Dumb blonde needs help with power cable matching to subwoofer

Look into the plug socket of the subwoofer and see the pins and shape of the socket.  As others here who have replied have mentioned, should be a standard 3 prong plug that works for computers, one up above the two lower ones.  They are readily available at Home Depot or hardware store too.  

Another take on this is whether it matches may not be the only question. People into audio often use aftermarket power cords, since the cords that come with powered equipment are often inexpensive “standard” cords (typically all black with molded plastic ends).  It is possible your husband had some more expensive cords with his system and it would not be fair to you for a buyer to give you a fair price on a sub and then also receive an expensive power cord without paying a premium price for that.  I see you have been working on this for a couple of months so if you have somebody helping you with pricing I suggest sending them pictures of the power cords you have, and other cables, so you can get some ballpark pricing recommendations.

Every dumb blonde I ever knew, was too dumb to know she was dumb LOL

It cracks me up that, as in most threads, nobody reads the actual 1st post by the author. 

She said;  "Hi! I have a buyer here for my late husband's Rythmik Audio Direct Servo Sealed F12 Subwoofer and I need to know what power cord goes with it."

She had a buyer there when she asked the question. Any answers after MC, Russ and mine would be moot.

kkirk,

If all of your power cables look like standard power cords it doesn't make a difference.  If they come in different thicknesses, strange looking plugs on the end and round or flat you probable have custom power cords.  If they are custom, if you take a picture of them and send them to me I will do research for you to let you know what they are worth. Some of them can be thousands of dollars! (Not mine.;-) ) Just an offer.
Bossman