Sounds like the attenuator in the preamp is not tracking at the same rate for both channels. It is not uncommon for this to happen from what i've seen.
The manufacturer of one of my preamps literally charts the difference in gain settings as one progresses through the volume control. They do this as standard practice when one of their units are sent in for repairs or inspection. It was viewing these results that made me start checking into precision stepped attenuators. The pots used for volume on this preamp are literally "mil-spec" devices. Even using what were probably some of the finest pots available at the time, the results were not nearly as linear in tracking left to right as i would have liked to have seen. You may be having similar problems.
If one of the units is tubed, the tubes from one channel could have slightly different gain curves as compared to those of the other channel. Sean
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The manufacturer of one of my preamps literally charts the difference in gain settings as one progresses through the volume control. They do this as standard practice when one of their units are sent in for repairs or inspection. It was viewing these results that made me start checking into precision stepped attenuators. The pots used for volume on this preamp are literally "mil-spec" devices. Even using what were probably some of the finest pots available at the time, the results were not nearly as linear in tracking left to right as i would have liked to have seen. You may be having similar problems.
If one of the units is tubed, the tubes from one channel could have slightly different gain curves as compared to those of the other channel. Sean
>