Monoprice Monolith Amplifiers and 15" Subwoofer at CEDIA 2016 - Page 3 - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 64Likes
Reply
 
Thread Tools
post #61 of 133 Old 09-20-2016, 11:16 AM - Thread Starter
Mark Henninger
 
imagic's Avatar
 
Join Date: Dec 2005
Location: Philadelphia, PA
Posts: 12,440
Mentioned: 276 Post(s)
Tagged: 0 Thread(s)
Quoted: 6596 Post(s)
Liked: 11343
Quote:
Originally Posted by lukeamdman View Post
So, Mark, based on what you just posted, what's the distance and power applied?
Truth be told I don't know or care about the details at the moment, it's not my battle to win or lose. Moving on to another thread, another topic. If I get more info, I'll be back. I just posted that for fun, to stir the pot so to speak.

Mark Henninger, Senior Editor at AVS Forum
imagic is offline  
Sponsored Links
Advertisement
 
post #62 of 133 Old 09-20-2016, 11:17 AM
AVS Forum Special Member
 
lukeamdman's Avatar
 
Join Date: May 2011
Location: Burnsville, MN
Posts: 3,523
Mentioned: 134 Post(s)
Tagged: 2 Thread(s)
Quoted: 1229 Post(s)
Liked: 1516
Quote:
Originally Posted by imagic View Post
Truth be told I don't know or care about the details at the moment
My point exactly. Moving on.
lukeamdman is offline  
post #63 of 133 Old 09-20-2016, 11:21 AM - Thread Starter
Mark Henninger
 
imagic's Avatar
 
Join Date: Dec 2005
Location: Philadelphia, PA
Posts: 12,440
Mentioned: 276 Post(s)
Tagged: 0 Thread(s)
Quoted: 6596 Post(s)
Liked: 11343
Quote:
Originally Posted by lukeamdman View Post
My point exactly. Moving on.

Mark Henninger, Senior Editor at AVS Forum

Last edited by imagic; 09-20-2016 at 11:30 AM.
imagic is offline  
 
post #64 of 133 Old 09-20-2016, 11:28 AM - Thread Starter
Mark Henninger
 
imagic's Avatar
 
Join Date: Dec 2005
Location: Philadelphia, PA
Posts: 12,440
Mentioned: 276 Post(s)
Tagged: 0 Thread(s)
Quoted: 6596 Post(s)
Liked: 11343
There is one promise I can make, if all you guys to say it's impossible for the sub to hit 119 dB at 2 meters, CEA2010 peak burst, which is a figure Thilo Stompler says includes a margin or error... if that turns out to be right, you'll get an AVS homepage article out of it and you'll be the stars.

If Thilo and Monoprice are right, they'll be the stars of that article.

Either way, new article when there's a clear answer. It doesn't end here.
JohnDean likes this.

Mark Henninger, Senior Editor at AVS Forum
imagic is offline  
post #65 of 133 Old 09-20-2016, 11:39 AM
Senior Member
 
DrDyna's Avatar
 
Join Date: Oct 2011
Location: Central Nowhere
Posts: 319
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Liked: 81
I posted it. Hornresp at 2.0 pi. The excursion limits are at 2000w.

How far out does it need to keep it's numbers? I'm not sure I've seen this level of interest in a commercial sub before, and I can think of quite a few that are probably a whole lot more deserving of a laser pointed critique of their performance.

Bear in mind that I wasted a grand total of about 120 seconds in hornresp, including both tries, so even with minor errors, I'm hitting 120 @ 20, 2pi loading. You better believe it'll do that at 10 feet in someone's living room corner.
DrDyna is offline  
post #66 of 133 Old 09-20-2016, 12:14 PM
AVS Forum Special Member
 
lukeamdman's Avatar
 
Join Date: May 2011
Location: Burnsville, MN
Posts: 3,523
Mentioned: 134 Post(s)
Tagged: 2 Thread(s)
Quoted: 1229 Post(s)
Liked: 1516
Quote:
Originally Posted by imagic View Post
There is one promise I can make, if all you guys to say it's impossible for the sub to hit 119 dB at 2 meters, CEA2010 peak burst, which is a figure Thilo Stompler says includes a margin or error... if that turns out to be right, you'll get an AVS homepage article out of it and you'll be the stars.

If Thilo and Monoprice are right, they'll be the stars of that article.

Either way, new article when there's a clear answer. It doesn't end here.
Again, Josh/DB.com doesn't use peak SPL figures.
lukeamdman is offline  
post #67 of 133 Old 09-20-2016, 12:18 PM
AVS Forum Special Member
 
lukeamdman's Avatar
 
Join Date: May 2011
Location: Burnsville, MN
Posts: 3,523
Mentioned: 134 Post(s)
Tagged: 2 Thread(s)
Quoted: 1229 Post(s)
Liked: 1516
Quote:
Originally Posted by DrDyna View Post
I'm not sure I've seen this level of interest in a commercial sub before, and I can think of quite a few that are probably a whole lot more deserving of a laser pointed critique of their performance.
You've missed a lot of discussion around Paradigm, Chase, JTR, Danley, etc. then.

JTR squashed all doubt by sending the subs to DB.com.

The extreme hyperbole, exaggeration, and inflated numbers of the Paradigm S2 were also squashed by, you guessed it, DB.com.
lukeamdman is offline  
post #68 of 133 Old 09-20-2016, 01:21 PM
AVS Forum Special Member
 
Tom Vodhanel's Avatar
 
Join Date: May 2011
Posts: 3,696
Mentioned: 54 Post(s)
Tagged: 0 Thread(s)
Quoted: 2059 Post(s)
Liked: 6057
Quote:
Originally Posted by imagic View Post
Not everyone thinks the math is impossible. Glad you guys have such high confidence though. I gotta tell you, the folks on the other side have high confidence, too. I'm still playing the part of neutral party; if I get more info I'll publish it.
If you have time ask them to post the complete data-set they have for the product. Also, ask them to list the measurement rig, distance to mic, and if they are using the peak or RMS values. A quick email like this would solve any confusion I'd reckon.

113dB/20hz...doable. 116dB? Man, that is really pushing it. But I wouldn't say impossible. What many aren't realizing here is excursion isn't even an issue at 20hz. It's going to come down to system efficiency, port losses, motor strength, voltage swings.

How much effective enclosure volume? What is the tuning and area of the vent? Those would tell us a lot..

Tom V.
Power Sound Audio

“Quality isn't expensive, it is priceless" --- fortune cookie
Tom Vodhanel is online now  
post #69 of 133 Old 09-20-2016, 02:01 PM
Senior Member
 
DrDyna's Avatar
 
Join Date: Oct 2011
Location: Central Nowhere
Posts: 319
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Liked: 81
Quote:
Originally Posted by lukeamdman View Post
You've missed a lot of discussion around Paradigm, Chase, JTR, Danley, etc. then.

JTR squashed all doubt by sending the subs to DB.com.

The extreme hyperbole, exaggeration, and inflated numbers of the Paradigm S2 were also squashed by, you guessed it, DB.com.
I'm not ****ting on DB.com, I'm just saying that most of the complaints being registered here about subwoofer measurements are true of most manufacturers, especially the ones shooting at this price point.

Considering it does the number in hornresp, I'm not sure we've anything to gain by picking it apart when we live in a world where Paradigm SUB 15 are allowed to exist.
JohnDean likes this.
DrDyna is offline  
post #70 of 133 Old 09-20-2016, 02:12 PM
AVS Forum Special Member
 
lukeamdman's Avatar
 
Join Date: May 2011
Location: Burnsville, MN
Posts: 3,523
Mentioned: 134 Post(s)
Tagged: 2 Thread(s)
Quoted: 1229 Post(s)
Liked: 1516
Quote:
Originally Posted by DrDyna View Post
I'm not ****ting on DB.com, I'm just saying that most of the complaints being registered here about subwoofer measurements are true of most manufacturers, especially the ones shooting at this price point.

Considering it does the number in hornresp, I'm not sure we've anything to gain by picking it apart when we live in a world where Paradigm SUB 15 are allowed to exist.
I never got a single negative vibe towards DB.com from anyone.

Models are great for getting an idea, but they aren't real world performance, especially considering 99% of subs are hitting CEA harmonic distortion thresholds well before xmax.

I don't think anyone is dissing the sub. Most of us like TC Sounds products (I've owned 5 LMS 5400 Ultras over the years), and it looks to have a nice large port.

When we see larger subs with a bigger amp, bigger cabinet, and bigger driver with more xmax hitting ~113db at 2m at 20hz (Cap1400), I'm sure you can understand the skepticism of a smaller driver with less xmax in a smaller cabinet with a smaller amp doubling (6db) its output.

If it ever makes its way to DB.com we'll know for sure and only then.
Scott Simonian likes this.
lukeamdman is offline  
post #71 of 133 Old 09-20-2016, 02:25 PM
Senior Member
 
DrDyna's Avatar
 
Join Date: Oct 2011
Location: Central Nowhere
Posts: 319
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Liked: 81
Quote:
Originally Posted by lukeamdman View Post

When we see larger subs with a bigger amp, bigger cabinet, and bigger driver with more xmax hitting ~113db at 2m at 20hz (Cap1400), I'm sure you can understand the skepticism of a smaller driver with less xmax in a smaller cabinet with a smaller amp doubling (6db) its output.

If it ever makes its way to DB.com we'll know for sure and only then.
The cap 1400 looks a little like extension was preferred according to the plot, it goes quite a bit lower than the sim I ran assuming 20 was as low as they were going in this one.
DrDyna is offline  
post #72 of 133 Old 09-20-2016, 03:32 PM
AVS Forum Special Member
 
coolrda's Avatar
 
Join Date: Nov 2002
Location: Bakersfield, Ca
Posts: 3,400
Mentioned: 185 Post(s)
Tagged: 0 Thread(s)
Quoted: 1079 Post(s)
Liked: 963
I could careless about performance. I'm ordering one just to get the Thilo teddy.

coolrda is online now  
post #73 of 133 Old 09-20-2016, 03:37 PM
Member
 
Steve1981's Avatar
 
Join Date: Jul 2011
Location: Maryland
Posts: 128
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 191 Post(s)
Liked: 127
Quote:
Originally Posted by Tom Vodhanel View Post
How much effective enclosure volume? What is the tuning and area of the vent? Those would tell us a lot..
Glancing at the TC Sounds website, one of their recommendations for the 15" LMS-R is a 5.1 cubic foot enclosure with triple 4" ports. From what I'm seeing, the Monoprice system seems pretty close in terms of size and port area to that recommendation. By WinISD's reckoning, with a nominal 1.2kW input, such a system would net ~108dB at 20Hz at 2 meters. That's hardly shabby by any measure, and the amp may well be able to swing a few dB of additional voltage. OTOH, port compression may also take a couple dB away.
lukeamdman likes this.
Steve1981 is offline  
post #74 of 133 Old 09-20-2016, 03:46 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 21,499
Mentioned: 185 Post(s)
Tagged: 0 Thread(s)
Quoted: 5972 Post(s)
Liked: 5035
My models from Unibox with TC LMS-R 15 (complex inductance included)

~5.2cuft tuned to 20hz with triple 4" flared port and 2kw input. 117dB@20hz is the result and this assumes 1m free space.
Attached Thumbnails
Click image for larger version

Name:	MonopriceSUBfr.gif
Views:	168
Size:	21.9 KB
ID:	1672337   Click image for larger version

Name:	MonopriceSUBxmax.gif
Views:	146
Size:	18.7 KB
ID:	1672345   Click image for larger version

Name:	MonopriceSUBventspeed.gif
Views:	149
Size:	18.8 KB
ID:	1672353  
lukeamdman likes this.
Scott Simonian is offline  
post #75 of 133 Old 09-20-2016, 04:48 PM
Senior Member
 
DrDyna's Avatar
 
Join Date: Oct 2011
Location: Central Nowhere
Posts: 319
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Liked: 81
Quote:
Originally Posted by Scott Simonian View Post
My models from Unibox with TC LMS-R 15 (complex inductance included)

~5.2cuft tuned to 20hz with triple 4" flared port and 2kw input. 117dB@20hz is the result and this assumes 1m free space.
Tune it higher.
DrDyna is offline  
post #76 of 133 Old 09-20-2016, 04:51 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 21,499
Mentioned: 185 Post(s)
Tagged: 0 Thread(s)
Quoted: 5972 Post(s)
Liked: 5035
Nah, I'm cool.

I know you can squeeze out some more dB with a higher tune but it will also be subject to more port compression effects ~20hz if I tuned it higher (or equally dB-robbing aggressive limiter in play).

Nope. That was my model. Someone else can do it again with a higher tune. Maybe Monoprice will.
lukeamdman likes this.
Scott Simonian is offline  
post #77 of 133 Old 09-20-2016, 05:26 PM - Thread Starter
Mark Henninger
 
imagic's Avatar
 
Join Date: Dec 2005
Location: Philadelphia, PA
Posts: 12,440
Mentioned: 276 Post(s)
Tagged: 0 Thread(s)
Quoted: 6596 Post(s)
Liked: 11343
Quote:
Originally Posted by lukeamdman View Post
Again, Josh/DB.com doesn't use peak SPL figures.
Then shouldn't they refer to that as something else on the website, as opposed to using the exact words I used?

I'm pretty sure this sub is gonna end up on that site, and I certainly hope it does.


Mark Henninger, Senior Editor at AVS Forum

Last edited by imagic; 09-20-2016 at 05:30 PM.
imagic is offline  
post #78 of 133 Old 09-20-2016, 05:35 PM
AVS Forum Special Member
 
lukeamdman's Avatar
 
Join Date: May 2011
Location: Burnsville, MN
Posts: 3,523
Mentioned: 134 Post(s)
Tagged: 2 Thread(s)
Quoted: 1229 Post(s)
Liked: 1516
Quote:
Originally Posted by imagic View Post
Then shouldn't they refer to that as something else on the website, as opposed to using the exact words I used?

I'm pretty sure this sub is gonna end up on that site, and I certainly hope it does.

You said "peak", which doesn't appear on that site.

Josh defines it as "2 meter GP rms", which is 3db below "peak".

So according to the definition, 119db peak is 116db max/rms.

I'm very skeptical of 116db max/rms. As Tom said, impossible...no...but man oh man that's really pushing it big time.
lukeamdman is offline  
post #79 of 133 Old 09-20-2016, 05:38 PM - Thread Starter
Mark Henninger
 
imagic's Avatar
 
Join Date: Dec 2005
Location: Philadelphia, PA
Posts: 12,440
Mentioned: 276 Post(s)
Tagged: 0 Thread(s)
Quoted: 6596 Post(s)
Liked: 11343
Quote:
Originally Posted by lukeamdman View Post
You said "peak", which doesn't appear on that site.

Josh defines it as "2 meter GP rms", which is 3db below "peak".

So according to the definition, 119db peak is 116db max/rms.

I'm very skeptical of 116db max/rms. As Tom said, impossible...no...but man oh man that's really pushing it big time.
Dang you are right my mistake, I meant to say Max, not peak. Thx.

Sent from my SAMSUNG-SM-G935A using Tapatalk

Mark Henninger, Senior Editor at AVS Forum
imagic is offline  
post #80 of 133 Old 09-20-2016, 05:42 PM
AVS Forum Special Member
 
lukeamdman's Avatar
 
Join Date: May 2011
Location: Burnsville, MN
Posts: 3,523
Mentioned: 134 Post(s)
Tagged: 2 Thread(s)
Quoted: 1229 Post(s)
Liked: 1516
Quote:
Originally Posted by imagic View Post
Dang you are right my mistake, I meant to say Max, not peak. Thx.

Sent from my SAMSUNG-SM-G935A using Tapatalk
I hope one is sent to DB.com and it's an output monster.

I've bought many TC Sounds products and loved them, and I've purchased my fair share of cables from Monoprice.com for 5+ years. They are my go to source for XLR, TRS, HDMI, USB, wall plates, and 12awg speaker wire.
lukeamdman is offline  
post #81 of 133 Old 09-20-2016, 05:44 PM
AVS Forum Special Member
 
LastButNotLeast's Avatar
 
Join Date: Feb 2007
Location: 08077
Posts: 8,347
Mentioned: 35 Post(s)
Tagged: 1 Thread(s)
Quoted: 1802 Post(s)
Liked: 1413
So can we hold off the rest of this conversation until they start MAKING the darn thing?!
Michael

Did you really need to quote that entire post in your reply?
Downloadable FREE demo discs: Demonstration Blu-Ray Discs (Independently Authored)
Welcome to AVS - Get out while you still can!
Don't guess, measure: Getting Started With REW: A Step-by-Step Guide
LastButNotLeast is offline  
post #82 of 133 Old 09-20-2016, 05:48 PM
Senior Member
 
DrDyna's Avatar
 
Join Date: Oct 2011
Location: Central Nowhere
Posts: 319
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Liked: 81
Quote:
Originally Posted by Scott Simonian View Post
Nah, I'm cool.

I know you can squeeze out some more dB with a higher tune but it will also be subject to more port compression effects ~20hz if I tuned it higher (or equally dB-robbing aggressive limiter in play).

Nope. That was my model. Someone else can do it again with a higher tune. Maybe Monoprice will.
It just looked like how people like to sim LLT style with the upward ramp, rather than something more typical.

Honestly, I just kinda ended up in the middle of this, and I'd rather not be.
imagic likes this.
DrDyna is offline  
post #83 of 133 Old 09-20-2016, 07:25 PM
Senior Member
 
Join Date: Nov 2014
Posts: 215
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 174 Post(s)
Liked: 88
Damn it, I initially wrote an extremely long post detailing why 119dB is impossible, but as I wrote and gathered evidence to make my case, I realized it is possible with a HUGE stretch. I still think it is impossible given what we know of that sub. However, 119dB is absolutely achievable with a 15'' woofer in that box size. I'll explain why later in this very long post.

But let's play devil's advocate for a second here. Pretend we're in a world where JTR subs didn't exist and the SVS PB13 is just announced. SVS claims the new PB13, with a 13'' driver, is capable of 110.6dB at 20Hz, 2 meter GP, with 5% distortion (right from Data-Bass). This would probably attract a lot of skepticism from people. Let's consider some examples:

PSA XV-30FSE, with *two* 15'' woofers in a massive cabinet: 109.4dB at 18% THD
2x Velodyne DD18+ with two 18'' woofers: 109.6dB, 26.8% THD
2x HSU VTF-15H with two 15'' woofers: 110.1dB, 31.9% THD
2x Reaction Audio PV-15X, again, two 15'' woofers: 110dB, 15.5% THD
etc, etc

How can a single 13'' have more output than much bigger double 15's and double 18's woofers in much bigger cabinets and power? Not only that, but with way less distortion? That's impossible! Right?

Back to this sub. Note that Thilo mentioned 119dB peak, so converted to RMS, which is what Data-Bass and most simulators use, it is only 116dB, and this is quite achievable if there is enough amp power.

The easiest proof? Look at the Data-Bass results for the TC Sounds LMSR12 Dual 15" VMP. This is a subwoofer with the 12'' LMS-R in a box with 2.4 cu ft of internal volume tuned to 18Hz. This little thing produced 109.6dB at 20Hz, 2 meters away (albeit with a LOT of power, way more than 1200W).

Now, given the picture of the sub, it seems reasonable that it could have 4.8 cu ft of internal volume. I'm choosing 4.8 cu ft to make the math simple, because that is exactly double the volume of the LMS-R 12 sub. If the enclosure size is doubled, efficiency goes up by 6dB. Therefore, for the same input power that produced 109.6dB in the LMS-R 12 sub, it would produce 115.6dB in a cabinet twice the size. The LMS-R 15'' has more cone area, more excursion (but excursion is not a problem at tuning), and better power handling, so it is actually possible to get more than 115.6dB, so 116dB is achieved.

But what about distortion? 2.4 cu ft is a very small amount of enclosure volume. The smaller the enclosure, the higher the distortion for a given output because the air stiffness increases with smaller enclosures, and a driver will produce more distortion because it has to try harder to overcome the stiffness of the air. Therefore, doubling the enclosure size would actually help a lot to lower the distortion.

What about port compression? Port compression just means as the driver's SPL output increases, the port SPL output does not increase the same amount. So it will just take more power to achieve a particular output because the vent velocity isn't high enough where it would limit the maximum output.

Therefore, with the bigger enclosure and higher power handling of the 15'' LMS-R, 116dB is definitely possible, just with a lot of power (around 6000W depending on how much thermal compression)

An analysis of the PB13's 20Hz performance for those interested. I originally wrote this to demonstrate how 119dB is impossible because the PB13U represents a 20Hz performance that is about as good as it gets for a 13'' woofer. However, turns out the amp isn't capable of much burst power. So with a very powerful amp, it is possible.

A lot of people don't know this, but the amount of output increase from porting a woofer can be drastically different. Four things affects the amount of output at tuning:

1. Amount of amplifier power
2. Amount of cabinet volume
3. Size of the port
4. The driver parameters (not Xmax), and most people do not know they even make a difference. Most people will be surprised how big of a difference it can make.

The two main driver parameters that make a difference are the suspension stiffness and the motor strength.

Motor strength is important, because subwoofers are generally in undersized enclosures. The stronger motor is better at overcoming the stiffness of the small air space. One thing worth mentioning is that motor strength is not simply a BL^2/Re figure. BL and Re are small signal parameters. These parameters will change drastically when the woofer is being operated at high excursion levels. For all woofers, the motor strength is reduced more and more the higher the excursion. Underhung woofers have a big advantage here because the motor strength decreases at a much slower rate as excursion rises (we call that having a flatter BL curve). However, underhung motors wastes a good amount of magnetic strength in order to achieve that, which is why most underhung motors use very large ferrite or neodymium magnets.

Generally, a higher suspension stiffness will result in more output gain from the port. This is the same as having a lower Vas. Again better at overcoming the stiffness of the air.

The amazing 20Hz performance from the PB13U is most likely attributed to the very high motor strength underhung motor that makes the woofer weigh 55 pounds. While there are no T/S parameters for the Ultra 13 woofer, it is very likely that it has a very stiff suspension. When you increase suspension stiffness, Fs goes up, and the only way to lower Fs is to increase moving mass, which lowers sensitivity. The lower sensitivity is evident in the relatively low upper bass maximum output despite a high motor strength that would increase sensitivity. What is even more impressive is that it does this with less than 1500W or so. The long term maximum output vs CEA 2010 maximum burst output showed just a 1.3dB difference. This means the amp's burst power isn't very high. Assuming the amp is capable of producing 1000W continuously, 1.3dB is just 34% higher power, so around 1340W for 110.6dB. Therefore, if one was to power the Ultra 13 woofer with a big 20,000W amp like Ricci uses, one would only need ~3.46x more power to hit 116dB, which is 4636W. The Ultra 13 woofer should have absolutely no problem handling 5000W for a very short period of time for the CEA2010 burst testing. Port velocity is under 20m/s, so no problems there. With a big amp it could probably even burst 120dB.

Last edited by bcodemz; 09-20-2016 at 08:03 PM.
bcodemz is offline  
post #84 of 133 Old 09-20-2016, 07:43 PM
AVS Forum Special Member
 
lukeamdman's Avatar
 
Join Date: May 2011
Location: Burnsville, MN
Posts: 3,523
Mentioned: 134 Post(s)
Tagged: 2 Thread(s)
Quoted: 1229 Post(s)
Liked: 1516
Quote:
Originally Posted by bcodemz View Post
Damn it, I initially wrote an extremely long post detailing why 119dB is impossible, but as I wrote and gathered evidence to make my case, I realized it is possible with a HUGE stretch. I still think it is impossible given what we know of that sub. However, 119dB is absolutely achievable with a 15'' woofer in that box size. I'll explain why later in this very long post.

But let's play devil's advocate for a second here. Pretend we're in a world where JTR subs didn't exist and the SVS PB13 is just announced. SVS claims the new PB13, with a 13'' driver, is capable of 110.6dB at 20Hz, 2 meter GP, with 5% distortion (right from Data-Bass). This would probably attract a lot of skepticism from people. Let's consider some examples:

PSA XV-30FSE, with *two* 15'' woofers in a massive cabinet: 109.4dB at 18% THD
2x Velodyne DD18+ with two 18'' woofers: 109.6dB, 26.8% THD
2x HSU VTF-15H with two 15'' woofers: 110.1dB, 31.9% THD
2x Reaction Audio PV-15X, again, two 15'' woofers: 110dB, 15.5% THD
etc, etc

How can a single 13'' have more output than much bigger double 15's and double 18's woofers in much bigger cabinets and power? Not only that, but with way less distortion? That's impossible! Right?

Back to this sub. Note that Thilo mentioned 119dB peak, so converted to RMS, which is what Data-Bass and most simulators use, it is only 116dB, and this is quite achievable if there is enough amp power.

The easiest proof? Look at the Data-Bass results for the TC Sounds LMSR12 Dual 15" VMP. This is a subwoofer with the 12'' LMS-R in a box with 2.4 cu ft of internal volume tuned to 18Hz. This little thing produced 109.6dB at 20Hz, 2 meters away (albeit with a LOT of power, way more than 1200W).

Now, given the picture of the sub, it seems reasonable that it could have 4.8 cu ft of internal volume. I'm choosing 4.8 cu ft to make the math simple, because that is exactly double the volume of the LMS-R 12 sub. If the enclosure size is doubled, efficiency goes up by 6dB. Therefore, for the same input power that produced 109.6dB in the LMS-R 12 sub, it would produce 115.6dB in a cabinet twice the size. The LMS-R 15'' has more cone area, more excursion (but excursion is not a problem at tuning), and better power handling, so it is actually possible to get more than 115.6dB, so 116dB is achieved.

But what about distortion? 2.4 cu ft is a very small amount of enclosure volume. The smaller the enclosure, the higher the distortion for a given output because the air stiffness increases with smaller enclosures, and a driver will produce more distortion because it has to try harder to overcome the stiffness of the air. Therefore, doubling the enclosure size would actually help a lot to lower the distortion.

What about port compression? Port compression just means as the driver's SPL output increases, the port SPL output does not increase the same amount. So it will just take more power to achieve a particular output because the vent velocity isn't high enough where it would limit the maximum output.

Therefore, with the bigger enclosure and higher power handling of the 15'' LMS-R, 116dB is definitely possible, just with a lot of power (around 6000W depending on how much thermal compression)

An analysis of the PB13's 20Hz performance for those interested. I originally wrote this to demonstrate how 119dB is impossible because the PB13U represents a 20Hz performance that is about as good as it gets for a 13'' woofer. However, turns out the amp isn't capable of much burst power. So with a very powerful amp, it is possible.

A lot of people don't know this, but the amount of output increase from porting a woofer can be drastically different. Four things affects the amount of output at tuning:

1. Amount of amplifier power
2. Amount of cabinet volume
3. Size of the port
4. The driver parameters (not Xmax), and most people do not realize how big of a difference that can make.

The two main driver parameters that make a difference are the suspension stiffness and the motor strength.

Motor strength is important, because subwoofers are generally in undersized enclosures. The stronger motor is better at overcoming the stiffness of the small air space. One thing worth mentioning is that motor strength is not simply a BL^2/Re figure. BL and Re are small signal parameters. These parameters will change drastically when the woofer is being operated at high excursion levels. For all woofers, the motor strength is reduced more and more the higher the excursion. Underhung woofers have a big advantage here because the motor strength decreases at a much slower rate as excursion rises (we call that having a flatter BL curve). However, underhung motors wastes a good amount of magnetic strength in order to achieve that, which is why most underhung motors use very large ferrite or neodymium magnets.

Generally, a higher suspension stiffness will result in more output gain from the port. This is the same as having a lower Vas. Again better at overcoming the stiffness of the air.

The amazing 20Hz performance from the PB13U is most likely attributed to the very high motor strength underhung motor that makes the woofer weigh 55 pounds. While there are no T/S parameters for the Ultra 13 woofer, it is very likely that it has a very stiff suspension. When you increase suspension stiffness, Fs goes up, and the only way to lower Fs is to increase moving mass, which lowers sensitivity. The lower sensitivity is evident in the relatively low upper bass maximum output despite a high motor strength that would increase sensitivity. What is even more impressive is that it does this with less than 1500W or so. The long term maximum output vs CEA 2010 maximum burst output showed just a 1.3dB difference. This means the amp's burst power isn't very high. Assuming the amp is capable of producing 1000W continuously, 1.3dB is just 34% higher power, so around 1340W for 110.6dB. Therefore, if one was to power the Ultra 13 woofer with a big 20,000W amp like Ricci uses, one would only need ~3.46x more power to hit 116dB, which is 4636W. The Ultra 13 woofer should have absolutely no problem handling 5000W for a very short period of time for the CEA2010 burst testing. Port velocity is under 20m/s, so no problems there. With a big amp it could probably even burst 120dB.
A lot of good points, but all we know is 1.2kw. Additionally, the LMS-R is not an efficient driver (87db).
lukeamdman is offline  
post #85 of 133 Old 09-20-2016, 07:48 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 21,499
Mentioned: 185 Post(s)
Tagged: 0 Thread(s)
Quoted: 5972 Post(s)
Liked: 5035
Quote:
Originally Posted by DrDyna View Post
It just looked like how people like to sim LLT style with the upward ramp, rather than something more typical.

Honestly, I just kinda ended up in the middle of this, and I'd rather not be.
That shape is likely caused by me using the full 'complex inductance' modelling which will add quite a hump in the 50hz region as seen. Most models would show the more "maximally flat" shape with out the hump. The same, this would be. But I know what you mean...

Either way, I agree. This isn't my fight and I don't really care either which way but if this gets tested it will only improve sales. Not the other way around. Just keeping it 'on the line'.
Scott Simonian is offline  
post #86 of 133 Old 09-20-2016, 08:01 PM
Senior Member
 
Join Date: Nov 2014
Posts: 215
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 174 Post(s)
Liked: 88
Quote:
Originally Posted by lukeamdman View Post
A lot of good points, but all we know is 1.2kw. Additionally, the LMS-R is not an efficient driver (87db).
Yeah there is no way it'll hit 116dB with that 1200W amp, unless it can burst 5000W.

However, woofer efficiency does not correlate with deep bass efficiency in a ported subwoofer. In fact often times it is the opposite. Part of the reason is that lower efficiency generally means higher moving mass, which generally means stiffer suspension, which increases port efficiency.
bcodemz is offline  
post #87 of 133 Old 09-21-2016, 06:09 AM
AVS Forum Special Member
 
Tom Vodhanel's Avatar
 
Join Date: May 2011
Posts: 3,696
Mentioned: 54 Post(s)
Tagged: 0 Thread(s)
Quoted: 2059 Post(s)
Liked: 6057
Quote:
Originally Posted by Steve1981 View Post
Glancing at the TC Sounds website, one of their recommendations for the 15" LMS-R is a 5.1 cubic foot enclosure with triple 4" ports. From what I'm seeing, the Monoprice system seems pretty close in terms of size and port area to that recommendation. By WinISD's reckoning, with a nominal 1.2kW input, such a system would net ~108dB at 20Hz at 2 meters. That's hardly shabby by any measure, and the amp may well be able to swing a few dB of additional voltage. OTOH, port compression may also take a couple dB away.
How would that work? Ports fifty inches long? That first resonance would be fun..

I would caution against any sim in these situations. Instead find a known(measured) unit that is similar like the 15hp. 108/20hz. So would something bigger(maybe?), with much more port area,and double the amp be able to add 5dB? Seems doable. Something seems off on this though. That slot port is HUGE...maybe 4" by 16"? 3.5 x 16? Maybe the angle is tricking me?

Tom V.
Power Sound Audio

“Quality isn't expensive, it is priceless" --- fortune cookie
Tom Vodhanel is online now  
post #88 of 133 Old 09-21-2016, 06:29 AM
Member
 
Steve1981's Avatar
 
Join Date: Jul 2011
Location: Maryland
Posts: 128
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 191 Post(s)
Liked: 127
Quote:
Originally Posted by Tom Vodhanel View Post
Instead find a known(measured) unit that is similar like the 15hp. 108/20hz.
I figured these might be a useful guide, though they presumably have a considerable advantage in amplification.

LMS-R 12" with dual 15" PRs tuned to 18Hz in 2.4 cubes: 109.6dB @ 20Hz
http://www.data-bass.com/data?page=system&id=65&mset=70

LMS-U 18" with dual 18" PRs tuned to 16Hz in 7 cubes: 114.5dB @ 20Hz
http://www.hometheatershack.com/foru...king-200l.html

Given the performance of the latter system, 116dB seems like it'd be a neat trick considering the other details.

Quote:
Originally Posted by Tom Vodhanel View Post
So would something bigger(maybe?), with much more port area,and double the amp be able to add 5dB? Seems doable. Something seems off on this though. That slot port is HUGE...maybe 4" by 16"? 3.5 x 16? Maybe the angle is tricking me?
The angle makes it a little difficult for sure. I'm estimating 2.5 x 15. It just seems huge since it's a piddly 15" driver instead of a 21 or 24" beast
Steve1981 is offline  
post #89 of 133 Old 09-21-2016, 06:45 AM
AVS Forum Special Member
 
Tom Vodhanel's Avatar
 
Join Date: May 2011
Posts: 3,696
Mentioned: 54 Post(s)
Tagged: 0 Thread(s)
Quoted: 2059 Post(s)
Liked: 6057
Quote:
Originally Posted by Steve1981 View Post
I figured these might be a useful guide, though they presumably have a considerable advantage in amplification.

LMS-R 12" with dual 15" PRs tuned to 18Hz in 2.4 cubes: 109.6dB @ 20Hz
http://www.data-bass.com/data?page=system&id=65&mset=70

LMS-U 18" with dual 18" PRs tuned to 16Hz in 7 cubes: 114.5dB @ 20Hz
http://www.hometheatershack.com/foru...king-200l.html

Given the performance of the latter system, 116dB seems like it'd be a neat trick considering the other details.



The angle makes it a little difficult for sure. I'm estimating 2.5 x 15. It just seems huge since it's a piddly 15" driver instead of a 21 or 24" beast
Just to be clear, I'm already assuming they meant 122dB 1m/peak(per CEA).

EDIT for correction.

Tom V.
Power Sound Audio
Steve1981 likes this.

“Quality isn't expensive, it is priceless" --- fortune cookie

Last edited by Tom Vodhanel; 09-21-2016 at 07:23 AM.
Tom Vodhanel is online now  
post #90 of 133 Old 09-21-2016, 06:54 AM - Thread Starter
Mark Henninger
 
imagic's Avatar
 
Join Date: Dec 2005
Location: Philadelphia, PA
Posts: 12,440
Mentioned: 276 Post(s)
Tagged: 0 Thread(s)
Quoted: 6596 Post(s)
Liked: 11343
Quote:
Originally Posted by Tom Vodhanel View Post
Just to be clear, I'm already assuming they meant 122dB 1m/peak(per CEA). Someone in china probably measured it this way(following the protocol) and told his manager who told someone else who told someone in some USA office who mentioned it to Thilo...and through the grapevine maybe it changed from 1m/peak to 2m rms(or peak)? Anyway, I'm saying 122dB 1m/peak(113 2m/rms) seems doable. 122dB 2m/rms? No way.

Tom V.
Power Sound Audio
Tom, I appreciate your knowledgeable insights on the topic of subwoofers, but the reality is Thilo measured it himself.. twice. Plus, he calibrated the mic in between.

Please don't add conjecture to the brew. The thread is already a mess, so let's see if this gets the DB treatment sooner than later, and how that number translates to all this debate, so that the guessing can end. Claiming the number came from a rando in a Chinese factory is inaccurate, it's speculation I feel compelled to dismiss based on first-hand knowledge of the source of the measurements.

Right now we're looking at something between 119 dB and 122 dB peak, based on the communications I've had, which involve Thilo. 119 dB peak is the "safe" spec. Nobody ever said anything about RMS.

Mark Henninger, Senior Editor at AVS Forum

Last edited by imagic; 09-21-2016 at 07:01 AM.
imagic is offline  
Sponsored Links
Advertisement
 
Reply Latest Industry News

Tags
cedia 2016 , subwoofer , tc sounds

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off