All the modulation effects are subtle with bass, especially a THUNDERBIRD. It is the nature of the low frequencies. Modulation (for the most part) are delay based effects and so with the low frequency (long period) of bass frequencies, the effect is less pronounced than what you get with higher frequency (shorter period) signals (such as guitar). What you can do to make the effect less subtle is add harmonic content - in other words, put in some overdrive/distortion ahead of the modulation.Hummmm. The only effects I use are an EBS Octave and and old MXR Phase 90, and that less than 10% of the time. I use the phase more and typically on slower songs to fill in those more open spaces. Its more noticeable during softer times of songs. The EBS to thicken up when I want to add more bottom or beef up higher played parts. I don't think I ever tried using both at the same time.
I have a Bass Chorus and it just didn't do anything in a live setting. Sounds really pretty at home! I've tried a few other effects, but the one I would never get rid of is the old Phase 90. It's been with me a long time.
@Gaolee use of a bit of octave up ahead of the modulation would have a similar effect - modulation less subtle on the up octave.
