rear firing tweeters....

>I have a pair of old Snells with rear firing tweeters...just curious why we don't see this configuration more today ? Phase issues? Placement problems? Engineering issues?

We're trying for uniform polar response which is already much broader than the midrange's dispersion with typical mid-bass driver sizes (5"+) and cross-over points (2.5KHz+) where the local directivity minima contrasts with the mid-range driver's increasing directivity to produce a harsh sound due to excess energy in the 2-4 KHz range.

If you have mid-range output headed out back as in a dipole having similar polar response at higher frequencies helps and a rear firing tweeter works well; although otherwise it's not a good idea.

Failed to mention...I also own eosone by polk rear firing mains in my ht set up...so I own 2 pairs of rear firing speakers...maybe more than I need ...ha...

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.