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Exploring the deeper subsonic . . .

#81
Then there is the vintage Phoenix Gold Cyclone!
upload_2021-7-31_1-3-11.jpeg


Goes down to 11 Hz in the right box...
Cyclone

Co-designed by Tom Danley?
 
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#82
AlexanderB said:
Yes? The SRX series is a good example of a club rig, where the subs will do fine in greater rigs, too. Has a "flat" (-3dB) frequency of 35Hz.
Easy peasy to put a little boost around 35 Hz, and you get a "true flat" 35Hz. See it all the time. With modern "super woofers", computer controlled speaker processors with Voice Coil feedback, two tier limiter etc, setting the HPF higher than ie mid 30-s is a choise by the FOH or systems engineer (baby sitter), not needed to run the rig safely. Maybe you do it differently in US, but look at the European acts and PA brands, this is common practice.

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DVA S2585N

Products - DAS Audio

SW221 | Tecnare Sound Systems

NEXO RS18 sub bass loudspeaker
Click to expand...

Yes I agree, probably fine to dial in flat response to 35hz as long as you don't push the drivers into over excursion. However, it's probably not a good idea to add +10dB of correction at 30hz.

Based on the curves, I sometimes suspect some corrective EQ is necessary to met the listed frequency response. For example the NEXO RS18 sub you referenced list -3dB at 30hz. Take a look at the frequency response plot:
upload_2021-7-30_18-13-2.png

This looks like at least -6dB at 30hz to me. My guess is this is the raw driver response in the box, and the processor corrects it to -3dB at 30hz. So to correct the response to flat at 30hz, you actually need at least +6dB. Keep in mind power doubles with each 3dB of boost, so if you are really hitting the sub hard with power in the frequency range need to ensure you have enough boxes to get the job done.

Sorry for the blurry images; that's actually how it looks in the official datasheet.
 
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#83
Wasnex said:
Yes I agree, probably fine to dial in flat response to 35hz as long as you don't push the drivers into over excursion. However, it's probably not a good idea to add +10dB of correction at 30hz.

Based on the curves, I sometimes suspect some corrective EQ is necessary to met the listed frequency response. For example the NEXO RS18 sub you referenced list -3dB at 30hz. Take a look at the frequency response plot:
View attachment 4351807
This looks like at least -6dB at 30hz to me. My guess is this is the raw driver response in the box, and the processor corrects it to -3dB at 30hz. So to correct the response to flat at 30hz, you actually need at least +6dB. Keep in mind power doubles with each 3dB of boost, so if you are really hitting the sub hard with power in the frequency range need to ensure you have enough boxes to get the job done.

Sorry for the blurry images; that's actually how it looks in the official datasheet.
Click to expand...

Agreed, and I would say the "super woofers" we have (since many years) are so specifically designed for maximum performance in very specific areas, and they were never intended to work in traditional, unprocessed applications. (Which is fine, as "everybody" uses speaker processors nowadays, or active cabs, where the compensation is done in the amplifier.)

Now that we have amplifiers with REAL power at very low $/W, we have cheap and capable speaker processing, and we have neo woofers, allowing for better cooling of the motor, traditional design and properties of these (sub) woofers is no longer applied.
These low Qts, long stroke, moderate Vas woofers will generate unusable results if you do a "traditional" speaker simulation, typically suggesting some super compact mid bass cab...

However, in the intended (still compact) cab with low tuning, most of these woofers will deliver massive lows, and never break a sweat. In my own PA cabs, I use 18" Ciare neodymium woofers, and they will not exceed Xmax (11mm?) with over 1kW per driver, through the pass band. And if that should still happen, Xmech is much larger, providing additional protection.

Simulation says so, and my practical experince using the rig says so. Doing the "worst" show yet, song after song pushing 1.25kW of QSC RMX5050 per driver, doing 30-40 Hz EDM dance music was effortless.
As long as the input is above 30Hz, the amps' 2.5kW per 2x18" will never hurt these speakers, and in fact, I do not even really NEED a limiter, other than to protect from sheer accidents. I will assume all the prsented woofers (including the JBL!) are having similar properties.

That said, it is also many years since I heard a PA or dance club rig struggle under too much bass. No clipping, no hammer down limiters, no "hitting the backplate", no cardboard sounding distortion and so on. Those things definitely happened in the 90s, but not so much anymore.
 
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#85
AlexanderB said:
By the way @Wasnex , I saw that some of these manufacturers actually present FREE FIELD data! That would mean that in a half pi or quarter pi environment, you will get the additional boundry effect from the room. Free lunch, anyone? :D
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I know what you mean, but it is not really free output. The output of the cab remains the same, but the environment has an impact on the measurements.

This issue is especially confounding because manufacturers don't always indicate how the cab was measured. I think the biggest impact is this makes it harder to compare different products.

Pretty sure the little VRX918S is measured in whole space, but I don't see any indicator for this on the spec sheet, other than the lowish sensitivity rating. I guess the whole space measurement for the VRX918S makes sense being as this cab is flyable. But the SRX718S was essentially the same cab without the flying hardware, and it has the same specs.

I would be surprised if the SRX828SP is measure in whole space because of the massive 141dB peak SPL number. The passive version, SRX828S only does 135dB peak. Should we assume that the 6dB difference is JBLs power amps and processing? Or maybe it's some other arcane issue such as the frequency response has not been smoothed by active processing. I have no way of knowing. But properly processed the SRX828S should have the exact same performance as the powered version.


Also regarding my earlier comment that powered cabs often have built in corrective EQ: Here is the raw frequency plot from the passive SRX828S vs the self-powered SRX828SP

SRX828S
upload_2021-7-31_13-28-22.png

Looks like the natural response of the driver drops off a cliff starting around 50hz.

SRX828SP
upload_2021-7-31_13-29-29.png

As you can see the response curves are significantly different because of the active processing. The cliff does not occur until 40hz with the powered version.
 
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#86
Bassamatic said:
The natural roll-of of our ears gets steeper down there, so you would need to push a huge amount of air to make it perceptible with matching huge amounts of power. For the movie "Earthquake" Cerwin-Vega, arguably the masters of the low end used stacks of special 18" subwoofers faced into the corners of the theaters to make the walls into giant horns, each with its own 1000-2000 Watt amp to get the required amount of LF.

On the other hand, you might think about the mechanical "bass shakers" that are designed to shake the floor for movie fans. Maybe you could place say, 4 of these on your stage to vibrate the floor while you are playing, and that might transfer to the audience. You would still need an amp that goes subsonic with some efficiency, and the crossover to do it.

For example -
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Also interesting would be a research project conducted by an architectural engineering school in, I believe, southern California. Musical application would be impossible, but still conceptually interesting, they built a complete parking garage (full size) on a movable table powered by very, very large hydraulics. There is video of the whole thing shaking, eventually to the point of structural failure.
 
#87
Good afternoon--I am OP, want to start with an enthusiastic THANK YOU! to everyone and an apology for being mostly absent, was at a work site for weeks. There is much to think about, many ways of exploring subsonic stuff--which way to go, which way to go . . . again, thanks for the knowledge and suggestions.
 
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#88
BarfanyShart said:
Reminds me of when I was in music school at my composition recital, I had these pieces with live solo performers playing on stage with electronic backing tracks. The backing tracks had these explosion/earthquake effects that I had made with synthesizers, and I kept adding lines out to the subs, placing subs around the theatre, all in a frantic effort to make the "explosions" sound bigger, as big as what I had in my head. Eventually my teacher talked me down saying, "nothing short of a real explosion that actually collapses this building is going to satisfy you, so focus on making these pieces work in a format using technology that you can reproduce in other venues, or on recordings." I think it is the same with subs, the kick drum really owns the bottom of the frequency spectrum, and provides the "feel" of subs in a standard mix, you don't have to be in that space as a bassist, and other people's equipment isn't going to tolerate or adequately reproduce your experimentation.
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I'm pretty sure the authorities would frown on using C4 or Semtex in a hall full of people . . .
 

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