Harman/Kardon hk775

1 9 8 0 1980
1 9 8 3 1983

Harman/Kardon 700s : super-high bandwidth, swift slew-rates, discrete components only, DC design and minimal use of NFB.
More of the same since the early 1970s at H/K but, this time... different. For two reasons.

As sternly touted by Dr Matti Otala himself in Japan over dozens of ads and articles, T.I.M. and I.I.M. were the real enemies and nothing else.
T.I.M. stands for Transient Intermodulation Distortion, a nasty one that stems out of excessive use of negative feedback and results from increased I.I.M. (Interface Intermodulation Distortion) - all from the excessive use of NFB to reduce said distortion !

According to H/K, TIM is ten times more audible than THD and can be detected at leveles as low as 0,03% - read the TECH 1 explanation for the details about all those nasty distortions few ever... suspected :)

Alongwith the Citation XX series which came a bit before the 700s and which were used a lot in Japan to crown the hoped success of the 700s said 700s weren't made in the USA, just like said Citation series. They were made by the Shin Shirasuna Corporation, a company also known for products bearing the SILVER name.

If the Citation didn't have SILVER equivalents, the 700s had their counterparts in the Silver lineup, with minor cosmetic differences, different names and different distribution areas.
They nevertheless were and still are 700s in disguise - and vice-versa !

See elsewhere on TVK the details of the Shin Shirasuna / Beatrice / HK turnaround - back to topic :

The hk775 is the only one which didn't have a Silver equivalent : being a monoblock, it was probably deemed too high-end for a Silver (re-) branding.

The hk775 is a fully symmetrical DC circuit design with quad differential cascode, a big toroidal transformer, two 15,000uF of caps, discrete components only (no ICs), protection circuit which remain out of the signal path and 300Khz of frequency response.
It is half of an hk770 - with a little loss in weight as both weigh 10,1kg.

Like the Citation XX, it has one subsonic filter and one ultrasonic filter, the slopes and cutoff frequencies of which I haven't been able to find...
Unlike the Citation XX, you need two hk775 to delve into the pleasure of powerful, tight and dynamic stereo.

Harman/Kardon hk775, image 1 Harman/Kardon hk775, image 2
Harman/Kardon hk775 specifications
Title Value
Configuration : 1x toroidal transformer with + and - supplies
high and low voltage supplies for out and driver stages
Power : 1x 130W (RMS / 8 Ohm / 20Hz...20Khz / 0,03% THD)
Power bandwidth : 8Hz...100Khz (65W output / 0,03% THD)
THD : 0,006% (1Khz ; rated output)
IMD : < 0,02% at rated output
Frequency response : 1Hz...300Khz (+0 / -3dB)
Damping factor : > 100
Slew rate : 150V / us (8 Ohm, rated output)
Square-wave rise time : 1,2µs (20Khz ; 8 Ohm ; rated output)
Square-wave tilt : < 2% at 20Hz
Total TIM distortion : < 0,007% at rated output
Total Interface IM distortion : < 0,007%
Power supply crosstalk : 0 [?]
S/N ratio : 123dB (IHF-A)
Input impedance : 1,2V for rated output
Input sensitivity : 24kOhm
Dimensions : 38,5 x 7,25 x 32cm
Weight : 10,1kg.
Harman/Kardon hk775 : 0 topic
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page online since : 2006
page updated : march 2010
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