Surrounds spinning in my head.

[oneoldude]

Here at HTG there are no stickies re: surrounds. Is it pointless to ask for a discussion re: the various types?

Dipole, Bipole, Monopole, switchable, er... what else???

Which do you use and why?

Any good designs around that will match the stickied designs?

[GrahamT]

I also started a thread about this recently to try to generate some discussion. There are a few related links in my second post:

http://htguide.com/forum/showthread.php4?t=16404

I still havent completely made up my mind on what I will do. Today I'm actually leaning to 3 bipoles with my Paradigm drivers, but that could change tomorrow.

Dipole, Bipole, Monopole, switchable, er... what else???

Quadpole like Axiom, adapted dipole like Paradigm ADP, or up firing monopoles like GR research AV\1 rs.

What is the layout of your room like? Most often monopoles are recommended unless the room layout makes that difficult.

[oneoldude]

Thanks for the heads up and the additional methods.

A bit of searching produced this:

http://www.paradigm.com/Support/TechFAQ/DipolarConfusion.pdf

Those are words from the man himself (Holman). Now that article was written in 1998 but I do not think the world has changed much since then. He makes a good case for the dipole. What are the arguments for the other flavors?

[silvercans]

With a 7.1 (or 6.1) setup wouldn't it be better to use monopoles? I figure that many dipoles may create a smeared sound field.

[Dennis H]

Those are words from the man himself (Holman). Now that article was written in 1998 but I do not think the world has changed much since then.

Actually, it has changed quite a bit. Back then, movie surround was a matrixed mono ambience signal and the idea was to smear it out as much as possible. There wasn't any multichannel DVD-A or SACD music. Now, movies and especially music have discrete 5.1 channels. Personally, if possible, I'd optimize the sound for music and call it good enough for movies. That means surround speakers similar to the front ones. Of course, that requires having some room between the surround speakers and the listener(s). If you're stuck with having a speaker in your ear then you probably won't want one like the mains and ambient-type speakers might make more sense.

[oneoldude]

The article above was written by Tomlinson Holman. He is the guy that put the THX certification system together for Lucas Films. I have heard (probably an urban myth) that THX stands for Tomlinson Holman Experimental. But no matter what THX stands for, since he was the founding father of THX, it seems like a good idea to at least listen to what the man has to say.

From the article it seems the whole idea of surround channels was to create a diffuse soundfield that mimics the experience of watching a movie in a good theater. What Holman describes is his testing to discover whether localized or diffuse soundfields are best in that application. He goes on to show that the vast majority of listeners, uninitiated and pro movie recording engineers alike, prefer the diffuse over the directional. He also points out that diffuse surrounds give the impression of listening to music from the perspective of an audience member while directional surrounds put you in the middle of the band or orchestra.

Being good capitalists, Holman and Lucas (THX) decided to satisfy the largest market possible and promoted (and perhaps still promote) dipole (or non-directional) surrounds. That means more customers for them. That is all well and good, but there is that nagging other shoe to be dropped.

Clearly, if large majority like a diffuse surround soundfield, then a small minority of others prefer direct. It really is a matter of preference rather than correctness. The question is not which is right, but rather, which do you like. So we are back to what the ancient Romans used to say some 2,000 years ago. "There is no disputing taste."

[oneoldude]

Dennis,

You are right that 5.1 has discrete surround channels while Dolby Pro Logic uses extracted surround information. But that sort of beggs the question.

I think the real question should be, "Whether you are listening to Dolby Pro Logic, 5.1 or 7.1, which sounds better to you - dipole (diffuse) or directional?"

I know that I like directional 5.1 better than dipole Dolby Pro Logic, but I have never heard 5.1 with dipole surrounds. So I really cannot answer the question for myself.

[Dennis H]

Yes, THX has staked their fortune to their "standards." Others have moved on. I guess it depends on which is more important to you, music or movies.

You might find the Dolby guidelines for mixing multichannel music interesting. They recommend monitoring with 5 identical full range speakers and no bass management. The sub is just used for the LFE channel if that channel is used at all. However, they do recommend checking the mix with typical home theater speakers and bass management just to make sure it still sounds okay.

http://www.dolby.com/assets/pdf/tech_library/4_Multichannel_Music_Mixing.pdf

[morbo]

Well, its true that Dolby mixes with and recommends identical monopoles all around. But they are not mixing for multiple listeners spread around a 'typical' room. Personally, I am in a very narrow room, so the side surrounds end up being just 4-5 feet away from off center listeners. While monopole surrounds in this room sound amazing in the sweet spot, home theater is a social activity, and other listeners find being so close to one surround very distracting. If I were to design for just one listener in the sweet spot, I'd forget the center channel and make the surrounds monopoles. As is, I am going to investigate something very much like Graham is, only using different drivers likely fullranges like the Aura NS3, if they can handle the decent ouptut levels when highpassed at 100hz, something I'll be testing soon.

[JonMarsh]

Yes, THX has staked their fortune to their "standards." Others have moved on. I guess it depends on which is more important to you, music or movies.

You might find the Dolby guidelines for mixing multichannel music interesting. They recommend monitoring with 5 identical full range speakers and no bass management. The sub is just used for the LFE channel if that channel is used at all. However, they do recommend checking the mix with typical home theater speakers and bass management just to make sure it still sounds okay.

http://www.dolby.com/assets/pdf/tech...sic_Mixing.pdf

BTW, this is basically what WSR (Wide Screen Review) does in all their screening rooms- in the big rooms, it's large Dunlavy's for example. IMO, this IS the way to go. Though when I've had surround, I've often cheated and used phantom center channel; my friend Chas at Ayre prefers that, too, calling it "HT 2.1".

To each his own- whatever floats your boat.

[oneoldude]

I agree with Jon.

I have found that, to me, the Phantom mode sounds better than having a CC. I do not know if it is the processing or the quality of the CCs of a combination of the two. But I like phantom best. So much so, that I canned my surround setup and went back to two channel for HT purposes. My friends with HT setups don't agree. Its a matter of taste I suppose.

I might feel different if I had bunches of people at wide angles watching. But that is not my situation.

In any event, I am thinking of trying it again. Onwards with the quest!

BTW, FWIW, my experience has shown that people with a long history of high quality stereo behind them do not like HT surround as much as neophytes to the audio scene. Hmm. It might all be Pavlovian.

[Dennis H]

I like surround speakers but it bugs me if the center is either lesser quality or not at the same height as the L&R. With a big screen and the center way above or below ear height, it really mucks up the soundstage for me.

On my to-do list is to experiment with two center speakers, above and below the screen, to put voices in the middle of the screen and about at ear level. The theorists will scream "comb filtering" with two centers but I don't buy it. The vertical distance is less than the horizontal L&R, which don't sound too bad as a phantom center, and everyone's head will be at about the same height, so they will all be in the vertical sweet spot.