I decided to replace the speaker in this redio with a salvaged speker from a Silvertone Model 20. That speaker has the transformer attached to it, whereas the Sonora has its transformer under the chassis. I tried snipping the wires between the transformer and speaker of the Silvertone and hooking the output leads from the Sonora transformer to it Silvertone speaker. I know the Silvertone speaker is good. Why does this setup not work? If I replace the Silvertone speaker with a generic 8 ohm speaker it works. What gives?

Hi Stan

Does the speaker have a field coil? This is a large coil of wire in back. Is so it needs to have the field powered for a magfnet.

Norm

:I decided to replace the speaker in this redio with a salvaged speker from a Silvertone Model 20. That speaker has the transformer attached to it, whereas the Sonora has its transformer under the chassis. I tried snipping the wires between the transformer and speaker of the Silvertone and hooking the output leads from the Sonora transformer to it Silvertone speaker. I know the Silvertone speaker is good. Why does this setup not work? If I replace the Silvertone speaker with a generic 8 ohm speaker it works. What gives?

:Norm, it is a permanent magnet speaker.
:Hi Stan
:
: Does the speaker have a field coil? This is a large coil of wire in back. Is so it needs to have the field powered for a magfnet.
:
:Norm
:
::I decided to replace the speaker in this redio with a salvaged speker from a Silvertone Model 20. That speaker has the transformer attached to it, whereas the Sonora has its transformer under the chassis. I tried snipping the wires between the transformer and speaker of the Silvertone and hooking the output leads from the Sonora transformer to it Silvertone speaker. I know the Silvertone speaker is good. Why does this setup not work? If I replace the Silvertone speaker with a generic 8 ohm speaker it works. What gives?

This is all too obvious, but just to be safe, I'll recommend that you be sure that you're connecting to the speaker voice coil and not the secondary of the output transformer. If you were going for the voice coil but accidently wired to the transformer secondary, you'd get no sound. Are you sure that the Silvertone speaker works otherwise? Connect a battery across the voice coil and see if it clicks.

Also, in my experience I have found that many of the speakers of then, especially the smaller ones, are usually 3.2 ohm speakers. If you can't get that Silvertone speaker to work, try a 3.2 or 4 ohm modern speaker vs. an 8 ohm. Whichever one is loudest and has the best tone is the correct speaker.

Thomas

:Thomas,
Never hurts to point out the obvious with me ;>). Here is what I found. The Silvertone speaker is 3 ohm and the modern test speaker is 8 ohm. The 8 ohm sounds fine. In aligning the radio, I ended up with very weak output. I retested the 35A5 tube and found the filament continuity was bad. Replaced that tube and got normal output. Retested the Silvertone speaker and it at least works, but nowhere close to the modern speaker...I think the 35A5 was not strong ehough to drive that speaker. I'm going with the modern speaker and new 35A5. All is well. Thanks a ton for this and all your other help!!!

:This is all too obvious, but just to be safe, I'll recommend that you be sure that you're connecting to the speaker voice coil and not the secondary of the output transformer. If you were going for the voice coil but accidently wired to the transformer secondary, you'd get no sound. Are you sure that the Silvertone speaker works otherwise? Connect a battery across the voice coil and see if it clicks.
:
:Also, in my experience I have found that many of the speakers of then, especially the smaller ones, are usually 3.2 ohm speakers. If you can't get that Silvertone speaker to work, try a 3.2 or 4 ohm modern speaker vs. an 8 ohm. Whichever one is loudest and has the best tone is the correct speaker.
:
:Thomas

35A5 tubes are pretty darn strong. The speaker may either have a malfunction (bad coil or magnet), or it may be a mismatch for the transformer. I know that 3.2 ohm speakers sound lousy on an 8 ohm transformer, but 8 ohm speakers may sound just fine on a 3.2 ohm transformer. I'm not sure. I've always had fine luck with 8 ohm speakers, though. If the 3.2 ohm speaker is sounding poor, it may simply be a mismatch. Try it sometime with a radio that is known to use a 3.2 ohm speaker. You could also purchase a universal output transformer and try this with that speaker, or you could try disconnecting the transformer on your radio and then wiring that speaker up with its own transformer. Most transformers are fair matches for 35A5 tubes, so it should work well if the speaker is in okay condition.

Thomas