Listening to a vintage Quad Receiver in an HDMI world

[Commstock]

I have a vintage Sansui QRX 7001 quad receiver and also Denon and Marantz AV receivers (AVR). Of them all, I prefer the sound (and look) of the QRX with the speakers in my listening area.
The challenge is listening to an HDMI-only source (DVD, NVIDIA Shield, etc.) and/or a 5.1 analog source on the 4.0 analog Sansui. Because of legalities, I know of no free-standing digital-to-analog converters for all surround types (DTS, DD, etc.). However, preamp outputs are post decryption, so herein the solution I use.
(Note that that anything you try is at your own risk.)

• One requirement for this solution is that the AVR has at least 5.1 analog inputs and 5.1 preamp outputs, which my Denon 3808CI and Marantz SR6010 have. BTW – these are features to bear in mind with your next AVR purchase.
• The second requirement is that the input impedance of the Quad receiver and the output impedance of the AVR are compatible. General accepted practice is that the input impedance of the destination (the Quad receiver line level inputs) be at least 20x (some say 100x) the output impedance of the source (the AVR preamp output). In my case, the Sansui line level input impedance is 50k ohms and the Marantz & Denon output impedance is roughly 250 ohms, which works out to be 200x, so this matchup is fine. You will probably find the input impedance input in your receiver specs, but the AVR output impedance may not be easily findable. To the Google Machine!
• The final requirement is that the audio levels match - we’ll get to that later.

With spec requirements satisfied, please see the first attached Diagram 1 for basic hookup.
Once hooked up, see Diagram 2 to set matching preamp levels.

If the source is 4.0, set either your source machine or AVR for 4.0.

5.1 is trickier.
For the .1, I turn off subwoofer in the source and make the front speakers full-range, then I run the front speaker signals to the sub and onto the front speakers.
For the center channel – there are two solutions:

• Set your source or AVR to “phantom center” (no center speaker) and this will distribute the center channel audio to the front left and right speakers. This works for many sources but, IMO, some phantom channel downmixing sounds muddy – for instance, the excellent J. Tull Stand Up 5.1 release.
• The other solution is to use your AVR for center channel only (as noted in Diagram 1). To do this, I set the Sansui at the max volume I think I want, and then use the AVR volume to control all 5 speakers.

It may sound complicated initially, but ultimately has made listening to whatever I want on the Sansui extremely easy.
If you want to listen to the AVR only for movies, etc., you will need dedicated AVR speakers or a quad amp/speaker switch box (see previous post).
Good luck.

 

[Clint Eastwood]

Welcome to the forum

 

[Commstock]

Glad to be here. Next time I see the High Plains Drifter in Carmel I'll say howdy!