Help - Nice small dipole or bipole for HT wanted.


Hi!

I'm trying to clearly decide on which way to go here, "bi or di" - ples for either side or rear surrounds.

Not looking to spend a whole bunch on them either. it would also be nice if they came in either wall or stand mounted configurations, as that has yet to be figured out.

They will probably be powered by the receiver's power plant too.

I've no idea who even makes such a thing, so any help here will be certainly appreciated. Thanks.
blindjim

Showing 5 responses by johnnyb53

Mirage Omnisat v2 series. Nothing's designed to create a naturally balanced, all-encompassing soundfield like the Mirage omnis. Very compact, easy to mount on walls, ceilings, or stands.

They are also well suited to home theater because of their dynamic range. The little satellites are around 89 dB efficient, yet can handle up to 150 watts each.

The tower version is very petite, yet is 93 dB efficient and can handle 175 watts.

If you want something very compact, but nicer, more efficient and plays a little fuller and louder, there is the OMD-5 from their OMD series.
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.
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.
In my 7.2 HT setup, I have previous generation Mirage OM-R2 L-R surrounds with a hemispherical soundfield (all in phase) and for the rear surrounds I have a pair of nearly omnidirectional Mirage Omnisats, v1. As they are mounted on the wall, they also produce a hemispherical soundfield (also in phase).
07-20-08: Blindjim
What about this... ?? the intended directional cues which are in play during the film. Localized sounds. Do they still possess the same snap and pop, or impact which is realized as coming from a directed & intended area?
With the OM-R2 surround speakers or Omnisats, absolutely. Mirage did years of research to get the right balance between direct and reflected sound, and to get the right tonal balance when wide dispersion brings more of the room into play. There's still a strong core of sound coming from the speaker itself, and Mirages (with sufficient power and current behind them) are very dynamic. Their titanium tweeter is particularly fast and smooth.

That's what I'm saying--with the Omnisats and omnipolar speakers, the directionality is as specific as one could want, but with the wide dispersion, you never sense that one speaker is handing off to another. Together they create a seamless soundfield with exemplary directional specificity.

Or is there a loss attributed to the dispersed sonic field? Ex. ricochets, gun shots, breaking glasss, approaching or departing entities?
Nope, they'll make you jump out of your seat.
07-21-08: Blindjim
Lastly,
Just how much power is 'sufficient power'?
Well, I guess that depends on how big the room is and how much you want to jump out of your seat.

Most of my system is powered by 150w per channel. The rear surrounds (where the Omnisats are) have variously used 150wpc and 60wpc. Both did fine. The Omnisats are reasonably efficient for their size and can also absorb a lot of power (150w), so they're quite capable of making you jump.

I'd say a 60wpc system would make the Omnisats sound good because they sounded really good powered by an Adcom GFA-535 II, and anything from 100-to-150wpc with properly set up bass management (cross over to sats at 80Hz) would give you theater-level volume and transients or better in a medium-large (say, 18x20) room. That's my room size and that's what I get.

Anytime I've played a film on DVD/HD DVD with bombastic soundtrack (Lord of the Rings, Batman Begins, Harry Potter, Indiana Jones, Transformers), guests have commented how it sounds so much better than they've ever heard in a theater. I think it sounds as good as an Imax setup, but more seamless.