Harman/Kardon HK775 Monoblocks (Pair) - $200 (Hubbard)

I'm selling (2) Harman/Kardon HK775 Ultrawideband Monophone DC Amplifiers (Monoblocks). These were from HK’s high-end 700 series that included a preamplifier, tuner, and stereo power amp and was released in 1982. These seem to be rare today.

Selling only as a pair, for the above price.

The following work has been done:

• Replaced all electrolytic capacitors, except the main filter caps, with 105°C models by Nichicon and Panasonic. This was in 2011.
  • (I’m including new 15,000 µF filter caps that will most likely fit. However, they are from 2011 and might need to be reformed before using.)
• Adjusted DC offset and idle current.
• Replaced the original 2-way binding posts with insulated brass 5-way binding posts that will accept banana plugs, spades, pins, or bare wire.
• Cleaned the exterior.
• Cleaned the switches with DeoxIT (functional unit only).

Note: One unit is fully functional and the other one turns on but has a very large DC offset—so it can't be used and will damage any speaker that is plugged into it.

Both are in very good cosmetic condition wth few scratches or other damage.

Includes photocopies of owner's manual and service manual.

Specifications:

Power Output:
130 watts, RMS, into 8 ohms, from 20-20kHz with less than 0.03% THD
Power Bandwidth:
Less than 8Hz to 100kHz at 65 watts per channel with less than 0.03% THD
Total Harmonic Distortion (1kHz): 0.006% at rated output
Intermodulation Distortion: Less than 0.02% at rated output (60Hz and 7kHz)
Frequency Response: Below 1Hz to beyond 300kHz +0, -3 dB
Damping Factor: Greater than 100
Slew Rate: 150 V/sec into 8 ohms at rated power output
Square Wave Rise Time (20kHz): 1.2 sec into 8 ohms at rated power output
Square Wave Tilt: Less than 2% at 20Hz
Total TIM Distortion: Less than 0.007% at rated output
Total Interface I.M. Distortion: Less than 0.007%
Power Supply Crosstalk: 0

Amplifier Configuration:
Each amplifier uses one toroidal power transformer with positive and negative supplies plus high and low voltage supplies for output and driver stages

Signal-to-Noise Ratio: 123 dB (IHF-A)
Input Impedance: 24 k ohms
Sensitivity: 1.2 volts for rated output
Dimensions for each amp:
385 mm/15.2" Width
72.5 mm/2.9" Height
320 mm/12.6" Depth
Weight for each amp:
10.1 kg/22.2 lbs.

I can demonstrate the working unit in Hubbard. I am available most evenings, and some other times, Monday through Saturday. Click the “more ads by this seller” link to see other items I’m selling.

Keywords: model, Harman Kardon, Harmon, mono block, power amp, amplifier, amps, Marantz, Denon, Pioneer, NAD