Most of what I have ever learned in studying the use of compressors is that they should be the last device in the signal chain. Since you are using them to smooth out louder parts and boost quieter parts so your sound is more even. Too much though and you'll affect your dynamics too much. Just the right amount and you control your dynamics with your fingers. If you put an effect after the compressor , it can introduce gain in the signal path and negate the purpose of the compressor. Since Bass is the most dynamic instrument as far as the variance in it's signal from quiet passages to fast transients and the fact that digital recording devices don't like to have their record level clipped like old tape recording devices where that actually caused a somewhat desireable effct know as tape compression when you clipped the input signal while recording,compressors are very important to get the best signal level recorded without the unpleasant affect from clipping the input to a digital recorder.
I have tried using 2 DBX 160 a's, one on each crossover output of my F-1X so I could compress the highs more to smooth out those loud fast transient signals when you slap or snap a string back against the fingerboard but be able to compress the lows less so the bottom end still came through clear and punchy and loud. But doing that, if you change the volume on the F-1X you have to adjust the threshold of each compressor accordingly to keep it starting to compress the signal at the right level. This led me to just putting the compressor last in the effects loop of the preamp. Plus this way my direct out to FOH or recording device is compressed where as with the compressors on the crossover outputs, your direct out is not compressed. For my other system where I use 2 seperate preamps for a biamp setup, 1 set for highs and 1 set for lows, I use a DBX 160 A in the effects loop of each and can compress my highs independently from my lows. I use a Sansamp RPM and a Sanamp RBI, The RB1 set for highs through a Crown Amp to 4X10 cabs, and the RPM set for lows to a Crown amp to 1X15 cabs.
Both setups sound great But I still usually prefer the Alembic F-1X, SF-2 DBX 160 A and then the cossover outputs the that amplifier cabinet setup. Imagine that. Ths Sansamp setup will definely get that Geddy Lee sound though and offers the independent compression option.
Will