I need someone to teach me a bit about CD-4 and Quadradiscs.

[Zeit]

Hello again people. I hope you are all well.
So, I get my Rotel RX-154A back from a shop that has done some maintainence on it tomorrow. I'm highly looking forward to listening to music in quad once again, as the receiver had been sitting around for months gathering dust because of the needed maintainence. Anyway, I'm becoming interested in CD-4. I might win the Black Sabbath - Paranoid quadradisc any time now. I thought I'd buy it as a quad collector's item for now, but I am planning to get to hear it properly also in the near future.
So, let me get this straight.... I need a Shibata stylus, possibly with a new cartridge on my Rotel RP-855 turntable, or another turntable altogether, a CD-4 demodulator (those JVC ones on ebay right now look really nice, the 4DD-5), and then, could I plug that into my Rotel receiver in the AUX inputs, obviously with the SQ button off?
Also, does a Shibata stylus and compatible cartridge work just the same as standard when playing regular stereo LPs into my Rotel receiver with the SQ button on, or is there some complications?
Thanks a lot in advance. Trying to get my head around this new stuff.

 

[Doug G.]

What I would do in your situation is feed the turntable outputs into the 4DD-5 and its outputs into the four discrete inputs on the receiver. This is how you will be able to listen to CD-4.

Feed the two direct outputs from the 4DD-5 into the phono input on the receiver. Then you can switch the direct outputs "on" on the 4DD5 and the turntable outputs will go to the phono input and you can then switch the receiver to SQ or any other matrix decoding it has and listen to those quad formats.

The direct outputs of the 4DD-5 are actually connected right to the turntable outputs when you switch them on so it's just like connecting the turntable directly to the phono inputs on the receiver in that mode.

I hope this is clear and good luck!

Doug

 

[Zeit]

Thanks a lot for replying Doug. It is clear. One more query though... Do I need a Shibata stylus or would an elliptical stylus or other hyper elliptical stylus for my Rotel RP-855 and the Audio Technica cartridge suffice? Surely I don't specifically need a Shibata? Oh and I won the Black Sabbath quadradisc on ebay by the way! I'm going to wait for a UK voltage demodulator to crop up on ebay also.

 

[Doug G.]

Although there may be rare instances of an elliptical stylus working for CD-4, generally you need a Shibata or similar stylus for success. Line contact styli, for instance. An example is the AT 440MLa which works very well.

A line contact stylus assures the 30kHz carriers will be traced and the ultra sonic frequencies passed to the demodulators.

What model AT cartridge do you have? And congratulations on the Black Sabbath win. That's one I still don't have.

Doug

 

[LizardKing]

On the cartridge question, would a Dynavector 17D3 work for CD-4?

It supposedly has a response up to 100kHz!!! It is a Micro-Ridge stylus...

http://www.dynavector.com/products/cart/e_17d3.html

 

[Doug G.]

It's bit like going out on a limb giving definitive answers with CD-4 but that cartridge should work.



Doug

 

[quadjoe]

It's bit like going out on a limb giving definitive answers with CD-4 but that cartridge should work.



Doug

Doug, will the 4DD-5 work with the output voltage of a Moving Coil cartridge? The Dynavector (an excellent cartridge, btw) has an output voltage of 0.3mV whereas the input sensitivity of the 4DD-5 is 1.5mV. I've never attempted to use a MC cartridge with mine so I don't know if it would work or not.

 

[quadsearcher]

Not to speak for Doug, but you would need step-up transformers or (pre-pre-amp?) to get a MC cart up to MM level so as to maximize S/N ratio. I have a 4DD-5 and wonder about this too.

 

[quadjoe]

Not to speak for Doug, but you would need step-up transformers or (pre-pre-amp?) to get a MC cart up to MM level so as to maximize S/N ratio. I have a 4DD-5 and wonder about this too.

I've thought about a step-up transformer or pre-pre, but I'd worry that it could attenuate the 30kHz carrier.

 

[Doug G.]

I lost track of this thread as I was gone for about a month and a half but yes, a typical MC cartridge will need extra amplification before the demodulator, via an active or passive device, and you would need to ascertain that the response of the pre-preamplifier or SUT will pass the ultrasonic frequencies.

I believe that is the purpose of the "CD-4" switch on that Ortofon MC amp in Linda's other post in that other thread. It probably extends the response of the preamp to pass the necessary frequencies for CD-4.

Doug