Bill Fitzmaurice

There are professionals, in that they get paid for what they do, and there are professionals, in that they know what they're doing. This bunch doesn't know what comb filtering and power alley are, let alone how to prevent them. They had both, with not only poor sub placement but also side by side tops. 🤥

The LPad can't hurt, but since you have dual woofers at 4 ohms that will even things out a bit. You usually have to reverse wire the tweeter with a 2nd order/2nd order crossover, another reason why I never use them. But it doesn't hurt to run a 2kHz tone through the system before you button it up, trying the tweeter wiring both ways, going with whichever is louder if there is any difference.

As did two more replies after you posted this. 😄

I always mic drums, and for that matter all of the instruments. It's not about volume, it's about dispersion. The only instruments that don't have a problem with dispersion are the bass and keys, and then only below 200Hz or so, where their speakers are omnidirectional. To prevent them from being too loud down low I high pass their channels as required by the venue acoustics.

Then don't. Keep them together. Although the name 'power alley' makes it seem that way you don't have a big central power zone. You have alternating power zones and null zones across the room. A more accurate description is low frequency comb filtering, as that's what it is. That can result in a total cancellation frequency where the distance from the subs to the wall behind the stage is 1/4 wavelength. Side by side or stacked to one side of the stage close to the wall eliminates that possibility. And no, they won't be heard as being to one side. You can't localize long wavelengths. The perceived location of low frequency sources comes from the harmonics produced by the mains.

Old school. Use them for now, but when the time comes to invest you don't want anything of that sort. A pair of 1x10 or 1x12 mains will work far better in the mids and highs, while a pair of 1x15 or 1x18 subs will work better in the lows. In the smaller gigs where you don't need the subs leave them at home. Self powered is the way most are going these days, although the more experienced still prefer passive speakers separately amped. When you get to this point know that the most popular way to set up is with the mains pole mounted above the subs. It's also the worst way. Subs work best when they’re placed either close together for mutual coupling, or spread very wide to cover large areas. The basic rule is to have them either less than a quarter-wavelength apart or more than two wavelengths apart for their pass band, which for 40 to 100 Hz means less than one meter or more than 15 meters. Boundary loading should be used whenever it’s practical to do so. Having subs next to a wall gets you 6dB of additional sensitivity, and putting them in a corner an extra 12dB. In most cases you’ll have best results aiming the subs towards the wall or corner from about a foot away. The wags will tell you that's all wrong, but that's why they're wags. The mains are pole mounted for proper projection and to prevent feedback, but not above the subs.

Aside from playing golf I've nothing else to do. 😄

That only has a 2nd order high pass, which is totally inadequate. 3rd order is the minimum acceptable for pro use. The 4th order I use reduces the power to the tweeter an octave below the knee frequency by an additional 12dB compared to a 2nd order. That makes the difference between clean and distorted, as well as between functioning and blown.

With bass cabs I use the Eminence BGH25-8. It's rated at 25 watts, because that's all there is above 2kHz with 500 watts program. There are few, if any, off the shelf 4 ohm crossovers, but off the shelf crossovers aren't very good. I design my own. This is an 8 ohm 2kHz 4th order high pass filter, which you can't buy from anywhere in the UK. The capacitors are poly or mylar, rated for at least 100 volts. The coils are air core, of the smallest available wire gauge with no more than 0.5 ohms DCR. A plus/minus 10% tolerance of the component values is permissible. This is a 4 ohm 2kHz 2nd order low pass filter. The capacitor is a non-polar electrolytic (NPE), rated for at least 50 volts. The coil may be solid or air core; what’s critical is that the DCR (resistance) of the coil for a 4 ohm system be less than 0.2 ohms. A plus/minus 10% tolerance of the component values is permissible. Being 4 ohms you can't buy one of these either. I always build my filters on separate boards, it's too easy to get confused with the layout and wiring putting them on the same board.

If you want to go twice as loud you need to increase power not by a factor of two but by a factor of ten, so going from 15 to 30 watts is futile, especially if you don't increase the speaker size. To make a change worthwhile you need 50 watts into a ten, minimum.

Ports can go anywhere, as their radiation pattern is omnidirectional. But most players, let alone people in general, aren't aware of that, so they tend to avoid cabs that don't look conventional. Being well aware of this commercial cab manufacturers tend to avoid breaking out of the cookie cutter mold. What's the first comment you see about a new product? It's almost always about how it looks. Too bad we don't hear with our eyes. 🫢

Bottom porting is perfectly feasible. It doesn't lower the tuning all that much, maybe by 3Hz. It acts more like a flare than an extension of the port. You just have to use cabinet feet at least 2.5cm high.

If they were on the dimmer circuit the low voltage would have been a major problem, so that probably wasn't it. But inexpensive dimmers create RFI/EMI that radiates through the air, which can cause what you experienced.

Offhand I'd say it's a 3012LF magnet structure judging by the depth of the recess in the mushroom.

Not if it's a 12. It could be a 3012HO, could be a 3012LF, which has a deeper rear 'mushroom'. Or it could be an OEM version of either. TBH neither the HO or LF are ideal for electric bass. An OEM with specs midway between them, along with the longer voice coil that the extended mushroom allows, beats them both. I've worked with a few of those designing commercial cabs.

A single brace connecting the middles of two 12mm panels gives the same vibration resistance as using no brace with 24mm panels. That's why I don't use 18mm in any of my designs, while some use only 3mm and 6mm, with no vibration issues.

+1. Doubling the power isn't worth carrying the second amp around. At the very least you want to double the voltage swing capability, which translates to four times the power.

I wouldn't blame it on the monitor. Think about what happens when your drummer leaves his sticks on top of a floor tom and you play a bit. The sticks rattle, especially at a certain note, because the head is vibrating, and not because the cab is sitting on the head. It's because the tom head is resonating in concert with the acoustic output of the cab. When a stage or riser or anything else in the vicinity resonates when you play it's for the exact same reason. The only fixes are to either strengthen the resonating surface making it too stiff to vibrate, damping the vibrations by fully covering the surface with a heavy carpet, or dialing out the resonant frequency causing the vibration with EQ.

Probably because they're not distributed in Canada or the US.

Once over the border the tracking should be handed over to Canada Post, but that does you no good if you don't have the Canada Post tracking number. I assume it's not the same as the USPS number.

There's no such thing as mechanical coupling that causes the riser to resonate. There have been a few studies that prove this is the case, this is one: http://ethanwiner.com/speaker_isolation.htm What will cause the riser to resonate is the acoustical output of the speaker. That will usually occur at a single frequency. The best way to prevent it is with a parametric EQ that allows you to cut the speaker output over a narrow range, sweeping through the frequencies until you find where it kills the resonance. Another option is to raise the speaker to 1/4 wavelength above the riser, which will cut that frequency, but finding how high to lift it is a trial and error process.

At half power you only have 3dB of headroom, whereas what you need for very clean is 10dB. That means running at 1/10 power. That makes it seem like you need a lot of power, but the reality is that on average it's rare to be putting out more than 20 watts. If that were not the case generations of players would not have been able to gig with an Ampeg B15. Where 1,000 watt amps are concerned that tends to be a specmanship situation. Very few can actually maintain that for more than a few milliseconds. If you look at amps with honest specs, PA amps from the likes of Crown, QSC and the like, take note of their power draw. It's typically measured at 1/8 to 1/12 power. That reflects their actual long term output at very low distortion. Note that where the 30 watt Ampeg is concerned the reason it was gig worthy is the natural compression of valves. Without compression it takes a lot more power to stay clean. By the same token using a compressor with SS allows a lot less power.

Clean is far more a matter of the speaker than the amp. Where amps are concerned 1% distortion is high. Where speakers are concerned 10% distortion is within the normal range. The cleanest amp in the world will still sound dirty with speakers that are dirty.

If you think that's bad get a load of this, and I do mean load: https://musysic.com/products/musysic-professional-4-channels-2x9600-watts-d-class-1u-power-amplifier-mu-d9600 😄