I’ll be brief since I don’t like writing too much anymore. Part of the reason I have been so disconnected for the past two years. Projects kept going though, and here is a restoration I made to an old 1960 Magnavox 88-02-00 Tube Amplifier.
Restoration
Which involved replacing all the old paper capacitors -with contemporary equivalents-, and replacing the resistors for something closer to the schematic. I also took the liberty to add a volume knob, two input switcher (for a future raspberry pi streaming action), input RCA jacks and output speaker posts (screw-on and banana plug), and also brought the whole thing up to code by adding a three prong 120V socket (commonly used in power supplies) a fuse a lighted switch and brand new wires. I also took care of adding an inline resistor to drop the voltage from 120V to the original 110v that was used in 1960, this is to avoid adding more power to the circuit which in turn
Special Change
The main change that I did to this amplifier was to replace its 6v6 tubes to their lower voltage counterpart the: 5v6. This is because 6v6 stock usually goes for way more dollars than the 5v6.
According to the datasheet the only difference between them is the operating voltage/current consumption. So all I had to do was to add an inline resistor to drop the voltage from 6.3V to 4.7V.
With this change securing new old-stock tubes is easier and more economic with zero differences in sound quality (theoretically).
Gallery
Since pictures speak better than words…
The 3D printed parts:
https://www.thingiverse.com/thing:2799993
Circuit
Conclusion.
This has been one of my favorite projects. The fact that this device still works after 58 years still amazes me. The sound is crisp and clear and its loud enough to fill a room.
To think that, in the present time, all of this plastic and metal can be fitted in an IC the size of a fingernail. This only speaks at to what the future will hold for technology.
For the time being, I get to enjoy a piece from the past.