This ebony classic is the Yamaha CR-840 receiver. It was produced from 1979 to around 1981 and retailed for about $500. It was a mid range receiver in Yamaha’s CR-XX40 lineup. It puts out 60 watts per channel into 8 ohms.
The CR-840 has the big flat toggle switches as do many of the other Yamaha models. Overall it has a very nice sleek hi-tech look to it, though some think the Yamaha models look somewhat sterile.
The CR-840 has a built-in AUTO-DX circuit that monitors the signal strength and amount of interference present. If needed it will automatically switch to the DX Mode IF Stage to increase the selectivity to 83dB.
It also has continuously variable loudness control which means that the frequency balance and volume are adjusted simultaneously to compensate for the ear’s insensitivity to high and low frequencies at low volume settings. So, a natural-sounding balance is maintained regardless of volume level. It weighs about 30 pounds and measures 20″ x 6-9/16″ x 15-1/4″.
One problem with the Yamaha CR-840 is that it uses output modules rather than discrete output transistors. These modules have a tendency to overheat and die. Unfortunately, original replacements are difficult to find and newly made versions tend to be out of spec and perform erratically. It has been speculated that the Yamaha IG 02970 output module was in fact a rebadged Sanyo STK 0060-II or STK-0080-II. The STK-0080-II is fairly easy to find which would make repairing these units far easier.
The Yamaha receivers have never garnered as much attention as the Pioneer and Marantz receivers but perform just as well. They do emphasize a “Natural Sound” so they tend to have a more accurate representation of sound which some find to be a little harsh. Prices are rising for these receivers though – especially the higher end models.