I have recently discovered that the SR-7145 radio has a hidden crossover in the radio. With the crossover on the output are as follows.
Head unit puts out 'dash' high fequency left and right
Amp puts out 4 channels...two are left and right low fequency and are the speakers in the front doors, the other two are full spectrum and are the speakers on the back doors.

I am taking this radio and amp (got it out of a picknpull) out of a 89 760.
Why? With today's technology i don't need a cd player or cassete deck...a radio and is all i need. and although i don't have the oh so popular ipod yet or any of its variants...when i do it will play through the radio as well. Seeing how this radio and amp are made by alpine....they sound great.

after turning the crossover off , i have all four speakers in my 77 245 sounding great...and after having a radio ripped out of that car (and it was nothing special) who is going to want this volvo stock radio anyways?
I think its a great radio upgrade. Just want to share....
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1969 145s (but not an "S"), and a baby 1977 245DL just rolled out 200,00