• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

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Had these GM70s for many years and was slowly collecting parts for an Amp with them, now the time has come to assemble everything :giggle:
6N6P - 6P14P-EV with CCS Load - GM70.
I made a PCB for the driver stage, at first i wanted to use cathode bias but now decided on fixed bias instead so i made a little bias supply on breadboard. The heater supplies are 180W Dell laptop adapters delivering 19.5V, found those in the electronics scrap bin. The power transformer is custom wound by german company "ampdesign" and has windings for 250- and 650V, B+ for the GM70s will be around 800V, don't really feel comfortable going higher than that (and have no measurement equipment for >1kv). Bias and Heaters are switchable separately from B+ via the two switches on the front.
Planning on using Toroidy TTG-GM70SE as the OTs but that'll have to wait, can't afford them right now.

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Stereo integrated Push-pull integrated amplifier with 2xE130L in each output connected with cathode feedback (33%). There is a 6101 in the phase splitter, and a 6N1P-EV in the excitation stage, while the ECC83 and 2SK2700 work in the gramophone preamplifier and RIAA corrector.


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