I have always been confused by the tweeters used in Polk 10s and RTA12s from about 1979 to 1983. I have a very nice 8 page cardstock full line flyer( i suspect 1980 to 82) from a Polk dealer I got when i was in college I got when I bought my 10s (1979-80 models) used in 1983 from a salesman at Mels TV Audio . Also a nice multipage set of reviews.
In the full line flyer it goes into a lot of detail on the parts used and shows the SL1000 and talks about it BUT it is black as are all the pictures with all the speakers. I also have two sets of Peerless here. One set has a 751... number on back and has flat spots on the otherwise round structure. The other has a 5514 and does not have these flat spots. My brother 10As have these also. THEY SOUND DIFFERENT. I think I finaly know why. I talked to a gentleman at a large speaker repair shop that has been around for ever and he seemed to know exactly what I was talking about. He said the 751... are early Peerless and were made in Denmark. The 5514... were made FOR Peerless in the US. I asked Ken about this years ago and I am not sure they had a record of it. but i get the feeling the early ones from Denmark are HF1000 and the later ones are SL1000 . Then when they redsigned it and made it silver with the plastic dome they still called it SL1000.
Point is there are two different Peerless tweeters and they do sound different. One made in Denmark and one made here for Peerless. Anyone know anything about this?? keith