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 

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.

Thanks. That sounds good for my use in stereo.

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

Craig

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. 

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

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.

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