Bill Fitzmaurice

While on the subject: The reason speakers are very inefficient, on average only converting 2% of the electrical energy they receive into sound, is impedance, specifically the impedance of air, which is very low. 8 ohms doesn't sound like it's a high impedance source, but it's a lot higher than air, so nearly all of the energy put into a driver is lost as heat. A horn loaded speaker acts as an acoustical transformer, just like the output transformer in a valve amp. The horn raises the impedance of the air mass that the driver operates into, increasing efficiency as much as tenfold.

Current doesn't determine the signal level, voltage does. Input impedance doesn't affect the signal voltage flowing in the cable. Losses occur when the amp input impedance is too low, not when it's too high. When the amp input impedance is less than some ten times the output impedance of the bass what's known as loading occurs, which results in signal loss. https://www.electronics-lab.com/article/input-and-output-impedances-of-amplifiers/ This being the case the higher the source impedance the higher the input impedance must be. Power amps tend to have an input impedance around 10k ohms, because the consoles that plug into them have an output impedance of 600 ohms or less. Instrument amps have an input impedance of 100k ohms or more, because passive pickups have an output impedance of 5k ohms or higher.

You don't need a new cab, you need new wheels. 😊

Those sites are useful, but they only scratch the surface of speaker design. They're the equivalent of the first day's lecture in a four semester course at University of Salford.

Even with identical drivers a sealed cab and ported cab will have totally different low frequency response and displacement limited output. You may be able to get a useful result, if you've got the engineering skill to pull it off, but otherwise it's a shot in the dark.

If they don't have a crossover that assigns different pass bands to different drivers they weren't truly designed to be mixed, advertising claims notwithstanding. I've yet to see definitive objective data that says otherwise.

Like he said. 115s in general don't add any low end to 410s, and they have lower sensitivity and maximum output. That said, where 410s are concerned the Orange OBC isn't exactly stellar, being loaded with entry level Eminence Beta 10 drivers. I'd be looking at replacing it, rather than trying to augment it.

He may have claimed to be a sound engineer, but he was not. That's the Myth of Wave Propagation, see my previous post above.

A pair of 210, vertically stacked, is a good option, but IMO the best option involves spending the least, which is the case if you tilt back your 115, perhaps with a touch of lift as well, which you get from a number of stands.

Your ears are to either side. They're quite capable of hearing midrange coming from behind you, which is a very good thing in the event that said midrange is the breathing of a Sabre Tooth Tiger. That's not a major concern today, but it was when our hearing evolved to become what it remains. I don't care to have my rig in front of me, if only out of 56 years of habit. It just doesn't feel right. Floor wedges are placed where they are because they have to be to prevent mic feedback. Where the OP is concerned since the 115 is what you have tilt it back, by whatever means, so that the center of the speaker is aimed more or less at your head. If you need more output then you'd want to stack a second identical 115 on top. As for the 410, it's the worst possible speaker configuration, unless one of the vertical banks of drivers are low passed. AFAIK the Barefaced Four X 10 is the only 410 with that feature.

You don't need to try a driver to know how it works. The data sheet SPL chart shows how it works in the mids and highs, speaker modeling software shows how it works in the lows. That said, the 320 is quite a bit better than the 300.

It's common for the low end of a speaker to be hard to hear when standing close to it. 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. This effect gave rise to the myth of wave propagation, that it takes a minimum distance from a source for the bass wave to be heard. But if that was true headphones wouldn't work, nor would car subwoofers.

The US is having problems with the supply chain of everything from fuel to food for the lack of truck drivers. Many of those laid off during the height of the pandemic moved on to other higher paying jobs. One reason why ships can't off load their containers is the lack of trucks to transport them from the ports.

It mostly has to do with the Asian side of that other pond. Outsourcing just about everything to there made economic sense when it was done, but not so much when there are hundreds of cargo ships loaded with hundreds of thousands of containers anchored off the West Coats of the US unable to offload. I would imagine similar scenarios exist on your side of the pond.

I can't imagine not having a stand or other method of tilting my speaker back to hear the mids and highs.

If you have to ask then chances are slim that you'd have the chops to do it yourself. The good news is valve amps are easy to work on, if you know what you're doing, and parts are readily available, so it's worth having a tech look at it, if you can find one who works on valve amps. SS is a different story, and the newer they are the harder they are to repair, if it can be done at all for less than the price of a new amp.

https://calculator.academy/speaker-impedance-calculator/

Cabs don't create hiss. They reproduce hiss that amps create, so don't blame the cab on that. Why is everything at 12:00? That gives the same result as if those knobs weren't there. Use them. You should be getting 90dB with less than a watt, so some output voltage testing with a pink noise source is in order. However, I wouldn't put a lot of faith in phone app meters.

It may not be that simple. Is the output balanced or unbalanced? Line or mic level? You need to know to determine what you'll need.

Where what you're hearing is concerned the narrower vertical dispersion of two stacked cabs versus one on the floor is more than compensated for by the higher position of the upper cab.

That's not the one I recall. Mesa does call it a passive radiator, the one I can't remember didn't. In general PRs are smaller than ported cabs for the same result, because a PR takes up less space than a port.

A passive radiator costs more than a port. 🙄 I recall that someone made one, but I don't recall who. I also recall that they didn't call it a passive radiator, they used a different term that implied it was something new and unique, but it was a PR.

Elevate the cab, or at the very least tilt it back so you're on the driver axis. Adding a 410 to a 115 seldom works well, as most 115s can't keep up with a 410. 90% of the time you'll get the best results with two identical cabs.

That would do. The larger the cab the lower and louder it can go with not much power. That's why even in home hi-fi big cabs ruled through the 1940s, when 25 watts was a monster amp, and they still do with Singled Ended Triode amp aficionados.

A tiny cab will have a tiny, as well as tinny, sound. It has nothing to do with power. In fact the less power you have the better result you'll get with a larger versus smaller cab. Google 'Hoffman's Iron Law'. Then have it tattooed on your arm. It is probably the single most important law of acoustics where bass players are concerned.