• 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.

Tube buffer for car audio

NeuSounds said:
hello there,

i own a car audio shop in jakarta, indonesia...
i want to build a tube buffer for use in a car...
can anyone help me with schematic and etc ?
thanks before.....


Unless you get involved with "inverter" circuitry, the "12" VDC available in an auto limits your options, severely.

The 6GM8 twin triode is a nice tube and it's intended for automotive service. :) Simple 6GM8 section cathode followers (1/channel), using battery bias, might do the job for you.

What's the RMS voltage coming out of the "head"?
 
NeuSounds said:
ussually from head comes 4volt, the bigger is 9volt....


If we use a 6GM8 section combined with a "1.5" V. cell for bias, 3 V. peak to peak, which is approx. 1 VRMS, is the maximum I/P allowed. To get that far, constant current sink (CCS) loading set for 1 mA. will have to be employed.

The beauty of the 6GM8 is its ability to function with only "12" VDC on the plate. :) However, miracles are not going to occur. To handle a more than 1 VRMS I/P signal requires conversion of the car's "12" VDC into a higher DC voltage. All methods of conversion I'm aware of have their shortcomings. :(