I had gotten an MB Quart "Reference" RSB 335 8-inch 3-way component autosound speaker package and built a modified "Daline" transmission-line cabinet for the drivers. I did not do any calculation or trial-and-error - I just had the cabinets built by master craftsman Brennan McGaffey and installed the drivers. I figured that with such a high Qts the woofers would work well in a transmission line. I could have flush-mounted the drivers and radiused the cabinet corners along the top section, this would have helped eliminate treble diffraction and smoothed out the upper octaves some. It seemed like a bit too much work at the time, for not too much gain in sound quality.

Overall, this project worked out quite well, they sound very good. The sound from these drivers is not neutral- they are voiced a certain way- slightly mid-forward (but pleasantly so) and a bit of extra "presence" as well (slight extra ~2 kHz level). Bass is taut, musical, and extension is better than you'd expect with an 8 inch driver. They are good sounding, particularly realistic on acoustic jazz and chamber works. They also work well with electronic music. Detail level is very good, imaging is also quite good.

Some day I will run some measurements of these and post the curves here. When I built these I did not have the capability to make decent acoustic measurements.

The lines are progressively stuffed with Acousta-Stuff and the midrange drivers are in stuffed, sealed sub-enclosures made from a length of large PVC pipe.

I used the stock MB Quart crossovers, which are of very high quality.

Here are the details of the woofer:

QM 200 TX 3 8” Midbass Drivers
Sensitivity: 87dB
Fs: 65.8Hz
Qms: 7.81
Qes: 1.13
Qts: .99

The MB Quart RSB335 drivers and crossovers

Here is the construction plan

Here are photos of the finished speakers, they were painted a matte grey to fit into my workshop decor scheme