Sansui QRX-6500

This Sansui QRX-6500 was one of Sansui’s early contributions to the quadraphonic genre. It was manufactured from 1973 until about 1975 and produced 33 watts per channel into 8 ohms when all four channels are driven and 37 watts per channel when each channel is driven. It retailed for $750.00 and has a very distinguished design. The gold/silver front panel fits nicely with the blackout dial window and green and amber lighting. Stick all this in a nice walnut finished solid wood cabinet and you have one very nice looking receiver.

The QRX-6500 has three main features; the QS 4-channel Synthesizer and Decoder, the 4-channel, 280-watt integrated amplifier section, and the super-sensitive stereo FM/AM tuner. Basically, Sansui took what they had developed in the earlier QR-6500 and improved upon it.

At the time their new QS regular matrix system with vario-matrix circuitry was the most advanced method of reproducing a sound field in 4-channel. The QS synthesizer could transform a regular 2-channel signal into a rich 4-channel output. This meant that user’s 2-channel stereo records were still usable on the quad receiver and quadraphonic records were not mandatory. Still, to get the most out of the QRX-6500, using QS encoded 4-channel recordings was recommended.

The QS regular matrix decoder could decode any QS encoded four channel signal. This would work with any encoded records, tapes or even FM broadcasts.


  • Tuning range: FM/AM
  • Power output: 33W/ch into 8Ω (quadraphonic)
  • Frequency response: 30Hz to 30kHz
  • Total harmonic distortion: 0.5%
  • Damping factor: 30
  • Signal to noise ratio: 70dB (line)
  • Channel separation: 45dB (line)
  • Speaker load impedance: 4Ω to 16Ω
  • Dimensions: 536 x 181 x 362mm – 21 3/16 x 7 3/16 x 14 5/16 inches
  • Weight: 22kg – 48.5 lbs

As I mentioned above, the tuner on the QRX-6500 is excellent. It utilizes three dual gate MOS FET’s and a precision four gang variable capacitor. Visually it has a lighted dial pointer and meters for both signal strength and tuning.

Sansui’s 4-channel Synthesizer/Decoder Control, a five-position rotary control located on the right side of the front panel, enables the selection of two different QS Synthesizer modes (Surround and Hall), two QS regular matrix modes (Surround and Hall) as well as the additional Phase Matrix mode for decoding SQ records.

The QRX-6500 is not for the feint of heart when it comes to repair or restoration. The 4-channel circuitry is complicated and makes for a crowded interior. Keep that in mind if you find one. It will most likely need some maintenance or repair which can get expensive fairly quickly depending upon what needs to be done.

Look at all the speaker outputs on the back panel! The QRX-6500 could be connected to up to five sets of speakers. There are also an amazing number of inputs for both 2-channel and 4-channel sources. There is even a de-emphasis switch – a vestige of the time when radio broadcasters were going to broadcast with Dolby noise reduction. Not so useful today. There are also three AC outlets on the back panel, one of which is controlled by a front panel switch.

The Sansui QRX-6500 is a beautiful quadraphonic receiver and has a solid place in quadraphonic history. However, unless you want to dabble in 4-channel audio you may be better off sticking with one of Sansui’s 2-channel offerings. If you want to play quad source material then you could also look at Sansui’s later QRX-X001 series which is excellent.

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12 thoughts on “Sansui QRX-6500

  1. Have a QR 6500 is is it under rated on a power wash 33 watch per channel just seems like a very small amount when you can have 10 speakers and can you Plug a higher wattage amplifier in and still run the receiver is the control unit

  2. Spotted a QRX-6500 at the local thrift store, bought it and on the way out leaning behind misc electronics were two panels with a artsy feel to them. OMG a pair of Bang & Olfsun Beovox 5000 panel speakers. I now have them hooked up to the Sansui and this is now my keeper system…The Sansui is a underrated beast. love it.

  3. I purchased a mint QRX-6500 at a local stereo shop. It is an awesome beast of power and a sound that cannot be beat for the money. I hooked up 4 Sansui SP-5500x speakers to this receiver and it gave an incredible sounding system. I dabble in cassettes, 8 tracks, vinyl, and reel to reel. Reel to Reel on this system is incredible and will leave your heart pumping.

  4. They just don’t make gear like this any more. Build quality is superb and it is sure no light-weight either in terms of performance and indeed – weight. I’ve had mine since 1974 and it is still going strong. Such a beautiful looking piece of engineering and still produces amazing sounds from some of the better quadraphonic discs both in QS and SQ although it does a brilliant job turning many stereo recordings into very acceptable surround sound. Seldom mentioned is the outstanding user manual which includes diagrams of all the circuit boards and lists every single electronic component. I’ve even scanned it and produced a pdf file in case I ever lose it.

  5. Just picked up a near mint qrx-6500 in its original packing. The man who sold it me bought it new! I opened it up and blew what little dust was inside out. I didn’t have to clean the potentiometers as there was no static or popping. The best $350 I’ve spent on vintage equipment.

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