Knoppson Headphones Amplifier, KHA-14A
Data per stereo unit [drawings]:
Amplification Tube: Philips ECC82
Rectifying Tube: Siemens EB91
Output Transistor: BC517
Output Impedance: <3Ohm
Output Capacitor: 1000uF (20Hz@8Ohm)
Resistors Type: Metal Film, 0.6W
The KHA has two selectable channels which
suits perfectly for two sources of audio.
One source may be a turntable's RIAA, the
other a CD/Computer or as in my case, an iPod.
This pre-amplifier is designed to both be capable of driving low impedance headphones as well as boosting the
line level in such a way as making arbitrary power amplifier (PA) reach it's maximum power output level. The unit is
equiped with a headphones jack which is breaking the PA input signal when a headphone is inserted. It does this
while still loading the (Tube) PA input with 1k Ohms. The reason for this is that a low resistance load on input
minimizes hum from PA and thus loadspeaker disturbance while listening to KHA by headphones.