Ideas/tricks for boomy bass guitar

Sounds strange that you're having such a problem with the tone/EQ, especially with as you say, a "fancy" bass. Not sure how much help I can be other than what I've said and throwing more free plugs at you, like:

Can we hear a sample so we can make suggestions in context?

A small suggestion I think Mike Senior put out once about bass is to add some distortion that will bring some of the energy into the higher frequencies and give you more to work with..

Although I'm not a fan of multiband-compression, I'd try some here. Like Nova-67P (my goto for bassguitar) Maybe a doubled track with HP/LP and distortion?

Thanks, tgraph and ginormous - that's of course what I tried first, since it can sound cool even with "normal" basses. But there is not much (read: nothing) usable going on in the "upper" range. So I can either distort the 50 - 150 area, the wavelength of which is so huge, it sounds like a synth. Split band compressing is just boosting the mud. I mean, I want 3k in a bass, maybe even 5k, but there is nada, nichts, nothing. No air, no strings, nothing that defines the instrument. Pickup noise, yes. 400 - 600 is "wood", which is okay per se, but as long as it's not accompanied by a balanced string or fundamental tone, it's pretty clueless. I just botch a usable context sound and focus on the rest :)

If you're missing high frequencies why not add it? Use ReaTune to record a MIDI track and then let that drive some bass VST (or even a synth), maybe raised one octave. Then mix in with the original. You don't even have to say anything to your client :)

Have you asked the player what HE was looking to get in the way of tone? You may well be fighting each other here. Not everyone wants or even likes a brighter more articulate bass sound. Also, what does the actual client think? I have one active bass set up with oldish rotosound roundwounds and one fender precision USA 62 reissue set up with ground rounds, which are pretty much the equivalent of those tape wounds sound-wise. I wind up using the precision a lot more than the active bass, simply because the sound IS really fat and thuddy. If you are trying to get the recording to sound like a modern, clean, articulate bass from a semi-acoustic with tape wounds, you WILL struggle. HAHA! I totally missed the part where you said his technique was somewhat lacking on that first track & the rest was OK. Not much you can do about that really, is there? But like I said before, what does the client think?

if it's a fancy bass, it could have active circuitry. was the DI active or passive? I'd use a passive DI. Once you record a cruddy sound, it's too late really.

Scroll down for Bassprofessor or MKII Maybe these are not cure for all problems, but definitely worth to check out.

I've used the Clarisonix enhancer on basses with no definition with pretty good results. Leave off the sub enhancer and crank the Clarity knob and adjust mix with the Reaper mix knob. Basically I'd take any soundly maligned Exciter or Enhancer plugins that was two steps forward and four back on anything else it was tried on and give it a shot.