I was disappointed hearing the song santa monica acoustic version with the MTX 5i and I notice the ALTO TS813 bass port looks bigger then the MTX 5i bass port so I try using the ALTO TS813 as midrange speaker and I notice the the ALTO TS813 performance is identical to the MTX 5i so this means polypropylene and paper cones has the same performance but I like the ALTO TS813 sound much more then the MTX 5i the ALTO TS813 has a bigger magnet and seems to have a more long throw design that helps all of the sound even the treble sound is better with the ALTO TS813 now I think the MTX 5i woofer is not a good speaker