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Old 1st November 2011, 03:20 PM   #11
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Quote:
Originally Posted by mclsound View Post
That is what i figured.I would rather run 2 15/side than one 18.If I could afford the 18's I would but that is $4000+amp$$.That is 5ft3/15 which is a fair size if you were to run 4 of them(well actually,I still have 1 pair of CSS SDX15's.
Thanks Spin

How do the CSS perform? Big box?

By the way, I'm fairly new at the math side of this. If anyone wishes to politely correct anything I typed, I'd appreciate being in the know rather than continuing on with incorrect info. I'm not infallable and I'm looking to learn something.

I will say that a sealed RE sub (15" XXX) that makes it to 26hz in a sealed box with better transient response is definitely high on my list. In 10 cubes its in the .68 Qtc range for 640 bucks a side. 54MM XMAX!
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Old 1st November 2011, 10:16 PM   #12
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Quote:
Originally Posted by SpinMonster View Post
Here is a screen shot of 3 models:
Green line= ported LMSr 15 TC sounds 10 cubic feet 2 drivers
Red line= sealed LMSr 15 TC sounds 10 cubic feet 2 drvers
Yellow line= Sealed 18 Ultra 5 cubic feet .54 QTC

I would imagine that these builds with really huge sealed boxes have too low a Qtc. When you grossly oversize a vented alignment it kills transient response and produces one note bass (EBS), doesnt it?
any Qtc between .5 and .7 will sound ok in a sealed box .5 being cleaner and flatter .7 a little punchier with a steeper roll-off.

an oversized vented box will have better transient response but very little punch, one note bass comes from too small boxes (high Q)

Quote:
Originally Posted by SpinMonster View Post
in the case of ported vs sealed, the sealed subs have the greatest excursion at the tuning frequency while ported boxes tuned maximally flat have the best transient response and the cone's motion is at the minimum motion point. Wouldn't the use of a sub that has 6db more output at 20hz also have less distortion since its the minimum motion point with 1/4 of the power to make the same SPL? 2 15's have greater cone rating area which would be more efficient. I run each side (two 15's side) with a Peavey CS4080hz. Its a total of 8000 watts and I never have them bottom out. I tuned to 20hz. Even at 15hz its still more output.

Am I missing something? I feel its comparable since the two 15s cost a bit less than one of these 18's.
Your not missing much, although I'm having trouble figuring out what you're asking...
Fc is the system resonance of a sealed box, the max excursion will be reached much lower than that.
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Old 2nd November 2011, 01:20 PM   #13
Ile is offline Ile  Finland
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Quote:
Originally Posted by SpinMonster View Post
How do the CSS perform? Big box?
Pretty well, distortion is below 10% at 20Hz until you reach 95db or 100db (2 elements). Here's 1-2 element closed versions measured in same outside conditions.

DIY CSS SDX15 sealed 100L - Home Theater Forum and Systems - HomeTheaterShack.com

DIY CSS 2xSDX15 sealed 140L - Home Theater Forum and Systems - HomeTheaterShack.com

These tells why one LMS5400 18" beats two CSS, compare distortion readings at low end.

LMS-5400 18"
DIY TC Sounds LMS-5400 18" sealed 100L - Home Theater Forum and Systems - HomeTheaterShack.com

DIY TC Sounds LMS-5400 18" + 2x18" PR 200L - Home Theater Forum and Systems - HomeTheaterShack.com

DIY TC Sounds LMS-5400 18" sealed 100L LT - Home Theater Forum and Systems - HomeTheaterShack.com

Last edited by Ile; 2nd November 2011 at 01:25 PM.
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Old 2nd November 2011, 06:10 PM   #14
doug20 is offline doug20  United States
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Quote:
Originally Posted by SpinMonster View Post
Running the simulations in 3 different software sources, I get an F3 of 45 for sealed 2.8 cubic foot boxes and F3 of 25 in a ported 5.3 cubic foot box.

I see so may guys running them in huge boxes sealed that would be a Q of .5x. Bigger than 5.3 in ported boxes would kill transient response wouldnt it?

Whats the big rave about these subs? Am I missing something?


What am I missing? Wouldnt 2 15" TC LMS-15 in ported 10 cubic foot boxes be a much better choice? Sealed they drop to 37hz Im not hating on the 18 just trying to understand the reasoning. two of the TC 15's even cost less. I'd rather have less cone weight and more drivers for power handling not to mention it beats the LMS ultra in extension out of the box. Lighter, deeper, more cone area, and cheaper.....

What you are missing is the fact that modelling Q is not all that meaningful in the real world (Remember EQing is required and EQing always changes the Q, Put it in a small box and have the proper EQing). What the LMS Ultra does in a 4cuft box is simply unmatched by any other subwoofer when we look at the lowest octaves. Its output potential with 4000Watts puts in in a class by itself.

If you do not care about < 20Hz performance in a 4 cuft sealed design then there is absolutely nothing special about the LMS5400 Ultra drivers. Other drivers like John's (AEspeakers.com) AV series drivers are better > 20Hz peformance subwoofers. Aurasound NS-18 was another driver that has better performance measurements above 20Hz. Both those design choice have superior linearity over the LMS5400.

You have to pick your requirements then you can pick what the best driver choice will be. Those wanting ultimate HT performance down below 10Hz will the smallest footprint choose 4 or 8 sealed LMS5400s + >= 8000Watts

Conclusion, the LMS5400 is special because of what it can do on a small footprint.

I own 2 LMS5400s ( twin sealed 4 cuft boxes). I also own 4 AV15X drivers, 2 TC2000 15" drivers and 4 Ficar audio Q18 drivers (IB array). If box size is not important I would buy something like the Mach5 18" woofers coming out and put them in 10cuft boxes....great displacement/specs!!! I only care about HT performance, 2 channel music can come from headphones for all I care.

Last edited by doug20; 2nd November 2011 at 06:19 PM.
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Old 2nd November 2011, 06:18 PM   #15
doug20 is offline doug20  United States
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Quote:
Originally Posted by SpinMonster View Post
In the case of ported vs sealed.....

Ported designs are a compromised solution to reduce costs and maximize output at the tuning point. They have MORE distortion overall vs properly designs sealed system.

Sealed designs allow for extension and people can simply add more sealed boxes to extend lower.

There are other design considerations for lowest harmonic distortion but when it comes to ported vs sealed the only reason to go ported is because output is required (ie. sealed version wouldnt offer enough output).
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Old 3rd November 2011, 09:39 AM   #16
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Quote:
Originally Posted by doug20 View Post
Ported designs are a compromised solution to reduce costs and maximize output at the tuning point. They have MORE distortion overall vs properly designs sealed system.

Sealed designs allow for extension and people can simply add more sealed boxes to extend lower.

There are other design considerations for lowest harmonic distortion but when it comes to ported vs sealed the only reason to go ported is because output is required (ie. sealed version wouldnt offer enough output).
Reduced costs? My subs cost exactly the same as a sealed 18. The boxes were way more complicated and large at 320lbs each. I think sealed systems are an escape from the harder to build large boxes especially when they see what volume the port alone would take up at 10-15 square inches per cubic foot. Building a single sealed 18 for each side would have cost less for cabinets and take up less space.

Respectfully sir, just about everything I have read says the exact opposite of what you say here. Distortion is lower on a vented system at all frequencies above the tuning point. If we are talking about a system that is flat to 20HZ, exactly what are you saying? A ported system woofer is at its minimum motion point at 20hz then, thus less distortion. Sealed systems are at their max excusion at the tuning point.....37 for the 18" LMS ultra.

As to your statement that the sealed system extends lower,
Where exactly on this graph do you see the output of a sealed system higher than the ported TC 15's?
Click the image to open in full size.

At no frequency from 15hz up, was the sealed system at a higher SPL with the same power. Ports dont just make a single frequency, they have output an octave in each direction. With 8100 watts, I have never had a woofer bottom out on program material, music or movies. So with that power outut and no needed equalization how can you possibly get anywhere near the same SPL at 20hz with a sealed system?

In the real world, at high SPL's you need so much equalization to get a sealed 18 to have the same output as a portd 15 at 20hz. I'm sorry but runnig an 18 with 2000 watts isnt going to be anywhere near as low as the distortion of a pair of ported 15's with 500 watts when the 15 is at its minimum motion point at 20hz. Boosting 20hz up 7.5 db for a sealed system pays penaties in amp power (if you have it and most dont) and excursion. the vast majority of guys running these 18's arent running amps that exploit the ability to withstand that kind of equalization. I'm blinking the soft clip lights on two CS4080hz's so eaxctly where does this power come from to run an 18 equalized at 20hz to be flat? So if you had the exact same amps, output at 20hz with two ported 15's is way lower distortion than a sealed system thats down 7.5db trying to catch up in SPL. I think HT is about SPL as much as 10hz output.

I guess in the end, it comes down to 10-15hz. I just dont see the frequency extension surpassing the results on a home theater output at max SPL's. Does having more output at 10hz really expand the experience of home theater that much that you would give up 7.5bd at 20hz? I say no but I havent heard a sealed 18.....or 4 of them. Now if someone wants to invite me over, I'm a retired guy living in colorado Springs that is sincere in wanting to better the experience. I'm just not buying the 10hz thing as that much better an experience. I can be wrong but I dont see someone saying, Gee Jason, the low distortion on that explosion was so detainled and clean. I do see the 20hz +7.5db thing making my house shake more exciting. No, I dont think you can distinguishe the distortion percentage at 120+db during a movie. I guess its OCD for some that they have to know what the test results were.

Last edited by SpinMonster; 3rd November 2011 at 09:58 AM.
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Old 3rd November 2011, 10:34 AM   #17
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Anyway to put a picture to the post:

The subs are 55" tall, 24" deep, and 21" wide. They are 320lbs each. The peavey amps are a great match. They are 4000 watts at the 8 ohm load bridged. Equalizing a single 18 7.5db to get it to match the 20hz output would require a doubling of power for each 3db or something like 18,000 watts. I had enough trouble getting 60 amp service for the system as it sits.
Click the image to open in full size.

The internal volume without the vent volume is just over 10 cubic feet so they can be sealed for two 18's if I think the cost is worth it later.

The home theater screen is 16' diag, and the room is 22x22x10 for scale.
Click the image to open in full size.

Music videos are my thing. Here is a better screen shot. we are so lucky to have projectors that can have this detailed a picture in home use. My kid thinks its way better than our IMAX here in town. Video games are a whole new experience.
Click the image to open in full size.

Click the image to open in full size.

Last edited by SpinMonster; 3rd November 2011 at 10:46 AM.
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Old 3rd November 2011, 10:45 AM   #18
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Quote:
Originally Posted by revboden View Post
Your not missing much, although I'm having trouble figuring out what you're asking....
I was ultimately asking if stuffing affects transient response. My system would be overdamped with a pound or two in there and I just wanted to cover all the bases.

Thanks for your input. The explanation of the system Q does help.
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Old 3rd November 2011, 12:53 PM   #19
doug20 is offline doug20  United States
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Quote:
Originally Posted by SpinMonster View Post
Reduced costs? My subs cost exactly the same as a sealed 18. The boxes were way more complicated and large at 320lbs each. I think sealed systems are an escape from the harder to build large boxes especially when they see what volume the port alone would take up at 10-15 square inches per cubic foot. Building a single sealed 18 for each side would have cost less for cabinets and take up less space.
First, cabinet costs in DIY are meaningless (its about the same amount of wood relative). Lets not go there at all. When discussions exist about cost then there is an assumption that the cost is 99% about the driver + amp costs.

No back to porting....Ported allows for greater output at the tuning frequency but it has so many other issues like port noise, linear response issues that its considered by anyone that has build them all a compromised solution. There is simply only ONE design that maximizes extension and that is the sealed design, its the only design that allows multiples to flatten out the curve down to 10Hz and below.

Remember the TOP HT rooms have sealed high end designs (like the LMS5400).

The measurements are there for you to find any design that matches the LMS5400. Illka did many, many, many comparisons on HTS. This isn't news at all.


Quote:
Respectfully sir, just about everything I have read says the exact opposite of what you say here. Distortion is lower on a vented system at all frequencies above the tuning point. If we are talking about a system that is flat to 20HZ, exactly what are you saying? A ported system woofer is at its minimum motion point at 20hz then, thus less distortion. Sealed systems are at their max excusion at the tuning point.....37 for the 18" LMS ultra.

As to your statement that the sealed system extends lower,
Where exactly on this graph do you see the output of a sealed system higher than the ported TC 15's?
Click the image to open in full size.

At no frequency from 15hz up, was the sealed system at a higher SPL with the same power. Ports dont just make a single frequency, they have output an octave in each direction. With 8100 watts, I have never had a woofer bottom out on program material, music or movies. So with that power outut and no needed equalization how can you possibly get anywhere near the same SPL at 20hz with a sealed system?

I never talk about a sealed design as one box. Its silly to build just one sealed box and think its a great choice if output is needed. Its all about the system.

Your biggest problem is assuming 20Hz or 15Hz is all that matters. That might be your assumption but the LMS5400 was design for people who want 10Hz. It was designed to allow 4000Watts to be thrown at it in a 4cuft box. That is what makes it special.


Quote:

In the real world, at high SPL's you need so much equalization to get a sealed 18 to have the same output as a portd 15 at 20hz. I'm sorry but runnig an 18 with 2000 watts isnt going to be anywhere near as low as the distortion of a pair of ported 15's with 500 watts when the 15 is at its minimum motion point at 20hz.
lmao, you have any REAL proof or is this just subjective banter? Im sorry but 15's + 500Watts is childs play as posted before I own them.

This has everything thing to do with clean headroom, non-distorted peaks, non-clipping peaks. Movie content down low has +30dB peaks. You might not consider it a priority (That is okay) but there are some who want the best HT system period and that requires designs that allow for clean peaks.

Get the clean peaks. Design a proper sub system in room (Follow Geddes, Toole, etc) and have the best over all system.







Quote:

Boosting 20hz up 7.5 db for a sealed system pays penaties in amp power (if you have it and most dont) and excursion. the vast majority of guys running these 18's arent running amps that exploit the ability to withstand that kind of equalization. I'm blinking the soft clip lights on two CS4080hz's so eaxctly where does this power come from to run an 18 equalized at 20hz to be flat? So if you had the exact same amps, output at 20hz with two ported 15's is way lower distortion than a sealed system thats down 7.5db trying to catch up in SPL. I think HT is about SPL as much as 10hz output.

I guess in the end, it comes down to 10-15hz. I just dont see the frequency extension surpassing the results on a home theater output at max SPL's. Does having more output at 10hz really expand the experience of home theater that much that you would give up 7.5bd at 20hz? I say no but I havent heard a sealed 18.....or 4 of them. Now if someone wants to invite me over, I'm a retired guy living in colorado Springs that is sincere in wanting to better the experience. I'm just not buying the 10hz thing as that much better an experience. I can be wrong but I dont see someone saying, Gee Jason, the low distortion on that explosion was so detainled and clean. I do see the 20hz +7.5db thing making my house shake more exciting. No, I dont think you can distinguishe the distortion percentage at 120+db during a movie. I guess its OCD for some that they have to know what the test results were.
You are not thinking about sub systems properly. I tried to post already that if you are thinking that a sub system is one box then you are not thinking right. People who want flat response down to 10Hz are really boosting their designs allow the LMS5400 allows for it ( Again, that is what makes it special overall most others). When people want 10Hz they are thinking about displacement (> 20Liters) and to get that it always requires multiple drivers.

As for the "experience" thing. Let me say this, since I have monster subwoofer systems in my house in multiple rooms. I can say without a doubt there is a difference when expectation is set a higher level. I have heard $150K Rooms with 4 JL113s and I found that room lacking. I have been to family places watched movies with their 12" subwoofers dropping like rocks at 25Hz and its like someone sucked the bass out of the room for me.

Once someone experiences 10Hz and has a certain expectation level there is simply no question that its easy to spot when content does not have it.

The cost/requirements of having that lowest octave is truely an expontential increase. Honestly, 20Hz or even 15Hz is easy. People either want to have the lowest octave or they don't, its okay either way but the only opinion that matters is the one with experience.
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Old 3rd November 2011, 12:57 PM   #20
DrDyna is offline DrDyna  United States
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Originally Posted by SpinMonster View Post
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