Help for a newbie.Bass boost in guitar pocket amp

[tenzz]

Hi to everyone.I`m new in electronics and its really nice to have a place to learn from other people.Right on to my problem.
Yesterday i finished my 1st project,a pocket amp based on lm386 without any add ons.Worked ok with no problems and very little noise.The only thing that i didn`t like was that it had too much tremble and little bass.Today i tried to connect a restistor and a capacitor in paralel,one side to the input (pin 2) and the other to the output (pin 5).Like a feedback thing with tremble cut.I got the sound that i wanted but there was an extreme noise.Removed the RC and everything was back at normal.
Can someone explain to me what i did wrong or what i can`t understand properly?
Is it stupid to feedback a LM386?My opinion is that the feedback is the source of the noise.Can it be solved?
Is there another way to add bass without the feedback or without cutting the tremble with an RC filter from the output to the ground?
Thanks in advance.
(sorry for any mistakes in language.my english are very bad sometimes)