This would be a great project if one has a rear wall that is big enough. We all know that quality bass is proportional to size and despite the commercial claims and reassuring graphs of small subs etc…once you hear a true bass horn sized to purpose you understand that they are commercial claims.
All fun…
13Audio 
My wall would be big enough but my neighbor might complain about the throat cutting thru his apartment.
The Denmarn Horn was rebuilt recently featuring a 9ft. section of the original horn. So maybe a new project for 13Audio?
E.
Tim,
I have been spinning a lot of mono jazz and classical lately and enjoying the sound very much. Then I think to myself, I could get used to having a mono only system. Then of course, I play the stereo LP’s and I like that as well and am happy that I have two speakers.
So I wonder, what do you do when you play a stereo LP? Do you change cartridges and then combine the two channels together? This is the only way to make it work, yes?
Norman
Norman,
The answer is here https://audio16.wordpress.com/2014/08/19/3148/
I designed and tuned a summation that take the stereo to mono without the negatives sides of doing that.
You can see the device here https://audio16.wordpress.com/2015/05/13/just-before-we-go-to-the-show/
Upper left side of image.
Well this allows the use of less (one pre and amp etc…) that often means more?
All fun….