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post #4051 of 5055 Old 02-22-2016, 11:06 AM
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Null hypothsis: Sealed sub and Vented sub are equal if they have the same FR, spl, distance to subject. ect. Listed below is the Vibsensor data for vented sub.
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post #4052 of 5055 Old 02-22-2016, 11:11 AM
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Vibsensor data for Sealed Sub:
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post #4053 of 5055 Old 02-22-2016, 11:20 AM
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The subwoofer use for the experiment was the Mini Marty. All ports were plugged for sealed subwoofer measurements. No hpf was used for the vented portion of the experiment. Placement remained the same for all testing. The movie clip for the Vibsensor was Edge Of Tomorrow. The movie was 3 db higher for sealed subwoofer testing.

FR and spl graph were done at 75 db of the vented and sealed version of the subwoofer to ensure similar output.

*No hpf was used for testing. Not using one with vent subwoofers may result in subwoofer damage.
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post #4054 of 5055 Old 02-22-2016, 11:23 AM
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The red line in the first graph is the sealed FR and the blue is the vented.
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post #4055 of 5055 Old 02-22-2016, 11:32 AM
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Note: Graph 3 of Vibsensor shows much more activity for the vented sub. also note the widith of activity, 5 vs 2.
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post #4056 of 5055 Old 02-22-2016, 12:08 PM - Thread Starter
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Can't wait to dig my teeth into the data...but at the surface, it looks pretty compelling that ported has higher Tactile Response...

Did you just test EOT, or did you also test sine waves?

Amazing job BTW getting the FRs to match up!
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post #4057 of 5055 Old 02-22-2016, 12:32 PM
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The Edge of Tomorrow was the only clip tested. I thought this would simulate the the way we use our systems, movie watching. I don't think using sine waves will give the wide dynamics of a movie and use of the LFE channel.

Dave started the Vibsensor testing and thread and we need his comments and a few other members for a better understanding of the data. The main resonance of the room is around 20 Hz. There is a time domain in the clip where the frequencies shift to low, around 10 Hz and the sealed sub excel down there. Even though the sealed sub excels at lower frequencies, the output is less and may not have the same impact of a vented sub for this clip. There is also an interesting finding with the Aura Shaker under 15 Hz. That data is not included for now.
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post #4058 of 5055 Old 02-22-2016, 01:26 PM
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A properly sealed sub should have a lot more output at 10hz and below so for the 10hz portion will be better. Now if you ported real low what is the difference? I will show the data when I have time. I already posted my sealed IB. I would never port to lose 10hz and under, that region just adds too much realistic effects on the body to discard.
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post #4059 of 5055 Old 02-22-2016, 02:26 PM
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The sinewave clip of EOT has more 10 Hz output in the sealed version of the Mini Marty between the time frame 5-10 second as expected. Giving up the 10 Hz output is not being suggested. The ami of the test was to determine if similarly matched sealed vs ported gave more TR. For you and a few other guys, you have the best of both world. There is little room gain in this experiment since the room is 4300 cu ft. The sealed sub can't get the freebie of significant room gain for increase under 15 Hz output.

The data support what was mention in the first few pages of the ULF thread by Dominguez1. Ported subs have a greater TR than a matched sealed sub. The implications are important for someone setting up a system. Room size, type of sub and number of subs should all be considered for the greatest TR for the HT.
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post #4060 of 5055 Old 02-22-2016, 02:56 PM
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I understand that. How does it feel subjectively?

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post #4061 of 5055 Old 02-22-2016, 05:45 PM - Thread Starter
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So, let me summarize the test that dj performed:

He used his mini-marty UM18 sub in two different configurations: one vented, and one sealed (vents plugged).

The distance from the omnimic was kept constant; he did not move the sub.

The frequency response of the vented configuration and sealed configuration were within 2 db, 25hz and up, and identical 25hz and below:



The SPL was kept constant at for both configurations to 75db.

Source material: EOT clip

Recording Device: iphone using the Vibsensor app

Basically, the only thing that was changed was if it was a vented configuration or sealed configuration. Distance, driver, FR, and SPL kept the same.

The below is the results between vented and sealed using the VibSensor PSD. I've modified the images so that they are both on the same scale so that you can directly compare the results:



You can see the largest discrepancy at 20hz (5.5 to 1.5). Smaller at 25hz (1.3 to 0.5). And finally, the smallest discrepancy at 30hz (.5 to .25).

The hypothesis was that around tune, the ported or vented sub would produce more Tactile Response than sealed. The measurements via the Vibsensor support exactly that:

  • 20hz (tune of the mini-marty) was the biggest discrepancy, and as it moved away from tune, the difference in Tactile Response become less and less, where at 30hz, they were very close in TR.

Comments welcome.
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post #4062 of 5055 Old 02-22-2016, 07:36 PM
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Now test it with two sealed drivers facing the same way but only if it was a near field experiment. I am curious if the second driver makes up for the port as they both are facing the seats.
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post #4063 of 5055 Old 02-22-2016, 08:15 PM
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I was hoping coolrda would have time today for a few comments. He could go over all 5 graphs an point out a few things we may be missing. My gut feeling form owning a couple of dual driver boxes is that the vented sub still wins in the TR nearfield setup.

At tuning, there is a tremendous amount of PVL compare to a sealed sub. The Vibsensor is helping us just fill-in one part of the equation. I have no doubt that people with all sealed systems and ultra low output also experience good TR. I also don't have firsthand knowledge of what the high output ultra low response feels like. I know in my room ear pressure can be bothersome at increasing output in the lower frequencies. I guess I need an invite to one of those room with good single digit output.

The thread has focused on SI unit and ulf and of course spl. The Vibsensor results need to be merged with this info to help fill-in the TR experience that is one of the end points that we are trying to have in our HT's. I will do more testing with the full system with info related to FR and overall spl with Vibsensor data as time permits.

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post #4064 of 5055 Old 02-22-2016, 10:53 PM
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It might be interesting to see whether the two responses decayed differently. I doubt this makes a difference but might be interesting to check.

The other thought, given the size of the delta between TR at tune and the other frequencies and hence whether 20Hz drowns out the rest, is whether this is, subjectively, a good or bad thing. Answering this would require knowing what "good" TR is though.
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post #4065 of 5055 Old 02-23-2016, 10:26 AM - Thread Starter
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Quote:
Originally Posted by 3ll3d00d View Post
It might be interesting to see whether the two responses decayed differently. I doubt this makes a difference but might be interesting to check.

The other thought, given the size of the delta between TR at tune and the other frequencies and hence whether 20Hz drowns out the rest, is whether this is, subjectively, a good or bad thing. Answering this would require knowing what "good" TR is though.
Great point about if is a good or a bad thing. The problem is that there is no reference for tactile response. I believe it's possible to create one, but you'll need a sound intensity meter to do so.

What we do know is that ULF is typically under represented from a TR standpoint. How do we know this? The hypothesis is that room gain influences SPL, not PVL. In other words, PVL doesn't have a gain and stays static.

In room this means that it can be perceived as louder (or more pressure) with our ears, but doesn't necessarily produce any more physical tactile response. This is perhaps why single digits in room (which is largely from room gain) doesn't have much of a physical effect other than a weight or pressure.

Here's and example:

Let's assume that thunder has very deep ulf in the 10hz range and it strikes at 115db. When that is recreated via our HT in a room, a lot of the spl is from room gain and thus has minimal pvl and physical effect.

Go outside and experience that same thunder at 10hz at 115db. It will have far more physical impact. There is no room gain outside, and so that sound wave carries a lot of PVL. I think we've all experienced this before.

Also, don't forget that the thunder could have been produced miles away...putting 10hz in the far field. When we are in the far field soundfield, spl and pvl are directly in phase. This means that all one needs to measure is spl to get an understanding of what it should feel like.

And this gets back to my point around finding a reference for tactile response. To get a reference, all frequencies should exist in the far field (outside) without any room gain. Then if you measure with the sound intensity meter, you'll exactly know what 115db at 10hz should feel like...or what a 100db should feel like, etc.
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post #4066 of 5055 Old 02-23-2016, 12:34 PM
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Hi Derrick just dropping by.

A lot of what's been covered in this thread has also been researched at great length in the past by SAE and other groups, published under the broad topic of NVH.

For anyone interested, I recommending looking into that topic for supplementary info.

The question(s) being asked here nearly the same.

Cool thread, and I thank you for sharing the link on the other forum.

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post #4067 of 5055 Old 02-23-2016, 02:29 PM - Thread Starter
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Hi Derrick just dropping by.

A lot of what's been covered in this thread has also been researched at great length in the past by SAE and other groups, published under the broad topic of NVH.

For anyone interested, I recommending looking into that topic for supplementary info.

The question(s) being asked here nearly the same.

Cool thread, and I thank you for sharing the link on the other forum.
Can you share the link to the other forum specific to this topic?

I didn't get much from the NVH wiki link in regards to sound intensity, pvl and spl...
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post #4068 of 5055 Old 02-23-2016, 02:39 PM
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This is why I ported very low, to increase the tactile response during the single and teen frequencies where it is harder to sense but the pressure. I still have to run spec labs and stuff to make sure I did not lose any data during my low scenes.

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post #4069 of 5055 Old 02-23-2016, 03:42 PM
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Quote:
Originally Posted by dominguez1 View Post
Can you share the link to the other forum specific to this topic?
Sure. It's here: https://community.klipsch.com/index....one-in-the-ht/

There's a couple of my responses there that would have been better served over here.

Most of the NVH info is either published in courseware or technical papers available through professional org memberships.

Topics like Chapter 6 & 7 out of this text would be noteworthy for reference: Fundamentals of Sound & Vibration, 2nd Fahy & Thompson

as would topics covered in:

Fundamentals of Noise & Vibration Analysis for Engineers, 2nd Norton & Karczub

My replies were specific in response to discussion about "Tactile Response", not "Home Theater ULF Scores."

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post #4070 of 5055 Old 02-23-2016, 05:23 PM - Thread Starter
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Originally Posted by MKtheater View Post
This is why I ported very low, to increase the tactile response during the single and teen frequencies where it is harder to sense but the pressure. I still have to run spec labs and stuff to make sure I did not lose any data during my low scenes.
Indeed...going from sealed to a 6hz tuned ported must have increased the TR down low. Did you notice a big difference in TR?
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post #4071 of 5055 Old 02-23-2016, 05:31 PM - Thread Starter
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Quote:
Originally Posted by RadiantNRG View Post
Sure. It's here: https://community.klipsch.com/index....one-in-the-ht/

There's a couple of my responses there that would have been better served over here.

Most of the NVH info is either published in courseware or technical papers available through professional org memberships.

Topics like Chapter 6 & 7 out of this text would be noteworthy for reference: Fundamentals of Sound & Vibration, 2nd Fahy & Thompson

as would topics covered in:

Fundamentals of Noise & Vibration Analysis for Engineers, 2nd Norton & Karczub

My replies were specific in response to discussion about "Tactile Response", not "Home Theater ULF Scores."
Thanks for the links...and welcome to the thread. I assume your Quiet_hollow on that forum.

In one of your posts, you mentioned that Tactile Response was just a matter of SPL. Interested to hear your thoughts on derrickdj1's test, and the test in post 4 and post 5 of this thread, which provide evidence of the contrary.
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post #4072 of 5055 Old 02-23-2016, 07:29 PM
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Actually my front subs are tuned to 7hz and my rear subs are tuned to 9hz. The difference is size of enclosures from rear(big) and front(enormous). The last time I measured(IB)some distortion I hit 4hz at 125 dB at 2% THD. It was the same to 8hz and then the THD dropped to .7% THD at 9-15hz at the same Spl. I did not go higher but during EoT I started to clip the mic at 135 dB during the 10hz intro. I am curious what ported down low will do. It feels more tactile however I want to make sure it is clean and not distortion causing it. It sounds clean or should I say feel. The 4hz burst sine wave feels like a puff air and at the same time you hear the door expand, Subtle but I love it.
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post #4073 of 5055 Old 02-23-2016, 08:01 PM
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MKtheater, hitting 135 db, I think that plenty for a TR, lol.
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post #4074 of 5055 Old 02-23-2016, 08:47 PM
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Originally Posted by derrickdj1 View Post
I was hoping coolrda would have time today for a few comments. He could go over all 5 graphs an point out a few things we may be missing. My gut feeling form owning a couple of dual driver boxes is that the vented sub still wins in the TR nearfield setup.

At tuning, there is a tremendous amount of PVL compare to a sealed sub. The Vibsensor is helping us just fill-in one part of the equation. I have no doubt that people with all sealed systems and ultra low output also experience good TR. I also don't have firsthand knowledge of what the high output ultra low response feels like. I know in my room ear pressure can be bothersome at increasing output in the lower frequencies. I guess I need an invite to one of those room with good single digit output.

The thread has focused on SI unit and ulf and of course spl. The Vibsensor results need to be merged with this info to help fill-in the TR experience that is one of the end points that we are trying to have in our HT's. I will do more testing with the full system with info related to FR and overall spl with Vibsensor data as time permits.
First of all, phenomenal job. This kind of testing can be exhaustive, as you know. You nailed it as far as covering all the key points and backing it up with the data and graphs from multiple meters. You should post this on the VS thread! This backs up Dom's data posting at the front of this thread. It further proves my earlier findings and mentions that TR seemed to be tied to a sub's native system response, i.e, what Winisd shows as cab/driver response rather than SPL. While they're both based in the DB world, theres clearly more going here. Anyway, I need to get caught up with the posts over the last couple weeks and look over your data some more.
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post #4075 of 5055 Old 02-23-2016, 10:40 PM
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Thanks coolrda, I will post the data in the VibSensor thread.
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post #4076 of 5055 Old 02-24-2016, 05:12 AM - Thread Starter
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Quote:
Originally Posted by coolrda View Post
First of all, phenomenal job. This kind of testing can be exhaustive, as you know. You nailed it as far as covering all the key points and backing it up with the data and graphs from multiple meters. You should post this on the VS thread! This backs up Dom's data posting at the front of this thread. It further proves my earlier findings and mentions that TR seemed to be tied to a sub's native system response, i.e, what Winisd shows as cab/driver response rather than SPL. While they're both based in the DB world, theres clearly more going here. Anyway, I need to get caught up with the posts over the last couple weeks and look over your data some more.
@coolrda , thanks for chiming in! Look forward to your lens on this

I agree with your comments around the subs native response with respect that the native response excludes any room gain. As per my previous comment, my hypothesis is that PVL doesn't have a 'room gain' and so any room gain doesn't pick up any tactile response...take a way room gain from the response, and it will look more like the native response.

However, I believe it is more than just that based on DJ's and my experiments. Consider this:



These are the responses of DJs test for both ported and vented at the listening position. If you removed the room gain from this response, they would still be exactly aligned (albeit a little different shape). Room gain affects a vented and sealed sub the same.

The call it "close mic'd" response after EQ would be the same, but yet the ported curve produces more tactile response.

Does that make sense? Would like to hear others thoughts on the subject.
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post #4077 of 5055 Old 02-24-2016, 05:31 AM
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Quote:
Originally Posted by dominguez1 View Post
Consider this:



These are the responses of DJs test for both ported and vented at the listening position. If you removed the room gain from this response, they would still be exactly aligned (albeit a little different shape). Room gain affects a vented and sealed sub the same.

The call it "close mic'd" response after EQ would be the same, but yet the ported curve produces more tactile response.
pedantry/devils advocate comment incoming

are they the same though? I mean they can't be exactly the same as the port and driver are in different positions so, in the near field, they will have a different response. Whereas that measurement looks like a measurement of SPL at the listening position and hence it is not a nearfield measurement and it is not what the seat, which is presumably the medium that delivers the tactile experience?, is experiencing either.

i.e. if we're being pedantic then it's more correct to stick with "for approximately the same measured far field SPL, ported delivered more TR"
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post #4078 of 5055 Old 02-24-2016, 07:04 AM
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Did you ever measure the distortion? An increase can increase more feel as well.
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post #4079 of 5055 Old 02-24-2016, 07:05 AM
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Did you ever measure the distortion? An increase can increase more feel as well.

Dom, I thought you did at one time.
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post #4080 of 5055 Old 02-24-2016, 10:28 AM
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The FR data was taken at the MLP(no close Mic) The I phone for Vibsensor was place on the seat at the MLP. This is the way data is being collected on the Vibsensor thread. I would suspect the sealed response on the low end would have been stronger but, little cabin gain due to room size with a single sealed sub. The room is approx. 4300 cu ft.

I did not do distortion measurement for this experiment. I have done distortion measurements for this system with the UM 18's and it is less than 2% thru most of the passband. The test was done a -15 on the avr to avoid pushing anything really hard. The clip form EOT has been played many times a 0 on the avr which is reference for the system.

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