I don't live in English-speaking country. I try to learn English on my own. I am interested in aquisition the General American accent (GA). My question is about the American /r/ consonant ([ɹ]) and the American r-colored vowels ([ɚ]).
I have a problem with realization of the /r/ English phonem. I know that exist 10-11 or even more options to articulate this sound, but the retroflex and the bunched (aka molar, retracted, dorsal) versions are the most famous. I have learned the retroflex version of this sound. I am OK with the [ɻ], alveolar and postalveolar realizations.
Now my main interest is the bunched /r/. I have tried many times to pronounce this for 3-4 weeks but I can't. I went through all the videos and articles about this topic that I found on the Internet. I have seen the MRI. The tongue tip must not be curl and lift up, the tip of the tongue should be located at the bottom or just neutral. Each time I try the tip my tongue wants to go up. If I hold the tip of my tongue and don't lift it up then I'm making completely different sound.
So, how to pronounce the clear "bunched /r/" without lifting the tip?
What I've tried: I looked at my mouth with a flashlight in a mirror, I used a pencil, I used a spoon.
Russian language is my native tongue. I don't have speech defects in my native language.