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Discussion Starter · #1 ·

Hey gang.  I have been mentioning this and discussing it a bit with people in various threads, so I figured I would keep the other threads clear and start a fresh discussion here.  The other day, while testing the capabilities of my new sub, I was playing some individual frequencies from 1-30 Hz to see how low my sub would play and what kind of effect I would notice.  The result...my sub started playing frequencies under 10 Hz, but at first I did not hear or feel anything.  Then, like a light switch, my room started shaking and rumbling at exactly 16 Hz.  Since then, I have been considering this and discussing the effects of low frequency with people.  Most seem to indicate that there is a nice effect below 16 Hz but only with a high enough SPL.  Others seem to assume they are getting lots of effect from below 16 Hz but have not tested in a way to be sure; they are assuming.

 

What made me really want to make this thread was this post I just read on the DIY forum:

 

"When we ran rew in your room the measurement for 15hz was over 120dbs. It was an impressive number but I didn't feel a thing."

 

Wow...120+ dB and no effect.  It would take an absolute sh!t pile of money to break 120 dB at 15 Hz with most ID subs.

 

Discuss.  Are we wasting money chasing output below 16 Hz?  Is there a reason most of the big ID companies tune their subs to have good output down to 16-17 Hz but in most cases no lower?
 

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It sounds like you found the resonant frequency of something in your room when you played back 16 Hz. It doesn't take much output for resonant frequencies to make themselves known. Whether its worth it to chase after 16 Hz playback, well that would be a personal choice, so there is won't be any absolute answer to that, of course. You can read conflicting reports of people who perceive deep frequency bass against those who sense nothing at those frequencies. According to wikipedia, frequencies as low as 12 Hz can be discerned in the right conditions.
 

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Quote:
Originally Posted by bear123  /t/1525553/how-low-should-you-go-is-15-hz-too-low#post_24560940


Is there a reason most of the big ID companies tune their subs to have good output down to 16-17 Hz but in most cases no lower?

One more thing, one of the reasons why sub companies don't normally tune their subs lower than 16 Hz is because the port has to be huge if you don't want a lot of port chuffing at such a low tuning point. 16 Hz tuning already necessitates a larger cabinet than most people are willing to tolerate.
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by shadyJ  /t/1525553/how-low-should-you-go-is-15-hz-too-low#post_24561007


It sounds like you found the resonant frequency of something in your room when you played back 16 Hz. It doesn't take much output for resonant frequencies to make themselves known. Whether its worth it to chase after 16 Hz playback, well that would be a personal choice, so there is won't be any absolute answer to that, of course. You can read conflicting reports of people who perceive deep frequency bass against those who sense nothing at those frequencies. According to wikipedia, frequencies as low as 12 Hz can be discerned in the right conditions.
I imagine some can detect or even hear these lower frequencies, just as some can see better than others or hear higher frequencies.  My question is more along the lines of:  if 16-30 Hz gives you 99% of the effect that you get from LFE, should the average home theater enthusiast concern themselves with specifically chasing sub 16 Hz output at great expense.
 

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Quote:
Originally Posted by bear123  /t/1525553/how-low-should-you-go-is-15-hz-too-low#post_24560940


Are we wasting money chasing output below 16 Hz?  Is there a reason most of the big ID companies tune their subs to have good output down to 16-17 Hz but in most cases no lower?
You are if you're trying to hear it, because you can't hear that low, for a number of reasons. If you want to feel vibrations that's something else entirely. FWIW commercial theaters don't bother trying to reach below 25Hz, as the required speakerage and amplification to do so in a large space is too expensive.
Quote:
According to wikipedia, frequencies as low as 12 Hz can be discerned in the right conditions.
What's actually being heard is harmonics. Even elephants, who communicate via very low frequencies, don't hear anything that low. They sense very low frequencies via their feet, which 'hear' those very low frequencies via ground conduction.
 

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I believe Carp or Archaea here did some extend test with low pass filter engaged centered at the low frequency and the conclusion was they prefer bass >16hz. Carp's system with 8 seal 18" SI's has tremendous output down to single digit by the way. He mentioned in one of the thread that below 16hz, his house and everything were shaking violently but didn't feel it much at his MLP. Hopefully he can chime in when seeing this thread. OTOH, other folks seem to enjoy
 

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Discussion Starter · #7 ·

 
Quote:
Originally Posted by tvuong  /t/1525553/how-low-should-you-go-is-15-hz-too-low#post_24561216


I believe Carp or Archaea here did some extend test with hi pass filter engaged centered at the low frequency and the conclusion was they prefer bass >16hz. Carp's system with 8 seal 18" SI's has tremendous output down to single digit by the way. He mentioned in one of the thread that below 16hz, his house and everything were shaking violently but didn't feel it much at his MLP. Hopefully he can chime in when seeing this thread. OTOH, other folks seem to enjoy
 
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^^ The only way to find out is to have folks with capable system apply a low pass filter at 16hz and play that Irene scene or any scene that has less than 16hz so that only 16 and below are playing.
 

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Certainly worth it from my listening position. And as bill says, it is the vibration that you experience the most. I have played a 120db sine wave @5hz and in my room it feels like you are under water the pressure is that much.
 

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Worth it! Read a little there are plenty of threads about this topic. I depends on many things and room and signal chain are the big two.
 

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To tackle the ultra low frequencies, the signal chain of your equipment comes into play as certain components may roll off in response proving counter productive. Having an enclosed room helps greatly as well as the type of floor, positioning of subs and the eq'd response. Once all the contributing factors are in working order, below 16hz is great depending on the movie. I have 8 sealed 18s and at 10hz my room goes crazy but not much in comparison at the seats. For that reason I purchased Crowson tactile transducers which are good down to 1hz. It takes the room out of the equation and if your signal chain supports, guaranteed to feel everything in any movie track. If I had my choice to double displacement making 16 subs or 8 subs and transducers, I'd take the transducers no question. My theater is in an open living room and on concrete slab so that also plays a factor.
 

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Discussion Starter · #12 ·

So regular subs for output down to 16 Hz, and beneath that go with transducers to get effective results
 

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That sounds like a good recipe to me. The transducers make the experience so much more engaging I'd never be without them. Even guys who have top tier set ups such as Craig John, JapanDave and Notnyt still appreciate what the transducers provide beyond just their subs.
 

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I haven't experienced transducers, but I don't see the appeal as much. Place your subs near-field if you want your body to be rocked. Transducers will shake your seat, but real sound pressurization will do that and also punch you in the chest. Accept no substitutions!
 

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The room construction/layout is a big part of what you feel at the listening position. I have the HT in the basement and the tactile is good at the MLP. The room above the HT and adjacent area vibrate like crazy. The trick would be how to focus all that energy at the MLP. Transducers are a smart choice if one wishes to have more seat shake'in experience. A vented sub tune to 17 Hz will have some added extension with room gain and tremendous output in the critical 15 Hz area. A couple of vented subs mixed with some sealed subs may do the trick. I already know people like to use identical subs, lol. Peak volume displacement is a useful tool when selecting which sub to buy. For example, an 18 in sub will almost have twice the displacement of a 15 in. sub.
 

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Quote:
Originally Posted by gpmbc  /t/1525553/how-low-should-you-go-is-15-hz-too-low#post_24561952


That sounds like a good recipe to me. The transducers make the experience so much more engaging I'd never be without them. Even guys who have top tier set ups such as Craig John, JapanDave and Notnyt still appreciate what the transducers provide beyond just their subs.
Greg, look like I need to be back at your place to test the transducer. It was awesome without it and now it must be awesome...er?
 

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Discussion Starter · #17 ·

Quote:
Originally Posted by shadyJ  /t/1525553/how-low-should-you-go-is-15-hz-too-low#post_24561968


I haven't experienced transducers, but I don't see the appeal as much. Place your subs near-field if you want your body to be rocked. Transducers will shake your seat, but real sound pressurization will do that and also punch you in the chest. Accept no substitutions!
Not sure if I agree with you Shady from what I am starting to learn about transducers.  Read up on them a bit and see for yourself what you think.  To me, it is simply a smarter and much more effective way to feel the effects of ultra low frequencies down into the single digits without spending many many multi thousands of dollars to do it.  Or if it is a normal living room and not a dedicated theater where a dozen 18" subs with 40k watts may not be feasible.

 

I agree a near field sub will improve how much you feel it at the frequencies it can play, but zero output at 9Hz does not do anything no matter how close it is 
 
 

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Quote:
Originally Posted by tvuong  /t/1525553/how-low-should-you-go-is-15-hz-too-low#post_24562030


Greg, look like I need to be back at your place to test the transducer. It was awesome without it and now it must be awesome...er?
Thx bud, the difference is substantial. I'll hopefully be finishing my AE 18" MBMs and coaxial surrounds this weekend. It'll be a new experience for sure when you come. When you came last time, I had the one transducer with an amp that was clipping which severely neutered the response/output. Now I've got 4 with the amp built for them and my furniture modified to bring the best out of them- whole new ball game.
 

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Discussion Starter · #20 ·

Here is something I am considering doing:

 

Apply a high pass filter in the 16-20 Hz region with a shallow roll off to drop output under 16 Hz, which should provide a lot more headroom above 16 Hz on scenes where my XS30 is playing its guts out on the 10-16 Hz stuff.  Add 2-3 dB of Eq in the 20 Hz area, which should still net a big increase in overall headroom available, and see what happens.  Then replay scenes like the washington monument, pod emergence, WWZ grenade scene,  to see which method gives the most impressive effects.  I don't listen at reference so perhaps this wont be too much eq down low, I listen at -15 to -10(if the wife is not around).
 
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