8x 18" LMS 5400 Ultras Sealed to 27 Cube 15hz Ported Build - Page 20 - AVS Forum | Home Theater Discussions And Reviews

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post #571 of 583 Old 07-29-2016, 07:25 AM
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out of curiousity, i looked around for a power cable and couldn't find one. is 240v powercon really that uncommon in the u.s.?

Listen. It's All Good.
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post #572 of 583 Old 07-29-2016, 08:51 AM
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Originally Posted by notnyt View Post
Hm, what could these be for?

Nice! These, as in plural?
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post #573 of 583 Old 07-29-2016, 09:51 AM - Thread Starter
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Originally Posted by LTD02 View Post
out of curiousity, i looked around for a power cable and couldn't find one. is 240v powercon really that uncommon in the u.s.?
It's like speakons, you can just get the end and make your own.
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post #574 of 583 Old 07-29-2016, 09:52 AM - Thread Starter
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Nice! These, as in plural?
yeah, for a pair of sp2-12000s

the joys of silence.
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post #575 of 583 Old 07-29-2016, 11:08 AM
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yeah, for a pair of sp2-12000s

the joys of silence.
Awesome man! Frees up amps for more subs! Lol
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post #576 of 583 Old 07-29-2016, 11:10 AM - Thread Starter
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Awesome man! Frees up amps for more subs! Lol
rofl, selling the FP14000s. I don't have any more outlets to run them
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post #577 of 583 Old 07-29-2016, 03:15 PM
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It's like speakons, you can just get the end and make your own.

with speakons, there are countless companies that sell the cables. same thing with 15/20 amp powercon. i was just kind of surprised that when i looked around that i didn't see *any* 240/250v 30/32a powercon given that a 30 amp breaker must have a 30a receptacle according to the n.e.c. maybe i just wasn't using the right search terms or something.

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post #578 of 583 Old 07-29-2016, 03:19 PM - Thread Starter
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with speakons, there are countless companies that sell the cables. same thing with 15/20 amp powercon. i was just kind of surprised that when i looked around that i didn't see *any* 240/250v 30/32a powercon given that a 30 amp breaker must have a 30a receptacle according to the n.e.c. maybe i just wasn't using the right search terms or something.

search for powercon 32a
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post #579 of 583 Old 07-29-2016, 04:26 PM
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search for powercon 32a

yeah...not a single cable comes up anywhere.

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post #580 of 583 Old 07-29-2016, 04:27 PM - Thread Starter
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yeah...not a single cable comes up anywhere.
Oh, I see what you're saying. There just isn't as much demand for them and the plug types vary all over the place on the other end.
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post #581 of 583 Old 10-19-2016, 03:26 PM
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@notnyt - do you still have that big dip at 80hz today when you don't use smoothing? Have you tried to reverse the polarity on the subs or the speakers one or the other and measure again? That looks suspiciously a bit like something I had in my room when my mains were out of phase with the subs. When I had previously measured using 1/6 smoothing I couldn't see the problem, but when we used no smoothing it came to light quick. Luckily Desertdome discovered it while we were playing around.




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One more thing. I'm embarrassed to say desertdome figured out after the meet when he was playing with his omnimic that while my eight subs were all in phase with each other --- they were out of phase with all the main speakers.

Here is a comparison of what we heard at the meet and what happened when the polarity was switched after the meet. Every speaker was in phase together, and the subs were in phase together --- just all the speakers were out of phase with all the subs --- meaning my crossover region between speakers and sub took a hit. I didn't ever consider that could be a problem, and didn't catch it when I'd measured and set things up. Audyssey didn't catch it either, on neither the Denon, or Onkyo. Worse yet, I've been using it like this the whole time I've had the sealed subs (I think), and didn't realize the issue. It was really easy to see when you use unsmoothed measurements, but I always pretty much use 1/6, which masks it to a larger degree. I learned I need to at least start with unsmoothed to more easily see something like that. Doh. Thanks DD!

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February 2017 - Kansas City Home Theater Crawl
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post #582 of 583 Old 10-19-2016, 03:27 PM - Thread Starter
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@notnyt - do you still have that big dip at 80hz today when you don't use smoothing? Have you tried to reverse the polarity on the subs or the speakers one or the other and measure again? That looks suspiciously a bit like something I had in my room when my mains were out of phase with the subs. When I had previously measured using 1/6 smoothing I couldn't see the problem, but when we used no smoothing it came to light quick. Luckily Desertdome discovered it while we were playing around.
it's just a null in front of the lp where it's easier to measure. i often disconnect the fronts when taking measurements.
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post #583 of 583 Old 10-19-2016, 06:37 PM
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Originally Posted by Stharlingny84 View Post
I went to Rob place the other day to demo his Home Cinema and it was an Extraordinary experience, The sound quality is just out of this world, the level of detail is unlike anything i ever heard, the dynamics are instant, the extension is incredible, the force and pressure of the midbass is tremendous, i mean i don't even have enough words to describe how PERFECT the sound quality was, it was like heaven on earth lol, Rob cinema is one of the most exquisite audio experiences anybody can have, his system can pleasure the most discriminating audiophile, and i been to some High end Room like for example Steinway Lyngdorf, the room was 130,000$ worth in equipment and don't get me wrong it sounded really good but if i have to pick i'll pick Rob system because is simply more superior, also i Demo the JBL M2 professional monitor speakers and i have to say the Rob Mains 4722 sounded superior to me, the imaging was right in the center and i felt the performers were right in front of me, the separation the instruments were excellent and the vocals of the performers were super natural.

But the best and my favorite part was the BASS (UNREAL), i have DUAL SVS PB-13 ultras and they are little toys next to his 8 LMS ultra 18 woofers, the best Demo was the incredible Hulk the last scene when hulk fell from the helicopter and hit the ground to fight abomination, the bass had the most greater definition and accuracy i ever heard in my entitled life, the bass was effortless and way beyond any subwoofer i ever heard at any price point, is funny how some People say the JL gotham (12,000$) is the best subwoofer ever lol, well is beautiful don't get me wrong but it can't touch Rob bass department.

If you want to get the best Home Cinema experiences in your life you have to get in contact with Rob and ask him for a demo, it is a must for any HT enthusiasm to experiences this level of Performance at least once in a lifetime, because i don't think you ever get this kind of Performance and especially BASS in anywhere else.

Well Done Rob and Congratulations.
I would say that is true of most DIY subs that are 18's or bigger.

But especially so for the LMS-18, FTW-21 and SI-24 drivers. By the time you bottom them out the cops are banging on the door with guns drawn. (and if not, add more... LOL)

Especially when you throw them into a Horn, where you gain 6-10db across the board and 12-16db near tuning (per cone...) as per modelling and data-bass charts:

When I converted 1 of my 4 sealed LMS-18's into a HzHorn it was just as loud as the remaining 3 subs and their connected amplifiers, COMBINED...

Horns also have very low amounts of chuffing because the mouth is so big, which helps keep THD lower than ported.

Going from sealed to ported you gain about 10-14db near tuning, and less then ~1db above 45hz. (Data-bass needs to measure more ported subs...)


The problem with 15-20hz horns is that they are big and hard to build... and they are totally useless above 80-120hz, unlike ported and sealed which remain musical to ~250hz. (There is no free lunch...)
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