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This is the first Archived Forum which was active between 17th April 2007 and 1st March February 2012

 

Latest post 02-12-2011 3:33 AM by Gary96. 8 replies.
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  • 01-28-2011 10:02 PM

    • Gary96
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    • Vancouver, BC
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    • Bronze Member

    Beogram 4002 CD4

    My 4002 turntable has the optional "CD4" with an on/off switch. I understand that this is what allows the old quadrophonic records to be played. 

    I read somewhere that this also brings up the amplification to the point that I can use any regular line in to my receiver. No need for an amp with a Phono input or a separate Phono Pre Amp. 

    Does this sound right? 


    If so, do I need to have the CD switch tuned to "on" for this to work? 

    If I have it turned on, will I lose any stereo sound if I am only using two channels? 

    Thanks for the help. Love the TT.

    Gary 

  • 01-29-2011 2:09 AM In reply to

    Re: Beogram 4002 CD4

    My 6000 had amplified sound whether it was switched to CD4 or not. The CD4 switch essentially diverts frequencies above 15 kHz to the decoder and thence the rear channels. The switch is useful as if you play most stereo records, it can activate the CD4 decoder and the ability to turn this off is necessary. The CD4 decoder is otherwise acyivated by the presence of a carrier frequency - 45 kHz - and this has to be present to allow CD4 reproduction. This is why one needs a decent stylus as simple profile cartridges cannot track at this frequency.

  • 01-29-2011 2:57 AM In reply to

    • Gary96
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    Re: Beogram 4002 CD4

    Thanks. That sounds good for my use in stereo.

     

  • 01-29-2011 5:42 AM In reply to

    • Craig
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    • Costa Del St Evenage
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    Re: Beogram 4002 CD4

    Just make sure that the actual decoder PCB is present. Some just have the switch fitted, but no PCB.

     

     

     

    CraigSmile

    For millions of years, mankind lived just like the animals. Then something happened which unleashed the power of our imagination. We learned to talk and we learned to listen..

  • 01-31-2011 8:59 PM In reply to

    • Gary96
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    • Vancouver, BC
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    Re: Beogram 4002 CD4

    Good call. Apparently that's what I have. I guess I'll either find a pre amp or upgrade my amp (always tempting) to one with a phono input. Thanks for responding. 

  • 02-04-2011 6:14 AM In reply to

    • yachadm
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    Re: Beogram 4002 CD4

    Gary

    To answer your question, the CD4 / RIAA amplifier is always powered, no matter the switch position.

    So, if you play a Stereo LP, it functions as an RIAA amplifier only, because the carrier signal is not detected by the amplifier (no matter the switch position). 2 line-level signals are delivered to your main amplifier.

    If you play a Quad LP (assuming you have an appropriate stylus, and the switch is at CD4), the carrier signal is detected by the amplifier, and 4 line-level signals are delivered to your main amplifier.

    Check to see if the PCB (under the 33/45 indicator lights) is installed - it has about 300 components on it. If it is present, but not operational, get back to us.

    Menahem

    Learn from the mistakes of others - you'll not live long enough to make them all yourself!

  • 02-04-2011 10:44 AM In reply to

    Re: Beogram 4002 CD4

    But always switch the button to off when playing a stereo record as it is not uncommon to find that the decoder can be fooled into detecting a spurious carrier frequency.

  • 02-04-2011 12:09 PM In reply to

    • Gary96
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    Re: Beogram 4002 CD4

    Thanks for that guidance. I'll go in this weekend and see what's going on with the CD4.

  • 02-12-2011 3:33 AM In reply to

    • Gary96
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    • Joined on 01-20-2011
    • Vancouver, BC
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    Re: Beogram 4002 CD4

    Finally had some time to get into the unit and take a look. Prior to this I found an online photo of what the board should look like with the CD4 installed. Unfortunately, mine has a very basic board and no CD4. Just the switch. Rats. I'll either wait and get a new receiver for my Home Theatre with a phono input (been wanting to anyways), or move the TT up into another room with my Beomaster 1600. Thanks for the tips.

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