Most of tube's internal resistance (Rp) is high, so they select output transformer to match suitable impedance with headphone. Dynamic headphones can make sound when an electric current is passed to a voice coil then to a diaphragm which is attached at the tip of coil by a magnetic field. At this moment,counter(back)-electromotive-force occurs by coil's movement. This counter-elective-force becomes reversal current to an amp, and it resists with signal when pass from an amp to a headphone, so it make the sound distort.The case of tube amps can minimize distortion by blocking current that is cause by counter-electromotive-force. However, semiconductor amps have low conductor output impedance; therefore they don't have to get impedance matching. Therefore, since most semiconductor amplifiers have a form directly connected to the headphone voice coil, there is inevitably a loss of sound quality due to a structure that is not resistant to distortion due to back electromotive force.
- Maintain low-frequency balances at low volume locations
- Increases the low-band density that is lacking in semiconductor amplifiers
- Stereoscopic, perspective, accurate sound image
- High-frequency noise cancellation, quiet background
- Supermalloy transceiver provides super-speed and widebands
- Protects your hearing and headphone from power on / off noise
- Accurate matching of various types of headphone impedance, maintaining lossless sound quality
The advantages of output transformers can be summarized as follows.
This is quoted from ADLAB articles.