I just found my old "Mr.Cheap" 4ch car amplifier..I remember..this amp was died..so..I want to check what's the problem with this bad stuff and I found that 2ch (rear channel) was fully broken.So, why I'm not remove the broken final stage transistor?..when i finished, I tried to crank this stuff..and I said "what the hell this stuff!"
Why I said that?..Of course I said that!
the sound was very harsh, and the vocal is very thin!.I like to hear sweet sound (I mean soft, detail, the bass is deep but not loud, the separation is good, e.t.c).So..why I'm not to mod this one?
Than I found a pair of Sanken 2SC2922 and 2SA1216, some ELNA caps, 2 pairs of Nichicon FW, some Panasonic M caps, JRC 4558 dual opamp, and a few SGS Thomson TL072..they're cheap component..but not the "Mr.Cheap" one..suddenly, I replace the caps at Power Supply stage, and input stage and of course I replace one of "Mr.Cheap" 4558 opamp to JRC 4558 and the other using SGS Thomson TL072..
After that, I let them cooling down for a few minutes..when I finished break, I crank this up.and the result..
Damn!..more staging, the sound was more sweet, and I found many other improvement like the separation, vocal detail, and many more..
but not finished at all!..I found the bass was too weak!.So I decided to change the final stage Transistor from KTB688 and KTD718 to Sanken 2SA1216 and 2SC2922
Than I cranked back the amp.and wow!..the bass more powerfull, tight, and deep!.the vocal was more warm, improved the separation, but a little bit harsh at the high frequency..