CD-4 Headaches

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Xdevo1973

Active Member
Joined
May 21, 2006
Messages
96
Location
New Jersey
Hi Everyone, I'm trying to figure out what the heck is going on with my CD-4 setup. I'm not sure if it's the demodulator or the phono cartridge/stylus setups. The demodulator is a Marantz CD 400-B with carrier auto detection. I have used two different turntables and two different cartridges. The first cartridge is a used AT12S and the second is a new AT clone from Ed Saunders. I just can't seem to get rid of distortion, especially after the third song on an album, even with brand new sealed albums. The Ed Saunders cartridge is very picky with tracking weight where the inner grooves lose front to back separation at anything over one gram, and it any degree of anti-skate. The AT12S is a lot more amenable to playing weight and retains front to back separation at a more reasonable two to two and a half grams. The sandpaper quad appears mostly in the left channel. Do I have a bad demodulator or two bad cartridges. Should I just assume that the demodulator needs a recap? Should I bite the bullet and get a better cartridge? They are so darn expensive. Should I just ditch the Ed Saunders cartridge and get a new stylus for the AT12S? Any help would be appreciated.
 
Sounds like an alignment issue, have you checked it with Stevenson protractor or something else?
 
The Ed Saunders cartridge/stylus is garbage. If you want Good CD-4, you'll have to spend a little money. #1, get a GeoDisc. I thought my cartridge was aligned until I got a GeoDisc. I was Waaaaaaay off. (The bonus is this helps with stereo playback as well). #2, track down an Audio-Technica AT440MLa. Expensive? Brother! Worth it? Amen!

I chased my tail for 10 years trying different demodulators, cables, various cartridges and even other turntables. A GeoDisc and that aforementioned stylus w/ cartridge later and I'm rockin' in 4 channels all the way to the inner grooves. Even troublesome discs play better now.
 
Thanks for the feedback; at least I know now. I'm torn between the AT440 or just ordering a new stylus for the at 12s.
 
I took the plunge on the AT440. They're very expensive, when you factor in exchange (because I'm from the frozen tundra of the North). But they've also been discontinued so, there's dwindling stock. However, I will say it's absolutely worth it. Even at the lowest carrier detection settings, I get great, un-distorted Quad sound. Turning up the carrier detection only increases the separation! My Ed Saunders was a splattery mess that couldn't even demodulate a test record.
 
I give another vote for the AT440mlb. I understand the newer styli will be compatible with the cartridge, but I can not say for CD4 as I haven't had the bad luck of wearing out my original tip in almost 2 1/2 years. I had Q-Eight's problems and related skinny wallet syndrome from trying vintage CD4 carts and different turntables and demodulators. Now, my problem was different however. I had a problem with capacitance in the cables. Once I replaced the "high end replacements" with stock Technics cables (on my SL1200mk2) from KabUSA, I had CD4 with problems, the AT440mlb fixed the rest. The problem with replacing an old AT stylus like your AT12S is that they are no longer made by AT and the quality may be good or not. I would find it a gamble as they are no longer testing for CD4 compatibility. I set my cartridge up with the alignment gauge for Technics, set the weight at 1.4 grams and my Saansui QRX7001 worked without any setup. I never had the built in demodulator work and it was thought defective. It worked even better after set up. I will also say that I also use it on my Technics SL5200 and after changing the cables, it worked as well as the 1200. While the demodulators may fail with age, most of the demodulators Ibought (please do not ask how many as my partner doesn't even know), only one did not work with the AT440mlb. Another went noisy after, but did work for over a year.
 
I see two cartridges being mentioned: the AT440mla and the AT440mlb. Which one should I get? Is the mlb version shibata? Is that cartridge CD-4 capable? Should I try to get an mla? Would the mlb be sufficient? They seem more common.
 
The mla version is earlier but I do not know the difference. I would go with the best price for either. I have heard no news that one works better then the other. The main difference is the mla version is considerably older stock.
 
I've found that moving coil cartridges work great, but first make sure that it has frequency response out to 50 or 60 KHz. These will always be some special stylus shape, not elliptical. I'm using a Sony XL-MC3. I also have found that any appreciable amount of stylus wear causes problems. I have one cartridge that's been used quite a bit and still sounds fantastic on stereo records, but when I try it on CD-4's the last track or two sound like sandpaper while the newer identical unit works flawlessly.
A moving coil being a low impedance device is much less sensitive to cable capacitance. I use an Ortofom MCA-76 pre-preamplifier before the demodulator. I have also used a step up transformer as well a home-built tube based pre-preamplifier, and they all work OK. Curiously with the tube based unit (which inverts phase) the demodulator outputs come out reversed front to back!
Reduce cable capacitance, I used pieces of Composite Video cable, it doesn't hurt to get a cheap capacitance meter off eBay to check different cables, and keep them short (half the length = half the capacitance). The Marantz manual says less than 100 pFd, but that the input of the demodulator is already about 50 pFd, thus allowing only 50 for interconnects and tonearm wiring! Mine now measure 58 pFd and works well with an AT14Sa that I recently purchased.
I also use the Marantz CD-400B and have found it to work better than anything else that I've tried over the years.
 
The Audio Technica MT440MLa (and, later revision, b) claim only a 20,000-25,000hz frequency response, but the proof is in the pudding. On my Technics SH-400 Demodulator, turning on the meter for Carrier Signal slams the needle to full if I don't turn the control down first. I've seen it mentioned before that Audio-Technica may have fudged those numbers a little bit to avoid confusion. The stylus it comes with is a line contact stylus, which, for all intents and purposes is an evolution of the Shibata.

LineContact.png
 
Well, an interesting turn of events. I ordered a NOS Kenwood CD-4 stylus (N-40A) that was actually built by Audio Technica and fits the 12S cartridge. It is allegedly a nude version of the original 12S stylus. I just installed it and it sounds absolutely wonderful. I'll have to baby this one!
 
Well, an interesting turn of events. I ordered a NOS Kenwood CD-4 stylus (N-40A) that was actually built by Audio Technica and fits the 12S cartridge. It is allegedly a nude version of the original 12S stylus. I just installed it and it sounds absolutely wonderful. I'll have to baby this one!

I had on-and-off CD-4 problems until I invested in a NOS stylus and demodulator maybe 4-5 years ago now. I've only heard it distort maybe 2-3 times since.

It's really quite amazing once you get it right...
 
Yep, I just played a bunch of CD-4s including those terrible Arista pressings, even though the albums are great (Both Melissa Manchester). Now I'm playing the Pure Prairie League. I also did Joni's Court and Spark album. All sounded great-even that God forsaken Doors Greatest Hits.
 
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