• 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.

Stereo amplifyer project

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Hello
I would like to build this tube amp circuit here Five Tube Stereo Amplifier and I was wondering if anyone knew where I could find some parts for it. I have found mostly everything I need from Surplus Sales of Nebraska but I can not for the life of me find a transformer for it. I'm still pretty new to tube radios but I have replaced a capacitor in one of my radios and plan on replacing another one very soon. I hope to use this circuit to hook up to the audio output from a DVD player and then run it to some Drive-in speakers. That way I can use a projector to project movies and use the drive-in speakers for the sound.
 
For the article's concern about correcting previous schematic errors, here's another: You must also install a capacitor of about .005 mfd between the wiper of each level control and the grid (pin #2) of the respective 6SQ7 input tube. Then, you must also place a resistor of about 10 megohms from each grid terminal and ground. Without these components, there is no bias applied to these tubes, and the sound will be very distorted. These components allow a "contact" bias to be developed, which is very commonly used with these types of tubes and designs.

Dave
 
For the article's concern about correcting previous schematic errors, here's another: You must also install a capacitor of about .005 mfd between the wiper of each level control and the grid (pin #2) of the respective 6SQ7 input tube. Then, you must also place a resistor of about 10 megohms from each grid terminal and ground. Without these components, there is no bias applied to these tubes, and the sound will be very distorted. These components allow a "contact" bias to be developed, which is very commonly used with these types of tubes and designs.

Dave

I agree to that. Better yet, give the input tubes normal cathode bias, because this method is very unstable and changes the operating point when the tube ages. (a resistor parralleled to a capacitor connected between earh and cathode). Would you like me to calculate the resistor and capacitor for you?

Fries with that? :D
 
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