Bill Fitzmaurice

While on the topic most commercial acoustical foam is convoluted or pyramidal. That doesn't do a thing, it just looks like it will.

Which I alluded to previously. Most guitar drivers have very short xmax, so they'll go into high THD at low volume. Bass players may still want high THD, but not at low volume. Nonetheless most of us wouldn't want the other end of the spectrum, drivers with no midrange bump, typical of PA woofers. This Eminence 2512 strives for response similar to vintage drivers, but with much higher output, as opposed to the B&C 12NDL 76, which doesn't peak in the mids 10dB higher than in the midbass.

Ouch. Cabs should be fully lined, with foam or polyester batting, 25 to 50mm thick. Mattress topper foam is inexpensive, as is furniture upholstery batting. Don't bother with materials advertised for speaker cabs, they're more expensive but don't work any better. Adhere it with spray glue.

Nope. Buzzing may indicate bad transducers, or it could be buzzing at frequencies too high to hear through the speaker.

Not Eminence, for one. Back in the day there were no bass drivers, just musical instrument drivers. Bass and guitar cabs were loaded with the same drivers, so they both had similar coloration. As technology progressed bass drivers were made with lower resonance and longer excursion to better suit bass, but in order to preserve the midrange tone Eminence in particular maintained to the extent possible with the lower Fs and longer xmax a similar rising response in the mids, even with the advent of neo. LaVoce, a relative newcomer, has taken that philosophy to heart, with response very similar to Eminence in their bass drivers, which is a departure for a European company.

There are tonal nuances, especially those created by the speakers which include mechanical power compression, cone break up and THD, which can't be duplicated using a DI. If you want what's in the PA to come close to what's coming out of your rig only a mic will do. That doesn't mean the guy in the FOH can't screw it up anyway, but at least you've got chance of his getting it right.

It's probably not as little as it seems to be. A look at an equal loudness chart reveals why. If the system is at 100dB at 500Hz, where our hearing is most sensitive, it has to be at 110dB at 50Hz to sound flat. That's a 10x power difference between the subs and the mains. Even when flat the mains should always sound louder than the subs, because our perception of loudness lies in the mids, not the lows. If you turn off the mains the subs shouldn't sound as loud as the mains. If they do they're too loud. The presence of subs shouldn't be obvious. What should be obvious is what happens when you turn the subs off. In that case the subs aren't loud enough. Pretty much all recordings since 1990 were mixed using subs in the studio, so if switching off the subs makes no difference you're not hearing what's on the recording. To that end the better FOH guys will take two RTAs when setting up the system. One will be that of their preferred reference recording, taken at the channel strip, to see the frequency content of the recording. The other will be that of the system. They'll adjust the system EQ to approximate as closely as possible the source frequency content while compensating for the room response.

The top chart is the modeled response of a typical twelve loaded cab, but it's not accurate above 200Hz or so. That's because modeling software uses Thiele-Small specs, which are only accurate to 2 octaves or so above the driver resonant frquency, in this case around 50Hz. A measured response chart would show the sensitivity increasing above 200Hz, with useful (-10dB) response to at least 3kHz. You shouldn't run this speaker much below 40Hz, as while sensitivity is dropping excursion is rising. Amp designers usually put in a high pass filter for this reason. Mine doesn't, but it does have full EQ. I pull the 32Hz slider all the way down.

Yes, the port output shifts 180 degrees below the port tuning frequency, so the combined result of the port plus cone output falls at twice the rate of the port or cone output alone. That's the downside of a ported enclosure. However, compared to a sealed enclosure it still has higher sensitivity to at least an octave lower than sealed, along with far lower excursion.

This is why you don't mic the port.

That means the tops aren't near their limit. At some point they'd be able to go significantly louder than one sub, unless it was loaded with an eighteen.

The bad news is to keep up with your RCF tops you'd need at the minimum a pair of 15" subs, especially outdoors. The laws of acoustics will not be denied.

You don't want to go to 140Hz, that gets into the directionally locatable frequencies, which limits placement options. 80 to 100Hz is the preferred range.

That's on the FOH crew, when they don't know what a bass is supposed to sound like and therefore neglect to EQ the bass channel appropriately. 🤥

If all you want to hear is boom-boom-boom then it's OK. Otherwise don't.

Subs don't deliver watts, they deliver decibels. There's no direct correlation between the two. There is a direct correlation between cabinet size and driver displacement and how low and loud a sub will go. The larger size of the TS indicates it would probably go lower, the larger voice coil indicates it might go louder, but since there is no measured SPL chart or driver displacement shown there's no way to make an accurate objective comparison. As to one 12" sub being adequate it probably would be if the mains are 8", but that's about it. The mains are the tip of the iceberg you can see above the water. The subs are that part that's underwater. They need to be at least twice the size and cone displacement as the mains.

I'm not one to jump back on board the vinyl train.

I suspect it's the same stuff.

Tolex will rip, and when it does it's nigh impossible to fix. Tuffcab when gouged can be touched up. That's why I went to the US equivalent, DuraTex, 20 odd years ago.

This is a US light switch, in the off position.

The way where you can hear it? That's probably as shown in the picture.

A de Havilland Mosquito is more pertinent to the conversation. It shows what can be accomplished with bent surfaces and bracing without exotic, heavy or expensive materials.

Where tone wood is concerned I've found that the lower the wood density the more absorbent it is of mids and highs, and the lower it is in sustain. Conversely the higher the density the brighter the tone and the better the sustain. I like a bright tone and long sustain, so I made my bass from rosewood, which is so dense it barely floats. That also would make it a back breaker if solid, so I made it of neck through construction with hollowed bouts, similar to Rickenbacker. It might not be everyone's cuppa, but it's served me well going on 25 years.

They do suffer from the same shortcomings. If you must have that driver arrangement AFAIK the only manufacturer that does it the right way is Barefaced. The purpose of any bass cab arrangement is to provide a desired low frequency output with wide midrange dispersion. A pair of quality 2x10 or 2x12 vertically stacked will beat an 8x8 in both those regards.