We used this technique for our last audio demo for the Get Lucky Synth because mostly the result can be even better as with a sub bass enhancer/exciter like Maxx Bass becasue you can control a lot more settings and nicely fit your sub bass to your original one. For example you can add a second square, or a sawtooth and pitch it to get different harmonics.
What you need to do is to simply add a deep square synth playing the exact same pattern like your original bass line. If you already have a MIDI bass line you can just duplicate it and add a synth instead of your bass plugin. If you have recorded an acoustic or e-bass try to play your additional sub bass line as accurate as possible. Maybe you can use a trigger to get the exact groove of the original bass (for this you can also read our gated synth article)
Regarding the sub synth, always take a square instead of a sinus oscillator because it adds more harmonics which are really great to get a deep sub impression. Cut the high frequencies then and add a tape saturation if you can to get even more harmonics. Just play around with the settings to get the optimal sub support for your original bass.
So this is all you need to do, to get a deep sub bass as you can hear in our Get Lucky Demo:
1. Record your original bass
2. If your original Bass was recorded as MIDI track just duplicate it and add a synth with a simple square oscillator. Else record the exact bass line with the square synth again or use a trigger (like a side chained gate) to let your sub bass (synth) follow the original bass groove.
3. Cut the low frequencies of your original bass
Original Bass EQed
4. Cut the high frequencies of your sub bass and gain the low frequencies (30 to 90 Hz)
Square Sub EQed
Final Song: Original Bass Only (no frequencies cut):
Original Bass (no frequencie cut)
Final Song: Sub & Original Bass together:
Sub & Original Bass together