Sandpaper CD-4

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Xdevo1973

Active Member
Joined
May 21, 2006
Messages
96
Location
New Jersey
Hi Everyone,

I am using an AT12S Shibata cartridge on a Philips 302 turntable with the Marantz CD-4 demodulator. Some album cuts sound good and some are downright excruciating. Is it the cartridge? Obviously this is more noticeable at the inner grooves but improves when increasing the playing weight but then that little plastic bump next to the stylus bottoms out on the record. Increasing the anti skate makes thing worse also.
 
Hi Everyone,

I am using an AT12S Shibata cartridge on a Philips 302 turntable with the Marantz CD-4 demodulator. Some album cuts sound good and some are downright excruciating. Is it the cartridge? Obviously this is more noticeable at the inner grooves but improves when increasing the playing weight but then that little plastic bump next to the stylus bottoms out on the record. Increasing the anti skate makes thing worse also.

Hi. Xdevo

Aa Yes CD-4, a tricky Quad system from day one, its a system that needs the demodulator to be precisely tweaked if it is working 100% for the cartridge and your turntable to be tweaked as well.
This is my own opinion I think it really comes down to the cartridge and when you get thing right it sound fantastic. the ATS12s made by Audio Technica was made for the CD-4 system but it was there cheapest in there line and I believe it did have some short comings the ATS14S & the ATS15S ATS20SS was there flag ship cartridges it all comes down to how much money do you want to invest in to get thing running right.
There is heeeeeeeps of information about the in`s & out`s of CD-4 on QQ for more info.
Bill...
 
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However, the AT12S is entirely capable of satisfactory CD-4 performance. My later derivative (AT912Sa) works fine. Assuming your records are in good shape and clean, the main cause of sandpaper quad is setup issues and cable capacitance in the cables to the demodulator.

What happens is the demodulator goes in and out of demod. mode because it loses the carrier signals momentarily.

You said it gets worse if you increase anti-skate. That's an indication you have tracking issues. Be sure the stylus is good too.

Doug
 
Invest in a Geo-Disc. It made me change from an "I hate CD-4 because it never plays right" person to an "I actually like CD-4 because it creates a much better soundfield than SQ does!" person.

My system was terrible before. I had no left carrier signal and therefore, no demodulation on that side. It wasn't until I sunk my teeth into a brand new Audio-Technica AT440MLa cartridge & stylus and the aforementioned Geo Disc that I actually started to get some more than acceptable CD-4 performance!

https://www.ebay.com/sch/i.html?_od...RC0.A0.H0.Xgeodisc.TRS0&_nkw=geodisc&_sacat=0
 
Invest in a Geo-Disc. It made me change from an "I hate CD-4 because it never plays right" person to an "I actually like CD-4 because it creates a much better soundfield than SQ does!" person.[/url]
Beware: the Geo-Disc is only useful if the tonearm's design allows you to see the exact middle line of the pivot.
 
The main thing is to get tracking right on, regardless of how you accomplish it. I used the gauge that came with my BIC 980 to get the stylus tip where it belongs and then spent some time making little changes in anti-skating at a time until I got rid of the "sandpaper". Now, I can change between any one of my CD-4 cartridges within minutes and have every one of them perform almost perfectly. Even the Stanton 780.

Doug
 
Invest on an Audio Technica AT440MLb. You won't regret it. Stereo specs, quad performance. Track it at about 1 3/4 grams. Play about 4 stereo or SQ records, and then put on a CD-4 record after adjusting your demod. You will be pleased.
The Quadhfather
 
I recently reduced the capacitance of my cables and everything seemed fine, no sandpaper sound on the inner grooves.
Over Spring Break someone damaged my stylus, actually the the entire cantilever was missing, torn off! needless to say that I was pissed! I had another identical cartridge on my other turntable and so swapped it over, now I'm back with sandpaper CD-4 sound on the last tracks!
Both cartridges are Sony MC3's, but the second one had more mileage on it but it still sounds fantastic for stereo use, but obviously even slight stylus ware causes problems with CD-4. I found a replacement on eBay (they don't come up often). I plugged in the replacement and now have perfect CD-4 again. I'm dubbing all my CD-4's to the hard drive, so this cart will be used exclusively for that purpose. The MC3 is a moving coil, it came out in the eighties and so is not really a CD-4 cartridge, however it does have a special stylus shape and frequency response to 60K. The MC1 and MC2 are similar but have elliptical stylus tips and lower spec's, so I doubt that either of those would be any good for CD-4. I also have a Grado F1+ (Moving Iron) and an Ortofon SL 20Q (Moving Coil) that I thought were also working perfect (after lowering the cable capacitance) but no, they both produce the same sandpaper sound on the last track, neither is new and so are no longer good enough for CD-4.
Moving coil cartridges are lower impedance than moving magnet and so shouldn't be bothered much by cable capacitance, the trade off is that you need a step up device. I,m using the Ortofon MCA-76 pre-preamp.
 
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