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Subwoofers, Bass, and Transducers > Your Home Theater ULF Score
dominguez1's Avatar dominguez1 12:16 PM 12-04-2013
Quote:
Originally Posted by bossobass View Post

It's a tradeoff.

There's no doubt that the floor (and ceiling and walls) physically react to the ULF pressure waves. Consider that the subs are dual-opposed, so that they don't in any way jump up and down. Consider also that they are in corners, where the structural integrity of the floor is highest (as opposed to the middle of the floor where the most deflection would occur). Then, consider that the room is on a 2"x10" @ 10" OC structure, supported in the center by a sandwiched quad-LVL beam and the entire floor system is 24'X27'…

Then that pressure wave is moving the entire floor system all by itself, thus, the tactile feel.

OTOH, concrete construction has up to 20 times less transmission loss. Here's a case in point. A while back I put in a pretty decent HT for a friend in her basement, which I had completely remodeled some years ago, so I already had the scaled drawings and construction details. 2 of the walls are concrete with studs, insulation, sheetrock and panelling over them. The floor is also a poured slab. The room is close to 2900 cubes with a 4' doorway that's open to the rest of the basement floor, an approx additional 5800 cubes.

I put a small dual-opposed 15" sub signal shaping through a Marchand Bassis and powered by an American Audio big iron amp. I set the Bassis according to the close mic and standard room gain profile, then measured the room before any tweaks, smoothing EQ or level cal.

I saved that measurement and have overlaid it onto a graph that has various subs I've built in various configs in various placements, all in my HT space:



Using the same sig shaping boost pattern I use in my own room, she gets +10dB more return in single digits than I do.

Now, that can be overcome with multiples, but if you look at the original measurement, that single digit peak was 103dBSPL. With a single 2X15" sub. cool.gif

So, that's the tradeoff. IMHO, the ultimate coup is to build your HT in a basement, but on a suspended wood frame floor. That way you get the benefit of far less TL with the tactile effect.
The above post shows the impact of transmission loss compared to a suspended wood floor versus concrete construction.

We've always known that the construction materials that encase your HT room does have an impact on db in your room. Where you have lossy construction, you will get less gain as compared to dense material like concrete or brick. The current ULF score methodology does not currently consider the construction of your HT walls and floor. So I'm going to take a shot on how this might be integrated in:

Currently, to calculate your ULF score we need two variables: Room Size and Subs. Trying to keep this simple, we could add 1 more variable; # of concrete/brick surfaces. From the post above, it looks as though from 10-20hz, there is an avg of 6db gain compared to the single raven. The HT owner has 3 surfaces that are concrete (2 walls and floor). Generally speaking and being conservative, what if we say for every concrete surface of your room, we add 2db to your room output. Let's take some examples on how this might change the current scoring:

Using the log calculation, for every 2db gain, we would multiply the number of SIs for HT by a certain factor:

1 concrete wall = 1.26
2 = 1.58
3 = 2.00
4 = 2.51
5 = 3.16
6 = 3.98

JapanDave's HT is all concrete; walls, floor, and ceiling
6 concrete walls = a factor of 3.98
3.98 * 23.5SI = 93.6 SI
2900cf / 93.6 = ULF Score of 31
GP 1/8 space estimate = 134.6db @ 10hz

MK's HT has 4 concrete surfaces (3 walls, floor)
4 concrete walls = a factor of 2.51
2.51 * 12 SI = 30.1 SI
1510cf / 30.1 = ULF Score of 50.1
GP 1/8 space estimate = 124.8@10hz

I have 3 concrete surfaces (2 walls, floor)
3 concrete walls = a factor of 2
2 * 4.4 SI = 8.8 SI
1900cf / 8.8 = ULF Score of 216.4 (upgrading me to 5 star)
GP 1/8 space estimate = 114.1@10hz

Basshead has 1 (?) surface; concrete floor
1 concrete wall = a factor of 1.26
1.26 * 3.6 SI = 4.5 SI
2400cf / 4.5 = ULF score of 529 (remains 4.5 star)
GP 1/8 space estimate = 116.9@16hz

Based on the above examples, it seems reasonable. The only way to see how well it works is to go through more member examples.

Check your score based on the new methodology above...does it make sense compared to what you've measured?

Depending on the feedback will determine if this is instituted or not.

MKtheater's Avatar MKtheater 12:47 PM 12-04-2013
I have all concrete except the ceiling. 4 walls and the floor, just a bigger gap in between on 2 of them. My whole basement is surrounded by concrete. Underground!
steve nn's Avatar steve nn 01:03 PM 12-04-2013
Quote:
Originally Posted by dominguez1 View Post

DIY is just sick...puts things in perspective compared to commercial. Congrats. Wish I had the DIY skills.

For me, I measure twice, cut once...then by commercial. smile.gif

Lol.. Wish we had some good examples of 10-18 cu ft 15-18" LLT's ($1000-1300 dual) to compare. smile.gif
beastaudio's Avatar beastaudio 01:17 PM 12-04-2013
Now I wish I had done compression measurements of the big LLT's I built out!!! Darn.... Scott Simonian probably could with his RLP 18's
Cowboys's Avatar Cowboys 01:27 PM 12-04-2013
Quote:
Originally Posted by basshead81 View Post

sub placement is key. I get great tactile response at low levels and can feel the bass at -30. The beauty of my setup(granted its nothing compared alot of setups her on AVS) is the entire seating area gets the exact same tactile sensation.

Is your room seal or open?
steve nn's Avatar steve nn 01:38 PM 12-04-2013
Quote:
Originally Posted by beastaudio View Post

Now I wish I had done compression measurements of the big LLT's I built out!!! Darn.... Scott Simonian probably could with his RLP 18's

I bet he could! We got to get to him before he goes off the deep-end with his 8 18"s. PM sent..
ahmedreda's Avatar ahmedreda 02:15 PM 12-04-2013
I have 4 concrete surfaces in my room. Using those calculations, that would put me at reference at 4.5 stars at 12.5hz (reference) and above reference at 16 hz and up using the 2xF15HPs that I exchanged. I am fairly sure that the output was being compressed before hitting reference when compared to the output of the FV15s at the same levels. The idea seems correct but may be lower factors. just my 02 smile.gif

Quote:
Originally Posted by dominguez1 View Post

The above post shows the impact of transmission loss compared to a suspended wood floor versus concrete construction.

We've always known that the construction materials that encase your HT room does have an impact on db in your room. Where you have lossy construction, you will get less gain as compared to dense material like concrete or brick. The current ULF score methodology does not currently consider the construction of your HT walls and floor. So I'm going to take a shot on how this might be integrated in:

Currently, to calculate your ULF score we need two variables: Room Size and Subs. Trying to keep this simple, we could add 1 more variable; # of concrete/brick surfaces. From the post above, it looks as though from 10-20hz, there is an avg of 6db gain compared to the single raven. The HT owner has 3 surfaces that are concrete (2 walls and floor). Generally speaking and being conservative, what if we say for every concrete surface of your room, we add 2db to your room output. Let's take some examples on how this might change the current scoring:

Using the log calculation, for every 2db gain, we would multiply the number of SIs for HT by a certain factor:

1 concrete wall = 1.26
2 = 1.58
3 = 2.00
4 = 2.51
5 = 3.16
6 = 3.98

JapanDave's HT is all concrete; walls, floor, and ceiling
6 concrete walls = a factor of 3.98
3.98 * 23.5SI = 93.6 SI
2900cf / 93.6 = ULF Score of 31
GP 1/8 space estimate = 134.6db @ 10hz

MK's HT has 4 concrete surfaces (3 walls, floor)
4 concrete walls = a factor of 2.51
2.51 * 12 SI = 30.1 SI
1510cf / 30.1 = ULF Score of 50.1
GP 1/8 space estimate = 124.8@10hz

I have 3 concrete surfaces (2 walls, floor)
3 concrete walls = a factor of 2
2 * 4.4 SI = 8.8 SI
1900cf / 8.8 = ULF Score of 216.4 (upgrading me to 5 star)
GP 1/8 space estimate = 114.1@10hz

Basshead has 1 (?) surface; concrete floor
1 concrete wall = a factor of 1.26
1.26 * 3.6 SI = 4.5 SI
2400cf / 4.5 = ULF score of 529 (remains 4.5 star)
GP 1/8 space estimate = 116.9@16hz

Based on the above examples, it seems reasonable. The only way to see how well it works is to go through more member examples.

Check your score based on the new methodology above...does it make sense compared to what you've measured?

Depending on the feedback will determine if this is instituted or not.

dominguez1's Avatar dominguez1 02:24 PM 12-04-2013
Quote:
Originally Posted by ahmedreda View Post

I have 4 concrete surfaces in my room. Using those calculations, that would put me at reference at 4.5 stars at 12.5hz (reference) and above reference at 16 hz and up using the 2xF15HPs that I exchanged. I am fairly sure that the output was being compressed before hitting reference when compared to the output of the FV15s at the same levels. The idea seems correct but may be lower factors. just my 02 smile.gif
How big is your room?
BeeMan458's Avatar BeeMan458 02:28 PM 12-04-2013
It's not fair. We don't have any concrete surfaces. (long, pathetic, sad, old man face) Boo-hoo me. tongue.gifbiggrin.gif
ahmedreda's Avatar ahmedreda 02:30 PM 12-04-2013
It is 12x20. I have concrete floors, 3 walls are concrete. 1 wall (12ft) and the ceiling are drywall.
Quote:
Originally Posted by dominguez1 View Post

How big is your room?

dominguez1's Avatar dominguez1 02:47 PM 12-04-2013
Quote:
Originally Posted by ahmedreda View Post

It is 12x20. I have concrete floors, 3 walls are concrete. 1 wall (12ft) and the ceiling are drywall.
8ft ceilings? This would put you at 1920cf. IMO, you should be at those levels. Same size room as mine, but with an additional concrete wall. Your room should have plenty of gain to get you high output.

Is it sealed?
carp's Avatar carp 03:43 PM 12-04-2013
Dom, I hear what you are saying and I like the idea but here is where it gets even messier and hard to calculate. Take my room for example. I do have 3 concrete walls, but my room doesn't take up the whole space in the basement I have a wall that separates my room from the laundry room next to me. What i mean is my room has 2 concrete walls and a drywall/studs wall but on the other side of that wall is room that is 8 feet wide and then has a concrete wall.

Add that to the fact that the right side wall in my room (when facing the screen) doesn't have concrete all the way up to the ceiling (concrete up to 5 feet), the screen wall has concrete up to about 6 feet, and the concrete wall on the other side of the laundry room has concrete up to 8 feet.
HopefulFred's Avatar HopefulFred 03:49 PM 12-04-2013
Maybe it would be better to approximate or calculate the percentage of surface area made by concrete/brick - and see here that gets you.
basshead81's Avatar basshead81 03:50 PM 12-04-2013
Quote:
Originally Posted by Cowboys View Post

Is your room seal or open?

I have one 5ft opening along a 20ft wall.
dominguez1's Avatar dominguez1 04:19 PM 12-04-2013
Quote:
Originally Posted by carp View Post

Dom, I hear what you are saying and I like the idea but here is where it gets even messier and hard to calculate. Take my room for example. I do have 3 concrete walls, but my room doesn't take up the whole space in the basement I have a wall that separates my room from the laundry room next to me. What i mean is my room has 2 concrete walls and a drywall/studs wall but on the other side of that wall is room that is 8 feet wide and then has a concrete wall.

Add that to the fact that the right side wall in my room (when facing the screen) doesn't have concrete all the way up to the ceiling (concrete up to 5 feet), the screen wall has concrete up to about 6 feet, and the concrete wall on the other side of the laundry room has concrete up to 8 feet.
I should have specified better. You should count the walls if they fall within your home theater area. In your case, it would be the 2 walls and floor. Its an estimate, so I wouldn't worry about the 6ft thing as you described.

Remember, there is no replacement for accurate measurement gear. This is the only way to truly know how what your room performance will be. However, hopefully this should give you a general idea of what to expect.
carp's Avatar carp 04:41 PM 12-04-2013
Quote:
Originally Posted by dominguez1 View Post

I should have specified better. You should count the walls if they fall within your home theater area. In your case, it would be the 2 walls and floor. Its an estimate, so I wouldn't worry about the 6ft thing as you described.

Remember, there is no replacement for accurate measurement gear. This is the only way to truly know how what your room performance will be. However, hopefully this should give you a general idea of what to expect.

Gotcha, thanks.
booga24's Avatar booga24 05:10 PM 12-04-2013
Pros,

I am considering VTF- 15 or FV15HP in a 12x20x8 sealed room, please let numbers speak for me smile.gif.
BeeMan458's Avatar BeeMan458 05:14 PM 12-04-2013
Quote:
Originally Posted by booga24 View Post

Pros,

I am considering VTF- 15 or FV15HP in a 12x20x8 sealed room, please let numbers speak for me smile.gif.

Have you looked at the first post in this thread? The first spreadsheet contains information regarding the FV15HP and the second spreadsheet contains information regarding the VTF-15H.

What are your expectations?

Have you checked out the Hsu and Rythmik threads?
ahmedreda's Avatar ahmedreda 05:44 PM 12-04-2013
It is sealed. The concrete walls are really concrete blocks. They have furring strips and 2.25" of XPS foam then drywall. Do they still count as concrete walls?
Quote:
Originally Posted by dominguez1 View Post

8ft ceilings? This would put you at 1920cf. IMO, you should be at those levels. Same size room as mine, but with an additional concrete wall. Your room should have plenty of gain to get you high output.

Is it sealed?

ahmedreda's Avatar ahmedreda 05:45 PM 12-04-2013
Quote:
Originally Posted by booga24 View Post

Pros,

I am considering VTF- 15 or FV15HP in a 12x20x8 sealed room, please let numbers speak for me smile.gif.

I have the same exact dimensions and I went with 2 of the FV15HPs and I am fairly happy with them.
Cowboys's Avatar Cowboys 06:01 PM 12-04-2013
^^ Only fairly happy???
ahmedreda's Avatar ahmedreda 06:11 PM 12-04-2013
Quote:
Originally Posted by Cowboys View Post

^^ Only fairly happy???
Well extremely happy biggrin.gif
Cowboys's Avatar Cowboys 07:54 PM 12-04-2013
^^ that's better.
dominguez1's Avatar dominguez1 08:04 PM 12-04-2013

Carp, so I recalculated your score with the concrete surfaces. This puts you at 5 Star, 191@10hz

 

It also estimates that you can hit 119db at 10hz. Does that seem realistic? Have you ever ran a max sweep?

 

That does seem like a lot...


Scott Simonian's Avatar Scott Simonian 01:52 AM 12-05-2013
Quote:
Originally Posted by beastaudio View Post

Now I wish I had done compression measurements of the big LLT's I built out!!! Darn.... Scott Simonian probably could with his RLP 18's

Quote:
Originally Posted by steve nn View Post

I bet he could! We got to get to him before he goes off the deep-end with his 8 18"s. PM sent..

Hey guys, wuzzup! Okay, what's going on now? tongue.gif
popalock's Avatar popalock 03:12 AM 12-05-2013
Hummm...

The concrete wall issue seems to muddy up the waters a bit. For instance, based on how my room volume is calculated in this thread, I have 4 concrete surfaces (including the floor), but all walls are built out with 2x4's and drywall. Since my walls are built out, are they still counted as concrete surfaces?

Also, since ULF is perceived through tactical sensation, wouldn't having a suspended floor deliver more ULF sensation vs a concrete floor?
dominguez1's Avatar dominguez1 05:45 AM 12-05-2013
Quote:
Originally Posted by popalock View Post

Hummm...

The concrete wall issue seems to muddy up the waters a bit. For instance, based on how my room volume is calculated in this thread, I have 4 concrete surfaces (including the floor), but all walls are built out with 2x4's and drywall. Since my walls are built out, are they still counted as concrete surfaces?

Also, since ULF is perceived through tactical sensation, wouldn't having a suspended floor deliver more ULF sensation vs a concrete floor?
Yes, they would be considered concrete. My walls are also drywall/studs, but behind them are concrete.

Love your thought about ULF and tactile sensation, but for this thread, we're only measuring ULF via room size/displacement/spl. Otherwise, tactile transducers would play a part in the score. I definitely think there is merit to that...just quantifying it needs to be hashed out more...see the link in my sig about measuring tactile feeling. smile.gif

With your 4 concrete surfaces, spl estimate is 127@10hz...does this sound right to you?
carp's Avatar carp 06:09 AM 12-05-2013
Quote:
Originally Posted by dominguez1 View Post

Carp, so I recalculated your score with the concrete surfaces. This puts you at 5 Star, 191@10hz

It also estimates that you can hit 119db at 10hz. Does that seem realistic? Have you ever ran a max sweep?

That does seem like a lot...

No, I don't think I could hit 119 db's at 10hz but I'm not positive. I did do compression sweeps once but i had problems with my omnimic clipping and I also got scared eek.gif but one of these days I'm going to do it again.
BeeMan458's Avatar BeeMan458 06:14 AM 12-05-2013
Quote:
Originally Posted by carp View Post

No, I don't think I could hit 119 db's at 10hz but I'm not positive. I did do compression sweeps once but i had problems with my omnimic clipping and I also got scared eek.gif but one of these days I'm going to do it again.

Well, that's one way of articulating how you think you have plenty of headroom.

...tongue.gif
basshead81's Avatar basshead81 06:29 AM 12-05-2013
Dom, I think this is pretty accurate myself. I have 1 concrete wall and 3 dry wall/stud walls. You calculated 116.9db @ 16hz which seems to be real close to what I have measured. Actually I have measured around 119db but thats at subs limits and distortion is up there a bit. So I would say your calculation is spot on in relation to clean output.
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