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84b vs 60 speaker - Printable Version

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84b vs 60 speaker - falcon123 - 04-16-2020

as you can imagine philco speakers arent readily available anywhere let alone here. i have a line on a 60 speaker im trying to shoehorn into my 84b. the parts are the same on each speaker except the field coils as they carry different part numbers and have dfferent currents 84=50ma,60=65ma yet both have the same resistance value 1140 ohms so inductively they must be different but both use a single 42 tube.to my mind it should work,BUT WHAT DO I KNOW??? is this feasible?

RE: 84b vs 60 speaker - Ron Ramirez - 04-16-2020

Yes, you can use an S-7 (Philco 60 speaker) to replace an SB (Philco 84 speaker). The SB, as you have noted, has a lower current capacity and therefore the size of the field coil is much smaller.

I'm frankly surprised that Philco, the constant cost cutters, even made a different speaker for models 84 and 37-84 when the S-7 could have been used instead.

The field coil of the S-7 isn't that much larger than that of the SB so you should have no problem installing the 60 speaker into your 84. The frames of both are the same size.

RE: 84b vs 60 speaker - falcon123 - 04-16-2020

thanks ron. as i looked at the '37 philco parts book i was confused by the small difference between the two. so much so that i figured i'd better ask as i thought i was missing something! it does make me wonder why they bothered making one or the other.

RE: 84b vs 60 speaker - falcon123 - 04-17-2020

do you know the 84b voice coil diameter and length?i want to try and rebuild the retrograde. i realize that the the audio transformer will need to be changed to accomodate 4-8 impedence. parts are a problem as all i have is ebay.i want to check the feasibility of using a modern spider the bugaboo is the suspected diameter of 3/4''.