Bill Fitzmaurice

That's the fault of the room, not the speaker. Reflections off nearby walls and the ceiling create low frequency null zones. If you're standing in one of those null zones the bass will disappear. When you move away from the null zone the true output of the cab will be heard.

FRFR means full range flat response. Ideally that's what PA is, but you can't get flat response to low frequencies at stage volumes without either the cab being large or there being a separate sub.

The thermal power rating is meaningless in and of itself, just as the driver diameter is meaningless in and of itself.

You don't necessarily have to keep the volume at zero, depending how the amp is laid out. Usually if you plug in to the send that prevents any signal from reaching the power amp unless you also plug into the receive jack.

Those specs are way shy of being useful. For instance, while it may be -10dB at 35Hz, what is the 1w/1m SPL? 98dB? 88dB? That's critical information which is lacking. I can say just by looking at it that it won't have a big low end, because the trapezoid shape causes the box volume to be too small to have a big low end.

Lumping all 212s, or for that matter all of any speaker configuration, into the same performance category is as valid as saying all vehicles with 380HP engines perform the same. There's a big difference between a 380HP BMW Z4 and a 380HP 2.5 ton pickup truck.

Sure. If I was looking for a vintage head it would be an Ampeg V4, which is rated similarly for power but it's a very different animal, quite gig worthy. I'd pass on any vintage speakers, the technology there has advanced far too much. You can get the same output, or more, from a modern 212 as with a vintage 412.

You can't go by the specs, as they're far too incomplete to be of any real use. I can say that the vast majority of powered PA, even those loaded with 15s, are made to work best in the vocal range, with the lows handled by subs. They also don't have pre-amps voiced for bass. That makes them very much a try before you buy proposition.

Since the channels are Normal and Bass and there's no tremolo, vibrato or reverb it's a bass rig. It is an updated Fender Bassman, Musicman being the company Leo Fender founded after selling Fender Musical Instruments. Based on that I'd expect it to be much like a Bassman, which means it's a guitar amp without tremolo, vibrato or reverb. The head is probably OK for low volume gigs, but the speakers were always the weakest part of the Bassman, and I'd expect the same with this.

Assuming that 5 watts is into 4 ohms, which it probably is, that's 4.4 volts at 1.1 amperes. An 18v power supply at 500ma is 9 watts, so you're probably OK where the AC supply is concerned. The battery charger amp hour rating is moot, all that says is how long it takes to fully charge the battery. By the same token what the amp hour rating of a battery tells you is how much power it can provide for how long.

4 ohms requires less voltage swing for the same result as 8 ohms.

If the amp output jack says 4 ohms, yes. Using it occasionally for bedroom practice with an 8 ohm cab wouldn't bother it, but I wouldn't gig it with an 8 ohm cab.

With valves the cab impedance should be equal to or lower than the tap rated load. With SS the cab impedance should be equal to or greater than the head rated minimum load.

Where workmanship is concerned if anything the Vietnamese would be better. The drivers are the same, all that would differ there is coming out of the Eminence factory in Kentucky or the one in Dongguan. The wood one can't say for sure. I doubt that they'd import Italian Poplar to Vietnam, it's probably a local species. There are major plywood mills in Vietnam, so one of them would be the likely source.

On this side of the pond there's a saying 'it's the economy, stupid'. Americans don't vote for ideology, they vote for their bank accounts.

Probably not. The Average American Idiot would tolerate him so long as their pocketbook wasn't affected. But a side effect of C-19 that bothers them even more than the deaths is the unemployment. As that has mostly impacted the uneducated working class that usually votes conservative his core base of supporters has shrunk considerably.

For the most part, maybe. 'Made in USA' these days is mainly a euphemism for 'Assembled in USA from parts that came from Asia'. As an example of how weird things have become, one of the main sources of winter clothing, especially that made for winter sports like skiing and snowboarding, is Vietnam.

This is likely C-19 related. Sales of everything entertainment related are down, because nobody's working very much if at all. so I'd expect manufacturers to find ways to cut retail prices to increase sales. Don't be surprised to see many more manufacturers selling direct on the internet.

That's only an option if the cabinet has enough volume to work with three drivers, which may only be confirmed by software modeling of the speaker response with the available box volume net of the ports and drivers, and the driver Theile/Small specs. One must also use modeling to determine the area and length of the ports based on the most effective box frequency tuning and keeping the port air velocity within acceptable limits.

I'm getting a deja vu vibe. 😉

That's true of a sine wave, but even a single note isn't a sine wave. It consists of the fundamental plus all of the harmonics of the fundamental, so it too is a complex wave form. Where bass instruments are concerned in the lower registers the second and third harmonics tend to be louder than the fundamental. https://www.puremix.net/blog/musical-instruments.html

The same way that a microphone diaphragm does, which is a speaker in reverse. For that matter the same way that your eardrums do, as they are microphones.

The electrical signal to the voice coil has changed.

The speaker doesn't translate a change in the treble control. It merely passes on the information supplied to it by the amp. When the treble control is turned up the pre-amp increases the high frequency content relative to the rest of the audio spectrum. Speakers do influence tone to the extent that the audio signal they reproduce isn't exactly the same as the electrical signal they receive from the amp. This is called 'coloration'. The ideal hi-fi speaker has no coloration, while guitar speakers intentionally have very high coloration. Bass speakers lie in between those two extremes.

My comments are purely observational. I haven't owned a valve amp since the early 80s.