help,first time playing cd-4,issues

[aifrecords]

So i bought the demodulator a marantz cd-400b, I bought a sansui qrx 5500 amp, then i bought what I thought was the right shabata needle the Audio technica 3600 series type bliss shabata stylus from turntable needles.com, since my turntable is a teac P-A688,and it comes with built in audio technica 3600 cartridge. after i finally got the demod right coming out of 4 speakers vs 2, then i proceeded to slap on the jefferson starship spitfire cd4. then i noticed the front left and rear left speakers,the music would sound crackley and every 7 seconds or so the sound would drop out just in those 2 speakers, then the same pattern crackling music for a while from those 2 speakers ,then drop out. the front two speakers are bsrs the back 2 are infinity. when i play sq and qs there no issues with this problem, so whats wrong? wrong needle? wrong cartridge? many hours research trying to get appropriate match for shabta needle with my cartridge and about to give up on cd4. then i played a stereo record, same problem happened.

 

[Doug G.]

First, connect the turntable directly to the amplifier and see if it happens. What you want to do is eliminate things one at a time. Being you are trying to get CD-4 working, eliminate the demodulator first. If it happens without the demodulator, swap the two cables to the amplifier and see if the problem stays on the left or goes to the right speakers.

If it doesn't happen without the demodulator, it could be the demodulator, itself, or a tracking problem and you may have to experiment with different tracking force and anti-skate settings. CD-4 is pretty sensitive to those issues. Then there is always the possibility of the AT3600 just not cutting it for CD-4.

Doug

 

[quadsearcher]

AT3600 is an entry level cartridge. About $30 new, usually seen installed on budget turntables. ( I used to get them for around $10 in quantity, early '80s.) One of the first carts I had. A typical low-cost performer. However, it is rated for 20Hz to 20kHz. I think I mentioned this in another thread. I've never seen reports that it exceeds its rated specifications so I would not expect it to reproduce bandwidth out to 45kHz needed for CD4, even with a Shibata. I've tried a handful of AT carts that were not specifically designed for extended frequency response (wishful thinking on my part), and as I'd expect, the only one that turned out to be listenable with CD4 was the 440Mla.

Apparently the turntable is low-end, with small motor known for unstable speed, non-replaceable (non-adjustable!) cartridge, non-adjustable tracking force, straight arm, no anti-skate, and the biggest deal-breaker: internal preamp with line level output! Demodulators do not accept line level, only cartridge ("phono") level.
I don't enjoy being the bearer of bad news, but I had to share what I found out about it.
There are good posts here about the "must-haves" of CD4, might take some searching.

I've come to the conclusion that one should expect to pay around $300 for the cart (use one that others have reported as working), and use with a traditional '70s TT with s-shaped tone arm, like better DUALs, Technics SL1200, BIC, with low capacitance cables. Then adjust cartridge position perfectly with a turntable protractor.

But what do I know, I've had a JVC demod for 10 years and can't get good play straight through one whole side. Of course my records are beat, not vacuum cleaned, and my table was a linear tracker (which might not be ideal for CD4).

Others have better luck (ask Doug), but they are typically using components designed for CD4, made in that era.
Some of these modern "turntables" are extremely low-cost to put it mildly. Amazon.com And as my grand-dad said, "you pay for what you get".

 

[Doug G.]

Yes, as I always "preach", if you try to cut corners with CD-4, you are bound to be disappointed. You need a cartridge made for CD-4. I mean, it may be something else and an old demodulator could have failed components just from age but it's most likely the 3600.

Doug