rear firing tweeters....

A common denominator in much of this is design engineer Kevin Voecks, who designed the original Mirage line all the way into the beginning of the M-1 bipolar. Early Voecks designs at Mirage also had rear-firing drivers. Then he moved on to Snell (actually worked at both Snell and Mirage simultaneously for awhile) after Peter Snell died, and he redesigned their line, incorporating the rear-firing tweeters. He has been director of engineering at Revel since 1997.

There are other companies that have used ambience tweeters as well, and it's hard to say how many arrived at this on their own or were inspired by Voecks.

I've had Mirage M5si's for 16 years. In my 2-channel LR system I use a pair of forward-biased omnidirectional Mirage OMD-15's. After getting married in my living room with live music and soon after hearing a pair of Mirage speakers with the Omniguide, I became hooked on this approach to energize a listening space with the same timbres, room energy, and soundstage of live players.

If you want to hear just what's on the recording, no more no less, sit in the narrow sweet spot with nearfield monitors. If you want something that sounds like live music filling your listening area, go with omnis, bi-polars, or at least something with ambient drivers such as the rear-firing tweeter.

I don't mind what my listening room sounds like, but I do mind being told what live music sounds like since I've successfully played it and mixed it for money most of my life. Rear firing tweeters are interesting, sometimes sound great, but are simply unnecessary if your main speakers aren't surrounded by mattresses or 6 miles of open space.

"If you want to hear just what's on the recording, no more no less, sit in the narrow sweet spot with nearfield monitors. If you want something that sounds like live music filling your listening area, go with omnis, bi-polars, or at least something with ambient drivers such as the rear-firing tweeter."

I think that's a bit much. There are plenty of full-range systems which can extract what's in the recording w/o requiring nearfield seating and which don't need "ambience" tweeters. This doesn't need to devolve into a religous argument.

My Vandersteen 5A's have rear fireing tweeters which provide extra high frequency energy for "problem" rooms...however, it also presents phase problem, so they have an "off" position for most setups.

I have Von Schweikert VR4JRs. I have a small room which is 17 feet wide at the front and 24 feet deep with my sitting position half-way back. Ceilings are 9 feet. The walls are treated with deep pile quilts behind and to the side of the speakers which are 30" from the front wall. I have found that on large scale orchestral pieces that the rear tweeter helps "enlarge" the performance, thus better simulating the event. For small venue performances and more intimate spaces the rear tweeter is not necessary. It is only a tool to help the room recreate the music. I believe it is more about the room than the speakers themselves. There's not much to argue about here. To each his own. I would not buy a speaker because of the rear tweeter but I wouldn't reject a speaker because it has one. My speakers project the sonic image of the performers very well with excellent height, width and depth. The rear tweeter is not trying to make up for deficiencies in the speaker design, it is giving the listener options in tuning the music to the room.