Yes , those without mono cartridges or without a mono button on their amp can put two Y adaptors between the turntable and the amp . No need to rewire the cartridge itself .
The two male RCA jacks from the turntable are put into a Y adaptor with two female RCA jacks going into one male RCA jack . This male RCA jack is then put into a Y adapator with one female RCA jack going into two male RCA jacks . These two male RCA jacks are then plugged into the phono stage of your amp .
Using a Y-connecter sums the channels to give a nominally L + R signal. This is the horizontal information on the record. The vertical information is L - R.
The problem is that cartridges have crosstalk, both from left to right channels and from L + R to L - R (the same thing if you think about the math of it).
By using a Y- connecter, you get the L + R signal plus some of the L - R signal via crosstalk.
A true mono cartridge never picks up any L - R information in the first place , so there is no way it can contaminate the L + R signal.
[Posted by chickenlogic ( A ) on January 06, 2005. Vinyl Asylum]