Help with date code on field coil speaker in early 50's Fender Pro

F15N = Field 15" N magnet I believe... C5563 = June 3, 1955? Kinda guessing here but makes sense to me if your amp is from the early 50's. Neat old speaker! Hopefully someone will be able to confirm/correct my guess

 

If you're talking Fender, I think they stopped making the TV fronts about 1955 so, but I don't understand the field coil speaker in it, but then again I'm no expert on these. Just sayin' that all the early Fender amps I've ever seen had alnico 5 Jensens etc. in them

 

Should be some more numbers on there the one you want looks like this 220xxx. 220 is Jensen's EIA code and the next three numbers are the date code.
@Wally had or has an early field coil speaker Pro. Hopefully he'll chime in.

 

This^^
There should be another number inked on.
I didn't think Pros had field coil speakers...I've seen plenty of early ones with the OT mounted right on the speaker frame, but I'll be danged if that one doesn't say "Field Coil" on it.
Maybe its a bell cover from another speaker.
A regular OT has 2 or 3 wires in and 2 out for the speaker.
A field coil has more wires going in.

 

As BobbyZ notes, we are not seeing the EIA manufacturer’s code which contains the date code...220 for Jensen, x for the last digit of the year, and yy for the week of the year. I owned a 1952 Pro with an OEM Jensen F15N. The EIA date code was 220 2yy. I forget the week.

 

Here's a 59 Jensen 15" Alnico I have for sale, code showing the date code, contract code, original cone number, speaker model etc:

 

In addition to the Jensen codes and for those who are not acquainted with Hammond organs, the “AO 22749 0” number is a Hammond stamp. There is a Hammond code on the cone as well.

 

They must have made a few with field coil speakers, two of them accounted for here.
Could be Jensen was just slower to make permanent magnet 15s?
Or maybe it was just the "N" magnet speakers that lagged behind?
Just pure speculation on my part, all of this took place before my time.

 

Ah... the 220 code! Now we're on with that at least 220 = Jensen 01= 1951 34= 34th week of that year. As to the rest, you got me! LOL!!!

What about this - Did Fender make special order amps back then whereas someone want a field coil speaker in the amp for some specific purpose? Just throwing that out there...

 

I think I read somewhere once that back in those early days, Fender would take special orders on guitars like colors etc. if someone wanted something other than the "white", and I think I remember that they did this practice for quite a while. Not sure how far in breadth that "special order" stuff went with them, but maybe they did this with amps as well. Or... another "maybe" is that Jensen was backordered on the normal N's etc. so Fender took what they could get at that particular moment in time when this amp was built? I suppose it's all speculation but one things for sure - I like this thread!

 

My ‘52 Pro, which lives in Oklahoma now, was a 5B5....very similar to your late 1951. It was a wreck when I got it....the cab had to e recovered, the speaker was reconed by Weber, and I did the electronics. I replaced all of the tone and coupling caps since those old paper in oils do not stand up over time. When I got it running, it was a dull and dark sounding amp....not correct at all. So, I went back into the circuit and started testing resistors. ALL of the resistors on the board had drifted significantly. I left the input grid resistors since they don’t carry much current and were dead on correct. When I fired the amp back up, glorious sounds emanated. I suppose I was listening to a brand new 1952 Pro....firm low end, brilliant high end, wonderful harmonics, great amp! If your Pro is dark sounding with little harmonic content and no dimension to its soundstage, you might look at the circuit again.

 

Your amp is running 6SL7s while the ‘52 ran 6SC7s. These are the same tubes but with different pinouts. If your amp was used much in it’s lifetime, the resistors likely will have drifted. The 250k plate load resistors all tested around 470kohms in my 5B5!! Yes, someone might take exception to all of those components being replaced, but I consider these things to be musical instruments as opposed to pieces of visual art. They need to be made correct, ime. PIO caps of that age were gone long ago....they just don’t last.

 

Note that the problem resistors in my 1952 5B5 included ALL resistors except for the input grid leak resistors. If your tech left the tone caps in, those need to come out as well. They are paper in oil, which have a shorter lifetime compared to more modern sealed film caps. got pics??