The amp will be destroyed earlier then without the transformer.
What happens when the DC offset changes to about 200mV for a short period of time wich is very usual in some cases and nothing that will destroy your loudspeakers. Lets say you have invested in the best transformer available wich only has 0,5 Ohm winding resistance. This results in a DC current of 400mA ! Funny thing is that the better the transformer is the worst this situation gets. This DC current ads up to the bias current of only one half of your symetric output, you can imagine yourself what happens next. Besides, even for this kind of DC current you will need a transformer with a very large magnetic gap in order to prevent it from saturation. In a real world example, imagine a DC offset of 50mV and a winding resistance of 2 Ohms you'll end up with only 25mA. That's nothing to worry about although a typical toroid transformer can allready go into saturation from current as small as this. Your loudspeaker also don't give a damn about this 50mV.
Output transformer in single ended tube amp are designed with a magnetic gap and have a DC current rating, wich is the aloowable current before saturation. In PP tube amps the transformer is part of the push pull output so the DC curent cancels out. This is also doable with transistor but then it has to be incorporated in the design. Something you simpy cannot do with a simple singel chipamp.
What happens when the DC offset changes to about 200mV for a short period of time wich is very usual in some cases and nothing that will destroy your loudspeakers. Lets say you have invested in the best transformer available wich only has 0,5 Ohm winding resistance. This results in a DC current of 400mA ! Funny thing is that the better the transformer is the worst this situation gets. This DC current ads up to the bias current of only one half of your symetric output, you can imagine yourself what happens next. Besides, even for this kind of DC current you will need a transformer with a very large magnetic gap in order to prevent it from saturation. In a real world example, imagine a DC offset of 50mV and a winding resistance of 2 Ohms you'll end up with only 25mA. That's nothing to worry about although a typical toroid transformer can allready go into saturation from current as small as this. Your loudspeaker also don't give a damn about this 50mV.
Output transformer in single ended tube amp are designed with a magnetic gap and have a DC current rating, wich is the aloowable current before saturation. In PP tube amps the transformer is part of the push pull output so the DC curent cancels out. This is also doable with transistor but then it has to be incorporated in the design. Something you simpy cannot do with a simple singel chipamp.
Last edited:
Appears to be advantage without coupling capacitor. Downside danger of any DC burn your good speakers. My curiosity is great, today who uses amplifiers even small powers without a PCB speaker protection: just turn off when we have DC by accident?
- Status
- Not open for further replies.