I just finished replacing the 12uf caps in a pair of LX10 crossovers. In the process I noticed that the value of R1 as installed is 4 ohms. Looking at the schematic of the LX10, the indicated value of R1 is 5.1ohms. One of the notes on the drawing seems to indicate that R1 was revised and the drawing was redrawn. The dates are a bit hard to read but I think they are '77 or '80.
The crossovers I have came out of a set of C56 Dorians with S1 system, probably from the late '60s. I'm wondering if R1 was revised from 4ohm to 5.1ohm when this drawing was redrawn? If so, should I change the 4ohm resistors to 5.1? These have the old white LE14's. I'm thinking maybe the revision was made when the LE14 went from the Aquaplas cone to the paper, or wouldn't that have anything to do with the resistor?
On another note, the value of R2 should be 7.5ohms. One of the xovers has a 7.5ohm resistor placed just as shown in the drawing. The other has a 15ohm resistor in parallel with a third resistor which is also 15ohm but only 5w as opposed to 10w like the other 15 ohm resistor is. The net electrical result is the same as a single 7.5ohm, bit I'm curious as to why JBL would do this? The serial #s are only about 100 apart.