That is the typical over simplified high school explanation.
We are talking about kilometers away outdoor acoustics here, not room acoustics.
Completely different game!
There is no need to get angry, please...
Mine was a statement not an explanation, there's plenty of confirmations of that kind of statement out there.
So, if you really want to teach something, do it with serenity next time. 🙂
I just said "I guess" and "AFAIK". 😉
Yours Completely different game!
it seemed unknown to almost everyone in this thread (OP included), except @cowanaudio, though.
However at least the following does remain, in your valuable opinion?
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Excuse if it sounds silly but if higher frequencies are more directional and if these arrays are dispersing to any control than shouldn't there be more bass from the PA or at least levelish levels in the car park? Or do the regs only cover the bass?
Any possibility of it being something like a stream from a jet vs very high aspect ratio props? They both excite air too, the jet has less dispersion up close but throws it further? Or no comparison?
That really depends on how low those frequencies are.
At these lower frequencies you don't really get the reflections, more the experience like when you put a sub close to a wall or more in open field.
But all of that is highly dependent on weather conditions as well (especially the wind).
The sources and other acoustics can still be pretty directional, our hearing isn't really at those lower frequencies.
So it's more a sensation of louder or softer.
To make this even more complex, your own room acoustics gonna add to this mix as well.
I'm pleased of it, and to end with?
Forget it, I just kidding...
May be, but a little while ago you said that
🤔
Please believe me, it's not for you (I assure you about that), but it's fine with me, I know you all will miss me a lot 😍, but I'll move on.
Thank you all.
yes I know what I said, please read the entire message again, because the kilometers away doesn't change any of it.
The car sub can be heard clearly approaching from the next block because sound only drops at 6dB per doubling of distance, and the car sub is loud at low frequencies. Buildings can create resonant corridors that reduce the inverse distance drop.
We have no idea of the frequency response, SPL level, or arrangement of the speakers used at the outdoor concert bass that can't be heard in the car park.
If you had attended the concert you could tell us the size and configuration of the PA subs, assuming there were any.
Last Sunday I heard a jazz band playing in Los Angeles with stage amps only, the only thing I could still hear in the car park was the snare drum.
The distance they "carry" depends on the output level, a 6dB increase carries ~twice as far.
The 35L ported box may be in a 1000 (or more) liter band pass enclosure created by the car. The car itself could increase level by 20dB.
A room inside a mall may reinforce the output of the car sub through standing waves.
There are many PA subs that have almost no output below 50Hz, car subs can easily be louder than them.
Years ago, I built a PA system with four 15" short horn bass bins, and while doing sound with it at the Santa Fe plaza, a car drove around it with subs pounding.
I could see on my RTA the car subs output was easily 12dB louder in the 25-40Hz range than my PA, and matched it in the 50-60Hz range. Annoying and eye-opening at the same time.
That led to replacing that set of bins..
Another aspect might be:
The car owner (let's assume it's one of those young or middle aged males) likes to be heard from far away to attract females and intimidate rivals. He pushes up the audible thumping 100 Hz range.
The concert organizer instead wants to entertain the auditorium but would still prefer not to annoy any neighbours. So he will do everything to avoid complaints.
The car owner (let's assume it's one of those young or middle aged males) likes to be heard from far away to attract females and intimidate rivals. He pushes up the audible thumping 100 Hz range.
The concert organizer instead wants to entertain the auditorium but would still prefer not to annoy any neighbours. So he will do everything to avoid complaints.
Both those links are about home hifi. edit the first does touch on the subject (length of wavelengths vs source) but doesn't elaborate.
Low frequencies can be controlled just as high frequencies can be, to create directional and steered arrays... you just need a bigger speaker (or lots of regular sized speakers) to do so.
Search for "cardioid bass array" to see heaps of writeups about the theory and implementation
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And on the discussion of a car bass being "louder" than PA bass, surely that's just down to perception.
What you're hearing from a car thumping down the road is probably upper harmonics from the resonant system of sub > boot > cabin > window > outside. I bet that it's the honky higher frequencies you can hear over the 50hz bass. Like a bass boost system in aforementioned bluetooth speaker.
Last summer there was an outdoor concert that I could hear from home (Jamie XX playing Sidney Myer Music Bowl, and I was Richmond). I took the measurement mic and laptop down to the park and found that there was an impressive amount of 50-80hz bass from a hundred metres away but because it was relatively well balanced with the rest of the spectrum it wasn't particularly noticeable.
What you're hearing from a car thumping down the road is probably upper harmonics from the resonant system of sub > boot > cabin > window > outside. I bet that it's the honky higher frequencies you can hear over the 50hz bass. Like a bass boost system in aforementioned bluetooth speaker.
Last summer there was an outdoor concert that I could hear from home (Jamie XX playing Sidney Myer Music Bowl, and I was Richmond). I took the measurement mic and laptop down to the park and found that there was an impressive amount of 50-80hz bass from a hundred metres away but because it was relatively well balanced with the rest of the spectrum it wasn't particularly noticeable.
I can see the stage and stacks from the road while driving past the oval. They face our way, which is 3km away. Comparing an electric bass and acoustic kick from the concert to electric bass and acoustic kick from the car
Would someone deliberately set the arrays to not consider the bass guitar in the mix? Some have pointed out that we are not really looking at much below the sub 50Hz where the car sub might have some muscle. In this range the PA should eat up the car sub right? Especially when the car park is along the length of the oval
But also the Sydney EDM festivals at Centennial Park. My regular customers would know when I arrived, as I would tell them by turning up the volume to levels not normally found coming from taxis
I really think there might be another factor here that hasn't been considered. Air is a fluid. Could the jet stream analogy apply and the much higher xmax and lower Sd car sub is dispersing louder further away and the wider aspect, lower xmax PA drivers are radiating wider up close but diffuse further out?
There is another difference that even with that complex arrangement of box ina box ina box, the basslines are rendered well inside a nearby building which is even more boxes ina box. By your logic, wouldn't just parking a pair of install cars each side of the stage be cheaper than an array of subs which can each cost more than a cheap boy racer hatchback with a single sub?
Some of those 90s louts are now knocking on 50 😛 and much more discerning about the material they are enjoying loudly to get that feel that cant be done at home levels
The full music from the concert from these responsible operators can be heard from my place 3km from the oval except for the basslines
As Art pointed out, the car sub may be more potent sub 50hz, but we are not talking about music from down in that range while discussing the 4 string Fender P on the stage and 4 string Fender J recording from the car + acoustic kick
If thats what the quality is like than surely I shouldnt be able to tell the individiual notes and the different effect settings of the two parralel channels that the Fender Jazz is fed through into the recorded mix with the track its the same dub coming from my car when I am standing on the beach about 60m away but i clearly can. Trying to find out why I can. Its the same thing with the same song called its the same dub on the other side of the oval where my wife is a pharmacist at the shopping centre She can tell when I am coming past the parks and turing towards the shopping centre and can bop to the riddim behind the counter
A PA array from the concert facing the same way should drown the Fender from the car out, according to HR just one PA 15 eats up even the 12W7@1kwrms
It's usually not a good idea to make comparisons to static flow unless you already know the answer.
Flow can be static?
I am guessing the analogy is way off. That's cool, I thought there might be some of that and maybe worth looking into
Get yourself a measurement mic and laptop (or even a phone/table), and explore the world with an RTA.
Everything you're talking about is purely subjective, once you start pegging your perceptions against measurements I think things will make more sense...
You're comparing 3km with output a block or so from the car?
https://sengpielaudio.com/calculator-distance.htm
A PA might do 150dB (if not regulated..) at 2 meters, 86.5dB at 3000 meters:
A car sub may easily do ~121 dB around it, 87 dB at 100 meters:
If you were around your car with the sub playing at "only" 116dB, it would be as loud as the 150dB PA at 100meters.
Anyway, temperature inversions, destructive interference and intervening structures aside, the inverse square law will apply to low frequency propagation.
Art
I should have used the word also heard
Still comparing the from the oval car park for band instruments and Centennial park rank for ED
The mention of distance from home is to address the responsible operators who are seemingly using amazing radiating patterns for bass but screeching electric guitars and vocals that make to 3kms away till late at night
I measured 808 kick with the boot open, peaking at 127dB recently. Surely this should get drowned out in the car park at the concert