A Day In The Amp Shop

A Day In The Amp Shop

A day in the amp shop for Pat Kauffman doesn’t always involve Twins, JCM 800s or speaker jobs. On Monday, Feb. 22, I came in specifically to repair 2 radios for 2 fellow co-workers.

First project was Joe’s family’s 1948 Philco model 48-250 which was bought new, in Brooklyn. The legend of the Philco starts with Joe’s grandfather buying it for his daughter (Joe’s mother)and she had it in her bedroom where she grew up. Joe’s parents had it in their loft in Manhattan through the 60s and 70s. In the early 80s, when it stopped working, they took it to a local TV & radio repair shop. The technician said that “tubes are on the way out and solid state is the way to go”. So he modified the radio with a solid state diode to replace the 35Y4 tube that they thought they couldn’t get anymore. Since the 80s, Joe’s family continued to use the radio but as time when on, the stations started to fade. A 60-cycle hum started to appear.

First, I removed the modification of rectifier diode and power resistor and installed a NOS 35Y4 tube, which we had in stock. Then, I replaced all capacitors in the radio, cleaned & lubed all pots, all controls, tube sockets and put a fresh coat of a Main Drag Secret Bakelite-Lovin’ rejuvinator.  Even I was impressed by the quality of reception, clarity and volume.

Shine and tune, Joe.

Second repair was a recently acquired 1959 Grundig. Tom bought this at  a local junk shop but unfortunately to our surprise, about half of the circuitry inside has been ripped out violently by previously frustrated technicians. After feeling stuck in a conundrum of a totally badass radio and a possible high repair bill/ frustration, it was probably not worth the time. I then struck upon the idea of just making it a line level audio amplifier, or to put it another way, Tom’s new ipod player.

I built a 6-watt audio amplifier with a single EL84 and single 12AU7 tubes. Using the existing transformers and speaker, I wired the circuit on the cuff, even designing and using the old tone controls. After digging through the entire shop for the correct lightbulb for the faceplate, I finally salvaged them from Tom’s other German radio under my bench, which has a habit of smoking during use. Maybe I could talk Tom into turning his radio into a waffle iron.

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