Should I build the wall? Not a Floyd question.

[Takeereasy]

Hi guys. I have a problem with the sound I am getting in my current set up. This section has helped me determine that at least one cause is poor room acoustics, namely a gap between the listening area and the rear wall. There is a walkway behind the sitting area that is seperated from the room only by a curtain instead of a real wall. This is leading to a loss in sound and I believe in a reduction of the overall quality of the listening experience.

I am going to build a wall to replace the curtain but I had a few questions first.

#1. Is a temporary or sliding wall acceptable, or should I build a frame and drywall it?

#2. If I do go the frame and drywall route would insulating the wall make a noticeable difference in the acoustics?

#3 are there any options I am overlooking with regards to the wall?

The room measures 9' by 12' with 7' ceilings. The wall I am talking about building is in the rear of the room and won't affect these dimensions in any way. The wall would be only 8.5 feet long because of a doorway that must be there. My only problem with building the frame is that the work would have to be done on the same floor as it is being installed on because of limited stairwell space.

Any help is appreciated guys.

 

[Ethan Winer]

Easy,

> The room measures 9' by 12' with 7' ceilings. The wall I am talking about building is in the rear of the room and won't affect these dimensions in any way. <

How do you figure that adding a new wall behind you won't affect the dimensions? Regardless, that room is already pretty small, so I wouldn't do anything to make it even smaller. A curtain is transparent to bass frequencies anyway, so it's certainly not hurting that aspect of the room's acoustics.

--Ethan

 

[goodman]

I think you are under the impression that it is desirable to have no open space behind your listening chairs. For good acoustics, I believe the opposite is correct. A wall behind you will just increase relected sound, which is not a good idea. You want to hear the speakers, not the reflections of the room.

 

[bpape]

I think a drawing would be in order. Sounds to me like you're wanting to put the wall right behind the seating. This has it's own set of issues. Once we see more what you are talking about, it might be easier to discuss.

 

[Takeereasy]

no laughing please

Attached is my best attempt at a room diagram in word format. I don't have any other program that will allow me to do a better job. I'm sorry....so very,very sorry. (this is self depreciating humor)

Let me explain the drawing a little. First off the little circle at the end of the curtain is a steel beam that I was planning to build the wall out to. Right now it serves as a makeshift doorway. What I meant when I said that adding the wall wouldn't change the dimensions was that I was only including the curtained room in the measurements, not the hallway beyond. Second the entertainment center is not that big. It is about 5.5 feet long, but I had to make it seem longer to fit the word entertainment in the text box. For some reason that was very important to me. I have bookshelf speakers on stands on either side of the entertainment center and my subwoofer goes in the top right corner.

The hallway behind the seating position is about 3.5 feet wide, the stairway behind it is about the same measurement. The stairway is also open leading to more loss. When I am have a movie playing if one walks in the hallway the bass is greater than at the sitting point. I have moved the sub around but with no result.

I am really sorry guys but I can't think of any other info you may need. If I'm missing something please let me know.

 

[Ethan Winer]

Easy,

> Attached is my best attempt at a room diagram in word format. <

A photo would be a lot better, for me anyway. Can you post a shot of the rear taken from the front of the room?

--Ethan

 

[Takeereasy]

I can see if work will let me take home a digital camera, we had a spare untill a week or two ago, but now it's in use by a new staff appraiser. If I can't then I doubt a good pic will be possible. I am really embarassed by the diagram but I figured it was worth a shot.

I think that my best bet barring any other options is to just build a framed wall. The aesthetics will improve dramatically even if sound quality does not. My only real concern is the space constraints provided by the basement. I'm going to have to build the frame in two pieces, and buy small sections of drywall as opposed to bigger slabs so that I can get them down the narrow stairs. (just to give an idea I'm forced to use a Futon as a couch because most furniture won't fit down the stairs and i could assemble the futon where it is) This room would be my absolute last choice as viewing room but it is the only available room in the house. I live in a 3 bdrm 750 sq ft home (my first home so no small jokes ) w 2 roommates (cousin and wife just while he's finishing school) and a live in girlfriend. This tiny dingy room is my Batcave, Fortress of Solitude, insert other epic hideout at will.... so I'm really not nocking it, just noting the deficiencies. Oh well, enough of my complaints.

If anyone has a different solution please feel free to let me know, and if I can get the camera I'll post the pics.

 

[Takeereasy]

Just one more quick thing, i forgot to say thanks for those that took the time out to look at the post.

Also Ethan I followed the link on your profile, all I've got to say is one day I hope to have a HT that is worthy of needing those products.

 

[Mudcat]

Ethan,

My wife plays cello for the Air Force (Principle). she used to play and teach at Hart or something like that in Hartford and also several New England area orchestras - Springfield is one I remember.

Lets see?

Do you know or heard of

Vivian Podgainy
Amy Frost
Drew Owens

 

[Ethan Winer]

Easy,

> one day I hope to have a HT that is worthy of needing those products. <

Actually, it's the other way around: The smaller or less perfect the room, the more you need acoustic treatment and bass traps.

--Ethan

 

[Ethan Winer]

Mudcat,

> My wife plays cello for the Air Force (Principle). she used to play and teach at Hart or something like that in Hartford and also several New England area orchestras - Springfield is one I remember. <

Cool. Yes, Hartt is in Hartford (the similar names are a coincidence).

> Do you know or heard of <

Sorry, no. But that's no reflection on any of them!

--Ethan

 

[Audioholics]

Actually, it's the other way around: The smaller or less perfect the room, the more you need acoustic treatment and bass traps.

OK, I guess its time for me to chime in...

Nice thought, Ethan, and I bet it sells lots of acoustical panels, but that's patently absurd.

Ethan, you do a good job of self promoting yourself for free on our forums, but please stick to truths and avoid misleading our readers by ignoring the benefits of proper room EQ systems and over-accentuating the importance of passive-only solutions.

And posting another non-relevant graphic of a small reverb chamber might look good, but when dealing with actual furnished rooms, smaller is far easier to tame.

 

[gene]

Just for the record, modal ringing can be resolved using active correction, usually much easier, more cost effective, and more space efficient than passive room correction.


But don't belive me, check out what peer reviewed Dr. Floyd Toole has to say about this:

http://www.harman.com/wp/pdf/Loudspeakers&RoomsPt3.pdf

 

[bpape]

I think there is some truth in both sides.

A smaller room MAY be easier to deal with in terms of bass room modes as they will be inherently higher up in the spectrum and therefore more easily dealt with. Also, there is a better chance to deal with room issues with pure absorbtion (soft) rather than having to go to harder, more difficult to construct traps. Yes. Sometimes you still need to do some of that to balance things out or to deal with very narrow issues but overall, general soft absorbtion has a better shot if your lowest room mode is at say 50-60Hz rather than 20-30Hz. Try trapping 25Hz with soft absorbtion across a corner. It will do some but generally not enough. 60Hz, no problem.

In terms of reverb time (RT60) the LARGER the room, the easier it is to deal with due to sheer additional volume. Air is a beautiful thing and a wonderful FREE treatment.

Also, in a smaller room, to get the same % of coverage to deal with RT60, you need less treatment - ie. less money spent.

Personally, I'd MUCH prefer to deal with the room passively as the room itself is a passive element which is changing the perceived response as opposed to anechoic or outside in free air. Dealing with it actively, deals with frequencies with a broad brush. By that I mean that EVERY seat in the room ends up getting the same changes whether that is a problem there or not. It does nothing to deal with the things that make one seat sound and measure considerably different than another. Also, by inserting additional active elements in the reproduction chain, you're just introducing an additional potential for corruption of the signal.

Just my 2 cents.

 

[Takeereasy]

Thanks for the additional input guys I really do appreciate it. I hope that my post isn't causing anyone any problems.

The wall is being built. Hopefully this will solve some issues for me. Also, I am ashamed to say that the matter has largely been taken out of my hands. I made the mistake of mentioning that I was thinking about the wall to the signifigant other, she like the idea and is expecting work to commence on the job next weekend. I get out of doing it this weekend because I have a regular poker game that I'm commited to, plus I have to research the costs associated with this build, and mainly cause I don't wanna.

Should I insulate the wall. Insulating this extra wall will serve no purpose in my basement but will it help with the sound?

I am also going to research active room correction some more (by this I mean start researching). I know I won't get it all but I'll give it the old college try. I just found out that I get my Holiday pay on the 15th with my reg cheque, so there will be some unexpected money coming my way that can go towoards purchasing what may be necessary.

Oh, and by the way since there were a couple of moderators looking at the post here is my chance to suck up. Congratulations on the nod from Forbes, I think it is a well deserved honour (that's how we Canadians spell honor). Your site is informative and very helpful, with friendly staff, knowledgable posters, and insightful articles, reviews and recommendations. It really seems like you guys are doing something you enjoy for a living,are excited by, and enjoy sharing with others. Congrats again and keep it up.

 

[bpape]

Yes. Insulate the wall. It will help keep keep sound from getting IN to the theater (it won't stop it but it will help a little bit) AND it will keep the wall from acting like a drum.

 

[gene]

Dealing with it actively, deals with frequencies with a broad brush. By that I mean that EVERY seat in the room ends up getting the same changes whether that is a problem there or not. It does nothing to deal with the things that make one seat sound and measure considerably different than another. Also, by inserting additional active elements in the reproduction chain, you're just introducing an additional potential for corruption of the signal.

What you are saying was true until smarter systems such as the one from Audyssey was devised. There are a few other companies working on similar solutions that show much promise. Active room correction is now a viable compliment to passive. In addition a single band PEQ is one of the best tools at smoothing out bass response allowing the user to place their subwoofers in virtually any location in the room (except the nulls)

Read our Audyssey System Review

 

[Ethan Winer]

Clint,

> I bet it sells lots of acoustical panels ... you do a good job of self promoting yourself for free <

I visit this forum and others to explain room acoustic problems and solutions, and for no other reason. There is a lot of misinformation floating around the web that needs correcting, and my only goal is to help. I often refer people to my Acoustics FAQ, which shows how to build your own treatment. This is hardly what you'd expect from someone in the business of selling acoustic products. But I believe so strongly in the importance of acoustic treatment that I'd rather help people build their own than have them go without.

That said, let's discuss the issues:

> avoid misleading our readers by ignoring the benefits of proper room EQ systems and over-accentuating the importance of passive-only solutions. <

I have already explained in great detail the many limitations of active room correction. Of the many points I made in that other thread, which do you not understand?

> when dealing with actual furnished rooms, smaller is far easier to tame. <

That simply is not true. One big reason small rooms have worse low frequency problems than larger rooms is because in a small room you are always near to a boundary. Aside from modes, which are also less of a problem in large rooms, comb filtering always exists near a room boundary. In a small room you simply can't get far enough from any boundary to avoid this, so the peaks are larger and the nulls deeper than in a larger room.

If you have an explanation for why you believe otherwise, I'd love to hear it. That is, don't just say I'm wrong, but explain why you think I'm wrong.

Thanks.

--Ethan

 

[Ethan Winer]

Gene,

> modal ringing can be resolved using active correction, usually much easier, more cost effective, and more space efficient than passive room correction. <

Modal ringing cannot be solved actively because it's a time-based phenomenon. I will grant you that in theory one could design a filter that has the opposite response of the filtering a room imparts. But in practice EQ simply cannot work because the correction is far too localized. Unless someone is willing to sit with their head in a vise. Any correction you apply that improves things in one place will make things much worse even an inch or two away.

> check out what peer reviewed Dr. Floyd Toole has to say <

I didn't see anything in there that contradicts what I've said. Most of that article addresses the basics of room resonance and speaker and listener placement. In one part he shows how EQ can tame a single mode at 47 Hz, and I already acknowledged that EQ can reduce modal peaks at very low frequencies. But to obtain "good bass" in a room involves much more than that. As I explained in the other thread, the bass range extends up to 300 Hz or so, and EQ simply cannot help that high. Nor can it reduce modal ringing in anything more than the crudest fashion at one very localized place.

> Active room correction is now a viable compliment to passive. <

Yes, with the key word being "complement."

--Ethan

 

[gene]

Ethan;

Again you aren't understanding that EQ systems have come a long way such as the Audyssey one which works very well for full range. If you wan't I can send you the white papers that goes into detail on how this system maps the room response so it doesn't just correct for one listening position. BTW, the developers of this system submitted their work to AES and one of the developers is Tomas Holman formerly of THX. In other words this is technology that is well peer reviewed and has a lot of sharp people involved in it.

Electronic room correction was given a bad rap in the industry b/c of limited systems such as Yamaha's YPAO, Pioneers MCAA and Tact which works as a development tool when you define a very narrow listening window about your head for averaging measurements. These approaches are the old microphone on the nose routine. You're not working with too may points and a 1" phase change is horrendous.

This theory works below 100Hz because of the sub/room intimacy as one + the fact that bass wave are slow transient response. It does not work when you go higher in frequency unless you use something like Audyssey's fuzzy logic which does 250 coordinate points with phase and distance calculations for each listening position! Then multiplies that times 6 or 8 (points of calibration) and you've got a lot of points of similarity to match up within each small frequency range. By comparison, systems like Tact for example can only do 9 points so it's doing gross averaging which most assuredly does not end up with minimum phase conditions at all frequencies.

In small rooms like (12x10) for example, it’s usually not practical for people to throw in bass traps and sound panels. This is why natural room correction (couches, bookcases, etc) along with an electronic room correction system like the one I mentioned, and/or at least a single band PEQ can do wonders for flattening out the bass response. Using a couple of small subwoofers placed equidistant from the listening position will further smooth out bass response for a wider listening area.

Now for large rooms like the one I am building in my new house, passive room correction along with this EQ system is gonna be the best of both worlds!