This is one of the less common receivers – the Onkyo TX-6500 MK II. It was made by Onkyo from around 1978 to 1981. They made a series of receivers with the entry level unit being the TX-1500. From there was the TX-2500, the TX-4500, the TX-6500 and the monster TX-8500. I believe they were 40, 60, 100, 160 watts per channel respectively. So, the TX-6500 MkII chimed in at 100 watts per channel.
The TX-2500 and TX-4500 were Onkyo’s last ditch effort to survive in the audio market around 1977. They had originally entered the U.S. market selling speakers in a collaboration with Mitsubishi but that did not go well. So, they put everything they had into the development of their receiver line. The receivers actually sold very well and turned the company back around for a while. A little later the TX-6500 and TX-8500 were developed and then the MK II line of those receivers came out with minor variations from the original line.
The Onkyo TX-6500 MKII featured a smoked glass front dial cover with 4 heavy duty looking bolts holding it in place. The receiver is really a very nice looking unit when it is lit up. It also features a very good phono preamp circuit.
The TX-6500 measures 540 x 190 x 435 mm or 21.3 x 7.5 x 17.1 inches. They are somewhat of a sleeper receiver among collectors but that is slowly changing. They sell from around $300.00 to $500.00 depending upon condition and aesthetics.