How to get Consistent Sub bass through key changes

Through note changes in the drop of a track what is the cause of the perceived difference in loudness and how is it fixed?? Is the sound selection not correct or is compression required to tame the lows and highs of the sound??
Choosing real good quality samples can fix the issue but using a Sub bass from a Synth seems to be more tricky for some reason. Curious on what works??

Heres a funny thing… for years i was trying to figure out the answer to this question. I tried all sorts of ways, Compression, Multiband compression… having individual notes on individual tracks etc.

Nothing worked particularly well. Until…

I got my room properly treated with giant bass traps and did a speaker calibration. Then suddenly the subs where even.

So if you are hearing the subs being uneven in with certain notes its most likely your listening environment rather than the sounds.

try listening in a few different places and take note of what notes are more prominent on different systems… If you still have one note thats sticking out you should be able to eq it out.

I just asked a question in the 2019 James Dymond tutorial about this.

I prefer using multi-samples for any basses that sit below 150-250hz. With samples its easier to use the sustain or hold envelope parameters to cut the bass down to a precise length at the same volume.

Depending on the samples, whether pitch shifted or multi-samples, the volumes between the notes may differ. The only way I’ve addressed this is using a sampler like Battery where I can gain-stage all of the notes the bassline will be playing to 0VU. They might have different peak volumes on a dbfs meter, but loudness wise they will sound at the same level.

The only trick is EQing or using a subfilter for a multi-note bassline. If using an EQ to boost, cut and rolloff…those settings will have to be specific for each note to stay at the same loudness. Which was the question I asked in the tutorial. Automation is too much of a hassle, and duplicating channels for different EQ/ different notes feels unnecessary. Maybe an auto gain might be a solution. I’ll see what the replies will be.

Additional TL;DR
When using a hold function on a sampler, this page has a helpful chart for knowing how many milliseconds a given note is at the projects tempo: Tuneform - Bold Your Music – Say if 140BPM, a 16th note would be 107ms exactly. I might set it at 104ms to have the right amount of space between the notes. – I prefer this to the sustain, because adjusting midi notes smaller than 16ths can be tricky without turning snap on and off.