# how non-equilateral can I get?



## cubiclecrusher (May 21, 2013)

I'm working with a general Family Room which is the location of the main TV-watching and sound-system for the home at the moment. I do not need a full THX, cinematic, experience in this room. I'm saving that for my basement re-model next summer. :bigsmile:

The room is basically 13' wide by 15' long.

I'm currently running a 2.1 system through a Marantz NR1602 AVR and even in this basic configuration, I cannot maintain an equilateral triangle. I am sitting 10 feet away from the L/R main speakers, but the speakers are just 8'7" apart. On some occasions, I feel like dialogue is either overpowered, affected by room acoustics, or otherwise compromised. I've halted further expansion in this room as I try to determine what my current "sound problem" is, and how to properly fix it. Acoustic room treatments and/or a center channel speaker are probably in my future for sure. However, I'm not sure about the side-surrounds.

I can squeeze a center channel between the L/R mains, and keep it at approx 10' from the listening position. However, the best I can do with the side surrounds is to have them 6.5' away from the sweet spot, with off axis listeners being even closer (within 3'-4').

Is there a make-or-break guideline on the distance of side-surrounds from the listening position? "Everyone" loves 5.1 Surround with movies, but I'm of the opinion that not all applications really need it - and if you can't do it "right" then maybe you shouldn't do it at all.

How bad can I bust the "equilateral guideline"?

I know I can mount the side surrounds a bit higher in an attempt to keep them from over-powering the rest of the channels, but I'm seriously contemplating forgetting about 5.1 in this room and stopping it at a 3.1 set-up (where all speakers can be 10' from the listening couch).

I know Audyssey can apply some room corrections. I know I can add some acoustic treatments to this room without breaking the bank or upsetting the wife. However, breaking the "equilateral guideline" with the side-surrounds, to such an extent, has me concerned. I'm concerned that EQ and treatments may not adequately correct for speaker placement limitations, leaving me with an investment I can't fully enjoy.

Would you have faith in room corrections and go forward with 5.1 in a space like this?

Or would you try to adhere to the "equilateral guideline" more strictly and stop at 3.1?

Should I sell it all and just get a soundbar? :unbelievable:

Got thoughts?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum, cubicle!

I can assure you that your issues with dialogue have nothing to do with your system or your room. The key is that you said it is a problem “on occasion.” If the problem was your room or system layout, it would be an “always” issue. 

The real problem, I expect, is the program material itself. There is no standard for the mixing of dialogue levels in relation to other sounds. So if you’re only using a two-channel system, the dialogue can be easily “lost in the mix” with programming that features prominent levels of ambient sound. If you were using a center channel speaker, the voices would be more-or-less isolated and as such more easily distinguishable. Or if not, it would be simple enough to turn up the center channel for that particular program.

Many rooms require some kind of compromise in their speaker layout, so you’re not alone. For instance, in both of my rooms (main and bedroom systems) one rear speaker is further away than the other. Modern receivers can compensate for problems like this with their delay and separate level adjustments.

The rear speakers being too close to the seating can indeed be a problem, because it is easy to localize them, which in turn draws attention to them and distracts from the viewing experience. Keep in mind one of the key perceived differences between speakers close-up and at a distance is that high frequencies naturally disperse and attenuate with distance. So the main reason too-close rear speakers don’t sound right and are easily localized is because their highs are unnaturally pronounced.

I’ve found that this problem can be effectively addressed with careful positioning and equalization. I had the same problem with our bedroom system, in that the wall one of the rear speakers was on was only a few feet from the bed . I first experimented with different heights to find the “sweet spot” where localization was minimized. Then I used the receiver’s manual equalization to roll out the high frequencies enough to where the speaker “disappeared” – i.e., sounded like it would in a larger room with the benefit of natural dispersion and attenuation of the highs. The final was adjustment was fine-tuning the volume levels of the two speakers to compensate for the differences in physical distance. 

It took some time, but the result is rear speakers with less-than-ideal placement that sound much like they would with ideal placement.

So, don’t give up hope. It might take some time and effort, and the results might not be perfect, but it’s worth a shot. As I always say, any surround sound is better than no surround sound!

Regards, 
Wayne


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## tonyvdb (Sep 5, 2007)

Are you currently using a center speaker? What model of center speaker is it? I am wondering if its may simply be an issue of it being to small. The center speaker gets used a fair bit, I would say more then even your main left and right channels. If its running out of steam because its too small or your receiver just simply does not have enough power to push it without distortion that could also be a big factor.


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## cubiclecrusher (May 21, 2013)

Thanks for the replies.

Wayne, I really appreciate the encouragement. The "on occasion" nature of this issue was confusing me, but I was complicating it - thinking that maybe there was a NULL in a specific frequency range related to my room acoustics or something more "technical" than simple variances in source material.

Both you and Tony reinforce the notion that a lot of info/signal/use is placed upon the center speaker channel.

My 2.1 setup could simply be "weak" in dialogue due to the missing center speaker. An upgrade to 3.1 could potentially cure my problem.

I run Wharfedale Diamond 10.2's for main speakers and my upgrade will be to purchase the matching 10.CS center channel. This is their mid-range center speaker, but their top-end CM model is really for use with their floor standing models and I'm assuming it would be complete overkill in my situation.

I'm comfortable doing this piece-by-piece so I may just add the center channel and stop there to re-evaluate.

The "Acoustic Treatment People" are happy to sell me $800 worth of panels and bass traps because it will be a "worth while investment" (from their POV) regardless. However, if the crux of my problem really is source material and the fact that I'm missing the center channel, then it would seem wise to simply buy that first and see where I'm at from that point.

I have so many projects going at the moment, it's hard to prioritize, so I really do appreciate the comments - it helps me "talk through it"!


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## tonyvdb (Sep 5, 2007)

Yes, I would agree that getting the matching 10.C would be a good start. Your room is a reasonable size and having everything coming out of just the two Diamond 10.2 may simply be too much at times.


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## cubiclecrusher (May 21, 2013)

I found a PDF paper on speaker placement that gives min-max distances for surround sound speaker placement. This includes the distance between the center channel and the front mains, and the max distance a side-surround speaker should be positioned behind the listener, given the listeners proximity to the side wall.

It doesn't specifically give me min-max distances between the listener and the side wall, but it does give some charts and guidelines that I've been unable to find elsewhere.

So I'll share the link, FYI:
http://www.octet-matrix.com/v/vspfiles/assets/images/home theater speaker placement guide.pdf


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## tonyvdb (Sep 5, 2007)

That chart is a good guideline but subwoofer placement is very room specific so not necessarily ideal. I also dont agree with the corner placement of the front main speakers. Corners are bad I will leave it at that. 
This chart from THX or Dolby would be a better idea


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## cubiclecrusher (May 21, 2013)

Thanks Tony. I do wish the THX and Dolby guides were a bit more specific in regards to relational distances, not just angles. 

Dolby specifically mentions that the front speakers should be equidistant from the listener, but does not go deeper than that.

In most drawings, one can see that side surrounds and rears are often positioned closer to the listener than the front mains, but "how much closer"?

Like you mention, many guides also advise against corner placement, but they don't specifically say how far out from a corner you should be. Some of the most detailed advice I've seen is to recommend that the boundary distances are all different. Meaning the distance from the main speaker to the front wall should be different than the distance between that speaker and the side wall; which should be different than the distance between the tweeter and the floor; which should be different than the distance between the tweeter and the ceiling! LOL

But I like numbers, and I want to see a statement like: "never put a speaker closer than 2' from a corner". Or something like: "if your viewing distance is 9', your side/rear surrounds should be no closer than 3'".

Understanding that one can always treat a room and adjust EQ settings for less-than-ideal situations, I still want to see some level of "tolerance" when it comes to distance, not just angles.

I suspect, that there are too many variables involved so these distances are not defined. Yet still, I hunt for them and crave them.


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## tonyvdb (Sep 5, 2007)

lol, no shame in wanting the numbers. 
You are correct, room acoustic, furniture placement, room dimensions all factor into the numbers. And on top of all that each speaker has different design characteristics. some have a wide angle disbursement of sound others are very directional.


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## cubiclecrusher (May 21, 2013)

Here is a bit of follow-up on my dialogue/bass/sound issue...I'm almost embarrassed to admit it though. 

As I mentioned in my post, my issue seemed sporadic. It didn't make sense to me - I was over-thinking it. Wayne pointed out that it's probably related to the program material. In my observations, this sound issue was most prevalent when using CATV.

I had a professional HT Installer come give me a free consultation yesterday. He was kind enough to dig into the CATV cable box audio settings and found some adjustments to make there - and this pretty much solved my problem. The Cable Box was using the "TV Speaker" setting, and apparently this compresses the output signal (or otherwise changes it). There were a few more minor adjustments, but on the whole these changes in the source-devices resolved my sound problem.

I didn't think about going into the source devices and "opening up" the audio signals to ensure there was no compression or conversion happening before reaching my AVR. Such a simple solution.

Anyway, I'm much happier with my 2.1 system now - btw. It's certainly not surround sound, but it's not voices-in-a-cave either. It's actually quite good for general TV watching and music listening (which the system is used for 90% of the time). I'll probably still go with a 3.1 upgrade, but I'm going to be able to have more patience in my pocket now.

OH - and getting back to the non-equilateral issue - I have more understanding for the fact that the "equilateral guideline" is just that - a guideline, not a rule. For the first time in my life, I heard about a technique where HT Installers point rear surround sound speakers at the ceiling to deliberately bounce the sound to the listeners ear. 

So I understand that careful calibration can solve most placement issues. However, I have been cautioned, and I tend to agree, that direct-firing, side-surround speakers should NOT be placed "too close" to the listeners ear. And, even in my application where the side-surround would be 3-4 feet away from the closest listener (and 2 feet above ear-height), this could still be "too close".


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