I recently purchased a nearly-empty Zenith radio cabinet, with the intention of doing a 'resto-mod' to include some fancy digital toys like a Raspberry Pi and solid-state storage. Might make it into a kind of Home Theatre server or something along those lines.
This is the radio model:
Zenith 6S643BT
6S643BT Ch= 6B16BT Radio Zenith Radio Corp.; Chicago, IL, bu
Note: the below is not my radio, just an image from the internet. Mine looks just like it, but missing the radio dial and knobs, with no chassis inside.
Although the cabinet is in excellent shape, there is no chassis inside anymore. The only thing remaining was the speaker, which is an 8-inch Zenith field coil model. The model stamped on the frame appears to be 49H427 (the H might be some other letter, it is heavily stamped and the ink bled).
The speaker appears to be in good shape. It appears to be functional based on tests with the ohmmeter.
I found a schematic for the original radio with amplifier section. Output tube was a 6k6GT.
Although I have no experience with field coil speakers, I do have some limited experience with tube amplifiers. I suspect I could build a simple monophonic amp that used a 6K6GT output tube (I have some handy) and make use of the original speaker as a monophonic music output source.
The question I have is if it is worth the trouble. I could put any modern 8" speaker into the hole in the cabinet.
Thoughts?
This is the radio model:
Zenith 6S643BT
6S643BT Ch= 6B16BT Radio Zenith Radio Corp.; Chicago, IL, bu
Note: the below is not my radio, just an image from the internet. Mine looks just like it, but missing the radio dial and knobs, with no chassis inside.
Although the cabinet is in excellent shape, there is no chassis inside anymore. The only thing remaining was the speaker, which is an 8-inch Zenith field coil model. The model stamped on the frame appears to be 49H427 (the H might be some other letter, it is heavily stamped and the ink bled).
The speaker appears to be in good shape. It appears to be functional based on tests with the ohmmeter.
I found a schematic for the original radio with amplifier section. Output tube was a 6k6GT.
Although I have no experience with field coil speakers, I do have some limited experience with tube amplifiers. I suspect I could build a simple monophonic amp that used a 6K6GT output tube (I have some handy) and make use of the original speaker as a monophonic music output source.
The question I have is if it is worth the trouble. I could put any modern 8" speaker into the hole in the cabinet.
Thoughts?
The main reason for using Field Coil loudspeakers was to reject mains hum. As the cycle rises and the rectifier pumps more current into the output stage, it passes through the Field Coil that acts as a smoothing choke and damps the hum when out of phase hence the tank capacitor value and reservoir value. Plus of course, there was no need for heavy magnets.
So my question then - is there any particular musical advantage to retaining the field coil speaker, when the 'choke' effect is not required any longer? I mean, I could use a cheap class D type amp in the unit, and keep down the weight, price, and heat. Or I could build a nice little low-power mono tube amp, incorporate the field coil into the PS as a choke once more and use the built-in output transformer.
Since the radio has been stripped of the radio chassis long before I got it, there is no particular reason for me to try to keep the authenticity factor. So if I did use the original speaker, it would be either because it lent some value to the output quality, or just to do it because it's kind of cool.
Since my knowledge of the old field coil speakers is very limited, I thought I'd ask what others think.
- Status
- Not open for further replies.