The backwave trap was constructed out of a 62" long Cubicon tube with inner diameter of 9.5". No particular reason to do it this way, the material was "available". Endcaps were routed out of scrap MDF. Tube was filled with 1.5 king size pillow worth of Dacron hollow core fiber. Since the Carver ribbon is too wide to fit inside the tube, I attached the driver on the front after cutting a slot in the Cubicon. (Don't rout, jig-saw instead.) Tightly sealed with 3/4 inch wide back adhesive weatherstrip.
The above measurements were taken at 1 meter distance with a couple of different mod's on the CXR1. This is full room response with SINE instrument measurement. The 0 dB line is 92 dB SPL.
The next plots were taken at 3 meter and show a significantly different picture. Since the driver has no smooth interface with the tube, some diffraction effects are clearly visible. (Calculated at 637 Hz and yes, it is there !) The measurements below were taken with the microphone at "listening" position, about 39" from the floor, close to the sofa.
A lot of high volume listening was done in this configuration, matter of breaking my drivers in. The mid is very smooth and rock solid. During the listening cycles over the last half week I learned that the response sitting down is different than standing up. I will show some examples later on. This has nothing to do with the drivers, just a matter of room or in this case furniture response.