AnalogMagik Tutorial No. 10:
Channel Balance
(Function available on Verison 2 Only)
Based on popular demand, AnalogMagik Version 2 has added a Channel Balance function.
Play Track 3 on side B (33 rpm) or D (45 rpm) of the TEST LPs, which is the 1 khz test signal track for Optimizing Gain level, the Channel Balance function will display the amplitude (volume) difference between Left and Right Channel in dB.
Please note that AnalogMagik is just a distortion analyzer which displays what it reads. It does not have the ability to make adjustments to fix channel balance issues with your phono stage or cartridge.
Most cartridges are made by hand, and will always have a slight channel balance difference. The unofficial industry standard seems to be between 0.1 dB to 0.9 dB. Beyond this level, you may hear a skewed sonic image.
Having an equal channel balance is important because the accuracy of the Azimuth (Crosstalk measurement) is affect by Channel Balance. If your phono stage or cartridge has a channel imbalance, the results will be less accurate.
Some phono stage, such as the Burmester 100 Phono, has the ability to account for Channel Balance difference, and if such a function is available on your phono stage, channel balance should be adjusted prior ahead of any other measurements. However, this will only compensate for the imbalance, it does not repair the actual imbalance with the cartridge.
However, for loopback test, “Monitor Source” should be set to “CPU” setting on the sound card. With this setting, the measured amplitude and phase difference became 0.12 dB and 0.17 degree respectively.
In the above loopback test, the mismatch between the two channels was contributed by both the input and output channel (the loopback cable used is an ordinary one, with output L -> Input L, and output R -> Input R).
For turntable adjustment, only the mismatch between the two input channels needs to be checked. We performed the test with an external signal generator to inject the same signal to the two input channels of USB Phono Plus. The measured amplitude and phase differences are only 0.02 dB and 0.19 degree respectively, which are negligible. The channel imbalance is so small, smaller than most cartridges and phono stages' inherent channel imbalances.
We have tested 20 samples of the ART Phono Plus, and nearly all of them have the same spec, they all gave very similar results.
Channel Balance adjustment on the Art Phono Plus is, therefore, unnecessary.
For the sake of argument, let's assume another soundcard is used, and there is significant channel imbalance, AnalogMagik will still allow you to achieve an accurate setup because we are concerned with "Incremental changes", or in the case of azimuth, finding the narrowest range between L and R channel. Inherent channel imbalance will cause the gap between L and R channel to widen, but you will still be able to find the narrowest point.
In reality, we found the majority of the cartridges on the market to have some channel imbalance, far greater than the 0.02% of the ART Phono Plus, therefore channel balance adjustment is unnecessary if you are to use the Art Phono Plus. However, we cannot say the same about other soundcards, which is why we recommend AnalogMagik to be used with Art Phono Plus only.
