Advice on adding CD-4 / Quadradisc capability to my system

better than an eliptical.

My only Direct drive TTs(my JVC and Technics) use P-mount cartridges so if I limit my self to using those TTs as they are, then the only affordable P-mount I've found is the Grado Prestige Black with an eliptical stylus(I haven't found a reasonably priced Grado line contact stylus option).

The 8MZ stylus is listed from Grado as "twin tip" It is a hyperbolic cut diamond. Similar in tracing function as a Shibata cut diamond.
 
There are those who insist a certain type of turntable works better for CD-4 than others but it is all talk.

It doesn't really matter what type the turntable is as long as it allows the cartridge to track well so it can retrieve the ultra sonic carriers consistantly. It can be a linear tracking, direct drive, radial tracking, belt drive (what I use - a BIC 980), or any combination as long as the tracking requirements are met. Heck, Panasonic even used BSR turntables successfully in their all-in-one CD-4 systems.

What is more important is to be sure the wiring is low capacitance (100pF or less) between the cartridge and demodulator so the ultra sonic carrier signals are not attenuated.

So, I would just take your best turntable for CD-4 (The SL-5) and put a good CD-4 cartridge in it and use that. Tweaking comes after installation.

Some of the best CD-4 cartridges of the day were:

Panasonic EPC-450C II, EPC-451C, EPC-460C (These are semi-conductor cartridges and require a demodulator which can supply the bias voltage necessary for the cartridge to function. All Technics and Panasonic demodulators had this capability).
Pickering XUV-4500Q
Empire 4000D I, II, and III.
Audio Technica AT15Sa and AT20SLa (although any of the AT quad cartridges work well)
Empire 440D
Shure M24H

A modern day magnetic with great CD-4 capability is the Audio Technica AT440MLa which has a line-contact stylus.

And yes, a Shibata type stylus is almost mandatory for successful retrieval of the carriers although some cartridges with ellipticals claim capability (grados, e.g.)

Doug
 
Last edited:
If the wires in the arm tube are loose from one another or loosely twisted, they are probably OK for capacitance. If they are tightly twisted together, capacitance may be problematic.

The RCA cables from the turntable to the demodulator are at least as important and you want to be sure you have low capacitance cables here.

Doug
 
Using my Heathkit C-3 cap checker the cables in my Garrard Syncro-Lab 75B with the pickup head unplugged have less than 33pF capacitance. I know my C-3 ain't terribly accurate so I tested a 33pF ceramic as a reference then checked capacitance between the positive and negative terminals of the two RCA jacks of the Garrard and got lower capacitance readings. So I think I've made up my mind to go for a 1/2" cart Option.

All that TT needs aside from adjustments is some tweaking to get the speed closer to speck and all should be good.
Next step after I get a good pickup will be to redo the capacitance check with some cables attached(and possibly try some different ones I have if it is not good enough the first time).

Marcmorin, thanks for the suggestion, but at 60$ for a P-mount prestige black cart with regular stylus, and 100$ for an 8MZ stylus(a G2 Shibata is only 10$ more) the stylus alone would cost around the same to twice that of some of the vintage cart/stylus combos I'm considering. So unless the vintage options slip through my fingers I think I should save the Grado option as a contingency backup.
 
Marcmorin, thanks for the suggestion, but at 60$ for a P-mount prestige black cart with regular stylus, and 100$ for an 8MZ stylus(a G2 Shibata is only 10$ more) the stylus alone would cost around the same to twice that of some of the vintage cart/stylus combos I'm considering. So unless the vintage options slip through my fingers I think I should save the Grado option as a contingency backup.

I'm guessing that you looked up what replacement stylus there is for a G2 cartridge, and you found the Gold-1 stylus for $110.00. Pretty much any used Grado body (except some very old FT and FC carts) will accept the 8MZ stylus. The Gold-1 stylus is a 0.6 X 0.2 eliptical. For what you can find a used Grado body for on that auction site, plus the 8MZ stylus......you'd have to spend a bunch of money for a new cart (take your pick of brand) to match the performance. In the AT line, all the "quad ready" carts had low (for AT) inductance. Inductance in a cart is similar to capacitance in cables when it comes to carrying the high frequency in quad. The AT 440 has near 500mH of inductance.....the AT 12Sa has 330......grados have 55, or 45, or 9 on their high out bodies, 2mH on their low output ones.
 
From what I've gleaned lately with CD-4 it is better to use a direct drive or quartz TT than a Belt or idler drive unit, and also a line contact stylus is better than an eliptical.

Not necessarily true - maybe what you're gleaning is that more quartz tables get honorable mention as they were considered a higher state of the art back when quads were current tech. I've seen reviews stating that's kinda sorta bass ackwards in a lot of cases as motor rumble can upset the retrieval of and color the much higher and precise CD4 channel data from the groove. A well built belt table can do a better job of isolating that noise and interference. Take that with a pound of salt ... never really noticed myself, as I use a direct drive table (Mitsubishi DP-EC10, right out of the golden age of quad).

And ya ... line contact, or shibata, or whatever they're calling them nowadays ... are definitely the sh!t for CD4. It's all about the stylus profile, how deep it rides, and how it's presented to the groove wall. Ellipticals are better than conical, but not really designed to retrieve a fully synched CD4 signal. Even if you do get good response, there's a chance there's some synch issues on the discrete channels. Does that really matter? Ida know ... what I can say is ... I can boost my Pickering elliptical to get a CD4 light on my QRX, but having to boost it higher than the AT shibata does point out that it's not doing as good a job. Even boosted, it cuts in and out sporadically. My Empire and Shure just fall flat on their pointy little noses and default to stereo ...

(Speaking of noise and interference - you should also compare the plinth mounting systems on your tables. The better the table is isolated from the environment, the better your results will be. That holds true for any vinyl, but is more important with CD4 and high end audiophile recordings. If the other factors point towards a table with a less than perfect suspension, sorbothane is your friend. Stuff can soak up 90+ percent of external vibration as long as you have it sized properly to the weight of the table. Amazon, da bay, and other retailers have stick on feet and pads for most any application. Only warning is to NOT put the bare sorbothane on any wood surfaces as it WILL leave stains. I set mine on cork coasters, mostly because I just happened to have some laying about.)

End trans.
 
Last edited:
Using my Heathkit C-3 cap checker the cables in my Garrard Syncro-Lab 75B with the pickup head unplugged have less than 33pF capacitance. I know my C-3 ain't terribly accurate so I tested a 33pF ceramic as a reference then checked capacitance between the positive and negative terminals of the two RCA jacks of the Garrard and got lower capacitance readings. So I think I've made up my mind to go for a 1/2" cart Option.
I like the fact that you measured the tonearm capacitance. Good show! So that allows a remaining 67pF in the overall 100pF capacitance budget. You will probably find that if you have an assortment of interconnect cables that some will have less capacitance and some will have more. If your turntable will be located near the receiver, you can reduce the interconnect capacitance by using a shorter cable or shortening a cable that has low capacitance per foot but has too much capacitance because of its length. Also, allow for some capacitance in the input of the CD-4 demodulator.

All that TT needs aside from adjustments is some tweaking to get the speed closer to speck and all should be good.
Speed accuracy is important. If the table is slow or fast the carrier frequency will not align with the demodulator and the result will be poor or no demodulation of the high frequency signals. Also note that the Garrard SL72B does not allow for any adjustments for overhang, tracking angle or azimuth. Picking the right cartridge will be critical.
 
Last edited:
The Garrards you own are not adjustable enough for CD-4. On the other hand, your SL-5 can do CD-4 with Audio-Technica or Grado P mount options with minimal fuss.
 
My strategy for the Garrard is to replace the existent Pickering cart with the quad version adjust the tracking, learn what all the adjustments are for, how to tweak them, get the adjustments good, and hope all is well.

I've never done precision adjustment on any of my TTs before(aside from using a strobe disc to adjust speed), and I've been planning to try and learn it once I secure a good quad cart.
I've always preferred working on the electronic aspects of my equipment more and thus focused my learning(read college and hobby directions) there.

It is tempting to stick a Grado in the SL-5 and be done with it, but unless I find a source for their cartridges and needles that is significantly cheaper I'd have to buy the cartridge then hope my relatives are generou$ come Christmas time. I was planning to put any Xmas funds received towards a CD-4 decoder....

Even with about 100$ in my budget now that I've found something was less expensive than expected, a Grado with a line contact stylus is still stretching things a bit.
 
Your issue with that is likely, the Garrard can not be azimuth nor overhang adjusted. It likely can't track at 1 gram to 1 1/4 gram great. With CD-4 there is no wiggle room for alignment or adjustment errors. All the above must be dead on correct for correct performance.
 
The tracking knob goes from 0 up to about 5(I don't recall nor did I try to memorize the exact upper limit) so if the knob is accurate then setting it for 1-1.25 grams should be straightforward and easy.

If anyone wants to see photos of the Garrard I'll be happy to post some.
 
But will the tonearm on it track in real life that light? And can overhang and azimuth be aligned correctly? Most Garrard changers can not. Most CD-4 is high end manuals and very high end automatics at best. CD-4 demands precise everything on tonearms, tonearm bearings, tonearm wiring, and tonearms designed to be easily optimized.
 
33pF is exceptionally low for a TT signal path, anything under 100pF is exceptionally low IMO. I have a JVC QUAD/CD-4 demod I got very cheap but I have not tried it out on anything so don't know if it functions as such. It does not interface strain gauge carts, only the Panasonic/Technics CD-4 demods do that and CD-4 SG carts go for silly-high money these days. I do also have a few entry-level Panasoic TT changers with built-in CD-4 demod/phono preamps needing overhauling, they are sim to BSR changers used in all-in-one systems of that period. Many entry-level TTs of that period like the Pioneer PL-112D had CD-4 compatible lo-cap cabling.
 
Also ... you can improve your chances by replacing the original TT interconnects. Those can degrade over time and suffer mechanical damage, and the solder points can shrink and crack some. Not usually an issue, but CD4 is more sensitive to these things.

Use good cables - AV video interconnects have lower capacitance than standard RCA audio and most of the OEM cable used when the tables were made.
 
Well I didn't manage to get the Pickering, but I did snag an Audio Technica AT-14S with stylus for about what my budget was, so I'm happy. Once it arrives in about a week or two I'll start working on getting it into the Garrard.

Pio1980, you should consider trying to restore functionality to your quad gear. I think you might enjoy it much more in working order.

Thanks for the suggestions sKiZo. I may retouch the solder joints in the near future, but if I'm not mistaken the RCA sockets are riveted in which makes them a b!tch to replace...So if they don't need replacement I'll probably save my self the headache.
I've got many different cables of assorted make and vintage laying around so odds are something has got to work. Perhaps I'll do some testing tonight...
 
Last edited:
Well I went and spent some time in my basement equipment work shop, and accomplished two things. First I proved part of my last post wrong...The RCA sockets are screwed on, and not riveted as I remembered incorrectly.

Secondly I think I've found my cable. With about 50pF over it's nearly 2' length and 80-85pF per channel when connected to the Garrard, it seems good enough. My alternatives are to either chop up another cable that would only give me one more foot for the same capacitance, tear apart my huge system in search of a better cable(which I REALLY want to avoid), or buy new.
 
Last edited:
Those cables seem plenty low-'nuff to me, depending on the internal capacitance of the Garrard which shouldn't be problematic.
 
The AT14S will work well for you if the stylus is good. All the Audio Technica quad cartridges were/are good.

Tracking force range, according to my original AT data is 1-2 grams. Use 2 grams. 2 grams with a Shibata-type stylus is like 1.5 grams or so with an elliptical.

Doug
 
The AT14S will work well for you if the stylus is good. All the Audio Technica quad cartridges were/are good.

Tracking force range, according to my original AT data is 1-2 grams. Use 2 grams. 2 grams with a Shibata-type stylus is like 1.5 grams or so with an elliptical.

Doug

Thanks for the tip. I'll start it off at 2 grams when I get it, and if all goes well perhaps try it at settings between 1.5 and 2 grams to see if it will be happy there...If I'm not mistaken the lower the tracking the longer the record and styli life, so the lowest force it is happy at is probably best. Also I try not to run things right on edge of their recommended operational parameters as a matter of personal policy as I like to baby my good equipment.

I just managed to snag an untested JVC CD-4 demodulator for about 25$ delivered. I'd assume this is a good design since JVC played a major role designing the CD-4 format, and let other brands clone this unit. So now, provided my stylus and decoder are good, I should have all the bare essentials to play my quadradiscs.:banana:

Now I just need to keep my eyes open for a cheap CD-4 setup disk.

I've also got a local lead on a cheap quad Reel to Reel deck :)
...With how well my quest to expand my quad system has been going lately it almost makes up for the torturous digestive bug that has been plaguing me since Sunday.
 
Back
Top Bottom