I'm sorry some of you guys have such problems with CD-4. As I've stated many times, playing CD-4 records, for me, is really no different from playing regular two channel records.
I agree with gvl-guy in that I believe a lot of problems stem from trying to use equipment not originally designed for CD-4. Getting the carrier signals to the demodulator unattenuated is probably THE most important aspect of CD-4 and it sounds like it's not happening for you. The demodulators work if they get the signals. My SE-405 and SH-400 work flawlessly with the turntable and cartridges I have (see the thread about "The latest discrete ...added..." I do agree that trusting a manufacturer's word isn't necessarily the best approach. I have always regarded a claim that a cartridge with an elliptical stylus working for CD-4 to be dubious and I have never gotten any of mine to work, even the very high compliance Empire 2000Z which almost works- almost. Almost doesn't cut it. Of course, the tracing radius is what is really important and if as small as, say, a Shibata, it should work but...
Are these MC cartridges you're using low compliance. Most of them are and that is not good to trace the carrier impressions in the vinyl. And then there is the extra electronics the signal is going through, adding complexity and additional chance for the carrier signals to be lost or attenuated. Linda says she has success with her MC setup for CD-4 and I don't doubt her (I forgot what she's using) but generally, these were not included in the original CD-4 equipment specifically designed for CD-4.
When I first got back into CD-4, some 18 years ago, I admit I had the usual sandpaper in the inner grooves and that thin sound like it was ready to break into distortion but that was all tracking and tracing and adjusting VTF/SRA and anti;skate and it has been great ever since. There was/is nothing wrong with the demodulators.
I acknowledge CD-4 discs are generally noisier than regular two channel discs but that's a trade off for having the wonderful experience of discrete quad from a disc. As far as a sealed disc being noisy, after having been around for 40-some years and maybe moved around a lot and sliding around in there against the inner sleeve, well, there's just no telling if that disc came out of the press that way.
Are we absolutely sure Atlantic and Asylum used recycled vinyl in their CD-4 records or is that a myth passed down through the years?
I will have a drink, though. Beefeaters with a splash.
Doug