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Westinghouse turntable amp head convert to guitar amp?

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  • Westinghouse turntable amp head convert to guitar amp?

    I recently found an old 60's or 70's Westinghouse turntable cabinet, sadly the turntable had been stripped from the cab and alls that was left was the speakers and head. I salvaged both and am interested in converting it into a tube guitar amp, hopefully this is possible. I've worked various electronic projects before so for the most part I know what I'm looking at as far as all the components on the circuit board itself are concerned, but I've never worked on any sort of amplification project before so that's where I need a little help as to whether or not this project is even possible. Here are some pictures of the head to see if that helps at all.












  • #2
    This amp appears to be the type called AC/DC where there is no power transformer and the "ground" of the circuit ties almost directly to one side of the incomming power line. Very dangerous to operate as-is. Tubes are very likely 50C5, 35W4 and 12AU6. Output probably about 3 watts. You will need to obtain an isolation transformer to make it safe, re-cap it, and get rid of any phonograph equalization. Have you looked for a schematic?
    WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
    REMEMBER: Everybody knows that smokin' ain't allowed in school !

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    • #3
      Tube types are One 12AX7 and the other two are 35C5. I have actually managed to find a schematic as well
      Amp disasters & other things - All kinds of tube creations

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      • #4
        Thanks for posting that schematic. Interesting amp with push pull 35C5s. Probably 5 to 6 watts. You still need an isolation transformer to make it safe. I would think something around 60 VA or more would do the job. Because of the half wave power supply, you need about twice the VA rating more than you actually use. If you just improvise a phone jack connected to the phono input, you should get an output but there may not be much overdrive. With a little work you could add another preamp tube for more drive. Just connect a speaker between the black and yellow or black and green wires, which ever seems to produce the most output.
        WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
        REMEMBER: Everybody knows that smokin' ain't allowed in school !

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        • #5
          Beware of tha nasty selenium rectifier. If that thing lets loose you will hate life. I would use a modern diode setup. IMHO though, these series filament amps are always more troble than they are worth.

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          • #6
            +1 it definitely needs a 120-120 transformer to make it safe, the mains is too close to your hands there. I think it's meant to amplify a crystal cartridge, much bigger output than your pickups, so it would be v disappointing gain-wise. Sorry!

            Oh +1 on the selenium rectifier too, unless you want your house to smell of burning rotten cabbage when it pops.

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