Turntable Oscilloscope Readings


After setup of my cartridge, I used an oscilloscope to verify zenith, azimuth, and anti-skate force using Analogue Productions Test LP. Phase between channels is right on (zenith), and distortion of amplitude sweep is the same for both channels (anti-skate). I minimized cross-talk for the worse channel (azimuth). All good.

The strange thing though, is when measuring channel outputs, the right channel was about twice the amplitude of the left channel as measured on the oscilloscope. However, I can hear NO difference between channels through the speakers. Balance and centering of the sound stage appears perfect.

The components involved are VPI Classic Signature turntable with VPI analogue drive system, Soundsmith Sussuro Cartridge, and Herron Audio VTPH 1-MC Plus. The oscilloscope is connected to the phono preamp via RCA cables using a BNC to RCA adapter at the oscilloscope.

Any ideas about what is going on? 
gareents

Showing 2 responses by lewm

I would assume the OP knows how to use his oscilloscope.  Also, as Mijostyn said, it doesn't really matter whether the scope is calibrated or not, if the OP took his readings at the same scope settings for each stereo channel, using the same pair of leads and the same channel on his scope. 
Do you have a SPL meter? If you can confirm with a meter that the SPLs from each speaker are about the same, measured at about 1 meter and preferably using a pure test tone, then I wouldn’t trust the oscilloscope readings.Actually, that makes me ask what was the program material that gave you the impression of 2X amplitude in one channel vs the other?