Help - Nice small dipole or bipole for HT wanted.

BW and Energy which my father and I both own each can be adjusted with a switch from mono to Dipole, the Energy goes further with adjustment for side, corner, rear placement.

07-18-08: Blindjim
The main questions remaining unresolved, are “Which?” (di or bi), and “Where?” (sides or rears)... and of course, “Who?”.

Dipole surrounds harken back to the analog Dolby ProLogic days and are outmoded with digital surround.

Dolby ProLogic was a primitive surround scheme by today's standards--you have a mono signal of very limited bandwidth (200-5K Hz IIRC) sent to two rear speakers. Surround directionality was very limited and dipole speakers' out-of-phase signals created an illusion of more depth.

But that's not how digital surround works now. Digital surround information is specifically located. I have been running a 7.1 (now 7.2) HT system for over three years now, and there are many films that make use of all the channels in specific ways. For example, during the Quidditch matches in the Harry Potter movies, you hear the golden snitch and the players on brooms flying in all directions, such as flying from behind your left shoulder over your head to the right front.

Furthermore, dipoles create a null area to the sides of the speakers and that's the last thing you want in home theater surrounds. The sound should be seamlessly enveloping.

With that in mind, bi-directional comes closer, but hemispherical or omnidirectional is best because it fills in the back half of the room more completely.

As to the "where," if you are only running two surround speakers, they should be to the sides, preferably on the walls, or positioned where walls would be, about a foot back and a foot or two above where your head will be positioned when watching.

I'm a big fan of 7-channel, however, and encourage you to think in terms of a pair to the sides and another pair to the rear.

If you can't do that for now, put 'em on the sides. You want it to be as seamless an experience as possible, and if you have only two surround speakers behind you, there's too big of a gap between the front and rear soundfields, and the surround effects will be distracting instead of enhancing.

I'm speaking from long experience with this. After having surrounds directly behind the viewing area for 6 years, moving them from the rear to the sides was a revelation.

A good eff rating is gonna be a good thing using the power plant of the Onkyo TX SR 805... 130wpc. .. and it’s a near lengthy run of wire too.

The Magnepans are a bad match on two counts here--they're only 85dB (or maybe less) efficient, and they present a 4-ohm load. Most AV receivers, even the better ones, don't like to go below 6 ohms much and very few can manage an FTC 4-ohm rating. The Mirage Omnisats are incredibly unobtrusive, present 8 ohms, are 89dB efficient, throw a room-filling hemispherical sound field, and yet convey excellent clarity and directionality. They come with a top-notch tweeter--Mirage's own titanium dome design with cloth surround to damp out any ringing. They are fast and detailed yet smooth and sweet. They even include wall-mounting brackets.

The last issue is price. Whichever side surrs, di’s or bi’s, are gonna have to be moderately priced or at least within reason.

The Omnisat v2 Satellites retail at $500/pair but are currently on sale at Crutchfield for $400/pair. Mirage makes a smaller version called the Nanosat that is $250/pair. With the sale, you could get a pair of Omnisate v2 Satellites for side surrounds and a pair of Nanosats for rear surrounds for a total of $650 including free shipping.

They also make a somewhat larger, more efficient (90 dB) version from their OMD line called the OMD-5 that goes lower and is available in piano black or rosewood for $750/pair. The difference in sensitivity between the Magnepan and the OMD-5 is 5dB, which almost quadruples the amount of amplifier power available to reach a given level of volume.

In my opinion, a bipolar's side-null is beneficial in a multichannel setup.

The reverberant energy is a separate event from the first-arrival energy (produced by the front channels), and different priorities come into play.

You do not want the rear channels to stand out as distinct sources; rather, you want them contributing to the ambience and sense of spaciousness, and perhaps the occasional off-screen sound effect. By aiming the null towards the listening area, a bipole can contribute more beneficial ambient energy, relatively speaking, without calling attention to itself as a separate and distinct sound source.

Duke
dealer/manufacturer (nope, I neither build nor sell dipole surround speakers at this time)

Johnnyb53

Well, thanks for the thoughtful response... especially the Mirage notes, and the current multi ch. sound tips exp.

Only way I'm gonna know for sure is to use what I got for now. All the Silverlines and a pair of smallish 87db Cantons first. P)lacing the Canton 220s as the sides, and go from there.

I had hoped to have another amp here but that addition will be a while yet, and I don't want to run 3 different types of power plants, Rec. SS, and Tubes for HT. So the 805 will have to suck it up and do five of the seven ch for the time being... with the Odyssey driving the mains.

Above the ear, huh? Yikes! gonna need taller stands.

07-18-08: Audiokinesis
In my opinion, a bipolar's side-null is beneficial in a multichannel setup.

The reverberant energy is a separate event from the first-arrival energy (produced by the front channels), and different priorities come into play.

In my experience, a cylindrical or hemispherical dispersion pattern for surrounds trumps bipolar *or* dipole. The surround speakers from many of the manufacturers have an in-phase 180-deg. dispersion pattern.

I had bipolars with the null facing into the room for the past several years. I just replaced them with Omnisats with a fully hemispherical dispersion. There's no comparison in how it fills out the back while remaining unobtrusive. In fact, that's the best thing about the surrounds with ultra-wide soundfields. They create a seamless soundfield and thereby disappear into the overall sonic environment.