I know there is the 801 series 80 (non-Matrix), 801 series 2, and 801 series 3, both Matrix. I'm guessing the 801M must be essential 801 series 1?
Hi dastro
It can get confusing but the label on the back of the speakers reveals the truth. Visually the first series 801 (non matrix) is a sealed box. Series 2 and 3 are ported designs and when used with the BAF are full range to 20 hz. Otherwise all 801' are good to 45 hz with the box size/tuning.
Some more info
The Series 80 is also known as the 801F. It was not officially called series 1 - but really is and would be if it was labeled as such. The 801 series 2 is the first model to use matrix technology, followed by series 3.
All details, specs, service manuals ,etc.... can be found at bwsupport.
Scroll down to the matrix 800 series and you will find that they included the 801 F with the matrix 800 series section. This is what makes it confusing.
http://bwgroupsupport.com/manuals/bw-archive