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Old 11th February 2014, 11:52 PM   #111
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Well, I think I solved the whole mystery of "why does PK sound completely different than 95% of the PAs out there?"

Here's the short explanation:
EDM and dubstep frequently have basslines with ZERO harmonics. Due to the lack of harmonics, it's possible to have very very very loud low frequency effects, and it doesn't sound muddy. This would NOT work with conventional instruments. For instance, if you had a rock track with a 35hz drum and a 2nd harmonic at 70hz, that track would sound 'muddy' if the fundamental was twenty decibels louder than the rest of the track.

But in EDM? It works. By stripping out the harmonics it allows you to crank up the very low frequencies to absurd levels, due to the fact that we're not sensitive to low frequencies.

BUT - and this is a big BUT - this trick only works if your subs are able to play very low frequencies, and play them with low distortion.

If you try the same trick with a vented sub that has a cutoff of 50hz, you'll probably destroy the subwoofer. This little problem might encourage sound engineers to use aggressive high pass filters, which actually compounds the problem. (But it keeps the subs from blowing up.)

I have to hand it to Sine143 - he gave me the clue that helped explain what the difference is. In his post, he stated that there weren't any 28hz basslines in brostep.

So I did a spectral analysis.

Before I get to that, let's start with a couple of tracks from the 70s and 80s:

Click the image to open in full size.
Click the image to open in full size.
Here's the drum kick on 'Goodbye Stranger' by Supertramp. In a post on another thread, Art mentioned that the drum from some Supertramp tracks was enough to loosen the plaster. In this snippet, I see a lot of energy in the octave from 50 to 100hz.

Click the image to open in full size.
Click the image to open in full size.
Here's an analysis of what may be the most famous club track of the last thirty years, "Blue Monday" by New Order. This track digs deep - all the way down to 30hz. I remember the first time I heard this in a club, the walls would shake with bass. The bass line is synthesized, and this technology was so new, the band actually had to build the instruments from a kit. Needless to say, this is one famous tune.

Click the image to open in full size.
Click the image to open in full size.
Aaaaand here's The Money Shot. "Here We Go" by Bassnectar.

In the spectral analysis of the three tracks, you'll notice a couple of things about the Bassnectar track. First, there's virtually no harmonics. The bassline is practically a sinewave, centered at 35hz. Second, the bassline is practically engineered to blow up vented subs. It's TWENTY ONE DECIBELS louder than the rest of the track.

I think that one graph basically sums up why the PK systems sound 'different.' If that Bassnectar track was played on a vented box with an F3 of 50hz, the 35hz fundamental would likely blow up the speaker. A bassline that's 21dB louder than the rest of the tune is a real speaker killer.

Click the image to open in full size.
The key is the lack of harmonics in the dubstep track.
If we look at the Fletcher Munson curves, a sound that's 110dB at 30hz will sound as loud as a sound that's 100dB at 60hz.
The Bassnectar track is taking advantage of this. If the bassline at 35hz had harmonics at 70hz and 140hz, the whole song would sound muddy and slow.
But the lack of harmonics means that you can have this monster bassline at a very low frequency, and it doesn't make the rest of the spectrum sound 'muddy.'

TLDR : Bassnectar's music would sound incredibly muddy if it had harmonics, but it's made on a computer, so it doesn't.

I think the spectral analysis of the tracks explains why 90% of the venues that I go to just can't reproduce EDM and dubstep properly, even though they sound perfectly acceptable with rock bands. It's the low frequency basslines with zero harmonics that are to blame.
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Old 12th February 2014, 12:34 AM   #112
sine143 is offline sine143  United States
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show the average of the whole track post intro (for bassnectar). this will give you a better idea of 35hz vs the rest of the bass.

Bassnectar is one of the few exceptions to the brostep rule, but with his 15 plus year pedigree in producing, he has a leg up on 99/100 brostep producers out there (plus he's been touring with big soundsystems, PK specifically, for almost 10 years now, longer than skrillex has know what edm was)0

Last edited by sine143; 12th February 2014 at 12:36 AM.
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Old 12th February 2014, 12:41 AM   #113
sine143 is offline sine143  United States
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and to say that bass music would sound muddy if it had harmonics is false.

one of my favorite tracks at the moment, Space Cash by commodo. Not only does it go low (28hz), but it features a fairly saturated bassline. Honestly on a decent soundsystem, this tune sounds like no other. bassline is ALIVE


Commodo - $pace Cash - YouTube
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Old 12th February 2014, 02:33 AM   #114
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Quote:
Originally Posted by sine143 View Post
and to say that bass music would sound muddy if it had harmonics is false.

one of my favorite tracks at the moment, Space Cash by commodo. Not only does it go low (28hz), but it features a fairly saturated bassline. Honestly on a decent soundsystem, this tune sounds like no other. bassline is ALIVE


Commodo - $pace Cash - YouTube
Basically I was trying to explain my perception of PK Sound systems.
Which is that they have crushing amounts of bass, but they don't make your ears bleed.
I believe this is due to a combination of both the system's ability to play low and loud, but *also* due to the content of the music that's being played on them.

Click the image to open in full size.
For instance, this two second snipped of 'Here we Go' by Bassnectar has a bassnote at 35hz that's over 20dB louder than the content at 70hz.

Click the image to open in full size.
If you played this Supertramp track at the same maximum SPL, it would sound a lot louder, because the bass, midbass, and midrange are all withing a few decibels of each other.

So that explains the peculiar combination of crushing bass, but without the painful midrange and treble that I hear at most shows.

The trick with the harmonics is the Fletcher Munson curves. For instance, if the Bassnectar track had a second harmonic at 70hz that was six dB below the fundamental the harmonic would appear more prominent than the fundamental. (Because we're much more sensitive to 70hz than to 35hz.)

But the 35hz note doesn't have a harmonic. So if played back on a system that has a fourth order rolloff at 50hz, like a vented box, the 35hz bassline would be much less prominent.

So it's not as simple as having a big amp, or a sub that plays low, or music that goes down to 35hz. It's all of the above. But some of these items are more important than others. For instance, I'd rather listen to this music on a system that can do 110dB and has an F3 at 35hz, instead of a system that can do 120dB and has an F3 at 50hz. Due to the steep rolloff of vented boxes, the second system will significantly reduce the 35hz fundamental.
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Old 13th February 2014, 02:25 AM   #115
djk is online now djk
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"The difference between a 150,000 watt bass system and a 15,000 watt system (assuming mutual coupling of 10 times more drivers) is 20 dB.
Bringing in 10 times the sub cabinets would allow a 10 dB increase in level (twice as loud) using the same power."

The contour lines of equal loundness get further apart at higher volume, and the limit for direct radiator efficiency from coupling tops out at around 25% or so.

100A?

I used to run a small show that pulled 120A on two legs (not counting the fog machines).
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Old 13th February 2014, 08:31 PM   #116
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Quote:
Originally Posted by djk View Post
"The difference between a 150,000 watt bass system and a 15,000 watt system (assuming mutual coupling of 10 times more drivers) is 20 dB.
Bringing in 10 times the sub cabinets would allow a 10 dB increase in level (twice as loud) using the same power."

The contour lines of equal loundness get further apart at higher volume, and the limit for direct radiator efficiency from coupling tops out at around 25% or so.

100A?
Dennis,

I recognize my quote, but don't understand the question.

A 150,000 watt sub system using 95% efficient amps would draw 438.6A (amperes) peak, (or average if running content with only 3 dB crest factor) at 120 volts from each leg of a three phase system.

Art
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Old 13th February 2014, 09:16 PM   #117
freddi is offline freddi  United States
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it seems costly to do a literal "bass bath" - cutting back on the lows, how much system would have been needed to do what I listened to in the wee hours last night? (tenor John McCormack singing lieder with Gerald Moore on piano ~1940)
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Old 14th February 2014, 09:22 PM   #118
tb46 is offline tb46  United States
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Hi Art,

I don't know what I'm missing as this level of PA is completely out of my experience range (well, not completely - I have been known to leave the area/stadium/concert-or-studio) but 150kW to 15kW used to be -10dB (not 20dB). As you say, if you have any kind of mutual coupling you'll get more output from a 10x increase in system power than 10dB, provided you'll also increase the number of loudspeakers (otherwise: burn baby burn).

To the best of my memory there is no 3dB crest factor in the power draw, the current and the voltage are already RMS values, and you're hoping that your system has a power factor of 1.

Just for fun I ran a few of the typical U.S. power system voltages into a spreadsheet, and it looks like bringing your own 440 (480) 3-Phase generator or power line would be advisable.

In what feels like another lifetime I used to hang out with military portable generators, that would have called for something big, or for multiples. You people have all the fun. :-)

Regards,
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Old 14th February 2014, 09:46 PM   #119
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Quote:
Originally Posted by tb46 View Post
Hi Art,

I don't know what I'm missing as this level of PA is completely out of my experience range (well, not completely - I have been known to leave the area/stadium/concert-or-studio) but 150kW to 15kW used to be -10dB (not 20dB).
Yes, the power difference between 150kW to 15kW is 10 dB.
My statement said "assuming mutual coupling of 10 times more drivers", which is where the additional 10 dB comes from.
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