Grundig CD-4 decoder - new to this - help please

The Prof said:

Dear Quad people.
I am new to CD-4 and I bought a Grundig CD-4 demodulator. I have a SME arm, Nakamichi turntable and Ortophon MC20 super II cartridge. I have a surround system.
After spending the day making up din plugs for the Grundig, I have switched it all on and I get the green pilot light coming on when I put on a CD-4 record, which I bought recently.
There is four channels of sound - coming and going. It sounds pretty awful and I would like to know what I need to do to get this all working properly please.
The cartridge output is going straight into the Grundig CD-4 demodulator. I don't know what I should be doing from now on. The unit is opened up and I can see adjustment pots.
There is a pot for the PLL oscillator - I tried twiddling all the pots but nothing seems to improve. There is a 'left' and 'right' pots at the back.
I would be grateful for some advice please.
Thanks a lot.

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Dear the Prof,

I am a lucky owner of Grundig CD-4 demodulator now.. I don't hace a user manual though and the plugs and wiring of DIN and what was deliverid with it are a mystery to me.

Could you kundly share your experience of 'making up din plugs for the Grundig'. I need two RCA from Tonearm cartridge to input into DIN of demodulator (and ground?) and 4 output RCA from DIN

Please kindly help and render good guidance

Also if you hace a copy of user manual please kindly shere

Thank you

Sergey

Try searching on http://www.hifiengine.com/ the site has lots of manuals for equipment. I found the circuit diagrams for my reel-to-reel on it, and it has lots of user manuals. You have to register to download.

Dear Sergey
The Grundig CD-4 works well. I replaced the power supply on mine however. But assuming yours is well - the left hand DIN plug looking from behind is the stereo feed from the catridge. (Not a pre-amp). You will need to look up the DIN plug wiring diagrams on the net. Its not difficult. YOU MUST USE VERY LOW CAPACITANCE cable from the turntable to the CD-4. This was the single biggest factor as to why my CD-4 wasn't working, and sounded awful. Once I wired up the system with very low capacitance cable it worked very well indeed. Wire you can use if your stuck for cable or on a budget is UHF coax antenna cable - its a bit thick but its very low capacitance and does work. The other DIN plug on the left is a return, to send the signal to a regular pre-amp for normal LP listening. The Right hand side (Hinten) is the front and back stereo pair, which need wiring in the same manner - and these outputs are line level and need to go to a 4 channel pre-amp of some sort. (A 5.1 Processor receiver would do if it has analogue inputs). Try it out FIRST before you mess with anything. Hopefully it will work straight off the bat. Get your channels in the right order! For getting a balanced output I put a mono record on and make sure its the same level from all four speakers. Good luck!

And make sure its a high output moving magnet cartridge - see above discussion.

The Prof said:

And make sure its a high output moving magnet cartridge - see above discussion.

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Thank you, dear the Prof, I'll follow your kind advices

DuncanS said:

Try searching on http://www.hifiengine.com/ the site has lots of manuals for equipment. I found the circuit diagrams for my reel-to-reel on it, and it has lots of user manuals. You have to register to download.

Click to expand...

Thank you, I've registered there and logged but alas no manual for Grundig CD-4

First get adaptors for DIN to cinch.

You need three with male connectors for DIN and female cinch connectors for left and right for the playback from decoder to amplifier (the two DIN sockets on the right side of your decoder). They should have pin 2 (ground), pin 3 (left channel), and pin 5 (right channel) connected. "Vorne" is for the front speaker amplifier, and "Hinten" is for the back/rear amplifier.

The third DIN connector "TA Eingang" (pick-up input) on the left is the input for the cardrige. This needs another third adaptor, with the same wiring. See service manual.

The fourth DIN connector "Ausgang direkt" (direct output) is for a direct connection from the pick-up input and can be connected directly to your amplifier' phono input. A fourth DIN to cinch connector is needed here. This enables you to use your record player directly with your amplifier without bandwith reduction. Set the switch on the front to "Direkt" for this. This is for stereo playback only!

The cables shown with your decoder look dangerous, throw them away.

Check main power voltage switch on the back and adjust accordingly matching the voltage of your mains. Set the switch without the decoder being plugged in to the mains to avoid short circuit and burning smell! You may need an adaptor from the euro-plug to whatever mains connector is used in your country.

The small switch on the back "Blend" must be set to "off" for maximum separation.

And then there are the two little potentiometers for setting the separation. Now another one can chime in here for an explanation...


http://www.hardwarebook.info/DIN_Audio

-Kristian

Thank you, dear krkier for your kind explanations!

krkier said:

***

The third DIN connector "TA Eingang" (pick-up input) on the left is the input for the cardrige. This needs another third adaptor, with the same wiring. See service manual.

***
-Kristian

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Sorry, I don't get what does it mean, 'another third adaptor'...

What you think could this ready-made adapter work?




And where to hook 'Ground' wire from tonearm and cartridge wiring?

Sorry for naîve dumb questions - I am only a user and not good with electronics..(

Sergey

as1serge said:

Thank you, dear krkier for your kind explanations!


Sorry, I don't get what does it mean, 'another third adaptor'...

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"Another third adptor" IS the third adaptor. You need:

One adaptor for connecting the output "Vorne" (front) to the amplifier front channels.
One adaptor for connecting the output "Hinten" (rear/back) to the amplifier rear channels.
One adaptor for connecting the input "TA Eingang" (pick-up input) to your records player cardrige.
One adaptor for (optional) connecting the output "Direkt Ausgang" (direct output) to the amplifier's phono input.

as1serge said:

What you think could this ready-made adapter work?

Click to expand...

They look promising. Those I use myself, just look if the cinch connectors are wired to 2, 3, 5 of the DIN connector.

as1serge said:

And where to hook 'Ground' wire from tonearm and cartridge wiring?

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Record player usually have an extra wire for grounding the metal parts and tone-arm. This you can connect to the amplifiers ground connection. Usually a screw to fix the cable to the housing.
The pick-ups have no deadicated ground connection, the four pins are the connection to their internal coils. One pin of each coil gets connected to signal ground of the amplifier over the wiring.

-Kristian

Thank you, dear Kristian, for your kind explanations.

Usually I connect the grounding wire to the screw in 'phono-corrector' preamplifier where there is a special socket indeed. There is no special one on Grundig demodulator thus is the question.

Hi again,

Just set finally a new tonearm with Pickering XUV cartridge and plugged it into Grundig CD-4 decoder and output into 5.1 input of amplifier.

Well, first notices:

- moving right switch from Stereo to QUAD didn't change anything, the sound was coming from all four speakers though, even in Stereo (!?)

- green lamp wasn't lightening up, thought it is just gone, when once or twice it blinked in more loud sound scenes...

- the quality of sound was quite neutral and non-impressive yet VERY VERY quiet - I have to put amplifier at max level for the overall sound just to reach normal listening loud level and twice the amplifier switched off by protection mode triggered!?

Please note that I used the old needle that came with the cartridge - I have a new one that I was intending to install after all adjustments finished..

But if it is the worned off needle that gives a low quality sound will the new one add loudness?? And this is the most worrying issue


Is this Grundig CD-4 decoder also a phone preamp for MM cartridge or should I install one between CD-4 and MM cartridge - I believe Pickering XUV is MM head?

Any idea what is happening, please advise

Thank you

One time I was getting distortion from a CD-4 cartridge which worked OK before. It had a sandpaper sound to it, which seemed to be the sandpaper type sound other people here have described. After I cleaned the stylus with a couple drops of stylus cleaning fluid on a stylus cleaning brush, the cartridge worked like it did before.

- the quality of sound was quite neutral and non-impressive yet VERY VERY quiet - I have to put amplifier at max level for the overall sound just to reach normal listening loud level and twice the amplifier switched off by protection mode triggered!?

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Try using another preamp, ie. stereo preamp to see if the XUV is putting out a high enough signal. Also, you should use a cartridge gauge or protractor to align the cartidge.

---------------------------------------------------------------------------

The seminal work of Baerwald ca. 1941 showed that the tracking error of a pivoted stylus could be minimized if the stylus is aligned such that it is parallel to the groove at two points along its curved path: specifically, at the two points that are a distance of 66 and 120.9 mm (or 2.6 and 4.76 inches) from the center of the spindle (note that these numbers assume that the inner and outer radii of the record's grooves are no smaller than 2.375" and no larger than 5.75" respectively, which is, thankfully, the case for most records). These two points are commonly referred to as "null points" as a tracking error of zero is achieved when the stylus is tangent to the groove at these points. A commercially available cartridge alignment gauge can be used to align the cartridge such that it satisfies the tangency requirements at the null points.

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http://www.audiophilia.com/features/cartridge_setup.htm


patents
http://www7a.biglobe.ne.jp/~yosh/alignment_gauges.htm

I got good results with my Pickering XUV. It worked good with the 4500Q stylus, but wouldn't work with any other styluses, including some that worked with a Pickering XV-15 that I have.

https://www.quadraphonicquad.com/forums/showthread.php?20028-Harman-Kardon-T35C-turntable-mods

Test the turntable with a conventional preamp, like the standard phono input on a stereo or quad amplifier. A moving magnet cartridge should not require a preamp to feed a demodulator, as they are designed for phono cartridge level outputs, and have their own preamp. Some of that German stuff is kinda weird, so you might want to check this. A worn stylus should not affect loudness, unless it's really badly worn or broken, but it will affect CD-4 subcarrier pickup. If you put your separation pots in the middle of their range, and can't get a decent sound level, then there might be something wrong with your demodulator. If you turn them all the way down (CCW) and don't get a hollow sounding audio, then the demodulator isn't demodulating the subcarriers. Good Luck!

The Quadfather

scifi said:

I got good results with my Pickering XUV. It worked good with the 4500Q stylus, but wouldn't work with any other styluses, including some that worked with a Pickering XV-15 that I have.

https://www.quadraphonicquad.com/forums/showthread.php?20028-Harman-Kardon-T35C-turntable-mods

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The other styli are probably for moving iron cartridges and the XUV is moving magnet. Are you talking about the earlier quad styli for Pickering/Stanton quad cartridges like the Stanton "Q" or "4DQ" or the Pickering equivalents? If so, those are moving iron styli and, since there will be no magnets if you try to use them in a moving magnet cartridge, there will be no output. The Pickering XV-15 series is moving iron.

I found that out a few years ago, myself.

Doug

The other styli are probably for moving iron cartridges and the XUV is moving magnet. Are you talking about the earlier quad styli for Pickering/Stanton quad cartridges like the Stanton "Q" or "4DQ" or the Pickering equivalents? If so, those are moving iron styli and, since there will be no magnets if you try to use them in a moving magnet cartridge, there will be no output. The Pickering XV-15 series is moving iron.

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Mystery solved. Thanks. I tried a 3 DTL, D-6-E and a stylus labeled PC24000 which came in an Astatic package with the following written on it:

Pl125-qd
D2400Q

See pictures attached. I was trying to find a stylus for use with stereo records and save the 4500Q stylus for CD-4 and SQ records. The D2400Q was made for the UV-15 and I thought it might work with the XUV.

A Shibata or a line contact stylus is better for all records, not just CD-4. I use my AT440MLa cart with the microline stylus for all my records.

I recently got an Orofon X5-MC. They still seem to be in business.
http://ortofon.com/hifi/products/historical-products/x5-mc-high-output

Frequency range at - 3dB 20-45,000 Hz
It has a nude Fritz Gyger diamond stylus. It might work good for CD-4 records.

Well, quite strange still ... I completely rearranged the amplification scheme so now two OUTPUTs of GRUNDIG CD-4 go to two separate stereo pre-amplis et after to two stereo power amps. The sound now is loud enough. But I still cannot adjust the (what exactly, really?) position of the cartridge or height of tonearm or the weight of the cartridge pressure to obtain stable GREEN indicator light up meaning GRUNDIG recognizes QUAD signals and decoding them. For some Quad records green lamp doesn't light up at all.. For some records it is blinking occasionally... The most stable green light reacts to Turbular Bells Mike Oldfield.. So the decoder itself kinda works. What should be adjusted so it provides stable recording. What is strange that in switch position STEREO the sound also comes from rear speakers like it does in QUAD - is it OK or some malfunction of the board?

Also I cannot make weight pressure of the stylus less than some 2 grams+ - the stylus just isn't descending on the record enough to reach it - the front brush of PICKERING HUV just doesn't bend enough and prevents further lowing of tonearm.. (

Maybe the needle is worn out also? But I presume the issue could be in bad adjustment of the stylus and/or cartridge and/or tonearm or all of them..

What other steps to undertake - please kindly advise..

Thank you

Sergey

The Quadfather said:

... If you put your separation pots in the middle of their range, and can't get a decent sound level, then there might be something wrong with your demodulator. If you turn them all the way down (CCW) and don't get a hollow sounding audio, then the demodulator isn't demodulating the subcarriers. Good Luck!

The Quadfather

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Dear Quadfather

I cannot locate any regulators, pots on the CD-4.. Where are they located and how to change the range?

Please help

Sergey