Sansui QRX-7500

Sansui QRX-7500 Front

 

In the early to mid 1970's Quadraphonic sound was just coming to the forefront. Sansui was one of the leaders of the 4-channel movement with their QR line of quadraphonic receivers. Around 1974-1975 they introduced the QRX line which included this beauty, the Sansui QRX-7500. The QRX-7500 was the top of the line at the time in terms of power output at about 30 watts per channel (4 channels into four 8 ohm speakers).

 

Sansui QRX-7500 Meter

 

The receiver features a built in CD-4 album decoder, SQ decoder (phase matrix), QS decoder (regular matrix), two phono inputs, and outputs for two sets of four speakers.

 

Sansui QRX-7500 Knob

 

What's the difference between the QRX-7500 and QRX7500A? Well, it all has to do with the decoding.

The QRX-7500A was a "hybrid" unit as Sansui moved from the discrete component vario-matrix decoder circuits to their custom Vario-matrix IC's that were used in the QRX-7001/8001/9001. There were two distinct ICs. The 'decoder' IC and the 'control' IC which enhanced the separation and decoding ability. The QRX-7500A has the decoder IC but not the control IC. The later receivers had both.

In all there are three variations of decoders built into the Sansui QR/QRX series over their entire production period. The QRX-7500 utilizes the basic QS decoder as originally designed. It's sometimes called an "RM" or regular matrix decoder. The basic decoder is capable of 3-12db of inter-channel separation. The QR series receivers, the QRX-4500, QRX-5500 and QRX-6500 also have this early decoder design.

 

Sansui QRX-7500 Lamps

 

With the QRX-7500A Sansui introduced the partially developed vario-matrix decoder circuit containing two of the three custom ICs required for full Vario-Matrix decoding. The circuit performs similarly to the 'basic' decoder mentioned above because the missing 'control' IC is the biggest factor in increasing inter-channel separation and this design doesn't have it. This decoder is capable of 3-12db of inter-channel separation. So, the QRX-7500A has the newer IC designed circuit but lacks the full Vario-Matrix capability of the later design. The Sansui QRX-5500A and QRX-5001 have the same design.

The fully developed Vario-Matrix Type A design with all three IC's was used in the QRX-6001, QRX-7001, QRX-8001, QRX-9001, QRX-777 and QRX-999. The QSD-1/2/1000 decoders also have the Type A decoder. The Vario-Matrix Type A decoder was limited by design by Sansui to 20db of inter-channel separation, though, in theory, Sansui claims that it is capable of infinite inter-channel separation.

 

Sansui QRX-7500 Inside

 

The slightly later QRX-7001 is the improved version of the QRX-7500 with the better decoder circuit as well as a beefier amp section. The QRX-7001 produced 35 watts per channel in Quad mode.

 

Sansui QRX-7500 Back

 

The Sansui QRX-7500 is a great quad receiver. It has its limitations given the early decoder design and some issues with solder joints on the circuit boards but overall it is a good performing unit. The QRX-7500A may be a better choice since it has the IC decoder design but if you really want a great decoder then you'll want the QRX-7001, QRX-8001 or QRX-9001. Expect to pay a premium for those however. Any of these units would most likely need a restoration and perhaps some modification which isn't cheap. Once done you would have an exceptional performing receiver though. For a full restoration check out QRXRestore.

QRX-7500's sell for around $300+ while the A version sells for around $400+. The QRX-7001 is around $500 and the QRX-9001 around $800-$1000.

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Sansui G-33000 Sells For Over $7000

Sansui G-33000

 

This Sansui G-33000 receiver recently sold, on June 23, 2016, for $7101.00. These receivers are very rare and don't come up for sale very often. The seller describes it as being in excellent condition:

 

This unit has been tested and is fully functioning without any static or interference.  Physically it is in almost mint condition with the exception of a few minor scratches on top of the receiver, and a small scratch on the back of the am.

 

Another recent sale on July 12th, 2016 saw a Sansui G-33000 go for $6600.00.

 

Sansui G-33000 Sells

 

Here's what the seller had to say about that unit:

 

Everything tested and in working order. Sounds great. Would describe as very good condition, due to some nicks around top edges. Also, a few tiny nicks on glass (barely noticeable, unless your real close to unit).  $1800 spent on restoration 01/2013. Will include copies of receipt and work done. Will also include bolts for connecting preamp and amp together.

Was doing some further testing. A problem developed with left channel. Where it won't work all the time?

 

Obviously the left channel problem hurt the sale price a little bit.

A previous sale on December 17, of 2013 was for $7700.00 so prices have been pretty stable for the last few years.

Just as a comparison a couple G-22000 receivers sold recently as well. One for $3875.00 on July 29, 2016 and one for $3889.00 on July 1, 2016.

 

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