4 LMS 5400s in my enclosures. Doable? - Page 2 - AVS Forum
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post #31 of 79 Old 03-22-2012, 11:51 PM
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I ran my LMS facing up for 6 month's with no noticeable problems. Mine has the titanium cone, slightly heavier.
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post #32 of 79 Old 03-23-2012, 06:44 AM
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TC actually spec the new ones at 47.6 mm and the old ones were 44mm. I always thought it seemed a little generous but never actually checked. 42 it is.
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post #33 of 79 Old 03-23-2012, 07:16 AM - Thread Starter
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Thanks, LINEARX

Yeah, Scott, I was worried too. I still am a bit worried actually. You can still hear faint mech noises from the spider area in some drivers more than others. One driver developed a bit of a scrape/clack when I tilted it a bit to clear the pole vent. I was so tired at that point I just said F' it and went to bed.

Even if all the drivers are good I'm a bit concerned that 1KW per driver will be too little. These things soaked up 250W free air with less than an inch of excursion at around 40Hz and clipped my Model Three. I moved them to my Hypex at 400 W and got just a couple Db more before that clipped. My Crown will do 1KW per driver all day long, but if it's clipping the drivers are at risk and that's just not acceptable.
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post #34 of 79 Old 03-23-2012, 07:46 AM
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Quote:
Originally Posted by Ricci View Post

TC actually spec the new ones at 47.6 mm and the old ones were 44mm. I always thought it seemed a little generous but never actually checked. 42 it is.

Yeah apparently the spider support is shorter in the new ones. I'd worry about bottoming out the VC at that point though. I think I'd rather have the cone bottom on the spider support. Either way, at that excursion level, its like 1db difference if that. If the old ones were listed at 44, its possible. My measurement methods weren't the greatest.

However, I did notice on the forward stroke that I was only seeing about 33mm of movement before bad clanking noises on the back stroke. I wonder how linear things are at that level. I tested the same thing on 3 drivers and same result each time.
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post #35 of 79 Old 03-23-2012, 10:53 AM
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Quote:
Originally Posted by pwz414 View Post

Thanks, LINEARX

Yeah, Scott, I was worried too. I still am a bit worried actually. You can still hear faint mech noises from the spider area in some drivers more than others. One driver developed a bit of a scrape/clack when I tilted it a bit to clear the pole vent. I was so tired at that point I just said F' it and went to bed.

Even if all the drivers are good I'm a bit concerned that 1KW per driver will be too little. These things soaked up 250W free air with less than an inch of excursion at around 40Hz and clipped my Model Three. I moved them to my Hypex at 400 W and got just a couple Db more before that clipped. My Crown will do 1KW per driver all day long, but if it's clipping the drivers are at risk and that's just not acceptable.

The big issue with this post is bolded above. Long throw drivers dont bottom out at 40Hz. Move that down an octave...
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post #36 of 79 Old 03-23-2012, 11:56 AM - Thread Starter
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It didn't bottom out. It was barely moving and it made a scrape/clack sound. I barely would have heard 20Hz. It was a clearly audible signal and it clearly scraped. I said to myself, this is BS and went to bed. I'll check again today.
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post #37 of 79 Old 03-23-2012, 12:34 PM
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Quote:
Originally Posted by pwz414 View Post

It didn't bottom out. It was barely moving and it made a scrape/clack sound. I barely would have heard 20Hz. It was a clearly audible signal and it clearly scraped. I said to myself, this is BS and went to bed. I'll check again today.

that wouldnt be clipping then, but perhaps something that is lodged down in the motor structure, or possible the motor shifted and is not centered.

(European models do not accept banana plugs.)

 

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post #38 of 79 Old 03-23-2012, 12:43 PM - Thread Starter
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We're talking about two different occurrences. I apologize if that's not clear. The clipping occurred with different drivers (still LMSU's).

While we're at it. I see a flat spot on this coil. The shipping boxes were in pristine condition; even the motors.

I can sense where this is going. "The newb over punted his coverage and doesn't understand the intricacies of the LMS-U."

There is distortion emanating from the spider area of at least one driver at very low output levels, another driver scrapes when I tilt it, and the third appears to have a flat spot on its voice coil. There are high and low spots in every surround. However, none of the drivers exhibit scraping during manual manipulation.


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post #39 of 79 Old 03-23-2012, 01:16 PM - Thread Starter
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Quote:
Originally Posted by Ricci View Post

The big issue with this post is bolded above. Long throw drivers dont bottom out at 40Hz. Move that down an octave...


Are you saying you're more concerned about them being under powered in the lower frequency range? Clipping can also cause thermal damage, right? So even at higher frequencies the clipping could result in the VCs getting too hot without the drivers bottoming out.
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post #40 of 79 Old 03-23-2012, 06:44 PM - Thread Starter
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Thankfully I can't reproduce the scrape I'm not worrying about these things anymore until the enclosures are ready.
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post #41 of 79 Old 03-25-2012, 09:52 PM - Thread Starter
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One cabinet is up and running. These things soak power! They sound nice though. My eq is set opposite to what they need. Boosted low and trimmed high.

Will these things be a little more efficient after break in?

No nasties, other than the room of course. One cabinet is equal to both cabs containing the 21s in the low end, but less efficient above about 40. To be expected.

Thanks for the help in deciding. I'm sure they'll just murder movie tracks.
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post #42 of 79 Old 03-25-2012, 10:22 PM
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Pics! Glad you got a couple of them up and running...

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #43 of 79 Old 03-26-2012, 06:57 AM - Thread Starter
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Here are some pics. Now my primary concern will be responsible break in and room treatments. We've just installed tile floors, the windows and heat exchangers rattle, but other than that the room has some nice perks. The lines run almost to the ceiling, room gain is high, and the subs have concrete on two/three sides (not yet, was floating near the center of the structure last night during play time).

The Crown will clip easily with two of these per channel. It is seemingly more likely to do so in higher frequencies. The infrasonic T Rex stuff from "The Fantasy Adventure Album" and the low stuff from Xzibit are nowhere near clipping, were as punchy stuff like Black Rob: "Whoa" and kick drums are more likely to clip. Interesting stuff.

Do you guys think when these things loosen up they be a little easier to drive?





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post #44 of 79 Old 03-26-2012, 10:25 AM
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Quote:
Originally Posted by pwz414 View Post

Do you guys think when these things loosen up they be a little easier to drive?

After a few weeks of use, i had to turn mine down a bit so that they were level matched again. They definitely loosened up for me.
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post #45 of 79 Old 03-26-2012, 01:46 PM - Thread Starter
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Good to know. The 21s were a bit quicker to clip the Crown at first, but that stopped almost entirely over a couple months. They sounded dramatically better and more effortless after a bit of time too.
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post #46 of 79 Old 03-26-2012, 10:03 PM
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Did you use the 10-19hz to break them in at all?

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #47 of 79 Old 03-27-2012, 06:31 AM - Thread Starter
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No, the basement is under construction. People, traffic, and particulates everywhere. The only amp that will tolerate the sustained 2 ohm load is restricted to the basement by power requirements. I didn't feel comfortable leaving them unattended down there. When construction is finished I'll take them out a couple at a time and give them a couple hours of break in.
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post #48 of 79 Old 03-27-2012, 06:44 AM
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They are d2, should be able to do series them 4 ohm stereo. 50v should be adequate. Do a pair at a time

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #49 of 79 Old 03-27-2012, 08:38 AM - Thread Starter
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Yeah, you're right. I'll figure something out. Don't you get nervous at the thought of leaving them unattended?
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post #50 of 79 Old 03-27-2012, 09:01 AM
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No worries once you set it up. Just be sure to secure them, and learn from my mistake... don't hang them from the ceiling. I have let drivers run for a couple of days before. Once you set a safe but effective voltage level just let them settle in.

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #51 of 79 Old 03-27-2012, 09:11 AM - Thread Starter
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How much excursion on the lowest AF?
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post #52 of 79 Old 03-27-2012, 09:21 AM
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I'll usually set it up to a couple of gain knob clicks below the start of mechanical noise for clean stroke, and then double check voltage. Some say 30v at 20 hz is enough but it all depends on amp and woofer combo.

I use the 10-19 bit I sent you and one of my old FTX-2001 for break in, it can do 1kw at 8ohm mono so it does the job.

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #53 of 79 Old 03-27-2012, 09:49 AM
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At those frequencies the excursion is enough to basically "self-cool" the sub even if you leave it in the box. I usually run a solid 20hz sine to break in. Wi, what file is that that you run 10-19hz?

(European models do not accept banana plugs.)

 

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post #54 of 79 Old 03-27-2012, 09:57 AM
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PM me your email

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #55 of 79 Old 03-27-2012, 10:53 AM
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downfiring these drivers long term I am not so sure about. I've never done it but I would avoid it if I could. the assembly weighs over 500 grams so you would have to assume that over time that weight will eventually pull the suspension away from center.
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post #56 of 79 Old 03-27-2012, 12:17 PM - Thread Starter
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Thank you very much, Ricci
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post #57 of 79 Old 03-29-2012, 08:55 AM - Thread Starter
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If these boxes are halved to accommodate a front facing vertically mounted alignment, how much bracing should be added? The internal dimensions would be 27” x 27” x 16.5”.

In this position they would have 6" between the pole vent and the rear panel.

They will be laid on their sides for a period of time before committing to cutting.

The positioning advantages of four "small" enclosures are exciting, but the thought of losing the noise cancelling of dual opposed sucks.

Thoughts?
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post #58 of 79 Old 03-29-2012, 09:01 PM - Thread Starter
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Holy s***!
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post #59 of 79 Old 03-29-2012, 09:23 PM
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Holy s***!

Huh???
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post #60 of 79 Old 03-29-2012, 09:28 PM - Thread Starter
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These things are ridiculous.
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