You can spot an early 1970’s Harman Kardon from a mile away. This top-of-the-line Harman Kardon 930 is no exception. The blackout dial face, classic green dial lighting, brushed aluminum bottom panel and red illuminated power button make it a very distinctive receiver. It was introduced in 1972, with an MSRP of $399.95, and produces a very conservative 45 watts per channel. The other receiver in the x30 series from Harman Kardon was the 30 wpc model 630. The 630 and the 930 were followed by the 430 and the 730 in 1976.
The 930 has some chrome plating in places and the knobs are machined metal. It’s later replacement, the 730, had a thick foil covering the face plate and plastic knobs with metal caps.
The signal and tuning meters leave a little to be desired as they are fairly small and hard to see.
The Contour switch, similar to a loudness switch, is used to compensate for the Fletcher-Munson effect. What? You’ve never heard of the Fletcher-Munson effect? Well, human hearing loses sensitivity to the lower frequencies as volume is reduced. This makes listening to music at low volume sometimes feel thin. Activate the Contour switch and the lower frequencies will get a boost relative to the high frequencies. This gives the music a more full sound at lower volumes.
The tone controls are two piece (dual concentric) knobs. You can adjust the tone for the left and right speakers independently. The outer knob adjusts the left channel and the inner knob adjusts the right channel. The three push button switches to the right of the tuning knob are the FM muting switch, MPX Filter switch and the Stereo Auto switch. The Stereo Auto switch allows you to listen to a poor FM signal in mono rather than stereo. The button should normally be depressed to listen to FM in stereo.
The Mode control is interesting too. It switches between stereophonic and monophonic operation depending upon the source. REV will reverse the left and right channels. STEREO is normal stereo. L+R combines the left and right channels. L sends the left channel signal to the left and right channels and R does the same for the right channel.
The HK 930 really looks nice in the optional wood case. You don’t see too many with the wood case. Another cool aspect of the Harman Kardon 930 is that the dial scale is lit when AM or FM is selected but goes dark when any other source is selected so it is less of a distraction.
- Tuning range: FM, MW
- Power output: 45 watts per channel into 8Ω (stereo)
- Frequency response: below 4Hz to above 70kHz +/- .5 dB
- Total harmonic distortion less than 0.5%
- Damping Factor: 30 or better to below 20Hz
- Input sensitivity: 1.5V
- 2 Phono inputs
- 2 Tape inputs
- 2 Aux inputs
- Dimensions: 432 x 121 x 350mm / 17 x 13 3/4 x 4 3/4 inches
- Weight: 13.2kg / 29 lbs
- Year: 1972
Under the 930 logo on the front panel you’ll see the words Twin Powered. This means that the 930 has dual power supplies. One for each channel. Notice the two large transformers in the above picture. It’s essentially like having a mono amp for each channel. The two transformers also make the HK twin powered receivers heavier than they look. I believe the HK 930 was the first solid state receiver to utilize dual mono amps in its design. Notice the four large 6800 mfd filter caps as well.
The dual power supply amp design is claimed to add more imaging and dynamics to the sound. Some original reviews stated that at low power output the difference is not that noticeable but that at higher power levels the dual amp design really begins to shine, especially with more dynamic source material.
In the 930, Harman Kardon utilized their famous ultra wide band frequency response circuitry and a 4-gang tuner. It uses a FET for the first of its two r.f. amplifiers. Overall, the FM tuner is pretty good but is not the 930’s strong point.
The power amp and pre-amp sections are separate so you can use an EQ if you want. Jumpers on the back of the unit connect the power and pre amps. In total, the HK 930 has 53 NPN transistors, 3 IC’s, 1 FET, 22 diodes and 8 power rectifier elements. There is a hole on the bottom panel for adjusting FM muting as well.
The Harman Kardon 930 receiver is a great receiver. Its unique dual power supply design gives it a place in audio engineering history as well as a great sound. While you can find the later model 730 fairly easily, the 930 is harder to find. The performance ratings are all very conservative and, if you like the HK x30 series look, then you should try the model 930 out if you get the chance.