Nearfield Ported MBM for Increased Mid-Bass Tactile Response - Page 62 - AVS Forum | Home Theater Discussions And Reviews
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post #1831 of 3158 Old 02-03-2017, 09:53 PM
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Originally Posted by bscool View Post
I'll be curious what you think when you get your Crowsons. I have tried my Kappa Pro 18" tuned to 41hz behind me and I can feel it more when right behind my chair, but I can tell it is coming from behind and I prefer it in front between my with the LRC since I still get some tactile feel from it although not as intense but I feel it coming from up front. And the Crowsons feel more "all" around me feeling, kind of enveloping. It could also be because my priority is music over movies.

I remember reading someone else on here that had both and liked them when combined.
I'll definitely post my thoughts. I'm much more movie oriented, but I'll definitely give music a go. I'm not sure how much the Crowsons will add to music if I cross them at 40-45Hz. Do you run yours crossed higher for music?

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post #1832 of 3158 Old 02-03-2017, 10:42 PM
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I have a few different preset profiles in the Inuke software I choose different ones depending on what I'm listening to, I use an HTPC to play everything so I can change profiles easily on the fly. My highest crossover is 250hz with 48dB Butterworth which can be way too high depending on what I am listening to. I don't use that for movies because it lets too much of the deeper voices come thru but for some music I like it.

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Originally Posted by Sekosche View Post
I'll definitely post my thoughts. I'm much more movie oriented, but I'll definitely give music a go. I'm not sure how much the Crowsons will add to music if I cross them at 40-45Hz. Do you run yours crossed higher for music?
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post #1833 of 3158 Old 02-04-2017, 01:14 AM
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@dominguez1

I think I found an app that should work for a Windows phone, does this look like what I need to measure/compare tactile feel?

Or anyone else with a Windows phone have an app they use?

https://www.microsoft.com/en-us/stor.../9nblggh0jv6h#
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post #1834 of 3158 Old 02-04-2017, 06:44 AM - Thread Starter
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Originally Posted by bscool View Post
So how would you compare two different sealed subs if I wanted to compare tactile feel? Use your same test method of comparing them at 1 specific frequency and measure tactile feel?

Because I have a Submersive and also a PSA XS30 both sealed subs that are very similar, so I would test each at say 50hz using the same SPL?

Because I know from actually playing each the Submersive is much more tactile and kicks harder and plays lower. Just trying to figure this out or how it compares or would apply when comparing sealed subs.

I can't use the Vibsensor app on my windows phone or I would do the testing and comparison myself .
Based on hornresp, my guess is that PVL would sim very similarly given the same SPL. This means that in theory, they should have the same TR if you perform the same tests I did (single frequency within sweet spot).

I suspect though that the Submersive might do better with the transients and be more efficient there, and also play louder across the band. Given that with real world material, this is likely the reason it 'feels' more tactile...but the reason is because of clean, accurate SPL; not because of increased PVL.

It's a test that hasn't been performed yet that I know of, so definitely worthwhile in my view!
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post #1835 of 3158 Old 02-04-2017, 06:45 AM - Thread Starter
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Quote:
Originally Posted by bscool View Post
@dominguez1

I think I found an app that should work for a Windows phone, does this look like what I need to measure/compare tactile feel?

Or anyone else with a Windows phone have an app they use?

https://www.microsoft.com/en-us/stor.../9nblggh0jv6h#
That should work!

I'd highly recommend though you find some device with IOS or Android and run Vibsensor so we are using the same tool, but if those aren't available, this should work.
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post #1836 of 3158 Old 02-04-2017, 10:08 AM
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Well when she didn't talk to me for 3 hours, I thought it was because she was kind and wanted me to enjoy the new subwoofer.


Turns out I was wrong.
Okay. So why are you selling the sub?




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post #1837 of 3158 Old 02-04-2017, 10:19 AM
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She (and I) don't appreciate the look of the Behringer in the middle of our family room. I could always keep it for the time when I eventually get my own dedicated room for a home theater. But that might be years. Someone could enjoy it now, and later on I can buy a new one.

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post #1838 of 3158 Old 02-04-2017, 03:57 PM
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I think most people here aren't "resisting" this new approach but are just trying to understand the physics. I personally want to understand it to see how it can be applied to a sealed sub.
Currently it looks like the reasoning goes like this (correct me if I'm wrong):

A sealed and a ported sub with allegedly similar perfomrance parameters are measured given similar calibrated SPL and vibration is registered.
Due to the SPL assumed being constant (all things equal) and the ported sub generated more vibration it is assumed that therefore the ported sub generates more particle velocity.

The issue I have with this is that the actual particle velocity was not measured separately to answer this question with absolute certainty.
The logical reasoning above makes a generally very difficult to verify assumption that "everything else is being equal" and if that is not the case the logical conclusion of higher PV might be flawed.

Here are specific points that in my opinion would need to be proven absoutely equal between the ported vs sealed sub to verify this assumtion:
  • Spectral composition of the measured signal
    Both compared subs would need to generate absolutely the same output signal in each frequency during measurment. It's not enough to just measure the overall SPL which would be some acoustical average. For instance if the ported sub outputs 5db more at 30hz during the test then it would therefore generate more measured vibration ,even if it would output 10db less across 60-80 range, which would result in equal average SPL but not equal spectral composition, thereofre not the same physical energy measured.
  • Dynamics and headroom
    Both subs would need to have the same or close to the same absolute impulse response with the tested signal.
    A sealed sub would need a much stronger amplifier or motor design to count the athmospheric pressure with greater xmax to reach the same dynamic range compared to the ported sub. Therefore even if the averaged SPL levels are the same the ported sub might produce a lot stronger "dynamic kick" and in the shape of the resulting air pressure (generated sound wave) might be less smeared over time due to less driver damping therefore potentially more generated vibration at the listening position.
    A good test here would be to measure a ported sub against an amazingly powerful sealed sub with great dynamics (like JL Fathom 113v2 or Funk Audio) to rule out this variable.
  • Time Domain Response of the sub
    Similar to the previous one it's important to test things like overhang around the port tune. It's widely accepted that sealed subs would have "tigher" base around that area with less energy generated over time becuase it would more closely follow the actual output signal.
    So if a ported sub would have more overang, it would produce more base energy over time for the same signal which would translate into more measured vibration.


Another very interesting thing to look into is the base response of the room. For instance a room that exhibits a lot of ringing in lower frequencies compared to a room that doesn't. Lots of poeple report that installing proper base traps (carbon membraine ones) makes the base much tighter and more tactile.
So it could be that this is why there's need to install near field subwoofers, because by installing those nearfield you're potentially reducing the effect of room reflection becuase the faster produced wave from a ported sub reaches the listener before the "smeared" reflected waves do.
So a theory to test here would be whether or not room ringing would "smear" the base response and therefore make it feel less sharp, ie, less tactile.

I personally am really interested in tactile effect, for me this is one of the more exciting aspects of a good system so I'm very interested in knowing how to achieve that with the sealed subs.
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post #1839 of 3158 Old 02-04-2017, 04:09 PM
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Part of me wonders if some of us are like the tube amp guys who love the "fatness" and "warmth," which is actually a form of distortion. Same for LP's.


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post #1840 of 3158 Old 02-04-2017, 04:39 PM
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I think what I'm really curious about is what is the cost of increased particle velocity. What balances the equation?

Also ViciousDelicious after doing more research about ported subs, I believe the actual assumption in play here is that bass produced by a Helmholtz resonator of an equal spl and frequency will be more energetic (more SI) in the nearfield than sound produced by a traditional driver.

I can absolutely believe the way a helmhotlz resonator effects a sound field could be and likely is different than a normal driver, but I also imagine it's far more complex than just better and there are likely downsides as well.

That said, if this assumption holds, then it would be the port itself that is beneficial, and there would be NO way to apply the principal to a sealed sub. There is not enough information here to make that determination. But if it were valid, I'm sure nathan could use one of his drivers in a custom ported enclosure tuned higher.
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post #1841 of 3158 Old 02-04-2017, 05:24 PM
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I suggest reading the VS thread start to finish and then probably read the opening posts of this thread again. You may find it helps your understanding.
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post #1842 of 3158 Old 02-04-2017, 05:26 PM
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I would suggest that perhaps a better way to handle an intellectual discourse would be to respond to questions and points that other people are making. Your post above brings nothing to advance others understanding and comes across more like a jab than an honest attempt at being useful. There is no need for that.

If the original posts would be so comprehensive and scientific as you seem to suggest there would not be all of this follow up conversation here.
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post #1843 of 3158 Old 02-04-2017, 06:08 PM
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Quote:
Originally Posted by 3ll3d00d View Post
I suggest reading the VS thread start to finish and then probably read the opening posts of this thread again. You may find it helps your understanding.
Quote:
Originally Posted by ViciousDelicious View Post
I would suggest that perhaps a better way to handle an intellectual discourse would be to respond to questions and points that other people are making. Your post above brings nothing to advance others understanding and comes across more like a jab than an honest attempt at being useful. There is no need for that.

If the original posts would be so comprehensive and scientific as you seem to suggest there would not be all of this follow up conversation here.
@3ll3d00d has provided invaluable information to both threads. What I have contributed pales in comparison to him and it has taken many hours out of my life. Nobody wants to keep rehashing information that is already available to read.

If you simply read the posts by @dominguez1 and @3ll3d00d in the two threads (use advanced search to display thread posts by user name) you will have info and links to reference material to last you an eternity. Many others have contributed as well.

I have been late to many discussions. I always do my best to read and use the search function before posting. Usually, all of my questions have already been asked and answered.
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post #1844 of 3158 Old 02-04-2017, 06:14 PM
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I have not been able to find clear answers on the 3 points I brought up in my previous post, namely the measurments that confirm identical frequency response, dynamic range and time domain response between the measured ported and sealed sub. If all of those being equal (or very close) we would still see such a profound difference in measured vibration then it would follow that there's more at play than just ported sub being better at one of those other parameters that from my understanding were not measured or being made equal for the sake of the tests performed here.

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Originally Posted by ViciousDelicious View Post
Here are specific points that in my opinion would need to be proven absoutely equal between the ported vs sealed sub to verify this assumtion:
  • Spectral composition of the measured signal
    Both compared subs would need to generate absolutely the same output signal in each frequency during measurment. It's not enough to just measure the overall SPL which would be some acoustical average. For instance if the ported sub outputs 5db more at 30hz during the test then it would therefore generate more measured vibration ,even if it would output 10db less across 60-80 range, which would result in equal average SPL but not equal spectral composition, thereofre not the same physical energy measured.
  • Dynamics and headroom
    Both subs would need to have the same or close to the same absolute impulse response with the tested signal.
    A sealed sub would need a much stronger amplifier or motor design to count the athmospheric pressure with greater xmax to reach the same dynamic range compared to the ported sub. Therefore even if the averaged SPL levels are the same the ported sub might produce a lot stronger "dynamic kick" and in the shape of the resulting air pressure (generated sound wave) might be less smeared over time due to less driver damping therefore potentially more generated vibration at the listening position.
    A good test here would be to measure a ported sub against an amazingly powerful sealed sub with great dynamics (like JL Fathom 113v2 or Funk Audio) to rule out this variable.
  • Time Domain Response of the sub
    Similar to the previous one it's important to test things like overhang around the port tune. It's widely accepted that sealed subs would have "tigher" base around that area with less energy generated over time becuase it would more closely follow the actual output signal.
    So if a ported sub would have more overang, it would produce more base energy over time for the same signal which would translate into more measured vibration.
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post #1845 of 3158 Old 02-04-2017, 06:20 PM
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Quote:
Originally Posted by Marc Alexander View Post
Quote:
Originally Posted by 3ll3d00d View Post
I suggest reading the VS thread start to finish and then probably read the opening posts of this thread again. You may find it helps your understanding.
Quote:
Originally Posted by ViciousDelicious View Post
I would suggest that perhaps a better way to handle an intellectual discourse would be to respond to questions and points that other people are making. Your post above brings nothing to advance others understanding and comes across more like a jab than an honest attempt at being useful. There is no need for that.

If the original posts would be so comprehensive and scientific as you seem to suggest there would not be all of this follow up conversation here.
@3ll3d00d has provided invaluable information to both threads. What I have contributed pales in comparison to him and it has taken many hours out of my life. Nobody wants to keep rehashing information that is already available to read.

If you simply read the posts by @dominguez1 and @3ll3d00d in the two threads (use advanced search to display thread posts by user name) you will have info and links to reference material to last you an eternity. Many others have contributed as well.

I have been late to many discussions. I always do my best to read and use the search function before posting. Usually, all of my questions have already been asked and answered.
They may have been answered if you read the entire some hundred pages of discussion between all the threads, but repeatedly referring to the 1st post is not helping anyone.

I get it. Lots of information, but that's all it is, a raw data dump and some "we noticed this". What we are looking for is an actual assessment based on some degree of science. Think about what goes into a scientific journal for peer review.

That people keep asking questions and you keep referring to the first post is telling as it indicates you are automatically assuming we haven't read it. I read the OP multiple times before I said anything.

You don't have enough information to make the leaps you are making nor are you making a scientific assessment or providing an explanation based on physics on what is happening.

Based on the informatin you have provided, my assumption is you are saying that. Helmholtz resonator will for one reason or another produce more TR/SI that a driver doing the same job.

If that is your conclusion, and you want to keep pointing people to the OP, then perhaps you should actually point that out.
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post #1846 of 3158 Old 02-04-2017, 06:25 PM
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amnesia0287: I have seen this vaguely addresed but in every single post it was more of "explaining away" rather than actual solid measurment. I agree with you on everything above, I have not felt that there's clear cut science and data here that I personally could understand and go "oh yeah, okay this all adds up".

People try to theorize why this or the other "woudln't matter" but the reality is that the physics involved (especially given we're measuring in a closed room rather than anechoic chamber or outside) is very complex and unless all of the variables are measured and proven to be equal you can't just use the linear equation descirbing particle velocity and SPL relatisnhip to sound intensity to infer this. Simply becuase SPL is not a simple function, it's a function of frequency response and time domain response measured and weighted averaged over time. Therefore in my view you need to prove that all of those components are indeed equal to say that SPL is truly equal in both cases.

Last edited by ViciousDelicious; 02-04-2017 at 06:28 PM.
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post #1847 of 3158 Old 02-04-2017, 06:30 PM
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And to be clear I'm very interested in this subject and I am thankful for all the investigation into the subject you guys have done, but what I want to know is not how to hack together improved SI by using something that is available. I want to know what improves SI, so that a subwoofer could be engineered from the ground up to actually INTENTENTIONALLY have better SI/TR
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post #1848 of 3158 Old 02-04-2017, 06:36 PM
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Agreed. I have breifly discussed this with Nathan Funk and his opinion is that what could be happening is what I have asked in point #3 - namely the overhang near the tuning frequency.
If the ported sub exhibits more overhang in that region it would therefore output more energy in a certain time than a sealed sub. That alone can explain the difference in the measured vibration since nor the SPL function nor the measurement used seems to be precise enough to capture or account for this variation.

Nathan suggested that Sealed subs can achieve the same effect with potential EQing of certain frequencies to compensate for the ported sub design's overhang. If the sub is good enough to handle the EQ without compressing its dynamics or too much added distortion this overall should result in both better tactile response and also better overall SQ of the system with the sealed design.
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post #1849 of 3158 Old 02-04-2017, 08:39 PM - Thread Starter
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For the record, the original hypothesis that started in the ULF thread 3 or 4 years ago was:

  • Ported produced more TR than sealed around port tune.

Within the ULF Thread, Vibsensor, this thread and really the Subwoofer/DIY forums, there have many accounts both anecdotally ("I switched to ported, and it just feels more visceral" or "my couch didn't shake this much when I had sealed") and quantitatively (via the Vibration Meter, Vibsensor, and DIY accelerometers) that demonstrate that ported is more tactile.

In my mind, I consider that to be truth. Whether folks choose to buy into this or not is certainly up to them...


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Originally Posted by ViciousDelicious View Post
I think most people here aren't "resisting" this new approach but are just trying to understand the physics. I personally want to understand it to see how it can be applied to a sealed sub.
Currently it looks like the reasoning goes like this (correct me if I'm wrong):

A sealed and a ported sub with allegedly similar perfomrance parameters are measured given similar calibrated SPL and vibration is registered.
Due to the SPL assumed being constant (all things equal) and the ported sub generated more vibration it is assumed that therefore the ported sub generates more particle velocity.
Yes, increased PVL and resulting increased Sound Intensity was the second hypothesis as to WHY ported produced more TR. Up until this year, we really didn't have any theoretical or measured data to support this...until @3ll3d00d made the discovery in the simulator; hornresp. As described in the first post in this thread, hornresp mathematically calculates the particle velocity for a given design.

As a result, 3 created multiple models in hornresp to try and determine the different levels of particle velocity for different types of subs (sealed, ported, horn, bandpass, etc.).

Summarizing of his findings:
  • Ported produced ~10X the amout of particle velocity near tune compared to sealed
  • Different driver sizes for sealed designs did not increase PVL. IOW, for sealed subs regardless of driver size, SPL at x level would always produce PVL at y level linearly
  • There are ways with vented designs that you can optimize PVL

So while particle velocity has never been measured directly, mathematical simulations show that there is in fact increased particle velocity around tune for ported designs.

Assuming hornresp is calculating particle velocity correctly (3ll3d00d validated this with the author of hornresp), then given the equation:

SIL = SPL * PVL

Mathematically, there would be increased SIL around tune for ported subs.

Certainly, to validate the math we would need a tool to measure these, but in my mind validation would just be to measure the mathematical precision of the SIL and PVL compared to the SIM, not so much as to prove if the levels are increased or not.

Quote:
The issue I have with this is that the actual particle velocity was not measured separately to answer this question with absolute certainty.
The logical reasoning above makes a generally very difficult to verify assumption that "everything else is being equal" and if that is not the case the logical conclusion of higher PV might be flawed.
Explained above.

Quote:
Here are specific points that in my opinion would need to be proven absoutely equal between the ported vs sealed sub to verify this assumtion:
[*]Spectral composition of the measured signal
Both compared subs would need to generate absolutely the same output signal in each frequency during measurment. It's not enough to just measure the overall SPL which would be some acoustical average. For instance if the ported sub outputs 5db more at 30hz during the test then it would therefore generate more measured vibration ,even if it would output 10db less across 60-80 range, which would result in equal average SPL but not equal spectral composition, thereofre not the same physical energy measured.
In the single sine wave tests as described in the first post, would these not be identical?

Quote:
[*]Dynamics and headroom
Both subs would need to have the same or close to the same absolute impulse response with the tested signal.
A sealed sub would need a much stronger amplifier or motor design to count the athmospheric pressure with greater xmax to reach the same dynamic range compared to the ported sub. Therefore even if the averaged SPL levels are the same the ported sub might produce a lot stronger "dynamic kick" and in the shape of the resulting air pressure (generated sound wave) might be less smeared over time due to less driver damping therefore potentially more generated vibration at the listening position.
A good test here would be to measure a ported sub against an amazingly powerful sealed sub with great dynamics (like JL Fathom 113v2 or Funk Audio) to rule out this variable.
In the single sine wave tests where SPL levels were played well within the frequency and output ranges of each sub, how does this come into play?

Quote:
[*]Time Domain Response of the sub
Similar to the previous one it's important to test things like overhang around the port tune. It's widely accepted that sealed subs would have "tigher" base around that area with less energy generated over time becuase it would more closely follow the actual output signal.
So if a ported sub would have more overang, it would produce more base energy over time for the same signal which would translate into more measured vibration.
Is this relevant for a single sine wave test?

Quote:
Another very interesting thing to look into is the base response of the room. For instance a room that exhibits a lot of ringing in lower frequencies compared to a room that doesn't. Lots of poeple report that installing proper base traps (carbon membraine ones) makes the base much tighter and more tactile.
So it could be that this is why there's need to install near field subwoofers, because by installing those nearfield you're potentially reducing the effect of room reflection becuase the faster produced wave from a ported sub reaches the listener before the "smeared" reflected waves do.
So a theory to test here would be whether or not room ringing would "smear" the base response and therefore make it feel less sharp, ie, less tactile.
In the single sine wave tests, the "base response of the room" would react with the sub identically.


Quote:
I personally am really interested in tactile effect, for me this is one of the more exciting aspects of a good system so I'm very interested in knowing how to achieve that with the sealed subs.
Your 2 or 3 points above are definitely things you can look for to optimize TR in your room, whether that be for sealed, ported, horn, etc. However, you won't be able to produce the same PVL and resulting SIL levels from a sealed sub relative to ported.

Make no mistake, ported isn't necessary to get great TR. Many have done so...but for those that want absolute optimal TR, then I'd say ported is the right path to go down.
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post #1850 of 3158 Old 02-04-2017, 08:42 PM
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Another thing to consider is that when the vibration was measured the measuring device was placed on the couch or other objects that would resonate and therefore move the phone.
Could it be that the ported subs due to the output signal pattern (accounting for port influence) would cause the couch to resonate more, ie would fall into the resonant frequency more than the sealed version. Maybe one could use a piece of fabric stretched and suspended in the air and put the phone on it to then measure vibrations, which would be less dependent on the resonant frequency of big furniture structures.
Also given that the tests on the other subs were performed with extremily high SPL it would not be unlikely that some of the subs would be approaching their mechanical/amp limits in terms of dynamics and would be producing more compressed waves.
The measued mean and max SPL does not tell us the entire picture about the time domain and amplitude of waves that are generated, just their average.

Another interesting test would be to see if anyone here that owns Wisdom Audio STS subs would be interested in testing them

http://www.wisdomaudio.com/products_sts.php

These subs use the Regenetaritve Transmission Line technology which if the ported theory is correct should accelerate particles even more given its tremendous output capabilities and efficiency.
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post #1851 of 3158 Old 02-04-2017, 08:49 PM
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Thanks for the detailed response dominguez1!

When I was talking about room treatmeent it wasn't relevant to the comparison itself but more as a question of whether having less lower energy reflection or ringing in the room would result in more "snappy" or "tactile" response from the base.
Maybe what is happening is that the balance of the timing of "direct base wave" and "reflected base wave" hitting the listening position could be different if ported subs indeed output "faster waves" but if the room is well treated then maybe this is not as important to get TR. A good test to verify this would be to perform the same test outside in the open, such that reflected waves would have less of an influecne on the overall measured vibration.

As to sine wave differences - while the averaged response over time might be similar the actual generated "waves" might be different based on different driver displacement, Xmax, power / driver compression, etc especially since some of those tests were running the subs really hot. At the listening postiion the subs would need to be quite close to their output capabilities and there the efficiency of the ported sub might be giving it an edge.

Ideally I would want to get the best tactile response for my room but I also want to go the sealed route to get the best quality as well. So I'm doing a bit of wishful thinking here myself trying to see if sealed subs can be made better with regards to TR in a particular room, since mixing both ported and sealed subs was not adviced by many.

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post #1852 of 3158 Old 02-04-2017, 09:06 PM - Thread Starter
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Originally Posted by ViciousDelicious View Post
Ideally I would want to get the best tactile response for my room but I also want to go the sealed route to get the best quality as well. So I'm doing a bit of wishful thinking here myself trying to see if sealed subs can be made better with regards to TR in a particular room, since mixing both ported and sealed subs was not adviced by many.
Meh...mixing ported and sealed can definitely be done. Ask me how I know

Seriously though...you have to have the right tools for the job, and it can take some tweaking, but the upside (especially for home theater) can definitely outweigh the effort.

You bring up some good points...and I encourage you to explore those, post back, and take this up a notch potentially.

Of course, if you wanted to purchase a PVL or SIL meter to put this to bed, I would't complain...

I do feel good on where we've landed given what we've found thus far. No...we aren't going to be publishing any papers soon, but that was never the goal.

@3ll3d00d has a sub project in the works now where he is specifically designing it to optimize PVL at certain frequencies...should be fun to watch. He's also in the process of building/writing software for a more robust DIY accelerometer and associated graphing software. My hope is that it will turn into the mini-REW for Vibration.
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post #1853 of 3158 Old 02-04-2017, 09:11 PM
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Last few pages of this thread are unbelievable. I have no idea or interest in what you you guys are talking about, however, I have the utmost respect for everyone who continually take the time to respond, and provide information. Amazing!

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post #1854 of 3158 Old 02-04-2017, 09:13 PM
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I should also mention that I bought a 1200D last summer after reading this thread. I am still in the process of integrating it into my system.

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post #1855 of 3158 Old 02-04-2017, 09:14 PM
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@ViciousDelicious (I feel silly calling another grown @$$ man Delicious!), why do you believe sealed will give you higher quality bass?
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post #1856 of 3158 Old 02-04-2017, 09:52 PM
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Has anyone tested with Rhytmik subs? If his theory is right then the adjustable Q should change the TR pretty drastically no?
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post #1857 of 3158 Old 02-05-2017, 02:47 AM
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I would suggest that perhaps a better way to handle an intellectual discourse would be to respond to questions and points that other people are making. Your post above brings nothing to advance others understanding and comes across more like a jab than an honest attempt at being useful. There is no need for that.
well it's either that or a pointer to another, pretty long, thread that has a lot of discussion on the subject and which would allow you to research further. You can interpret it however you want.

Generally I think you are conflating "tactile bass" and "tactile response". The former is a subjective description of the sound quality of a particular system which may exhibit some or all of the following aspects; midbass efficiency, v good integration between sub and mains, good pressure response, good tactile response, smooth/on target frequency response (and probably a bunch of other stuff not mentioned). The latter is basically a synonym for vibration and is something that can objectively be measured with some pretty cheap equipment. Note that measuring pressure response or particle velocity directly is effectively impossible at home (either because the equipment doesn't readily exist or is prohibitively expensive).
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post #1858 of 3158 Old 02-05-2017, 07:21 AM
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There is a link below. This thread was looking at 1 MBM for each LRC with 130dB+ capabilities in a limited width space and I kept modeling ported 18's and 21's trying to find the ones with the highest output. I also tried to figure out how to get a pair of 15-18s in a V to fit so he could use 2 subs instead of 1 per LRC but it wouldn't work and then Mark Seaton came in with a simple idea which I hadn't thought of instead of making them a V make them directly face each other like you would for an Infinite baffle set up. This would give make them work in the limited space he had available.

I think this way may get you close to ported "particle velocity" yet using a sealed subs. The manifold will act as a port, is my theory anyway and increase efficiency.(I don't know how to use Horn Resp to look at the #s to compare them) I also don't know if it would show what you would actually feel or experience in real life because a smaller port will have higher particle velocity but it can't be too small, like a port 1" vs a 6" will show higher air velocity but it needs to be a minimum size at the same time to work in the real world.

I know this works as far as increasing output and efficiency just from trying two separate subwoofers out in my room and putting one corner of them touching so they in a V shape with drivers firing towards each other(this could work with 2 1200D also I would imagine if someone wanted to use 2 on 1 chair, unless it would put the ports too far back for the chair?). It increases the output and subjectively it feels like more tactile feel just having them in the V out in the room. I haven't actually tried it and measured it for tactile feel directly behind my chair but it seems like it should help since it is "funneling" and "focusing" the air more.

https://www.avsforum.com/forum/155-di...l#post50409841

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Ideally I would want to get the best tactile response for my room but I also want to go the sealed route to get the best quality as well. So I'm doing a bit of wishful thinking here myself trying to see if sealed subs can be made better with regards to TR in a particular room, since mixing both ported and sealed subs was not adviced by many.
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post #1859 of 3158 Old 02-05-2017, 07:44 AM
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you can model this in hornresp. The slot, if tuned correctly, can act as a low pass filter and increase efficiency before that LPF kicks in. It's tending towards a 4th order bandpass in that regard. I suspect if you model this you won't see a substantial rise in PVL as the slot is relatively large but you will gain headroom and hence output capability, i.e. probably no more PVL per SPL but absolutely more SPL capability.

FWIW I've seen people say similar things (re that "funnelling" effect and tactile impact from distance) about slot loaded subs before.
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post #1860 of 3158 Old 02-05-2017, 08:22 AM
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I love reading this thread eventhough much of this is over my head. It is like listening to Edison and Tesla discussing DC versus AC
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