Tactile Respone in the HT

[derrickdj1]

Tactile Response (TR) is one thing most of us would like from our HT.  This makes the movie more immersive and just plain good fun to experience.  One premise is that a vented and evenly matched sealed sub should produce the same TR.  For this testing, similar spl and FR is needed to be valid.  We did some testing for the ULF thread on AVS.  It's a long, long thread but here is a link to one page with some interesting results: http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1488059-your-home-theater-ulf-score-136.html

[Quiet_Hollow]

Tactile response is simply a matter of SPL.....at any frequency. Natural frequencies aside, play anything loud enough, and eventually the body will "feel" something regardless.

 

Infra sound at sufficient SPL will pulverize organic tissue. Ultra sound at sufficient SPL will burn it.

 

105 dB SPL at the listener is the magic number. That's sufficiently loud enough to be felt at any frequency.

 

If the above weren't true, bookshelf speakers would be rather unexciting, and the decomposition of a square wave wouldn't look like this:

 

 

and the energy/spectrum distribution wouldn't look like this:

 

[derrickdj1]

Our study looked at match subs, seale vs vented.  Assuming the spl are equal across the FR, shouldn't the TR be the same?  There was a feeling the vented subs on average had more TR.  Using a water hose analogy, a spray is not the same as a concentrated stream.  This is what happens at port tuning.

 

Here are two Vibsensor graphs that show what is happening at port tuning.  For the sealed sub the graph shoot up to 2 and for the vented sub the graph shoots to 5.  The 5 is at tuning for the vented sub vs 2 for the sealed, above or below tuning of the subs, the numbers get very similar.  To my knowledge, I have not seen any published data clearly showing this.  This study also takes spl level out of the equation.  I include a graph show the FR of the vented (blue) and sealed sub (red).

 

Tom, this should apply toward horn sub and may be a reason so many people love them for HT.

Edited February 23, 2016 by derrickdj1

[Quiet_Hollow]

The 5 is at tuning for the vented sub vs 2 for the sealed, above or below tuning of the subs, the numbers get very similar. To my knowledge, I have not seen any published data clearly showing this. This study also takes spl level out of the equation.

I paraphrased the first 5 posts of that thread in my first response. SPL is still involved. It's just immediately dispensed as a contributing factor for the sake of argument. For why, I cannot fathom.    The data are cool to look at, but that's about it as there is almost no structure.

 

The entire thread is no less interesting , and it is good evidence of the difficultly involved in grasping the concepts of sound energy, power, and basic Metrology. There's a lot of blood shed that takes place in the first year physics and acoustics classes. That thread is what that bloodshed tends to look like. 

 

I'd tread carefully when attempting to directly reference stuff like this, and not to forget, we're essentially cross-posting a three year old thread. Which, incidentally, is dated about two years after Audyssey announced their LFC technology.

Edited February 23, 2016 by Quiet_Hollow

[Quiet_Hollow]

Assuming the spl are equal across the FR, shouldn't the TR be the same?

A better question would be, "Is SPL related to the OP's concept of tactile response?"

 

I'd wager, "Yes, in time."

Edited February 23, 2016 by Quiet_Hollow

[Paducah Home Theater]

105 dB SPL at the listener is the magic number. That's sufficiently loud enough to be felt at any frequency.

 

That's the weirdest thing I've read all day.  It's still early though.  

 

So you're saying a screaming guitar solo played on high notes at the bottom end of the neck in a concert, which would in fact be at 105 db or higher, is easily felt all throughout the body?  Hard to wrap my head around that.  

Edited February 23, 2016 by MetropolisLakeOutfitters

[derrickdj1]

The ULF thread has a lot of good info.  Yes, spl is involved but the null hypothesis that the two subs should have the same or near same TR was proven incorrect.  One thing for sure, I will take a vented sub nearfield over a ported if size is not a factor.  One of the biggest factor with different HT is that TR can vary widely.  The thread was developed so that people could get an ideal as to what might be need in a room to accomplish ULF with good TR.

 

It's not perfect but, I am not a where of any source that compares drivers, room size and even ID brands on a common, easy to understand level.  Database.com is a good site for driver info and limited sub testing.  It's been a fun thread to be a part of.

 

The thread is not a technical or research paper/document, it is just a thread with contributions by forum members.   The Auddysee tech sounds like Pioneers BGC which is a totally different subject.

Edited February 24, 2016 by derrickdj1

[derrickdj1]

 

105 dB SPL at the listener is the magic number. That's sufficiently loud enough to be felt at any frequency.

 

That's the weirdest thing I've read all day.  It's still early though.  

 

So you're saying a screaming guitar solo played on high notes at the bottom end of the neck in a concert, which would in fact be at 105 db or higher, is easily felt all throughout the body?  Hard to wrap my head around that.  

 

Certain part of the body have different natural resonance frequencies.  The eye is different from the chest cavity, ect.  105 db is a magic number for LF to deliver a tactile response.  The TR also depends on the furniture.  Steel frame stuff will not vibrate as easily as wood frame.  Leather is better than cloth.  So, TR can be a different animal in every HT.  We have all heard the story on someone's buddy having a better room or worse room with similar equipment.

Edited February 24, 2016 by derrickdj1

[Quiet_Hollow]

It's not perfect but, I am not a where of any source that compares drivers, room size and even ID brands on a common, easy to understand level. Database.com is a good site for driver info and limited sub testing. It's been a fun thread to be a part of.

No doubt. Good topic for discussion.     

[Paducah Home Theater]

With my four 18's in an array I'm just now getting to where any frequency that comes out of them can shake the chair (sometimes more like half the house) without there being a ton of distortion.  Finally happy in that regard but my happiness was short lived due to frying that Crown amp.  A Speakerpower SP1-4000 from Seaton will be here tomorrow, I can't wait.  I've been without subs for nearly a month now.  For what I paid for it, it best not destroy itself quite so easily.  

Edited February 23, 2016 by MetropolisLakeOutfitters

[Quiet_Hollow]

So you're saying a screaming guitar solo played on high notes at the bottom end of the neck in a concert, which would in fact be at 105 db or higher, is easily felt all throughout the body?

Nope....what I'm saying is, if your body is exposed to sound energy in sufficient quantity that holding an SPL meter right next to your skin makes it read 105 dB SPL, that barring any significant nerve damage you're very likely to feel it, regardless of frequency.

 

...let's also keep in mind the context. I'm talking about being physically present in front of typical sound system with an SPL meter in hand. IOW not some random act like holding a pistonphone to my elbow.

Edited February 23, 2016 by Quiet_Hollow

[Quiet_Hollow]

Yes, spl is involved but the null hypothesis that the two subs should have the same or near same TR was proven incorrect.

What post # in the AVS forum refers to that? I'd like to discuss.

Edited February 23, 2016 by Quiet_Hollow

[derrickdj1]

The orignial ideal was discussed in the first few pages of the thread.  For the experiment, that was done on page 136, I wrote that.  A null hypothesis is common when doing an experiment.  AVS has the name science in it but, it is a forum just like this one.  I spent several years doing research in graduate school and post grad doing research and don't expect forums to produce the same level of work.  The thread contain a lot good info and has helped many people.

 

If research methodoloy needs a discussion I can easily do that and provide examples but, the post was about TR.  Since I did this particular experiment find some points pertaining to it to discuss.  I will be glad to explain why each thing was done or certain things were not done.

Edited February 24, 2016 by derrickdj1

[Quiet_Hollow]

All good. I'll post over there on that topic from here on out.

[derrickdj1]

TR is belived not to be related to room gain.  TR is tied more to a subs native respone which includes it's design, sealed, vented, ect.  TR consist of two major components, spl and PVL(particle velocity).  The particle velocity can be illustrate with a water hose or flashlight analogy.  For example, a 75 watt flash light and a 75 watt planel light 3 ft X 2 ft. at a distance of 30 ft, the panel will be easier to see.  As distance is decrease and once you get closer to the source the flashlight beam will appear brighter.  The beam is similar to a port.  At tuning , the PVL is max.

[Schu]

Tr used to be all about spl... movement and directivity NEEDS to be part of the equation now.

[derrickdj1]

Tr used to be all about spl... movement and directivity NEEDS to be part of the equation now.

 

There are component of the tactile response that we don't know.  Things we do know is that the box design has a great impact on TR as well as spl.  We can think of the air movement as particles and there velocity impacts TR.  The pds log graph shows in a striking fashion what is going on around tuning.  5 for the vented sub and only 2 for the sealed version. 

 

Due to the complex nature of tactile response, what we can say is that Vibsensor gauges the total energy being delivered to the couch.

 

This does not mean throw out the sealed subs.  Sealed subs can add more weight to a room.  This will be seen in room pressurization.  Hold your ears, lol.

Edited February 25, 2016 by derrickdj1

[moray james]

as teens we used to hope for a little tactile response when at the movies with a date.

[derrickdj1]

Thanks Tom for sharing you view on Total energy delivery from the subwoofer.  I edited the above post to reflex the Vibsensor interpretation to clarify the end result of the complex  TR is an energy measurement.

[derrickdj1]

Further studies of TR includes close mic measurement for sealed, vented driver and port versions of the Mini Marty subwoofer.  A75 center frequencies of 75 db at 50 Hz was used to standardize the test.  A HS filter in the subwoofer EQ is used in all the models to stay consistent with the previous data.

 

Note: The port close mic measurements were higher than the sealed and the vented driver had the lowest in FR.

Edited February 26, 2016 by derrickdj1