Any tool, even basic EQ, is a "specialized tool". Bottom line is that multiband will provide a more natural result than single band. The difference may be insignificant at times, but that doesn't mean it's wrong to use multiband. Of course the caveat is "when used correctly", but that applies to every part of the chain, including the bassist's fingers. So while we should acknowledge that multiband is more difficult than single-band, I'd prefer to assume that the operator knows how to use it.
I also disagree with "fix specific problems". Same as EQ, compression (multiband or otherwise) can be used because it's wanted, even if it is not needed.
I suppose it's a matter of context. As a studio engineer, your focus will be fixing problems. For performing bassists, it's about making our ears happy (along with supporting the band by sitting well in the mix, etc). I'm cool with the sound of my bass run thru my amp set "flat", but flat is never flat (outside of the studio, anyway), and there's nothing wrong with tweaking tone and dynamics to make your ears happier regardless of the quality of your rig.
'Multiband will provide a more natural result than single band'
Perhaps - if there are specific issues with your signal and how it's split which need to be addressed, and you absolutely know that you must accomplish it with a multiband compressor after extensive experimentation. That will depend on your goals and setup, but I wouldn't make that a categorical statement intended to steer people toward multiband compression as a first option. I can't agree categorically that a multiband compressor will be 'more natural' than a single band because the context of the situation will define whether it's the most natural, or the best solution.
There is so much misconception and confusion about using even a standard compressor that a multiband compressor can be viewed as either three powerful, separate ways to make fine tuned adjustments to solve whatever problems may be present (or to allow you to 'customize' your sound to your heart's content).... or they could be three separate ways to make things worse. I'm a Star Trek fan and I always think about Mr. Scott and this quote from Star Trek III where he's commenting on how complex the USS Excelsior's transwarp drive is, but how easy it was to sabotage it: 'The more they overthink the plumbing, the easier it is to stop up the drain.'
The hope is that the operator knows how to use it, but I remember how much of a learning curve I went through when first learning to use a multiband compressor in the studio. In a live setting, one might not have the opportunity to dig in to the degree that it usually requires to really hone in on the specific settings that might yield the most benefit, because with crossovers, attack/release ratios, boosts/cuts, etc in a lot of multiband units, there's a LOT going on.
Yep - we can use EQ or compression simply because we want to. But sometimes what we
want doesn't always work in a given situation. It can create new problems which need solving. So we're back around to where we started.... sometimes.
Here's a perfect example of why I use the 'fix specific problems' phrase a lot:
My double bass with its Realist pickup has the usual piezo pickup 'problem areas' in the signal which present as harshness in the mids, and often a bloated bass range. I use my Radial ToneBone PZ Deluxe to 'solve the problems' with impedance matching, and to smooth out the EQ points before it ever hits my amp or the front of house so that I already know I'm approaching the overall 'natural' tone I'm seeking. That often includes using the HPF portion of the preamp, the sweepable mids, a slight cut in the bass, and a slight bump in the top end. There's also an Aguilar DB316 midrange EQ pedal that I can use to fine tune another additional problem area in the mids if necessary. The goal is that when I hit my amp, I have to use very little of its EQ section to fine tune to the room... which usually involves a few more very specific yet small changes to the low mids. I'm lessening the 'problems' I have to solve in the room and with my desired tone before I ever turn the amp on - hopefully. So when I say 'fixing specific problems', that's the kind of stuff I mean. I'm not trying to be pedantic for the sake of being pedantic. And I rarely, if ever, use a compressor live with my double bass or electric rigs... mostly just in the studio. YMMV.
Our work in the studio and playing live should feed and inform each context. Every new challenge adds to the toolbox of knowledge. It's my job to make my ears happy (and my clients' ears) in both instances, and some of the nitpicky stuff I would try in the studio I won't deal with live - it's simply not worth it in most instances, due to the number of factors in a given room out of my control. Context matters for sure.
