Quad 33/303 Hum (grounding issue?)

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09-Oct-2018 12:55 AM



Posts: 1

Hi all,

Let me first state that I am without much experience in this world. I find myself often losing track of conversations on this forum, though many of them seem to have the potential to be exceptionally helpful! I feel neither my terminology nor my knowledge of electronics is up to scratch, so please do forgive me if I appear to speak out of turn. 

I am trying to set up a Stanton T.62 turntable to use with my Dad's 33/303 system. I have been using the 33/303 for some time now with an AUX source going into the Tape Input on the 33. The 303 is powered by the 33. This has worked wonderfully and without issue.

As I now move to connect the turntable, I have taken advice found on this forum to rotate the Disc Adaptor board into the M1 position. Also as per the advice of this forum I am using an MM cartridge (Ortofon OM Pro S). I connect the phono output of the turntable to the Disc Input of the 33. 

Unfortunately I am consequently met with a loud, across-the-frequency-range hum that does not exist on any other inputs. The hum disappears if I disconnect the cable coming from the Stanton. It also changes in volume as I move the volume knob, so I believe that it is related to the Stanton.

The ground output of the Stanton remains unconnected, and I wonder if this may be the problem. Given the 33/303 has no ground input (does it??), I'm left feeling somewhat lost as to how to resolve this issue.

My questions to you - can I resolve this? If so, how?

Thanks so much for reading this far, any and all help is hugely appreciated. Getting this thing up and running means a lot to my Dad.

All the best,



15-Oct-2018 04:54 AM



Posts: 1525

The 33 is earthed via its power code. The 303 is earthed to the 33 via its 4-pin DIN signal interconnect. The turntable's audio lead should have a flying earth lug which should be connected to the earth screw on the back of the 33.