Audio Amp vs. Bananas

A low-end audio power amp destined for a pair of ancient-yet-still-serviceable speakers arrived, but attempting to poke wires through the side holes of the banana jacks showed they were oriented in random directions. Back in the day, banana jacks had D-shaped shafts fitted into D-shaped panel holes, but those days are gone.

A few minutes with screwdriver, wrench, and (tiny) punch sufficed to line up the holes for E-Z poking:

Fosi audio amp - jack alignment
Fosi audio amp – jack alignment

Despite the new convenience, I decided to solder banana plugs to the speaker wires, leading to the discovery my few remaining plugs came from the very bottom of the usability barrel:

Cheap banana plug - solder side
Cheap banana plug – solder side

I have no idea how one might affix a wire to that blank stub, but poking a small center drill into the brass lump produces an easily solderable recess:

Cheap banana plug - center drilled
Cheap banana plug – center drilled

Dab with flux, tin, insert wire, add solder, repeat with all four plugs, and I’m set with a boomin’ system.

6 thoughts on “Audio Amp vs. Bananas

  1. The preamp in the shop-stereo hit EOL after 40 years (one channel died, and it will be a pain to unshield it and rebuild). OTOH, I did a new phono section in the ’90s, so it’s not completely new territory.

    The replacement seemed all right, at least until I turned it on yesterday. It seems that the 38F idle shot environment means it’s not ready to work properly until something (switching supply at a guess) is warmed up. After a few minutes it was acting like it had proper Vcc and Vee, but sheesh!

    I’m used to mechanicals not being happy in the cold, but really?

      1. Sleeeeepy ‘lytics. [grin/wince]

        Tried it this morning, even colder inside. Though I had left it on, the final amplification section was not happy. OTOH, the tape-out section is OK, so volume control is in the computer.

        I doubt it’s covered in warranty, since it was an Amazon buy (and out of the return window). It will be interesting to see what’s inside… Once I have time.

        License exam in two weeks and I’m going to try for the trifecta. Extra or bust! (Practice tests look promising, though there’s only a 2 hour window. Not sure if administrivia will get in the way. OTOH, the following month would be OK. General should be a given.)

        Hmm, rebuild the old amp? Maybe.

        1. I’m sure the instructions (if you could find them in the box) tell you to use it only at elevated room temperatures, then clean when necessary using a mild cantaloupe.

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