Robbie said:  "A modern stereo pickup will give tolerable results with
an ordinary needle for LPs."

You will need to wire the channels of the pickup cartridge in series
with _opposite polarity_ to extract the vertical signal.  This is
equivalent to "left minus right" for a stereo record.  Alternatively
wire one channel in reverse polarity at the cartridge and press the
"mono" button on your amplifier.  And remember to remove the polarity
reversal before playing stereo records.

Jeffrey Borinsky