Rangkaian Penguat Headphone

Penguat Headphone Hi-fi

This circuit can be used for a headphone amplifier, arose after the purchase of commercial equipment with separate pre and power amplifiers without a headphone output. The intention is to permanently insert the headphone amp between pre and power amps. The gain control being used to pre-set the gain so that the pre-amp's gain control is normally used for setting the listening level.

Skema Rangkaian Penguat Headphone

Its advantages are :

• low output impedance to drive several pairs of phones
• The active gain stage is, almost, perfectly logarithmic and ...
• Independent of the absolute value of the pot
• Excellent channel tracking
• O/P noise reduces with gain reduction.

The first stage is a conventional series feedback circuit using the ubiquitous NE5534, the gain being set by the feedback AOT (adjust on test) resistor to suit individual needs, this stage provides the necessary low impedance output for the variable gain stage. The resistor/ capacitor networks around the input stage may seem a little extravagant, but are necessary to reduce any possible RF pickup especially the 470 pF between the two IC + and - inputs.

The complete second stage consists of a zero gain follower, an inverting gain stage and the output emitter followers, 'volume control' gain being set around these three stages. The x10 gain of the inverting stage gives the closest approach to a logarithmic law, stability being ensured by the 27pf capacitor in this stage's feedback. The output complementary pair runs in Class-A at about 80 mA and should be mounted on a small heatsink.