Rear speaker reflection, good or bad?

[liquidice]

With my new setup, was thinking of putting some acoustic foam behind my rear surround speakers, however, I'm wondering if the wall reflections would actually benefit the sound to create a greater ambiance? One thing about these speakers also is that they are very direct, they are actually designed for use in a recording studio, but there has to still be some reflection.

[SlmShdy1]

From what I've read, reflections can sometimes be good especially for direct speakers. For more ambience, you might want to look into diffusers. That way you're not getting any direct reflections and it won't sound like a bad echo.

[Rob J in WNY]

Reflections from speakers, arriving at your ears at slightly different intervals, can collapse a stereo surround soundfield considerably, but it can add a pleasing ambient nature to surround effects and other environmental sounds. There's a whole science to this, and surround speaker design/application takes advantage of this possiblity with both bipole and dipole type surround speakers.

The front soundstage, to me, gets priority when it comes to preventing soundfield collapse. It can be even more critical when it comes to music playback.

I think your rear surrounds may offer a bit more clarity if they are moved away from the tight corner location. However, that's just my opinion. If you want a more discrete, direct sound from your surrounds, then go for the treatments. If it doesn't sound unpleasing to you now, then forego the wall treatment. You can also try moving your surround speakers forward or laterally as well and see how you like the sound - inches can make a difference - but just keep your listening position squarely centered in between them.

[liquidice]

good enough for me. Honestly, I think it sounds just fine. If you were to look at my older setup, my only option was to have the surrounds right at the ends of the couch, and that kind of sucked for anyone not seated almost directly in the middle. Here, I have more room to place with the surround, and I think the corner might actually be playing into the ambiance. I'm sure I'll eventually move the surrounds to be two channel in some other room, and then replace those with bi or dipole speakers. That is all in the future though.

Thanks for the feedback.

[Big Daddy]

Originally Posted by liquidice

good enough for me. Honestly, I think it sounds just fine. If you were to look at my older setup, my only option was to have the surrounds right at the ends of the couch, and that kind of sucked for anyone not seated almost directly in the middle. Here, I have more room to place with the surround, and I think the corner might actually be playing into the ambiance. I'm sure I'll eventually move the surrounds to be two channel in some other room, and then replace those with bi or dipole speakers. That is all in the future though.

Thanks for the feedback.

Usually when speakers are close to the wall, the lower frequencies will be emphasized. When they are away from the walls, you hear the upper frequencies more.

If your primary interest is watching multi-channel movies and not multi-channel music, you are better off with more diffuse surround speakers such as bipole speakers. The advantage of bipole speakers for movie applications is that they reflect off the walls and fill the room with sound.

[liquidice]

Originally Posted by Big Daddy

Usually when speakers are close to the wall, the lower frequencies will be emphasized. When they are away from the walls, you hear the upper frequencies more.

If your primary interest is watching multi-channel movies and not multi-channel music, you are better off with more diffuse surround speakers such as bipole speakers. The advantage of bipole speakers for movie applications is that they reflect off the walls and fill the room with sound.

...and not dipole? I've long wondered which one would be better for me. Does it just come down to personal preference? Also BD, I don't want to jack my walls up with foam, but might mess around with it anyways. Keep in mind I'll have some thicker curtains covering the windows soon, so do you think that would take care for the main reflection points?...or should I do something in the center of the back walls, between the corner the where the large window starts. Johk made a comment on my gallery thread about if there is an opening on the left of the room, treatment on the right would make it disappear, but I'm not exactly sure what he meant my that?

Edit: I did read your guide on Bi vs Di. Honestly, I would lean towards Bi myself, I was just asking above for your own personnal preference.

[Big Daddy]

Originally Posted by liquidice

...and not dipole? I've long wondered which one would be better for me. Does it just come down to personal preference? Also BD, I don't want to jack my walls up with foam, but might mess around with it anyways. Keep in mind I'll have some thicker curtains covering the windows soon, so do you think that would take care for the main reflection points?...or should I do something in the center of the back walls, between the corner the where the large window starts. Johk made a comment on my gallery thread about if there is an opening on the left of the room, treatment on the right would make it disappear, but I'm not exactly sure what he meant my that?

Edit: I did read your guide on Bi vs Di. Honestly, I would lean towards Bi myself, I was just asking above for your own personnal preference.

Bipole speakers offer two advantages:

1. More flexibility in placement.
2. They have better bass response than dipole speakers.

For dipole speakers to be effective, they have to be placed on the side walls on the same line as your listening positions because the null spot of the dipole speakers facing you is in the middle and that way you will experience a diffuse sound. Some believe that dipole speakers belonged to the age of Dolby Pro Logic.

[liquidice]

thanks BD. I was also cruising your other threads today about acoustic sound proofing, and was curious to hear your thought on putting foam behind my mains speakers. Would it really help?...or not the most noticeable thing in the world. Keep in mind I'm caught between style and AQ/PQ, so I only want to do something if I really have to. If I were single and this was my own little space for me and mostly me, then that would be a whole other story.

[Big Daddy]

Originally Posted by liquidice

thanks BD. I was also cruising your other threads today about acoustic sound proofing, and was curious to hear your thought on putting foam behind my mains speakers. Would it really help?...or not the most noticeable thing in the world. Keep in mind I'm caught between style and AQ/PQ, so I only want to do something if I really have to. If I were single and this was my own little space for me and mostly me, then that would be a whole other story.

If you put acoustic foam behind the speakers, you will probably hear more detail and treble and less reflection from the back wall and bass sound. That is the experience I had with my front speakers, but my front speakers are bipolar and have the exact same drivers on their backs.

[liquidice]

ahhh, so really, I might be ok except for the backwall. I didn't want to put foam on the wall with my tv if I really didn't have to. I guess maybe I'll just wait to see what happens to the acoustics once I have the curtains in place. I suppose I'll have to calibrate again too. Of course I did hang a blanket from the window when I can auto calibrate. I guess we'll see...

Thanks BD.

[jomari]

to add on the discussion here, your picture frames are already diffusors, not the good kind by the way.

this is one reason i hate seeing picture frames of big ol posters in a room, because it causes reflective points that bothers the hell out of me.

id personally prefer to have acoustic treatments behind your fronts. in a nutshell, its a great way to 'hear' your speakers true voice, compared to a number of reflective points in the room.

also try using the flashlight technique, to determine your initial reflection point too.

sorry. going to bed.

diffusors, are a good option by the way.

[liquidice]

thanks jo-man. I've got a truck of acoustic foam just waiting to be experimented with. I need to know how Big Red made his panels so I can do the same, they look great covered in cloth. When I do finallly get around to getting the curtains I want, I'll see what that does to the room, and then play around from there. I'm not going to go overboard like crazy though

[aramis109]

Originally Posted by liquidice

thanks jo-man. I've got a truck of acoustic foam just waiting to be experimented with. I need to know how Big Red made his panels so I can do the same, they look great covered in cloth. When I do finallly get around to getting the curtains I want, I'll see what that does to the room, and then play around from there. I'm not going to go overboard like crazy though

What, no foam on the ceiling or hanging from it?

[rded]

Originally Posted by liquidice

thanks jo-man. I've got a truck of acoustic foam just waiting to be experimented with. I need to know how Big Red made his panels so I can do the same, they look great covered in cloth. When I do finallly get around to getting the curtains I want, I'll see what that does to the room, and then play around from there. I'm not going to go overboard like crazy though

Bigred bought his DIY materials from ATS ACOUSTICS.

[liquidice]

yeah, but I wand to see step by step pics! I guess I'll post something on his thread.

[Sir Terrence]

Typically in most rooms the live end dead works the best. The front of the room up to the sides of the speaker should be relatively dead. As you go down the side walls, it should be a mix of diffusion and absorption. This is especially so for movies, and can be helpful for music as well. Diffusers should be used only when the listening position is at least 5ft away from from any walls. That is to keep from interfering with the direct energy from the speaker. The ceiling can be a combo of diffusion and absorption as well, depending on how live you want the room to sound.

Overuse of absorption is bad for both movies and music.

[jomari]

Originally Posted by Sir Terrence

Overuse of absorption is bad for both movies and music.

Sir Terrence definitely hit it on the nail on this one. if ever we use too much acoustic treatments, we might end up with an anechoic chamber. unless you're going to make a studio to dub your rock band skills, id pass.

personally, i like the room a tad 'reflective' towards the back end of the room, past the surrounds (i have a living room plus dining room in an open layout, thus giving me a bigger surround environment.)

as you've observed, id also like the idea of having the front stage 'singing' using their original voice, compared to it having reflections distracting you from the experience.

again, a personal choice.

[liquidice]

wow, great info here, more than I bargained for. Jo-man, you use acoustic panels behind your main sound stage then? I know your not keen on posting pictures, but would you take a shot of how you have your arrangement? I'm considering building some frames for my foam, and then covering with with a grey colored burlap material so sound waves can penetrate the cloth through to the foam. This probably won't happen for awhile. I do notice that when I stand in the middle of the room and clap my hands, I do get a slight 'echo', but nothing to bad. Honestly, my sound is quite nice from my listening position, but I don't know if I would like it better with or without absorption. I guess I'll have to experiment.

[jomari]

id consider placing a good acoustic panel behind your fronts, something more sturdy than foam. remember: what your trying to acheive here is to null the reflections, and just like a basstrap, you want something dense enough to accomplish that.

a good comparison point would be imagining building your risers with foam instead of the wood you used.

you can use fiberglass and or a suspended method for this, and/or consider what crazy did for his. not the best looking, but hey, it worked for his initial steps to treating a room. my best suggestion is to look up ethan winers guide to creating acoustic panels and better built bass traps.

the echo will still be there. heres a quick experiment - have someone clapping at the location of your front speakers and see the difference if you compare it with something behind them (like a pillow or throw, heck a heavy set curtain can do for example).

any difference? if there isnt any, then id consider it moot.

remember the placebo effect tho. and learn to dislearn it.

[liquidice]

jo-man, thanks for the info. I've seached out the fiberglass, and it is sold in my area. This probably won't happen for awhile, but eventually I'll do a similar project such as BigRed did. It seems he followed the guide to a 'T'.