Call me crazy, but all of the light heads that I have tried, do not go as deep as the older heads. They will push bass, but not the real deep bass that you normally hear through an audio subwoofer.
To be fair, that's your perception based on an equation with a lot of variables. The reality is that the endpoint for most PA setups (at least those at a higher/pro level) is D-class power amps pushing your signal out into the venue through whatever system they have. Point being, class D (lighter weight) power can reproduce those subs without issue. In fact, there have been double blind tests demonstrating most listeners can't identify the difference between class D and other power amps when the preamp topology is the same. So, your next comment (and one that was made by others in this thread) is more likely the issue - i.e. manufacturer's intent/design.
Whether that is from damping, transformer, mosfets, HPF cutoff set at 30 hz vs. 25 or 20 hz, something else, or a combination, I don't know.
Maybe all of the above. I have always preferred the quickness and feel I get from solid state amps, although I've owned and liked some tube heads. In my experience, the qualities that differentiate them a lot are hard to define & describe, like speed and texture. It's the way they respond really, not a lack of capability in reproducing frequencies. Some of the factors you mentioned above will just affect those qualities in various ways. Also, that may be why I like the sound of the DB751 a lot. I feel like it gets lumped in with tube heads a lot because of the weight of the amp and the slam/heft/whatever that players use to describe it. What I hear is quick, cutting, authoritative tone. Not something I would typically characterize as synonymous with tube amps being pushed.
To my surprise, many bassists don't care for the heft and use HPF filters set between 50-100 hz to remove it.
IDK, why play bass if you are going to remove the best part? I am in the minority though.
Not all cabinets can produce the depth properly either, which may be why some cut those frequencies.
This again speaks to perception. My experience says that pumping frequencies under 40-50Hz brings out boom and mud that can overpower the punch and definition in my signal. The latter is where I perceive 'heft'. I get that there's a beauty to pant-flapping power behind you on stage, but they aren't pushing that stuff through the PA for a reason.
You allude to this with the comment on cabinets not reproducing those frequencies. If you send a DI signal before your amp/amp EQ, they FOH is usually rolling you off with an HPF somewhere around (maybe above) 40 Hz. If you're mic'ing a cab for the FOH, your cab is doing that for you.
Some bassists prefer a "piercing" bass vs. a full bass too.
Perhaps I've beat this to death, but you're presenting this as a dichotomy rather than a range. I've heard bass that is really cutting, grindy, and/or treble heavy - that can also be "full" if done well. On the contrary, I've heard people using big mosfet or tube amps that sound like a flabby, wet blanket. It's all relative, and there's no magic bullet. Being able to dial in your sound and slot yourself together as a band is really important to sounding good live, regardless of the head you're using. I enjoy playing some palm muted, scooped, bass heavy stuff at home. If I brought that tone to my band mix, it would be a terrible fit. Tools for the job...
I blame the Ampeg 810. These cabs have a very poor low end extension but to a lot of people this is still THE classic bass tone. I guess it makes sense that others try to emulate that tone. Many modern Class D amps seem to be voiced kinda like an Ampeg WITH an 810, completely lacking the low end "heft" of many older tube amps (including SVTs with a DIFFERENT cab than the 810). It's probably also cheaper to manufacture amps that can't deliver the low end heft you get with classic tube amps like Hiwatts, etc.
Counterpoint, I don't dig the ampeg sound, and I have played a lot of class D heads in the last 7-8 years. Unless you scoop the EQ or engage some sub-bass EQ, I find most of them
do not sounds like Ampegs.
Also, that last statement is based in zero evidence or technical data whatsoever. It's more expensive to produce and maintain tube-amps, sure. Low end 'heft' is really a matter of having enough power/headroom to reproduce those notes efficiently, EQing the amps properly, and having a cabinet that can handle what you're feeding it. It's cheaper to manufacture less powerful amps in general, regardless of the topology. So if you want the heft of a 200 watt HiWatt or a 1000 watt solid state amp for the price of a 50 watt bass combo, that's just having unrealistic expectations.