The PHILCO Phorum

Hi:

In the Philco 37 630 and 37 620 series, the standard 8" speaker used(with 3 soldering posts), the ohm rating for the field coil was never mentioned or noted in any of the Philco schematics or parts list. Coming across many of these type speakers I have noticed differences in field coil size and differences in ohm value.
I have mixed and matched these type 8" and even 12" speakers to different chassis 's of the 630 and 620 series and never had a problem. What is the reason for the various size field coils?? (Better sound output)?
Thanks.

All are rated at 1140 ohms. The value is not given in Bulletin 250 (37-620) or Bulletin 251 (37-630), but is given in Bulletin 251A (revision for both 37-620 and 37-630).

The 8 inch K-38 speaker used in Model 37-630T has a larger field coil than that used in Model 37-620B (S-7), even though they have the same DC resistance. Heavier field - better bass response. Ditto the 10-1/2" speakers used in the console models (H-24 and HS, respectively) - note that the originals were 10-1/2" diameter, not 12".