I have the following setup:
Thorens TD-160 Super turntable
Mayware Formula 4 arm
Denon DL103 pickup
Lundahl LL1678 step-up transformers
American Audio - Audio Genie Pro phono preamplifier (temporary solution for measurement)
Analog dual channel oscilloscope (battery operated)
The issue is some hum in the right channel. If I swap the R and L cables coming from the turntable, the hum moves to the other channel. There is a grounding wire attached to the arm, this wire is not connected to the chassis. The chassis is connected to the mains earth though the IEC mains socket earth pin. The other end of the grounding wire is attached to the earth screw on the phono preamplifier.
I checked the continuity between the arm wires and the earth wire (no connectivity) and between the R and L GND (no conn). How is the R channel is different from the L channel so that it picks up some hum and the L channel does not? (The motor generates some more hum in both channels, but the hum in the R channel is present even with the motor off).
Sorry I can't give any quantitative data because my measuring phono preamplifier has variable gain. In my case the hum peak-to-peak is about 4x the peak-to-peak noise in the R channel. The L channel noise is the same but no hum.
Thorens TD-160 Super turntable
Mayware Formula 4 arm
Denon DL103 pickup
Lundahl LL1678 step-up transformers
American Audio - Audio Genie Pro phono preamplifier (temporary solution for measurement)
Analog dual channel oscilloscope (battery operated)
The issue is some hum in the right channel. If I swap the R and L cables coming from the turntable, the hum moves to the other channel. There is a grounding wire attached to the arm, this wire is not connected to the chassis. The chassis is connected to the mains earth though the IEC mains socket earth pin. The other end of the grounding wire is attached to the earth screw on the phono preamplifier.
I checked the continuity between the arm wires and the earth wire (no connectivity) and between the R and L GND (no conn). How is the R channel is different from the L channel so that it picks up some hum and the L channel does not? (The motor generates some more hum in both channels, but the hum in the R channel is present even with the motor off).
Sorry I can't give any quantitative data because my measuring phono preamplifier has variable gain. In my case the hum peak-to-peak is about 4x the peak-to-peak noise in the R channel. The L channel noise is the same but no hum.
Probably should next try swapping the wires at the cartridge. Make sure that all the terminals fit tightly
and are clean.
and are clean.