[michaelv]

Bpape,

 I don't use subwoofer in this case. I have two main speakers and this is for 2-channel music only. Does it apply the same?

thanks.

[bpape]

If you're not using a sub, then there are still issues to consider, it's just more difficult since you have to find a place that has both the proper imaging characteristics  for your seating position AND has minimal or complementary SBIR issues.

SBIR is the constructive and destructive interference based on the distance to the wall behind and the wall beside the speaker.  Since bass radiates spherically, some waves come off the front and side wall in phase with the dircect signal and cause a peak.  Others come out of phase and cause a dip in the response.

You can use this to your advantage by finding a place where the 2 distances aren't the same so you get different response reinforcement/cancellation.  You can also use it to try to generate an inverse curve to any anomolies based on your seating position. 

Corners are even worse for main speakers since you're now reinforcing all the rooms modes and all of their harmonics since it's a full range signal generator instead of just a low frequency one.

Bryan

[John Casler]

Bpape,

 I don't use subwoofer in this case. I have two main speakers and this is for 2-channel music only. Does it apply the same?

thanks.

Open all the windows and doors in the room, when you listen.

A door or window opening will not "reflect" bass.  In that space, it is better than "any" bass trap, since it is not a trap, but an "escape".

It will work to a small degree to reduce the bass that is pressurized and returns from that immediate area.

[michaelv]

I can try to move speaker around but the most i can do is to move speaker 2 feet from the side wall, and 1 feet from the front wall (behind the speaker) which also has bass traps in the corner.

I have a door in this room, but i always close it when i listen to the music. I will try to open the door which leads to the wet bar . Do yo u mean that opening the door will release low frequency and , in  turn reduce the deep or peak due to the bouncing of low freq?

thanks.

[klh]

It's worth a try.

[John Casler]

I can try to move speaker around but the most i can do is to move speaker 2 feet from the side wall, and 1 feet from the front wall (behind the speaker) which also has bass traps in the corner.

I have a door in this room, but i always close it when i listen to the music. I will try to open the door which leads to the wet bar . Do yo u mean that opening the door will release low frequency and , in  turn reduce the deep or peak due to the bouncing of low freq?

thanks.

Well don't expect miracles, but letting the reflected energy "out" is actually better than "trapping" since "all" of it goes out, unless you are letting it into a closet, then frogeddeboudet.

A Bass Trap is a mechanical effort to reduce the interactive effects of the room boundaries.  If you subtract some of those "interactions" you have contributed even more.

[michaelv]

After struggling with different placements, i finally try to put 4 accoustic panels (2" thick) in the backwall (behind my seating position). I put them leaning against the wall , but the bottom is about 2" from the wall. The bass now is well defined, stronger. I can feel the bunch in my chest without distortion....  I am thinking of creating some sort of frame that is 2" away from the wall instead of leaning the accoustic panels against the wall.

[bpape]

Exactly.  What you just proved is that it was in fact an SBIR issue.  Try another one directly beside each speaker on the side wall and see what happens.  May work, may not.  Depends on the issues.

Bryan

[michaelv]

thank, bpape.

Do you mean that i should move the first reflection point panels out of the wall about 2" ? I have them against the wall now. I'll try it over the weekend.

By the way, what SBIR stands for?

thanks again.

[bpape]

No.  What I meant was to try another pair of panels directly beside the speakers in addition to the ones behind them.  Leave them down a little lower.

SBIR stands for Speaker Boundary Interference Response.  As I said in a previous post, it has to do with waves bouncing off the close surfaces to a speaker and interfacing with the direct waves (some in phase and some out of phase).  The panels behind and beside on the close surfaces tend to absorb some of the reflected wave before it can come back and blend in with the direct waves.  You'll not eliminate it but if you can reduce the intensity of the reflected wave, you minimize the amplitude of the peaks and nulls created by the interference.

If you look closely at some of the RMAF pics in the Selah Audio thread, you'll see panels behind and beside Rick's speakers.  The rear ports and open baffle nature of those speakers in that room were causing issues that needed to be tamed.  Those 4 panels did wonders.    It's not a flaw in the speaker by any stretch.  It's just the combination of speaker and room and setup - not uncommon at a show in a hotel room.

This is why there is no single correct way to deal with every room/speaker situation.  Every one is different.  At the show, we set up 3 different speaker systems in 3 basically identical rooms and the solution was completely different in each one.

Bryan

[ooheadsoo]

Bryan, if I read correctly, he put the panels behind his head, not behind the speakers.

[bpape]

Doh!    That's what I get for reading too fast. 

The wall behind the listening position is also a common culprit.  Many times one of the worst nulls in the room is one that comes off the back wall.  The frequency is a function of the distance from the rear wall to the seating position.

Anyway, whatever works for you is a good deal. 

Bryan

[boead]

My Original and longest lasting setup in my old home:

Excellent near-field listening. Bass was great.

Same room, different setup that was more traditional.
The deeper the red, the deeper the bass. The bass in the room was horrible!


Ed (hornshoppe) suggested I move the sub.


The addition of corner traps.



All foam material was Sonex.

[michaelv]

Thanks for the sketchs.

I have another question.

Along the wall, there is a closet which i removed the door. Should i leave it empty, or re-install the door and stuff something inside the closet?  When i stand inside the closet, i can hear the bass is rumbling...very strong...

thanks.

[amplifierguru]

Probably because the mids and highs are cut back in there.

You need to come out of the closet

Cheers,
Greg

[michaelv]

yeah...make sense... i should not listen to music inside the closet.....

someone suggested me to use something like Quiteline Filter  from
http://www.musicdirect.com/products/detail.asp?sku=WAQUIETFIL-8

I am sure these little things can make different...Has anyone tried it?

thanks.

[Ethan Winer]

Michael,

> someone suggested me to use something like Quiteline Filter <

Most "power cleansing" products are a scam, or at least a waste of money. Especially at that price! If you're having a specific problem with AC power, such as clicks and pops when the refrigerator goes on, or buzz from solid state light dimmers, then a power line filter might be useful. But $215 is awfully high - the right price for a device like that is well under $100. More to the point, the device you linked makes claims that are impossible. Real power line filters are pass-through devices. Here's an article that explains AC power problems and solutions:

www.ethanwiner.com/dimmers.html

--Ethan

[michaelv]

Thank Ethan.

I have dimmer in my room since i have track light on ceiling. Every time i dim the light, i hear the buzzing sound from the transformer of the light head (i use low voltage track light head), but i don't hear anything buzz from the amp or speaker. I guess it's not affected my system, but sometimes, the light is way down for a few second and back on the level i set on the dimmer. Don't know what's going on.

[Ethan Winer]

Michael,

> Every time i dim the light, i hear the buzzing sound from the transformer of the light head (i use low voltage track light head), but i don't hear anything buzz from the amp or speaker. <

In that case a power conditioner will not help because the noise is mechanical. I assume the transformer was made to be used with the same dimmer you have? It sounds like the internal iron plates of the transformer core are not stuck together properly. Maybe you could stuff the transformer into a shoe box? Or move it outside the room?

--Ethan

[michaelv]

I'm not so sure since i bought the track and light head from homedepot. So i guess they are compatible or i may have defective light head.  When i take off all low voltage light heads and replace them with  line voltage light head, I don't hear the noise anymore, except the dimmer itself has buzzing sound since the day one i install the track light.

now, i turn off the light and use only table light every time i listen to music.