I am pretty partial to the aphex punch factory. Great optical compressor. I set the input to about 3 o clock, compression to about 2 o clock, and output to about 2 o clock with my active spector, anything past that, and i start to get a little noise. Not only does this really tie all the notes together REALLY well, but this adds some serious punch to rig, almost like having a kick drum in my cab. i know alot of people frown on this sort of thing (almost over compressed), but i really dig the sound. Use it with my bass and tuba with the same settings.
Wow, after digging around for two days someone answered my question almost exactly.
Im looking to buy a box for my sousaphone,so, can I ask: did you try other compressors? any ones to avoid for bass horn? I really like my highs Im getting off of my genz shuttle/ mark 2x10. But the lows, especially with filters and distortion on eat the band up and Id love to get more thump than watery wallup in that range. Would love to hear more about what you learned in the process