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post #3361 of 3386 Old 06-24-2015, 09:54 AM
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Ok, just thought I'd update you guys on the VibSensor tutorial. I'm getting there. Ran into few roadblocks.

Excuse #1 . A weeklong family invasion and baby shower.

Excuse #2 . The theater being turned into a staging area for several home projects going on. Not COOL!



Excuse #3 . New sub build. I couldn't help myself. Lots of sneaking around when I was suppose to be helping with excuse 1 and 2. Lots of questions like why did it take 4 hours to cut out the new chair bottoms. Um? Because... Uh? I'm a perfectionist. Hey man, whatever works. It got done. The new near field sub is deployed and operational. Performance matched expectation and exceeded in some ways. 120db@5-6hz doesn't suck.



The build thread of the new sub system will come later so I can get the VibSensor done. For something so simple its truly mind boggling how technical and in-depth the study of vibration and PSD and its relation to FFT is. You could easily spend 4-5 years in college and a lifetime studying and experimenting with this. The applications are staggering. I can tell you this, VibSensor is a first cousin to SpecLab. Ones 2D and the other 3D. Its been a lot of fun playing with the accelerometer with taking a variety of real world measurements. The problem with using the VibSensor is it assumes were at a certain level of study or already know basic engineering of vibrational and PSD. We don't or at least I don't so I have to start from scratch and explain to a small degree the basics, for instance what the graph elements mean. Anyway, this at least shares priority now, so it'll be done and ready to post in the coming weeks.
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post #3362 of 3386 Old 06-28-2015, 12:02 PM - Thread Starter
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post #3363 of 3386 Old 06-28-2015, 12:15 PM - Thread Starter
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Quote:
Originally Posted by Scott Simonian View Post
I think I put in 3x 21SW152's for the JBL's but I forgot honestly. Three UM 15's would be close in displacement so that works too. I didn't even see UM15's on the list. Either way, close enough.

Watched Lone Survivor this weekend and the whole system sounded great but bass was pretty good too. The Chinook drop off sequence was something else with this subwoofer riser. You guys that can get away with a 10" tall riser should try it. Two 18's is plenty. Wow!
Congrats on your 5hz ULF Card...



We have the same size room, and I have roughly 8 SIs in my room when you convert my subs. I can't imagine having 19 SIs in my room...absolutely insane! That must be a hell of a ride.

I just love that sub riser of yours. Does it wobble your seat for the 10hz and below stuff?
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post #3364 of 3386 Old 06-28-2015, 12:49 PM
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Darn, I still can't get the ULF card to work. Next week I will have access to a different computer and I will try it on that.
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post #3365 of 3386 Old 06-28-2015, 12:51 PM - Thread Starter
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Quote:
Originally Posted by dominguez1 View Post
Ok...here's the first go on these:



PSA V3600: Added 6db from XV30SE, and then extended to 12.5hz. I used 12db down from 16hz similar to the Cap1400 difference between 12.5hz and 16hz.

DSS Marianna 24: I compared the XXX on db (small box), versus the estimate for the XXX in an optimal box. At 20hz, it was only a 1db difference. At 16hz, 3db, and at 12.5 and 10hz, 4db difference. These seems to make sense as the small box starts to hamper efficiency and gets more power hungry down low.

Marianna 18: Sames as HST18

Cap2400 17.5hz tune: Up 2db from Cap1400

Thoughts?
Going once....twice...

How many cubes is the Marianna 24?

Does anyone know what the optimal cubes for the RE XXX 18in driver (.707 Qtc)?
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post #3366 of 3386 Old 06-28-2015, 06:18 PM
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Dom, I used the optimal box size for the REXXX when I posted it.
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post #3367 of 3386 Old 06-28-2015, 06:37 PM - Thread Starter
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Quote:
Originally Posted by MKtheater View Post
Dom, I used the optimal box size for the REXXX when I posted it.
Yes, but what was the size in cubic feet?
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post #3368 of 3386 Old 06-29-2015, 08:27 AM
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25 cubes!

Yamaha RX-A2030
speakers- 9 Behringer B215XL's
subs- SI 18ht x12 IB powered by Sanway FP14K.
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post #3369 of 3386 Old 06-29-2015, 09:02 AM
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Quote:
Originally Posted by dominguez1 View Post
Congrats on your 5hz ULF Card...



We have the same size room, and I have roughly 8 SIs in my room when you convert my subs. I can't imagine having 19 SIs in my room...absolutely insane! That must be a hell of a ride.

I just love that sub riser of yours. Does it wobble your seat for the 10hz and below stuff?
Sweet! Thanks. Yeah, it sure does. I had mentioned a page back that the Chinook drop off sequence in Lone Survivor really rocked the couch! Felt like kitty on a woofah.

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25 cubes!
Yep. Sounds about right.

My Dual 18" LLT subs 120dB down to 10hz ***FOR SALE***

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post #3370 of 3386 Old 06-29-2015, 10:11 PM
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Originally Posted by dominguez1 View Post
^^^Nice DO sonos! Are you using SI 18HTs? Need an update to your ULF card?
Thanks. Finished the rear subs. More details on that to come but builds and projects are backed up. Yes they are SI's. Replaced the Dayton's with 4x18's. Big step up sound quality-wise with matched subs and a substantial gain in ULF and ULFTR. Room really pressurizes and quickly nauseates one whether your in the room or not. The 4-6hz region is nuts. I now have to get the electronics part of the sub systems straightened out but I'm done adding subs. I have updated my ULF card per your reminder. BTW, the tutorial is getting ironed out and I'm hopeful to get it too you by weekend after next. At least part one.





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post #3371 of 3386 Old 06-30-2015, 07:21 AM
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Those are awesome! Bosso would be proud. I wish I can make something look that good, I need to stay with holes in walls.
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Yamaha RX-A2030
speakers- 9 Behringer B215XL's
subs- SI 18ht x12 IB powered by Sanway FP14K.
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post #3372 of 3386 Old 06-30-2015, 07:34 AM - Thread Starter
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Wow, nicely done coolrda!

What did you wrap the Sonos with? How many cubes per?
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post #3373 of 3386 Old 06-30-2015, 11:55 AM
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Quote:
Originally Posted by dominguez1 View Post
Wow, nicely done coolrda!

What did you wrap the Sonos with? How many cubes per?
Thanks guys. Synthetic Ostrich which is not cheap but nothing like the real thing costwise. Each cab is 9.2 cubes. The wax paper keeps the legs from scratching until I finalize the middle leg height. May trim another inch off.
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post #3374 of 3386 Old 06-30-2015, 08:33 PM
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Dom, I sent you a PM. I was correct, the ULF card would not work on my windows 8 computer. The card was done on Microsoft Office or an older version of Open Office. Something with osd vs odt or some other computer language.

The card opened right up on an older Widows 7 computer and I was able to record the new data based off my old ULF card from page 74. I don't know if the SI of 1.1 for the UM 18 is the same or if there is an update. I have also included the 8 Aura Pro shakers for the Tactile Feedback score. I left out the 10 and 12 Hz data for the vented subs as you did on page 74. I am still having problems uploading it to AVS. Thanks in advance for your assistance in helping me update the score card.

Derrick
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post #3375 of 3386 Old Yesterday, 06:20 AM - Thread Starter
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Originally Posted by derrickdj1 View Post
Dom, I sent you a PM. I was correct, the ULF card would not work on my windows 8 computer. The card was done on Microsoft Office or an older version of Open Office. Something with osd vs odt or some other computer language.

The card opened right up on an older Widows 7 computer and I was able to record the new data based off my old ULF card from page 74. I don't know if the SI of 1.1 for the UM 18 is the same or if there is an update. I have also included the 8 Aura Pro shakers for the Tactile Feedback score. I left out the 10 and 12 Hz data for the vented subs as you did on page 74. I am still having problems uploading it to AVS. Thanks in advance for your assistance in helping me update the score card.

Derrick
In the next ULF Calculator update, it will have the latest subs tested by Josh as well as other production subs that I/we have estimated. The UM18 will be on there. Having said that, I've got a working unpublished version with the new subs....so here is your new ULF card:



The newly tested UM18 bumped your score up some.
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post #3376 of 3386 Old Yesterday, 08:16 AM - Thread Starter
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Quote:
Originally Posted by coolrda View Post
Thanks. Finished the rear subs. More details on that to come but builds and projects are backed up. Yes they are SI's. Replaced the Dayton's with 4x18's. Big step up sound quality-wise with matched subs and a substantial gain in ULF and ULFTR. Room really pressurizes and quickly nauseates one whether your in the room or not. The 4-6hz region is nuts. I now have to get the electronics part of the sub systems straightened out but I'm done adding subs. I have updated my ULF card per your reminder. BTW, the tutorial is getting ironed out and I'm hopeful to get it too you by weekend after next. At least part one.





I'm really interested in hearing more about the difference in tactile response between your new vertical dual opposed configuration vs your prior design (drivers firing at your HT seating). Is it possible for you to compare results from just the rear subs using the VibSensor?

I know you mentioned that it was a step up in ULFTR, but is that because your subs are firing down at your riser, exciting the riser more? Or is a vertical dual opposed design more tactile than front firing or the opposite?

Do you have the new design running hotter than the old, adding to the TR?
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post #3377 of 3386 Old Yesterday, 08:37 AM
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Hey, Dom. One little thing on my new card.

You have my RLp18's listed as RPL18's.

My Dual 18" LLT subs 120dB down to 10hz ***FOR SALE***

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post #3378 of 3386 Old Yesterday, 10:04 AM
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Quote:
Originally Posted by dominguez1 View Post
I'm really interested in hearing more about the difference in tactile response between your new vertical dual opposed configuration vs your prior design (drivers firing at your HT seating). Is it possible for you to compare results from just the rear subs using the VibSensor?

I know you mentioned that it was a step up in ULFTR, but is that because your subs are firing down at your riser, exciting the riser more? Or is a vertical dual opposed design more tactile than front firing or the opposite?

Do you have the new design running hotter than the old, adding to the TR?
I have lots of VibSensor data on the rears alone so a direct comparison is available and coming. The biggest reason is the displacement as 4 of the SI's equal 9 of the 15's. I do think though that's there's more too this DO vertical stacking concept. One of the first things I'm going to test with the accelerometer is the cabs. I'm really curious how much difference there will be.
My tactile testing so far has been my impression only of the two both seated and standing on the riser and standing off the riser. I feel more air movement, not pressurization though there's a big gain there, but air blowing.
No change in the electronics and I just unplugged and plugged in new cabs. Tonite is will be the first chance I've had to do some extensive testing with sines and clips.
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post #3379 of 3386 Old Yesterday, 03:52 PM
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Dom, this is what I get for a ULF card : SI=1 UM18=1.1

Room Size: 4300

Number of subs 8

Type: 6 Sealed (3 dual boxes) and 2 Vented boxes

10 Hz, 12.5 Hz, 16 Hz, 20 Hz
SI Equivalent: 6.6, 6.6, 14.6, and 12.6
ULF Score: 652, 652, 295, and 341
Groundplane SPL: 105.6, 109.1, 121.1, and 126.2
Stars : 4.5, 4.5, 5, and 5
Reference Estimate: Above Ref at 16 and 20 Hz
Subwooferage 2 Vented subs in Chase VS 18.1 boxes with UM 18
3 Sealed dual driver boxes withe UM 18
Power: 3 I Nuke 6000 DSP amps and 3 I Nuke 3000 DSP amps

Tactile Feedback FX 8 Aura Pro Transducers

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post #3380 of 3386 Old Yesterday, 07:19 PM - Thread Starter
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Originally Posted by derrickdj1 View Post
Dom, this is what I get for a ULF card : SI=1 UM18=1.1

Room Size: 4300

Number of subs 8

Type: 6 Sealed (3 dual boxes) and 2 Vented boxes

10 Hz, 12.5 Hz, 16 Hz, 20 Hz
SI Equivalent: 6.6, 6.6, 14.6, and 12.6
ULF Score: 652, 652, 295, and 341
Groundplane SPL: 105.6, 109.1, 121.1, and 126.2
Stars : 4.5, 4.5, 5, and 5
Reference Estimate: Above Ref at 16 and 20 Hz
Subwooferage 2 Vented subs in Chase VS 18.1 boxes with UM 18
3 Sealed dual driver boxes withe UM 18
Power: 3 I Nuke 6000 DSP amps and 3 I Nuke 3000 DSP amps

Tactile Feedback FX 8 Aura Pro Transducers
I must have had your score wrong on the original. I only had you down for 2 18.2s with UM18s, but you have 3 18.3s with UM18s, for a total of 6 UM18s in sealed enclosures?

You also have 2 Vented 18.1s with UM18s?

Last time I had you down for 5300 cubes, was that incorrect and should have been 4300 cubes?
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post #3381 of 3386 Old Yesterday, 08:05 PM
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Dom, the last time I did have only two dual cab subs and the room was 5300 cu ft. I had a contractor add some walls and built another sub. I tried the Dayton amps for the shakers but, they would get hot and shut down during movies. So, I replaced them with an I Nuke 3000 DSP amp and have been problem free. This is the reason that I needed a new ULF card
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post #3382 of 3386 Old Yesterday, 08:30 PM - Thread Starter
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Dom, the last time I did have only two dual cab subs and the room was 5300 cu ft. I had a contractor add some walls and built another sub. I tried the Dayton amps for the shakers but, they would get hot and shut down during movies. So, I replaced them with an I Nuke 3000 DSP amp and have been problem free. This is the reason that I needed a new ULF card
Wow! You've made some serious upgrades! Congrats!

Here you go...



FYI, reducing your cubic feet from 5300 to 4300 was equivalent to adding 2 more UM18 sealed subs.

Nice job derrickdj1...you've come a long way from your original Chase subs! How's the signal chain? Are you 5hz club material?
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post #3383 of 3386 Old Yesterday, 10:20 PM
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Thanks. No, I will not be joining the signal digit culb, lol. I think, I have enough with the shakers. The cost of making the room smaller was a bit more than adding two UM 18 but, worth it. I did want to build another sub at the end of summer but, I will put that on hold. This thread has be very helpful in the development of my HT.

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VibSensor Tutorial

My first experience with an accelerometer app was a a couple years ago with an app called Dynolicious. It measures all kinds of automotive specs using the iPhone’s accelerometer. At first the test runs and horsepower numbers were erratic but after reading the instructions and purchasing a mount to keep the phone rigid, the acquired data runs incredibly matched the real world timings and dyne tested HP figures. It was then that I started to get a grasp of just how valuable an accelerometer could be.

Typically commercial and scientific grade accelerometers are used to help find and isolate what I call a negative event. To find the certain frequencies of noise in machinery that causes resonances or unwanted vibration in motors and compressors, so they can be addressed and suppressed, to identify seismic events for early warning, for airbag deployment in a vehicle collision and to test all sorts of aircraft, boats, rockets, spacecraft, satellites, vehicles too withstand normal operation and the list goes on and on. Accelerometer’s identified the cause of the catastrophic failure to the space shuttle’s wing and tiles. Everyday thousands of tests are carried out with the use of accelerometers to test everything imaginable.

An accelerometer measures proper acceleration which is the acceleration it experiences relative to freefall and is the acceleration felt by people and objects. The amplitude is defined over a range of frequencies. The amplitude can be constant or variable. During a sine vibration test, the vibration wave forms are swept through a range of frequencies, however they are of discrete amplitude, frequency and phase at any instant in time. Therefore its important to compare the various graphs to get a complete picture of whats happening. Its makes it easier. Its important to be mindful that displacement increases as the frequency decreases for a given acceleration. At low frequencies, the displacement could exceed the limits of the test equipment. So it's important to stay in the limits of the VibSensor's range, even though it does seem to have headroom above its rating of plus/minus 2g's.

A quick word about Vibration and the Human Body. It is interesting to note that in the longitudinal direction, that is feet to head, the human body is most sensitive to vibration in the frequency range 4-8 Hz. While in the transverse direction, the body is most sensitive to vibration in the frequency range of 1-2 Hz.

The purpose of this tutorial is too help us understand the basic use and simple terminology used when testing and acquiring data using an Accelerometer, specifically, the accelerometer in our PED's with with the use of an app called VibSensor. This app will be used to test the Tactile Response of subwoofers and all related components that reproduce low frequency effects. VibSensor acquires data, calculates and then graphs it in both the time and frequency domain.

Objectives

1. Explore the differences between acceleration and velocity over time and frequency.
2. Through testing and experimentation find the most efficient way to improve tactile response.
3. Try to understand and possibly find solutions to fix problem rooms.
4. Find an appropriate balance to the ULF/ULFTR equations. Yes there can be too much of a good thing.
5. Achieve the appropriate level of LFTR and ULFTR. That can be from subtle to bone crushing.


Terminology

Velocity is the rate of displacement of an object. It is measured in meters per second (m/s).
Acceleration is the rate of change of velocity of an object. It is measured in meters per second per second(m/s2).
Mass is the physical size of the matter we want to put in motion (move, vibrate, accelerate).
Density is the compactness of that matter.
Stiffness is the physical constraining properties of the matter we are trying to put in motion (cement, wood, steel, rubber, water, etc). It is resistance to movement.
Force (wattage, voltage, amps, preamps) is the amount of power needed to accomplish this acceleration and vibration, both constant and random, whether sine or transient in nature
Displacement (size/number of subwoofers) is represented by movement of an object from its resting place and the volume of its peak to zero cycle. The amplitude at a given frequency.
Power Spectral Density (PSD) or Acceleration Spectral Density (ASD): Defines the intensity of the random vibration signal vs. frequency. Its units are usually G^2/Hz or (m/s^2)^2/Hz.


Tutorial

The VibSensor is a free App available to Android and IOS device users at their prospective app stores. VibSensor uses the accelerometer in a Portable Electronic Device. You will also need a source for test signals, a test CD like SOHO54’s. but REW or Omnimic test files are fine. There’s hundreds of uses for an accelerometer, but we will focus on how this can help us measure and acquire data regarding tactile response in the home theater environment.

After downloading the app to your PED, and prior to use, you should eliminate all background app’s that may be running. Likewise, you should shut off the timed auto lock feature. Now, with the app open you will see a display and at the very bottom five icons. If you click the INFO one it will bring up the version number which for IOS its 1.3.0. Below that is the contents, and clicking on User Guide will take you to the operation guide. After reading through the USER GUIDE several times and referencing it after test runs I came to the conclusion that the User Guide left a lot to be desired, The explanation wasn’t nearly as detailed as it should be. Maybe this is all we can expect, this is after all a FREE app. After setting out to compile my own data and try to figure out whats going on here and how to read the data, it came to me that it could be that the Author of the User Guide assumes that the User has a certain grasp of accelerometer engineering expertise. The Author may assume that we are well versed or are at least familiar with this type of testing. So I set out to get an Internet education as my knowledge of this subject is zero. A huge pile of data later and I mean huge, I’m trying to filter what I've learned into whats relevant here without overwhelming. To get enough info here to get the ball rolling but not too little so that we don’t know what the data is telling us. Fortunately, the app is doing the hard work of recording, compiling and computing/fourier transforming it into graph form for us.

Objective #1 can be answered by observing a Pendulum, something we should all be familiar with. If you observe the period or one complete cycle of a pendulum’s swing you can see the relationship of velocity and acceleration (rate of change in velocity). While they are related they're two very different aspect. Maximum velocity is achieved at the zero or rest point of the swing while max acceleration occurs at the two peak amplitude’s of the swing. Minimum velocity occurs at the peak and minimum or zero acceleration occurs at the rest point or where acceleration turns into deceleration. A great animation is shown Here.

Objective #2 is to find a more efficient means to promote tactile response. In the past, brute strength force has been the method of choice to overcombe the mass and other deficiencies to provide the necessary tactile slam. I believe a change in how we approach low frequency response is in order. For example transfer function/room gain has little to no impact on ULFTR. Sealed cab roll off below the turn compounds the situation. VibSensor should help us identify and employ more efficient solutions to TR.

When you start VibSensor the first page loaded is the LIVE window , unless you are viewing another window and need to hit the BACK button. You now should be on this page. Your PED should be orientated to look like this.




Now with the PED placed as such tap the PED or surrounded area of the counter. You'll see the top view of the vibration sensors in each axis display there intensity of the strike. There's a little scale at the bottom which displays max saturation in each of the three axis from the zero point out. At g/2 the meters has reach its max record level. It's g/2 because it's half of the total vibration sine. Next to the vibration scale is a axis scale that shows the direction of all three axis of the meter, red top to bottom,green side to side and in blue up and down, which is coming toward us (hence the blue dot because we're looking down the barrel so to speak). As you shake the meter or strike it or tilt it you will see it how it displays it in realtime. This window really is just to get an idea of how an accelerometer works.

Now let's acquire some data. Hit the ACQUIRE button at the bottom of the main page, second from the left.



You can title this Test 1, set delay at 5 secs (gives you time to place device and/or start test signals before sampling), then duration at 10 secs. Now place the meter on a desk or kitchen counter, press start and tap or strike around the meter until the test duration ends. Now let's view the data.

Now hit the VIEW DATA button at the bottom. The next window opens which shows your DATES.



It displays the year then below that the day of the week, the month and date the Run was recorded. To the right is the amount of runs or tests taken that day. For illustration purpose, I'll pick April 4. When you hit that date the next window opens called RUNS.




Here you'll see the date the test was taken and the exact time of day as well as any notes or name of that particular test. To the right side you will see the duration of the test in seconds or minutes from underneath that with the test with high or low frequency sampling.

Hit the specific test run button you want and the DATA window opens.



Now we're getting to the good stuff. Here you see tons of data, the top part shows it numerically and underneath that graphically. Now I want to skip to the Tilt data under the numerical readings and the RAW data window as this could be a source of confusion.



If you look at the tilt data, X and Y axis will be at or close to zero, while the z-axis close to 1G. Viewing the RAW data graph it reflects the same thing. Why is this? Simply, the z-axis is always under constant acceleration and experiencing 1G while on earth. This means everything, our bodies, objects around us and this meter. While we are accelerating at a rate of 1g constantly, the surface of the earth is keeping us from moving towards the core. so the RAW data shows the true gravity of each axis, whereas under the vibrational graph it adjusts for gravity and aligns and zeros each of the axis. So while the meter will read plus or minus 2G's, it reaches the max at plus 2G's with just one G of acceleration. Fortunately it doesn't matter as even a few tenths of a G is noticeable.

On the DATA page if you look below the graph you see X, Y, Z axis buttons. When clicked you can isolate different axis to view each axis separately. The scale button is located at the far bottom right which allows us to zoom in on the graph at 1x, 2x and 5x. I have started to view the Raw data more and appreciate seeing all axis on different lines at once.

If you haven’t already, take some time to play with the meter. Ok, lets make a test run. Start VibSensor. The Settings window, set Frequency Range to High. Units can be change after the test runs so its not important. !g=9.81m/s so then 0.1g is about a meter of amplitude. Place the meter on the surface to be tested. Click the Acquire button and start your test signals. After the run is finished and the test recorded, click the ACQUIRE button and the next window opens. You should name each run, even though its time stamp, with as much data of what your testing, the test signals used, levels of MV and test signal signal DB, etc, as possible. The more info the better for correlation and analyses later and to share with us here. I use a 5 sec delay but you can use what ever is needed to get it flat and secure if for some reason it needs to be moved after initiating the run. Now for duration what I’m doing is timing my test signal to know the proper duration then using that.

Now lets go back to viewing that run I made on 4/4/15. This is pretty explanatory even though I could have put more info in the title. If your in a hurry at least use a pen and paper to record the details then you can edit the title later.

Again, clicking on the first test opens this window.



LogPSD shows us a 360 degree axis view on a 2D graph. Click the PSD button.



Lets increase the resolution to 5X.



Hows that for nailing the frequencies. This is a serious piece of equipment, in some ways, more than a mic-based measurement system could ever be.

Comparing the PSD (linear view) and zooming it shows the amplitude and width of frequency but not how long it lasts. We really don't know if this is a short transient or a one minute narrow band sine wave, do we? But, click on the Vibration and open that window and now that gives us the Time domain of window/view which shows us the duration.
And let's zoom in.





Look at the shape of that 25hz sine. Incredible detail. But wait. Check out that 20hz and 15hz.



Whats that all about? Omnimic shows flat even response but I feel the tactile fall flat. Then it comes back on at 10hz. 20 and 15 are short-circuiting for some reason. Whats going on there? Is it suppose to do that? The mic doesn't show that. 20 and 15 measure higher SPL. I don't get it, whats happening? EXACTLY. At this point we tell our buddy that his room sucks for ULF and dismiss it as unknown cause. A mic-based system WON"T work. We need a mechanical/accelerometer meter to analyze this. Both measurement systems used as a tandem will though. To the best of my knowledge, accelerometer have never been used in the HT environment for testing except with Tactile transducers. Hey look at that, go figure.

SpecLab user's, feel free to compare various sines and movie clips. It would be interesting to compared the graphs side by side. I’ve looked at these graphs so much I could almost draw you a SpecLab 3D drawing(MATLAB?) from the 2D graphs, so you will eventually get used to it. I think you’ll be surprised how they match using two different recording mediums, mic and accelerometer. I believe we will see that as we use these three test components together, Omnimic/REW, VibSensor and SpecLab that it will give us more insight to what really going on in our sources, systems and rooms. What one test can’t resolve, another can. I believe we will be one step closer to seeing the whole picture. I believe it will help raise efficiency, allow us better simulation thus eliminating trial and error purchasing and experimentation.

I know about 0.00000001% of info related to this testing and subject. This is all new. I couldn’t find any research pertaining to accelerometer testing in this the home theater and subwoofer field. So this is just a rough start, but, its a start. This will give us the real mechanical data with regard to tactile response of our rooms. So let the compiling begin. More to come with Pics on the testing placement I’m using and various components tested including the human body.
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Originally Posted by dominguez1 View Post
I'm really interested in hearing more about the difference in tactile response between your new vertical dual opposed configuration vs your prior design (drivers firing at your HT seating). Is it possible for you to compare results from just the rear subs using the VibSensor?

I know you mentioned that it was a step up in ULFTR, but is that because your subs are firing down at your riser, exciting the riser more? Or is a vertical dual opposed design more tactile than front firing or the opposite?

Do you have the new design running hotter than the old, adding to the TR?
Ok, here's the first of many test runs to come. It felt much more tactile with the new subs as it should. Everything was the same except my pre/pro has a separate sub volume control which is currently set@-11.5 and on the test in April it was @-7.5. MV was -20 on both. I measured the spl/unweighted on the EoT 30-10hz drop it was 30hz/107db, 25/109, 20/110, 15/112, 10/114. Clearly the mic'd FR isn't showing the whole picture. Anyway here's the two sub systems head to head minus the 4db lower level of the new stack. Can't wait to see if others are experiencing that 20hz TR null.

Old subs.



New Subs@-4db
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Looking at the graph above I've finally figured out the scale. I didn't understand the 0.1 then a 0.1 above it. I thought it was cutting off another decimal but that didn't make sense. It's not 0.1 then 0.15 but rather 0.0 then 0.05 which is rounded up to 0.1. The 0.15 would be rounded to 0.2.

Ok so I went back and ran it at -7.5db/sub level. But there a ton more TR with the new setup thats not showing up. The co-located 15's measured higher(unless they were EQ'd which I didn't record). I'm running the new subs without EQ. But then I saw what was happening. There's much more TR on the Y axis. So while the front firing subs due to better time alignment possibly has more acceleration in the Z axis, the less time aligned, and not sharing a common baffle, new subs prove superior on the Y axis. The new subs as a two-axis pump is superior to the old subs, single axis pump.

Old subs.


New subs.


Combined new much better TR at 20 and 15 is really strong now.



This is the kind of data accelerometer testing can extract.
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