STK084 Audio Amplifiers
STK084 Audio Amplifiers circuit diagram
This design is based on the 80 Watt Audio Amplifier, and was developed mainly to satisfy the requests of correspondents unable to locate the STK084 Audio Amplifiers. It uses the widespread STK084 1 IC but, obviously, its power output will be comprised in the 40W range, as the supply rails cannot exceed ±30V.
As amplifiers of this kind are frequently used to drive small loudspeaker cabinets, the bass frequency range is rather sacrificed. Therefore a bass-boost control was inserted in the feedback loop of the amplifier, in order to overcome this problem without quality losses. The bass lift curve can reach a maximum of +16.4dB @ 50Hz. In any case, even when the bass control is rotated fully counterclockwise, the amplifier frequency response shows a gentle raising curve: +0.8dB @ 400Hz, +4.7dB @ 100Hz and +6dB @ 50Hz (referred to 1KHz).
Technical data:
Output power:
80 Watt RMS into 8 Ohm (1KHz sinewave)
Sensitivity:
115 to 180mV input for 10W output (depending on P2 control position)
Frequency response:
See Comments above
Total harmonic distortion @ 1KHz:
0.1W 0.009% 1W 0.004% 10W 0.005%
Total harmonic distortion @ 100Hz:
0.1W 0.009% 1W 0.007% 10W 0.012%
Total harmonic distortion @ 10KHz:
0.2W 0.056% 1W 0.01% 10W 0.018%
Total harmonic distortion @ 100Hz and full boost:
1W 0.015% 10W 0.03%
Max. bass-boost referred to 10KHz:
400Hz = +5dB; 200Hz = +7.3dB; 100Hz = +12dB; 50Hz = +16.4dB; 30Hz = +13.3dB
Unconditionally stable on capacitive loads
STK084 Audio Amplifiers
