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?
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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.
It may be artificial...but rear firing drivers seem to created an enhanced firm of depth......these spatial ques might not be for everybody
I have always wondered about the benefits and have never heard an a-b comparison. Maybe the question is -- At a particular price point, do you want some of your money invested in rear firing tweeters vs having that money spent on some other aspect of the speaker. The 'less is more' argument, particularly if they are usually switched off.
Remember the Bose speakers that were designed to point 8 little EQd woofers (each) at the wall with one or two pointed at the listener? People loved those things...and then Bose took the front speakers off and turned them around to sell as Pro Sound speakers. About a zillion people bought those...and for nearfield PA stuff they're not too bad with proper EQ, although I think a good 2 way horn design is better. A lot of Bozes on that bus.
The reason there are rear-firing tweeters has to do with human hearing/perceptual rules.

When the ear hears a sound, the brain makes a copy of the sound and then looks for sounds that might be similar. If it finds one, it does a comparison and looks for differences. This is part of the brain's processing to sort out where the sound is coming from.

Essentially what is happening here is the speaker designer is taking advantage of the brain's processing by providing short-delay echo information. The result is that you get improved imaging and soundstage, because the brain is better able to sort out from where the sounds appears to be coming. So its not *just* for better polar response!