I collected quad records of all the major types at the end of the quad era. But my first CD-4 demodulator was a cheap one. I couldn't find a good one and probably couldn't afford it if I did. My first cart was an AT14S which had a worn stylus. I couldn't find nor could I afford a replacement stylus. So I played the records and put up with the distortion. After awhile I gave up on getting decent sound out of CD-4 and disconnected the demodulator. I was under the impression that the carriers was never correctly pressed into the vinyl and the quad was unextractable without distortion. So I replaced my Shibata stylus with a new elliptical, and played my CD-4 records as stereo records through my Audionics Space and Image Composer (SQ decoder). A number of years later I found a JVC 4DD5 at an Alabama flea market and decided to give CD-4 another chance. I had to work on the demodulator, as it had a few bad capacitors, but I got it working. I found a new old stock stylus for the old cart off the internet, which I had just started using. I also found that the internet allowed me to find many records I had missed during Quad's commercial demise, including CD-4 records. I hooked up the demodulator and put on the new stylus, and for the first time I actually got mostly distortion free music. But those records had been mistreated by playing with an elliptical stylus. Yet they were playing well. I found that as I played more records it actually improved. The point is, the records are sturdier than a lot of people give them credit for. Once cleaned good, they usually play OK. The exception is when someone played them on a cheap BSR turntable with a crystal cart, it can wipe the carriers from the record. I only found one record like that. Most people who bought CD-4 records had the better gear because they cost a lot more than SQ or stereo records, about double. And if you weren't equipped to play them, you opted for the stereo version.
The AT440 MLa does have a Shibata type stylus, but the Microline stylus is an improvement on the Shibata design and will out perform an average Shibata, I believe. The Microline stylus will dredge up gunk from the groove that cleaning methods fail to get. I expect this on a new aquisition if it isn't still sealed in the wrapper it came in. After a few plays with you having to stop and clean the stylus, there is no more and the record will play flawlessly. I picked up some of my CD-4 records at flea markets mixed in with stereo records. They all play. So get you a good quad era turntable, and a new AT440MLb, which is the newer version, a good demodulator (the JVC 4DD5 is generally recognized as the best), and you should be on your way to good quad. You might want to get yourself a cartridge alignment protractor kit. Good alignment is necessary. And you will be tracking that cart at just under two grams, not 1.4 . Now be aware that turntables for CD-4 are required to have low capacitance wiring. It's more than just the lead wires, the tone arm wires have to be low cap too. That's why I say get a quality quad era turntable. The low cap wiring will be evident, because they are thick like video cables. Any of the major brands of the era will suffice. Marantz, Pioneer JVC of course (it's their system), Fisher, Sansui. It's a little more trouble getting it all set up, but once it's right, you'll know it. See the archives on setting up the demodulator. I have discussed this in detail in several postings. And as far as bad records go, you won't know until you try to play them, unless they're obviously scratched up. You probably won't find many that don't demodulate well. There are a few records that have a reputation as hard to track. The worst one most will agree is Cat Stevens Greatest Hits. Get that one to play well and you've hit CD-4 nirvanna! And yes, the records are made with super tough vinyl developed for CD-4. And when you want to play your SQ records, just turn your demod to the stereo setting and it serves as a preamp. It has to be plugged into the auxillary "line level" jacks, as it's output level is the same as a tape machine. You connect your SQ decoder in the tape monitor loop, and decode that way. Most SQ decoders have a tape connection so you can do this and still have a hookup for your tape equipment. The Microline stylus will not harm your SQ and QS records.
The Quadfather
As I'm poised to dip a toe into the CD-4 waters, my interest is piqued by your last comments that CD-4 records were made with super vinyl to combat record wear.
Reading through past QQ posts on the subject, I've seen some conflicting reports about how fussy CD-4 records can be and how they can (allegedly) be trashed if played using a non-compliant (non-Shibata?) stylus or whatever..?
Please forgive the potentially incorrect terminology throughout my post, hitherto I've only been an ever-so-humble SQ and QS vinyl spinner (SQ and QS may have some shortcomings but they seemed so much easier to handle, especially to a Quad vinyl rookie like yours truly, who hadn't so much as played a slice of vinyl in a decade or more up to the point I decided to go Quad vinyl..!) and as I am starting to acquire used CD-4 records right now, I want to make sure I am not picking up stacks of used CD-4 records that are to all intents and purposes useless.
Thanks in advance.