Hey...Look At Me! I'm Quad!!
One thing about 70's audio equipment, they were fun to look at! They were more than some black lumps of indistinguishable hardware like today. Each manufacturer had their own unique look. Some manufactures included different ways of monitoring your new quad setup. Usually they were in the form of VU meters, but some thought outside of the box. Let's look at three different approaches.
PIONEER QX-747/949 (QX-747 shown) These were the two flagship models that Pioneer offered in the mid 70's. Each one offered a very simple but rather effective way of looking at sound. Many people confuse these displays with that of a real oscilloscope, but in actuality it's a mechanical device that uses four incandescent bulbs. Very cool looking at night with the lights off! In my humble opinion, these were the best looking receivers ever made. Too bad they were plagued with problems and very poor SQ/RM decoders. They were updated to The QX-747A/949A models which had full logic, but they were not all that great either. The "full logic" decoders did OK in moving an individual sound around the room, but couldn't do more than that. Plus, they had a very slow steering circuit that allowed for plosives to occur prior to steering, much to the demise of the sound field. The CD-4 demodulators in these weren't all that bad, but they hid the carrier level adjustment on the very bottom of the unit, which makes them hard to adjust. The A models had an auto carrier level. Also, the tape monitor switches are poorly made and can cause problems. All of the units that I have heard have become noisy over the years (probably bad caps in the preamp). Be sure to play the unit for around 15 minutes before you buy one (if you can) to check out this problem.
MARANTZ 4400 Stereo2+Quadradial 4 This was my dream quad receiver in the 70's. 50 watts times 4 power, built in oscilloscope, Dolby, and a power supply that could anchor a boat! Shown here with the optional CD-400 demodulator and SQ decoder module (underneath), this thing can rock and roll! They cost around $1200.00 new in 1975 with no options. People got many years of good service out of these things. Time, however has taken it's toll on most of them. Very few still have a working scope. If you have one that still works, hang on to it! Here's a tip...if your scope is still working, switch it off when you are not using it or it will burn out the phosphors in the tube. These tubes are incredibly hard to find!
HEATHKIT AD-1013 AUDIO SCOPE So, you have a favorite receiver, but it doesn't have a neat display? Try this one on for size! Heathkit sold these in kit form or pre-assembled in the early to mid 70's. It is an actual quadraphonic and/or stereo audio scope with built in tone generator. You can monitor your system just like the Marantz or look at each channel individually. This unit has 4 line inputs and a place for probes to use it as a test scope. It also has multipath inputs for checking FM. One thing to note... Many receivers did not offer true 4 channel line level outputs when you use the internal SQ/QS/CD-4 decoder. I worked around this by using some automotive speaker-to-line-level adapters and ran them off of the "B" speaker outputs on my Sansui QRX-7001. The scope level changes with the volume level, however.
