Connecting cabinets 212RH&115RH ?

As a new owner of two MM cabs I �d appreciate advice on the following question: On the back of the 115RH (75) there are two ports; one ordinary and one for "series-connection" to another cab (Am I right?)...If I connect the 212RH (150) to that seriesoutput, what impedance will I end up with? Best regards from Swedish bassplayer Kristjan Aunver

That's a good question... I have always assumed that the second jack on the speaker cabinets is a PARALLEL connection. I have never owned one so I am not sure.
Plug an unwired 1/4 plug (or a cable not plugged into anything on the other end) into each cabinet. Then take an ohmmeter and see if there is a short circuit between the two jack bodies (ground connection). If there is, then these jacks are wired in parallel.
If the jacks are wired in parallel, your 4 ohm 2-12 cabinet in parallel with the 8-ohm 15 cabinet will give you something like 3 ohms.
If the jacks are wired in series, the the total would be 12 ohms.
Of course, this is assuming that the factory speakers (or identical units) are in the cabinets. If you measure the resistance across the jacks tip and sleeved, you should measure about 5-6 ohms on an 8-ohm cabinet and about 2.5-3 ohms on a 4-ohm cabinet.
Steve

hi, thanx for precious advice - do you know where one might find info on my cabinets (ohm?)...and the MM HD130 I own....like a manual? I�d like to them both with my amp...but I�m unsure that how to connect them; choices are parallell or in series...suggestions?

I have never seen a schematic or a manual on these. If you can't do the tests as I have explained them above to figure it out for yourself then you will have to ask someone who owns them!
Steve