Hi, I'm working on a project which involves taking this old broken radio I had lying around from the late 1930s to early 1940s and connecting a modern amplifier to it's 4" 4ohm speaker.
The original tube amplifier appears to be beyond repair (at least easily), but I tested the original speaker by connecting it to a Lepai LP2020A+ and it still works really well. I was surprised by how decent the sound quality was when connecting that amplifier to this really old speaker.
Since the Lepai amp worked and sounded good, I went ahead with taking it apart and integrating it with this radio. One important part of this project is using the original volume potentiometer on the radio as a replacement for the Lepai amp's volume potentiometer. After confirming the original pot still works with my multimeter, I attempted to remove the Lepai's volume pot with less than ideal results due to my inexperience with desoldering components. Despite the desoldering job being a bit sloppy, I still ran wire from the original pot over to where the Lepai's pot was to see if it worked, which it didn't. Since making this modification, I can't get any audio output from the Lepai amp and when turning it's new volume pot, all get is static as the knob is being moved.
I'm not sure whether the damage is permanent or if it's simply a bad connection. At this point I'm looking for another amplifier solution being that the Lepai is a bit too large anyway. Since I'm a lot better at soldering than desoldering right now, perhaps some sort of non-assembled DIY amplifier kit would a better fit this project. I was a number of those on eBay but don't know if there's a better source for those or whether they're decent quality.
The features I'm looking for in the ideal mini amplifier are:
Thanks for any advice you have to offer. 🙂
The original tube amplifier appears to be beyond repair (at least easily), but I tested the original speaker by connecting it to a Lepai LP2020A+ and it still works really well. I was surprised by how decent the sound quality was when connecting that amplifier to this really old speaker.
Since the Lepai amp worked and sounded good, I went ahead with taking it apart and integrating it with this radio. One important part of this project is using the original volume potentiometer on the radio as a replacement for the Lepai amp's volume potentiometer. After confirming the original pot still works with my multimeter, I attempted to remove the Lepai's volume pot with less than ideal results due to my inexperience with desoldering components. Despite the desoldering job being a bit sloppy, I still ran wire from the original pot over to where the Lepai's pot was to see if it worked, which it didn't. Since making this modification, I can't get any audio output from the Lepai amp and when turning it's new volume pot, all get is static as the knob is being moved.
I'm not sure whether the damage is permanent or if it's simply a bad connection. At this point I'm looking for another amplifier solution being that the Lepai is a bit too large anyway. Since I'm a lot better at soldering than desoldering right now, perhaps some sort of non-assembled DIY amplifier kit would a better fit this project. I was a number of those on eBay but don't know if there's a better source for those or whether they're decent quality.
The features I'm looking for in the ideal mini amplifier are:
- Approximately the size of a Lepai LP2020A+ but smaller is better
- Can be stereo or mono output only since it's only going to power one speaker.
- Yields decent sound quality
- Has build in on/off switch
- Has built in LED diode anywhere on the board (not important but useful)
Thanks for any advice you have to offer. 🙂
The Lepai pots can be flakey - I have had one go on me and tapping it with a hard object fixed it. If you want an even better replacement for the Lepai check out the TPA3116D2 thread. A much better sounding amp with up to 50 watts for $17 and no case as you won't need that anyway. The TPA3116 is a wonderful sounding amp - one of the best in this power range at any price.
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