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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
mijostyn's avatar
mijostyn
8,164 posts
 
Gareents, you have to look at the scale. There might not be much difference. 

oldears and Hvymec if there is a calibration error it is the same for both channels therefore it factors out. 

Cartridges can easily be off 1 dB between channels at certain frequencies. With the right scale this can look like a huge variation when in reality it is not. 
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tablejockey
3,771 posts
 
"I can hear NO difference between channels through the speakers. Balance and centering of the sound stage appears perfect."
 
Makes sense going the distance using  test equipment with the level of gear you have. On the other hand, your ears are pleased notwithstanding scope measurements.

May be one of those things you accept, or take it to a turntable doctor.

lewm
12,453 posts
 
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. 
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