Anyone's GX-95 have this effect? What's the difference in Dolby C
perfoemance with GX-95 and GX-95MKII if you have both machines.

Also someone gave me a GX-75MKII tape guide replacement part,
do you know it is the same part used in GX-95, because the one I got is
almost perfect if it had its broken tape guide replaced.

Dolby B is much less sensitive to media. It works pretty well on all good quality tapes, and even on cheap ferrite tapes, I never noticed irritating artifacts. Worst thing is a loss of the top octave when decoded, when a cheap tape doesn't "hold" the increased treble from the encoding filter. You can always turn the decoder off, which has the effect of boosting the top octave. Of course, with the decoder off, you won't have noise reduction but instead will have treble boost. The increase it gives to the top octave is usually welcome on those cheap tapes anyway.

This isn't the case with Dolby C or HX in my experience. Some tapes just can't be made to sound good with them. You can't expect a tape encoded with Dolby C to sound good if the decoder is off, so cheap tapes really couldn't be used. When they don't retain the increased HF from encoding, you can't just turn off the decoder so the tape sounds bad either way.

I have 20 TDK SA/SA-X and one SONY Metal Master. Don't really want to open those as they are extremely hard to find nowdays.

I used TDK D/B/EF and TEAC cdx to try the dolby c recording and all got same result. Is it likely the machine is out of "fine tunning"? But as far as I know the original owner never opened the machine, and it only recieved 40 hours of usage in total and was taken care very well.

What model do you have and use, could you please try your model with those tapes + Dolby C and see what happens?

Cheers