This is my small, minimal and very simple stereo amp for tablets/smatphones.
All components, eccept tubes (NOS), are recycled from old non-recoverable radios (resurrection from the grave)
The chassis is from an old Phonola radio from the early 1950s, upside down from what it was originally to obtain a support surface for the smartphone
The two little lamps (2x6V in series) on the side, are used to light up the smartphone (at night)
The big filter CAP was put close to the output transformer because I needed to cover a big hole
I choosed 12AT7/ECC81 and 6AK6 because their very low heaters current (power saving), you might try to use ECC82, 12FQ7, ECC83 at place of 12AT7 (same pinout), and use 6G6G (same tube different pinout) at place of 6AK6
For smartphone recharging I used a cheap 12V to 5V car audio USB power supply
NOT SUITABLE FOR CHILDER USE, SHOCK HAZARD!
Note: I am planning to add a small Bluetooth module (recycled) to this amplifier.
Output Power 1+1 W
Output audio transformers: 10K SE (EL95/ELL80)
Tubes; 12AT7/ECC81 - 6AK6(=6G6G octal)
Total heathers current: 0.3A @ 12V
note: 6AK6 heaters in series (6+6V)
Main voltage: 110/120 Vac (about 135-150Vcc after filter cap)
Output: 5Vcc 1A for device recharging
All components, eccept tubes (NOS), are recycled from old non-recoverable radios (resurrection from the grave)
The chassis is from an old Phonola radio from the early 1950s, upside down from what it was originally to obtain a support surface for the smartphone
The two little lamps (2x6V in series) on the side, are used to light up the smartphone (at night)
The big filter CAP was put close to the output transformer because I needed to cover a big hole
I choosed 12AT7/ECC81 and 6AK6 because their very low heaters current (power saving), you might try to use ECC82, 12FQ7, ECC83 at place of 12AT7 (same pinout), and use 6G6G (same tube different pinout) at place of 6AK6
For smartphone recharging I used a cheap 12V to 5V car audio USB power supply
NOT SUITABLE FOR CHILDER USE, SHOCK HAZARD!
Note: I am planning to add a small Bluetooth module (recycled) to this amplifier.
Output Power 1+1 W
Output audio transformers: 10K SE (EL95/ELL80)
Tubes; 12AT7/ECC81 - 6AK6(=6G6G octal)
Total heathers current: 0.3A @ 12V
note: 6AK6 heaters in series (6+6V)
Main voltage: 110/120 Vac (about 135-150Vcc after filter cap)
Output: 5Vcc 1A for device recharging
Last edited:
The amp is still to be finished, I still need to isolate the connections of the output transformers, I have to cover them with something, or better bring the cables underneath.
Also I will add 0.1 uF capacitor in seriers at the input, reduce at 47Kohm the potentiometer and add 470 Kohm resistor between triode grid and GND and a small 220 pF capacitor in parallel to the feedback resistor just to avoid high frequency oscillations.
Also I will add 0.1 uF capacitor in seriers at the input, reduce at 47Kohm the potentiometer and add 470 Kohm resistor between triode grid and GND and a small 220 pF capacitor in parallel to the feedback resistor just to avoid high frequency oscillations.
Last edited:
