at 100Hz, and a 6" panel will be effect significantly lower than that. You'll need more than one of course...the amount of surface area you cover has a lot to do with how good the room sounds in the end.

Frank

Just to point out if straddling a corner it goes WAY below 100hz. Maybe that is where speerchucker is not understanding this. I see him hunting down every thread on here so the only thing I can think of is he does not understand straddling a corner?

[Glenn Kuras]

Originally Posted by Weasel9992

Egads indeed. Since I have to answer you in two places here's some RAL testing so you don't even have to go looking for it. The Tri Trap is still at 12 Sabins/unit at 100Hz, where the test ends. You have to extrapolate, but it's very clear that it's still working just fine well down below 100Hz. Unless you're accusing anyone of falsifying the data...?

Frank

Here is the testing that goes below 100hz.

[jproc]

Originally Posted by speerchucker

Where do people get this misinformation?

Look up the actual sabine charts, not info on some retailer's website. Look at the AMOUNT of absoption at those frequencies. Egads.....

Dude... Glenn and Frank are two of the most knowledgable and helpful acoustic treatment experts you're likely to meet anywhere....

[Glenn Kuras]

Originally Posted by speerchucker

Where do people get this misinformation?

BTW I find this a little insulting that you would even say "misinformation", as if we are trying to spread something that is untrue. Myself, Frank, Ethan and Bryan spend a great deal of time not only doing research but educating people on acoustics and get NOTHING FOR IT. If you have something to prove then I would highly recommend you figure out how to prove your point instead of killing the acoustic forums with your underhanded insults.

[Glenn Kuras]

Just to help clear this up I just posted this over at a thread that was kind of the same thing.

http://www.gearslutz.com/board/4686122-post77.html