stepaan wrote:Now I know that error is definitely on my turntable (but still don't know what is it ;-))
Many things can change balance between channels, and since you are sure the problem is with your turntable, these are some things you can look at :-
Check all cartridge alignment, i.e. Vertical tracking angle (tonearm height effects high frequency content). Azimuth (i.e. the angle of the stylus to record as viewed from the front). This will certainly effect balance, particularly in the high frequencies, and more so with elliptical than, for instance, a spherical stylus.
Check bias. Most cartridges don't actually need as much bias as is often set, i.e. 1 gramme is usually sufficient for playing weights up to around 2 grammes, so you can play around with the bias either side of the playing weight and see if this make a difference, but I would suggest the 1 gramme setting.
Channel balance of the cartridge. If the cartridge is fairly new and you have always had the problem since fitting it, the cartridge could have a low channel. This can happen !
Check all your connections from the cartridge right up to the amp, but especially the cartridge tags for bad connection. Apply some isopropyl alchohol to inside of the tags with a stylus brush and push the tags onto the cartridge pins a couple of times for each pin which should clean them. If is fitted to an SME style headshell, then clean the tags at the other end of the wires as well.
The only other thing that could effect balance that I can think of is either friction in the lateral bearings, or if the internal tonearm wire is twisted, for instance if it has been internally re-wired incorrectly, forcing bias on the tonearm.
I hope this helps you find the problem.