bass boosted tracks for car audio

I have recently begun creating my own bass boosted tracks for car audio. I thought I would share my technique and get some tips from more experienced people. It’s been kind of a touchy subject with others in the car audio community, no one likes to share techniques.

After a month of trial and error this is where I am at so far:

I drag the song I am editing in once
split to mono
apply an initial low pass filter 75hz 48db
select a patch of audio and do a plot spectrum analysis to find the bass peaks between 30 and upper 40’s
i then use the bandpass filter to isolate a chosen frequency
bass boost to 12db
use the wave terrain oscillator to help smooth out the peaks
amplify it to -1 peak amplitude

I usually repeat the process for the next freq. if there are any. Most of the time there are 2 different notes i boost.

I then drag another copy of the song into the project, keeping it stereo, apply a high pass filter @200hz then export as a wave.

I was wondering how to isolate the mono bass notes from playing at the same time. I’m sure there are issues but this has to be a primary concern with my process. Since I know there are instances when the same note hits those frequencies at the same time. I’d like to know how to combine the two mono tracks and remove the common intersects.

The simplest thing I can think of is highlighting individual sections of the song and going through the process for each section all on the same mono

  1. Make a copy of the original (stereo) track.
  2. Convert the duplicate track to mono.
  3. Apply a 120 Hz 12 dB per octave high-pass filter to the stereo track
  4. Apply a 120 Hz 12 dB per octave low-pass filter to the mono track
  5. Use the Track Gain controls to adjust the balance between the two tracks
  6. Select both tracks and “Mix and Render” (“Tracks” menu) to a single track.
  7. Amplify (or Normalize) so that the peak level is just a little below 0 dB.
  8. Export your “remastered” version.