qsxm3

[yiancar]

hey guys, i notices hum in the preamp and desperate to find the fault i made the observations below.

connecting only the right channel everything is ok. once i connect both right and left channel hum appears in both channels.
also reversed the inputs to check if its the cardage but it seems to be related with the left channel of the preamp

any help with that ?

[peranders]

Do you use shielded wires to the cartridge? Do you have a separate ground wire from the tone arm?

[yiancar]

yes i thing its shielded. there is a ground wire even i see no difference with it connected or not

[peranders]

Are the shields tied together in the turntable end?

[yiancar]

i think so yes, any way i can check that for sure

[peranders]

They should not be connected in both ends. It would be good to know if the turntable is humming with an another phono amp.

[yiancar]

the channel grounds are connected together, the cable shield/phono earth runs seperated

[yiancar]

i find it very confusing when both channel of the preamp have ground there is hum everywere. you thinking that the cable picks the hum?

[peranders]

From my amp you should have a straight connection to the cartridge four connections and a separate ground wire from the tone arm.

[yiancar]

any chance to modify that so to have a common channel ground?

[peranders]

I recommend that you take a look at your turntable's wiring first.

[yiancar]

this also means that i should use isolated rca plugs so the grounds do not touch the chassis?
i mean what i dont get is that the 2 "ground" wires from the cartage will be in parallel as they are now right?

[peranders]

Isolated contacts is a must.

[yiancar]

this is how my turntable is wired

u recommend separating the grounds from pin number 2.

any good isolated rca to recommend?

[peranders]

Wow, it's an old thing with DIN connector. Do you have some sort of adapter DIN-RCA? You have one signal ground from the cartridge and one ground for the chassis/tone arm.