Diffused? Confused!!

[Clive]

I have 2 questions
(1) I was reading the May copy Of AVI about surround speaker placement. When I joined this forum I was given advice to elevate my surround speakers and re-do placement. This I have done, thanks to you guys with great results. I had my rears removed from immediately beside the sweet spot and I placed them on the wall behind shooting from the corners towards the sweet spot. (This is in a 5.1 setup)

According to the writer of "Ask the Home Theater guy" he has condemned this setup for traditional surrounds speakers. He suggests that these speakers should be directed towards a back wall or side wall but never directley towards the listenning area (Sweet spot)so as to create a more diffused sound from the rears. The point was, that, if you or anyone in your company should ever have to take their eyes of the screen and look in the direction where a sound is coming from then we have basically failed to setup our surrounds to create that feeling of being in the action.
I can't say that of all the setups I've seen both in stores or on the internet have used this setup or even suggested this setup.....Have I missed something along the way?

(2) If my receiver is rated at 105 wpc and I decided to add separate amps to my setup. Do I need to have amplifiers that is rate higher/much higher or does it really matter? I was reading a thread here not too long ago where someone said that the recievers' power output is usually not the best, but greater results can be realized when separates are used. What would you suggest here (power rating) for the best results for sonic and/or spatial detailing. Also, would using one 5 ch amplifier with equal power rating a good way to go?

Thanks in advance for your help I feel a little ops: > That's right!




CLIVE




HEY!! Why buy movie tickets when you can own a Theater?

[Andrew Pratt]

Clive I'd suggest starting a seperate thread on receivers vs seperate amps and we'll concentrate on the 5.1 speaker placement in this thread if that's ok?

I went looking on the DD website to see if I could find the placement diagrams that I once had seen. I'm still looking for those but I did come across this in their mutli channel write up

"The ITU-R1 has a specification for listening room layout intended for critical evaluation of multichannel programs. These ecommendations also appear to be a good starting point for mixing room setup, and have been informally adopted as such. Aside from time alignment, a specific geometry is described. With the center speaker directly in front, the L/R speakers are each positioned 30 degrees away from center, forming a 60-degree angle. This angle may be reduced somewhat (say, 45 to 50 degrees) and give qually successful results. The surround speakers are each positioned 110 degrees off center. This puts the surround speakers to the sides and somewhat behind the listener, which is not only what often appens in typical homes, but has proved to be a good way to hieve overall front/back soundfield integration and envelopment. If the surrounds are too far to the rear, the listener finds himself lost somewhere between two separate soundfields, rather than rapped inside one cohesive soundfield."

Here's a comprehensive outline from the Dolby site.
Dolby recomended speaker placement guide.

The following diagrams are DD's recomended placement for the surround speakers.






This is an alternate placement layout.


and for those without a rear wall...


Now they go on to talk about DVD-Audio set ups as well...

"The multichannel music programs on DVD-Audio discs are mixed under different circumstances from movie soundtracks. Films are mixed in large rooms called dubbing theaters that are sized and configured like actual cinemas, while DVD-Audio music programs are typically mixed in much smaller recording studios.

As shown in Figure 13, dubbing theaters (and cinemas) use multiple surround speakers arranged along the sides and rear, mounted high to create a diffuse, enveloping surround soundfield. The advice we've given so far for placing surround speakers is aimed at duplicating this effect at home. In most DVD-Audio mixing facilities, however, there are five identical speakers arranged at ear level in a circle around the mixer."

"Chances are that you will be pleased by the sound of ultichannel DVD-Audio programs with your surround speakers optimally placed or movie playback. However, if you wish to more closely replicate that mixers hear when preparing music for DVD-Audio releases, you have two choices. One is to effect a compromise by lowering your surround speakers to a height of four or five feet from the floor to split the difference between the diffuseness desired for film sound and the more direct radiation preferred for surround sound music. The other alternative is to install and switch between two pairs of surround speakers, one optimized for film playback, and the other, identical to the front speakers, placed at ear level for optimum DVD-Audio playback. This purist (and potentially costly) approach is facilitated on some A/V receiver models by the inclusion of connections and switching for two pairs of surround speakers. However, while this approach may optimize the effect for a listener in the center "sweet spot," those seated off-center may hear too much of one surround speaker or the other."

[Lex]

Nice research Andrew. Interesting Topic too. Carry on

Lex

[Clive]

Thanks Andrew for the reply and detailed information. According to the alternate placement layouts grafts, all positionings seem to be somewhat accepted. The emphasis seem to be on height and distance. This I will check later, however I seem to be at a disadvantage because the rightside of the room has an open concept staircase which leads to the main floor and I dont have a door, walls or a corner to create any deflections. Moreover, looking down from the very top floor, you can see the speaker on the shelf.

Should I then take the THX route and use dipoles on the sides? Would the fact that I have an open corner in the room change everything?

On the brighter side my reciever does have 5-channel surround and A/B speaker switching and I do have a pair of JBLs sitting idle.

Still more help, thanx!




CLIVE




HEY!! Why buy movie tickets when you can own a Theater?

[Andrew Pratt]

Well as the DD site indicates it sort of comes down to a comprise between optimal for movies and optimal for music. I have never owned true direct radiating rear speakers since i've had bipoles or now my dipoles. I will say though that in both cases I have set them up so that I have had sone set of drivers fireing directly at my ears with the second set pointed towards the rear wall. In a general sense the maggies I have now are acting more like direct radiating speakers since they are positioned behind and to the side a little of the listening area...they do project sound to the front and back though so I sort of get the best of both worlds. This set up is best for music since directional cues are a good thing. For movies though if your speakers are too directional it might become distracting...of course a lot depends on the room's layout and the speakers in question which is why Dolby has more then one placement option. If you can the best thing to do is to simply try various positions and see how you like the effect.

[Clive]

Thanks Andrew I'll do that.
Oh Boy, more hole in the walls! :cry:




CLIVE




HEY!! Why buy movie tickets when you can own a Theater?