Bill Fitzmaurice

The size of the motor/voice coil doesn't directly relate to driver sensitivity, but as often as not higher sensitivity drivers have large motors/coils. What is curious is the 100w rating of the 2x15. The reason behind four inch voice coils is they can shed heat better than smaller coils, allowing for high power handling. A four inch coil only rated for 50w makes no sense. That's not the only thing on their site that makes no sense.

As I recall the original Sunn amps made by Conrad Sundholm used Dynaco kit power amps.

It may look unorthodox but if your drummer has trouble hearing you turn the lower cab towards him. It won't affect the non-directional low frequencies but it will allow him to hear the directional mids and highs.

The concept that a 15 complements a 210 is a myth. Sometimes it works OK, but not always by any means. The thermal power handling is moot. What matters is the mechanical power handling, a spec which unfortunately never makes it into the advertising. Doubling the driver count with identical drivers quadruples the effective mechanical power handling, while avoiding potential destructive phase interactions.

The only sure match is another cab loaded with the same drivers.

If I was to have a speaker for upright use only I'd load it with an eight inch. The upright low frequency limit is much higher than electric bass, so there's no need for the lower response or low frequency output capability of larger than an eight. An eight will go high enough to make a midrange and/or tweeter unnecessary, and will have 1.5 times the midrange dispersion angle of a twelve. For higher output requirements I'd use a stacked pair. On the low frequency limit, the two instruments do have the same fundamental frequencies, but the main content lies in the harmonics, not the fundamentals. When an open E is played on electric most of the content is at 82Hz and higher, when played on an upright most of the content is at 123Hz and higher.

The LPad goes between the high pass filter and the tweeter, so it's 8 ohm. Besides, you can only find them in 8 ohm. Where questions are concerned better to ask than to have a problem.

That's normal for +/-3dB. If you see a bass cab claiming response to 40Hz that's probably -10dB. It's absolutely not -3dB.

They may be back but at those prices it won't be for an extended stay. 🤥

I heard that effect quite clearly through the PA at a concert last winter. It created a constant drone that was so bad that not even halfway through I left. It was Max Weinberg's (of Bruce Springsteen's E-Street Band} band, with a supposedly pro at the FOH. How a deaf guy got that gig I can't figure.

If in doubt before the full sound check take your bass and DI into the FOH and run into the board from there, making sure that the spund from the PA is what you want, not what he wants. If necessary remind him of the pecking order. No one ever bought a concert ticket based on who was running sound.

An old story, so forgive me if you heard it: A 9,000 seat outdoor venue near me was being threatened with closure over noise complaints, low frequency noise in particular. They hired a 'professional' company to come up with a solution. Said solution was a cheap PC with sound level software, with a mic that measured the level in the FOH. An alarm light lit if the level they'd hit exceeded the standard that they assured would not be too loud in the area. For a full season the light never lit, yet the complaints increased with every concert. For this the venue paid them $25,000. 🤥 Just before the start of the following season, on the threat of being shut down, they hired me. The first thing I noticed about the gear they had and the standard that was being used was that the levels were being measured with 'A-weighting'. They were upset to say the least when I told them that 'A-weighting' doesn't measure low frequencies. 😄

The main problem is PA subs that go an octave lower than bass cabs. The cure is to high pass the bass channel strip around 60Hz. FOH guys who are also bass players or recording engineers known this. But those who aren't usually don't.

That rarely happens. Most sound men make it what they think bass should sound like, and they're usually wrong. My number one complaint about concert sound is pounding deep bass that has no resemblance to what players want for tone, at levels that drown out the rest of the band.

Alex is correct insofar as what he talks about, which is frequency response. As to whether by looking at charts you can tell what a speaker sounds like, you can. But that's 'charts' in the plural. A waterfall chart will tell you most of what a frequency response plot doesn't. Then there's THD, polar response, power compression and a half dozen more. Speaker emulation devices adjust frequency response, some high end studio plug-ins can adjust some other parameters, but none can do it all. The main thing they can't do is to vary all of the various parameters as a function of the volume that the speaker is being played at. If your charts are going to be truly accurate they have to be measured at various power levels, because they will change at various power levels. Even if you had software sophisticated enough to duplicate all of the charted results at one given power level it wouldn't be able to do so at any power level without an unaffordable level of processing, along with the necessary interface to tell the software at what power level it's operating at any given moment. That would require something with capabilities similar to Klippel analysis. It would be less expensive to run six different speakers.

Speakers reproduce the signal that's sent to them by the amp. In this case the amp is sending hiss. You don't hear it through the woofer because woofers don't respond to high frequencies.

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.