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I haven't dug into my original speaker at all, other than to know that it doesn't work--the radio works fine, there is an aftermarket speaker plugged into it (cobble-job), but I'd like to ditch that and replace the original speaker. Does anyone have specs on it?

Do you see any labels having a P-xxxx number for the radio? This would be the Philco number and not the PA-xxxx Packard used for accessories. I have three or four schematics for mid 30s radios which mention 37 but they go by the Philco number. Didn't see any specs for the speaker -- just the Philco part number.

Most of the main speakers in that era use an electromagnet for the field coil which sometimes serves a dual purpose as being part of a filter circuit for the power supply. No idea if yours might be one of them but I doubt you will find any off the shelf speakers today that will have the electromagnet. Maybe there is a radio person who might have a suggestion and proper way to remove the speaker without sending the unit to a radio repair shop.

When you take it out of its case, see if you can find the Impedance rating in ohms on the speaker. If not, you can approximate it by measuring the resistance. This video show how easy it is. You need a multimeter.

https://www.youtube.com/watch?v=4Ocgo1p8Z3Y

You need the diameter.

For my car, I found an rugged outdoor speaker at a stereo repair shop. It was pancake flat and red plastic, but the impedance and diameter matched so I put some similar-looking black cloth over the front and mounted it in the case (which was now mostly empty). I did that in 1978. Still works.

With most speakers being 4 or 8 ohms, do you remember what your original Packard speaker was?? Just curious if it was something oddball. Chris.

Your original speaker may also have an electromagnetic magnet rather than a regular magnet. Not sure if that means that a modern replacement won't work but not having the magnet in the circuitry could mean that some redesign of the radio itself would be needed.

It's a PA-5154, photos attached. The wire plugged into the speaker socket runs to an aftermarket speaker, the other speaker wire goes to ground.

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According to this sitehttps://sites.google.com/site/identifyingcarradios/home the PA-5154 is a Philco 1432 but there might be a P suffix designation on the number. I have a P-1432H schematic but do not know if there is a significant difference between the P or H or a no suffix designation. Not sure it is the correct schematic for your radio but here is the one I have.

The X on several of the wires in various places denotes the wires are connected thru a plug to another part of the system such as the control head or the 3 wires connecting the speaker. Someone else more into radio circuitry will need to say if the electromagnet field coil is actually needed as part of a power supply filter or if it is just being powered off the main incoming 6v supply line and can be eliminated with no adverse effects.

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Thanks, HH!

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Although I grew up in the '50s helping my grandfather in his radio/TV repair shop, my memory of these details is fuzzy. However, can say that the electromagnetic coil isn't powered by 6v DC as AC or pulsating DC is needed for an electromagnetic coil to work. It should not be too difficult, though, to see in the schematic whether it can simply be disconnected or whether it is part of the voice coil assembly's functionality.

However, can say that the electromagnetic coil isn't powered by 6v DC as AC or pulsating DC is needed for an electromagnetic coil to work.

The electromagnet is fed directly off the 6v incoming line and is pure DC. There are many DC magnets out there -- solenoids and relays are all over the cars and yes, all are straight DC electromagnets.

There are a couple of chokes and a capacitor at the front of the 6v input in the radio. Incoming voltage passes thru one choke and voltage continues on thru the second choke to supply the tube filaments. The 6v to the magnet comes from between those chokes and along with a filter cap on the line also feeds the power transformer, vibrator and rectifier tube filament thru another choke. The other end of that same 6v line has another choke & filter capacitor arrangement with the electromagnet acting as the second choke. It forms what appears to be an identical circuit as on the front side which makes me think it might be part of a tuned circuit. I am really not up on radio intricacies to know if it is or if the second layout is important and is acting along with the front set of components.

I am kind of suspecting there is some kind of frequency internal noise filtering going on with the 6v line to help control any spark, brush or switch opening and closing pops that might get into the radio. Even with the radio noise suppression capacitors in various spots thruout the car the auto electrical environment is a very dirty place as far as noise makers so losing a filter if it is one could be an issue. Radio and vacuum tube circuit intricacies are not my specialty.