Bill Fitzmaurice

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.

The advantage to playing open notes is it frees the fingers to fret other notes. JJ would have avoided open E for the same reason we all did back then, the speakers couldn't handle it.

You don't need to use identical drivers, but they should be spec matched as close as possible, as should the enclosure. There's no need for a low pass filter in the extension, the woofers aren't doing much above 3.5kHz anyway. That's one reason why a 2kHz capable tweeter gives a better result. If you're going to run into problems it would be using an 8 ohm 210 along with the 8 ohm 110. That puts half the power into the 110, half into the 210. Doing that you might as well have the extension be a 110 as well.

I doubt that had anything to do with how standard orchestral tuning of the double bass was arrived at. How they decided on E I can't imagine, it's not an octave below the cello, which has a C as it's lowest note.

I play Classic Rock and R&B. They didn't go below E, neither do I. For that matter I doubt that James Jamerson ever hit a low E. That's not a key for horns.

What I can't do with four strings I don't need. 😊

It seems that one's IQ is inversely proportional to the number of strings on the instrument. I remember using those on my bass back in the day, and they were horrid in how they killed the mids and highs because of their capacitance and inductance, two terms not in the vocabulary of most six-stringers. 😊

The only way they'd sound different direct versus daisy chained is if the cables are seriously undersized. All cables have some voltage drop, and when you daisy chain that drop is higher compared to when each speaker has its own lead to the amp. But with the length and gauge of correctly sized speaker cables the voltage drop in either configuration should be virtually unmeasurable, let alone audible. I keep seeing these references to getting more headroom with lower impedance loads. I imagine the reason for this notion is the higher power output into a lower impedance load. That notion should be divested. What happens with a lower impedance load is that for the same voltage output from the amp you get more SPL from the speaker. That's all well and good, but you also draw more current from the amp, so from the standpoint of current you don't have more headroom, you have less.

I'd just run one amp that does what you want it to all by itself. That's valid when you have one cab that's optimized for the lows and one optimized for the highs, as in a PA sub and main, but not with two identical cabs.

An eight foot ceiling won't provide a significant boost, if anything it will cause a null. This calculates floor and ceiling bounce: https://mehlau.net/audio/floorbounce/ If you do a few calcs you'll see that the closer you are to the speaker the lower the cancellation frequencies. That's why you can't hear your lows on a small stage. Extend that distance to where the audience is and the reason why it's louder out there becomes clear. I always do my sound check from the dance floor, adjusting my volume and EQ for how it sounds there. Whatever that results in on stage I live with.

Definitions vary from person to person, but what most consider to be boom is a response peak in the midbass, from 80-120Hz. The usual cause of boom is an enclosure that's too small for the driver, especially when it's sealed.

That's because the speakers of that era, both the ones we played through and the ones the recordings were listened to on, weren't capable of going low. Don't forget that the #1 playback system in those days was a car radio/CD player, and cars didn't have subs as standard equipment then. Even studios didn't have great sound. The Yamaha NS-10 and LS3/5A weren't exactly bass monsters, and while Altec A7s were big and loud they didn't really go all that low. Give a listen to anything from the 50s to the early 80s and there one thing you'll almost never hear: a low E. The inability of vintage speakers to play a clean low E above bedroom levels is what started me building my own.

Yeah, but how many bass amps have bridge mode? I suppose some do, but still that's very much a PA thing.

That's correct. It's not how Tony Hofmann wrote it down, but that's the gist of it. Why his last name ended up getting another 'F' with respect to his law no one seems to know.

There's very little difference in the sensitivity of different bass drivers, so that's not going to work. Higher power handling to get more bass out of a smaller cabinet is a requisite, but the thermal ratings aren't what matter, mechanical ratings are. You can't get those unless you have the driver data sheets. If you really don't want to get high output in the lows use a sealed cab. Even when the same size as a ported cab they give up almost an octave of low frequency extension. Look at it this way. Violins don't go as loud as violas, which don't go as low as cellos, which don't go as low as double basses. Size is the reason why. The same physics apply to speaker cabinets.

How they're wired should be in the owners manuals. If they're not wired +1-1 I can't say why. For that matter I'd expect they'd use 2 pole Speakons, so that would be the only option.

If it's a mono signal the +1-1 poles should be used on the amp output and speaker input. There are special circumstances where both the +1-1 and +2-2 poles might be employed, but you'd seldom see them utilized on a bass amp and speaker. It's fairly common with PA, using a dual channel amp and bi-amped speaker. The low frequency output of the amp and low frequency input of the speaker would go to the +1-1 poles, the highs to the +2-2 poles. Using a standard wired 4 pole 4 conductor cable it would be plugged into either amp channel output jack and into either input jack on the speaker, if it has two, and always be right. Many's the HF horn that was blown using 1/4" plugging the LF output into the HF input.