HARMAN KARDON 980 or HK980 is an amplifier made by HARMAN in the 2000 era that produces up to 80 Watts of power at 8 Ohm loads. 120 Watts at 4 Ohms.
The amp has a wide amplification range from 5Hz to 150kHz.
INFO
Amplifier were introduce since 2005.
This is a view of the inside of amplifier.
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MANUAL HERE
SCHEMATIC
SCHEMATIC DIAGRAM HERE.
This is an image of power amp section after croped and edited.
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If we look at the schematic, we will see that this amplifier consists of several blocks, they are:
- Preamplifier, Q1 and Q2 use transistor 2SC2240.
- Muting Feature, Q3 uses MPSA06 transistors.
- Voltage Amplifier Stages, it using 2 stage of transistor by Q7-Q8 ( BF423- A1380 ) also Q6-Q9 ( BF422- C3502 ) and 1 current mirror transistor by Q5 ( BF423 ).
- Servo Bias, using only 1 transistor, namely Q10 (C4793). Q11 is unused.
- Driver Power, using 2 transistor levels, each Q12 and Q13 (C3502 and C4793) while in the other phase using Q14 and Q15 (A1380 and A1837).
- The last is the Final Power Amplifier, using 2 pairs of power transistors ( Q16, Q17 and Q19, Q20 ) numbered C5242 and A1962.
NOTE
Power Supply for the amplifier is a symmetrical 48VDC.
That means it is possible reach up to 210 Watts at a 4 Ohm load for the amplifier.
For the MUTING function, if there is no bias voltage for Q3, the transistor will be switch off and the audio signal will muted too.
The Amplifier mute. Likewise the opposite.
We could be adjust the trimpot until the voltage between the Q16 and Q19 emitters is 10 to 11 milli Volts.
Transistors 2SC5242 and 2SA1962 have a power dissipation until 130 Watts ( PDF HERE ).
With 2 pairs of the Power transistors, its possible for this amplifier to produce up to 260 Watts of power.
