Xlr + Subbass Crossover + Low Filtre

I copied the rcf705 as an active transition. However, I am using 4 ohms to drive 21 inc subbass. However, the preamp level is very low.
How can I find such a higher quality study?
 

Attachments

  • ART705AS-Base Amp Sub.pdf
    1.2 MB · Views: 50
  • ART705AS-Input Board.pdf
    65 KB · Views: 37
  • ART705AS-Preamp Board.pdf
    103.6 KB · Views: 38