Vacuum tube based 2.1 Home Theatre Amplifier

[rrunner]

I have built a 3 + 3 w tube amp based on Chinese DIY kit(6P+6N combination), There is distortion in sound above 60% volume. Is there any way to tame the sound using a combination of capacitors/resistors at the output stage and make sure the speakers are not affected by chance if cranked at full volume.
Will biasing the tubes get rid of the distortion, what do I do if there is no inbuilt option in the provided kit, is there an alternate easy method.

 

[radium7]

I have built a 3 + 3 w tube amp based on Chinese DIY kit(6P+6N combination), There is distortion in sound above 60% volume. Is there any way to tame the sound using a combination of capacitors/resistors at the output stage and make sure the speakers are not affected by chance if cranked at full volume.
Will biasing the tubes get rid of the distortion, what do I do if there is no inbuilt option in the provided kit, is there an alternate easy method.

please send the circuit diagram, photos of your built. so i can suggest you some solution.

 

[rrunner]

Ok, here it is. Funny thing was when I tried to do full bridge rectification the power transformer became extremely hot and I had to remove the 2 extra 1N4007 diodes the board allowed to retrofit as modification.

Inside a wooden diy chassis.

Barebones version.

 

[srinisundar]

Nice build.

 

[radium7]

Barebones version.

The circuit looks very simple. without checking the amp directly it's difficult to tell the fault. i can give you few tips, this can help you
1. Check the resistors for correct value and correct place.
2. Check the capacitors for polarity and value.
3. Measure the voltages at plate, cathode and grid of all 3 tubes. Give the voltages here.

1. Check both speakers have same type and level of distortion. Check whether it is hum or distortion. if it has hum check the heater wiring (6.3V), if the power transformer has 6.3V with CT, then connect the CT to the ground. Always use twisted wires for heater wiring.
2. Swap both 6p1 tubes and check. Faulty tubes may make this type of problems. if you have extra 6p1 tubes use it and check.
3. The 9th pin of 6N1 tube is connected to the shield between the two triodes. In the pcb 9th pin is kept unused, it should not be left like this. connect the 9th pin of 6N1 preamp tube to ground.
4. For singal wires use shielded wires, the input wiring looks complex, pls make it simple. This type of potentiometers are poor. Although it is new sometimes it may have problem. Check the pot.
5. Increase the power rating of the 6p1 cathode resistor. Try 270 Ohm 5 watts wirewound resistor.

 

[rrunner]

I have used Delta BM34 Power Transformer. There is an earth wire on the input side in green and there is an unshielded wire on the output side. I have not utilized it in my build, wondering what is the use of that wire. People who are familiar with this type of transformers can you please suggest its usage.