LMS 5400 18" 6.1 cu ft sealed - Page 7 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #61 of 103 Old 02-19-09, 10:00 AM Thread Starter
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Re: LMS 5400 18" 6.1 cu ft sealed

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cochinada wrote: View Post
You are certainly right, at least speaking for myself. By the way, how do those subwoofers compare next to the LMS? Is there any test made around maybe by IKKA?
I have not seen any tests equivalent to Ilkka's done on the Mal-X or the Avalanche, however we know from hearing the results of other DIYers that both of those drivers are "heavy weights" and can produce some impressive numbers.
I think I read in another thread that someone was sending a Mal-X to Ilkka for testing. Test not complete yet.
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post #62 of 103 Old 02-19-09, 10:24 AM Thread Starter
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Re: LMS 5400 18" 6.1 cu ft sealed

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That's great but did you think how are you going to open that door afterwards?
By the way that thing hanging on the wall looks very nice!
Hmmmmm . . . . . the door . . . . just a closet. It'll probably have to be stabilized to control vibration.

The "thing" on the wall is an American Indian Mandella. I'm still working on getting the tribe to provide it with their spirit and tribal protections. You just can't go up to the Assiniboine chief and say, "here, would you drive away the bad spirits?"

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post #63 of 103 Old 02-19-09, 11:02 AM Thread Starter
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Re: LMS 5400 18" 6.1 cu ft sealed

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kyle_k wrote: View Post
Phil, i'm happy to see you like your sub, it makes the efforts here worth while.

yes, TC sounds is making a return, Thilo and i have been quietly working on new production and products. We did go through a major overhaul of the products for the 09 built. Currently the designs are finalized and we're in the prototype / sample phase with various venders. The pieces will not be built in san diego anymore. We're having a larger, more capable build house overseas run the production. Obviously quality will be a chief priority for us. The 09 LMS Ultra 18" has been one of the drivers that undertook some major changes.
Hey Kyle!
Thanks for the update. All of us are just dripping with anticipation for the next product from you two. Hopefully the 09 LMS Ultra 18" changes will allow for better price point for marketing and that the level of performance has been improved even if the only thing you've added is a new "servo drive" system and a new logo on the dust cover.
I hope you and Thilo are aware that the LMS 18" driver has become the defacto standard against which all other drivers are measured and compared. It's even developing mythological qualities through places like YouTube.
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post #64 of 103 Old 02-19-09, 11:16 PM
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Re: LMS 5400 18" 6.1 cu ft sealed

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ISLAND1000 wrote: View Post
Hey Kyle!
Thanks for the update. All of us are just dripping with anticipation for the next product from you two. Hopefully the 09 LMS Ultra 18" changes will allow for better price point for marketing and that the level of performance has been improved even if the only thing you've added is a new "servo drive" system and a new logo on the dust cover.
I hope you and Thilo are aware that the LMS 18" driver has become the defacto standard against which all other drivers are measured and compared. It's even developing mythological qualities through places like YouTube.

Parts Express has the final say in pricing, but they have been known for good sales and im sure they will find a good balance for the market the lms finds itself in. I dont want this driver to be un-uptainium, thats no fun.

I wouldnt say there good reason for a servo system on this driver. The force is very linear (1% modeled fluctuation inside of 27mm) inside the working range and the servo has its own set of sensory uncertainties that add secondary complications. Also, getting a servo device to work right and remain transparent to the system and its integrity is somewhat of a skill.
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post #65 of 103 Old 02-19-09, 11:42 PM Thread Starter
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Re: LMS 5400 18" 6.1 cu ft sealed

OK on pricing. I've shopped Parts Express many times over the years and always thought their price structure was excellent.
My servo remark was kinda tongue in cheek. I read all the TC literature regarding the LMS motor and VC structure and linearity before I bought it. I felt your information was honest, logical, and fairly simple . . . . it just took 75 pounds of large this, big that, and huge magnets to make it all come together. And then half way through the 2nd run, I think it was, you changed the cone to (Titanium)!!?? What a stroke of genius THAT was. Anyway, before I melt from too much enthusiasm thanks for being on the cutting edge of driver technology and giving us DIYers a way to spend nights and weekends at home making music to our ears unlike thousands of others who wander in the Home Theater darkness without so much as one 40hz @ 110db to their name.
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post #66 of 103 Old 02-20-09, 02:02 AM
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Re: LMS 5400 18" 6.1 cu ft sealed

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ISLAND1000 wrote: View Post
OK on pricing. I've shopped Parts Express many times over the years and always thought their price structure was excellent.
My servo remark was kinda tongue in cheek. I read all the TC literature regarding the LMS motor and VC structure and linearity before I bought it. I felt your information was honest, logical, and fairly simple . . . . it just took 75 pounds of large this, big that, and huge magnets to make it all come together. And then half way through the 2nd run, I think it was, you changed the cone to (Titanium)!!?? What a stroke of genius THAT was. Anyway, before I melt from too much enthusiasm thanks for being on the cutting edge of driver technology and giving us DIYers a way to spend nights and weekends at home making music to our ears unlike thousands of others who wander in the Home Theater darkness without so much as one 40hz @ 110db to their name.

no prob!

i did quite a bit of research on linear technologies last year, in part because of a new one i developed (patent officially filed yesterday, i'm kind of excited, and out $8,000 dollars too!!) but in doing that, i got really accurate modeling analysis on the lms and what it takes to get BL back. Its actually not *that* bad. but a bit deceiving to make comparisons. By definition, the L is removed from the coil therefore there is a loss not only in BL, but also in moving mass. In order to make apples to apples, L should be added in the correct ratio such to get back the exact mass of the standard overhung coil. The final BL losses after accounting for gap re- dimensioning (including thermal expansion) is just over 10%. The beefy motor on the LMS-5400 is needed for that heavy moving mass and wide voice coil. Makes for a really capable subwoofer at the end of the day. We're making more efforts to lighten up moving mass and tighten up the gap to make future lms's more practical for smaller examples.

The ti cones are second to none when i comes to beauty. unfortunately our vender just could not get quality control of the metal and nearly 2 out of 3 failed our QC (blemishes) by the last run, so we had to powder coat, but our costs still remained sky rocketed so we moved to aluminum for audiopulse products. The 09 lms's will be fitted with a different cone. We're using acrylic rochacel with fiberglass on both sides epoxy'ed together. This is a bit lighter than aluminum and titanium but its remarkably stronger and more durable. In fact, its very similar to lightweight airplane wings.

The idea is to make people that already have lms's jealous again! ...hard to do
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post #67 of 103 Old 02-20-09, 10:49 AM Thread Starter
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Re: LMS 5400 18" 6.1 cu ft sealed

I don't know that the emotion would be jealousy . . . . maybe more like "holy cow, why didn't I think of that?"
You're in an interesting area of engineering where abstract thoughts and math turn into concrete ideas and materials and those in turn become "product". It don't get any better than that.
I've followed the development of cone material with interest from paper to titanium. I realize the difficulty of working with titanium like in the LMS cone, it turns out to be slightly heavier than some other highly exotic combination materials such as you've mentioned for the 09 Pulse series.
A while back I bought an AUDAX driver that used "Aerogel" as the cone material. I used it long enough to form an appreciation for the lightweight material and the subsequent low Le of the voice coil. Unfortunately the minimal strength of voice coil former didn't match the power I needed and the voice coil former deformed and began to rub.
How would your layered cone material compare to "Aerogel"?.

A question came up about the level of BL. Amplifier engineers are always struggling with back EMF and what to do with it in terms of reducing distortion levels. Has back EMF ever been a design consideration in building the LMS/Pulse?
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post #68 of 103 Old 02-20-09, 11:45 AM
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Re: LMS 5400 18" 6.1 cu ft sealed

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kyle_k wrote: View Post
no prob!

i did quite a bit of research on linear technologies last year, in part because of a new one i developed (patent officially filed yesterday, i'm kind of excited, and out $8,000 dollars too!!) but in doing that, i got really accurate modeling analysis on the lms and what it takes to get BL back. Its actually not *that* bad. but a bit deceiving to make comparisons. By definition, the L is removed from the coil therefore there is a loss not only in BL, but also in moving mass. In order to make apples to apples, L should be added in the correct ratio such to get back the exact mass of the standard overhung coil. The final BL losses after accounting for gap re- dimensioning (including thermal expansion) is just over 10%. The beefy motor on the LMS-5400 is needed for that heavy moving mass and wide voice coil. Makes for a really capable subwoofer at the end of the day. We're making more efforts to lighten up moving mass and tighten up the gap to make future lms's more practical for smaller examples.

The ti cones are second to none when i comes to beauty. unfortunately our vender just could not get quality control of the metal and nearly 2 out of 3 failed our QC (blemishes) by the last run, so we had to powder coat, but our costs still remained sky rocketed so we moved to aluminum for audiopulse products. The 09 lms's will be fitted with a different cone. We're using acrylic rochacel with fiberglass on both sides epoxy'ed together. This is a bit lighter than aluminum and titanium but its remarkably stronger and more durable. In fact, its very similar to lightweight airplane wings.

The idea is to make people that already have lms's jealous again! ...hard to do

Nice stuff. I can't wait to see your patent as it pertains to linear motors. When will the patent application documents be available to read? I think that the move to Rohacell will be a good one and I'm actually happy to see it. You are right about making LMS owners jealous. I have another one lined up but I'm hesitating because I don't want to have buyers remorse when the 09 model comes out. I can already see myself selling the 2 older versions to upgrade to the newer versions.
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post #69 of 103 Old 02-20-09, 03:59 PM
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Re: LMS 5400 18" 6.1 cu ft sealed

This is exciting stuff!

It is great to see that even when someone appears to be down, they are not out, but actually regrouping to come back stronger than before!

I love the fact that you are not just sitting back and saying "it is good enough". It is great to see that you have found areas to improve.

I don't have much direct experience with your drivers, but I am well aware of how the designs work. I do plan to gain some experience with them in the near future.

One question, with using such a long throw design, have you had issue with surrounds "puckering" at high excursion?

Also, based upon the BL curves I have seen with some of your drivers, it appears as though they are linear right out to the limits of excursion. I assume a tight manufacturing tolorance needs to be in place so as not to have motor force exceed the mechanical limits.

I also noticed that your designs to drop off motor force near the limits of the woofers excursion. How much overhead is allowed in the suspension to allow for manufacturing variances to prevent possible damage?

Sorry, one more question, how are you controlling the suspension linearity with such long throw? Tighter tolorance in the gap requires very linear suspension. Is the suspension design also improved in this case?

I eagerly await your patent drawings to see what innovations you have come up with.

Quote:
kyle_k wrote: View Post
no prob!

i did quite a bit of research on linear technologies last year, in part because of a new one i developed (patent officially filed yesterday, i'm kind of excited, and out $8,000 dollars too!!) but in doing that, i got really accurate modeling analysis on the lms and what it takes to get BL back. Its actually not *that* bad. but a bit deceiving to make comparisons. By definition, the L is removed from the coil therefore there is a loss not only in BL, but also in moving mass. In order to make apples to apples, L should be added in the correct ratio such to get back the exact mass of the standard overhung coil. The final BL losses after accounting for gap re- dimensioning (including thermal expansion) is just over 10%. The beefy motor on the LMS-5400 is needed for that heavy moving mass and wide voice coil. Makes for a really capable subwoofer at the end of the day. We're making more efforts to lighten up moving mass and tighten up the gap to make future lms's more practical for smaller examples.

The ti cones are second to none when i comes to beauty. unfortunately our vender just could not get quality control of the metal and nearly 2 out of 3 failed our QC (blemishes) by the last run, so we had to powder coat, but our costs still remained sky rocketed so we moved to aluminum for audiopulse products. The 09 lms's will be fitted with a different cone. We're using acrylic rochacel with fiberglass on both sides epoxy'ed together. This is a bit lighter than aluminum and titanium but its remarkably stronger and more durable. In fact, its very similar to lightweight airplane wings.

The idea is to make people that already have lms's jealous again! ...hard to do
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post #70 of 103 Old 02-20-09, 06:23 PM
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Re: LMS 5400 18" 6.1 cu ft sealed

Quote:
ISLAND1000 wrote: View Post
I don't know that the emotion would be jealousy . . . . maybe more like "holy cow, why didn't I think of that?"
You're in an interesting area of engineering where abstract thoughts and math turn into concrete ideas and materials and those in turn become "product". It don't get any better than that.
I've followed the development of cone material with interest from paper to titanium. I realize the difficulty of working with titanium like in the LMS cone, it turns out to be slightly heavier than some other highly exotic combination materials such as you've mentioned for the 09 Pulse series.
A while back I bought an AUDAX driver that used "Aerogel" as the cone material. I used it long enough to form an appreciation for the lightweight material and the subsequent low Le of the voice coil. Unfortunately the minimal strength of voice coil former didn't match the power I needed and the voice coil former deformed and began to rub.
How would your layered cone material compare to "Aerogel"?.

A question came up about the level of BL. Amplifier engineers are always struggling with back EMF and what to do with it in terms of reducing distortion levels. Has back EMF ever been a design consideration in building the LMS/Pulse?
the cone we have now is very durable, a bit lighter than our current metal cones like i said, but strong enough to stand on... literally, we did stand on it and it did not crack. Its probably not lighter than your Audax cone, but ours is also pretty beefy (~4.5mm thick). Formers are a tricky issue, they have so many issues that you really have to comprises. The new forums we have are actually stainless steel, believe it or not they came out to be about the same mass as our previous titanium formers. Stainless bonds better and is easier to form than ti and it should hold up to higher temps for that reason. It also has almost the exact same electrical properties so it will sound very good. Aluminum formers conduct heat well, but also current so they sound much worse because of eddy currents generated from the moving B field.. its that whole Faraday's law thing. The amount of distortion depends on the ratio of wire to former.

The back EMF is not a problem with the LMS designs, but i has been with the 4HP's, we have made some 4HP's with a BL^2/Re over over 500. For those that don't know that is outright insane! the Qts actually drops below 0.1.. its a scary about of force, but its hard on amps. If they don't make enough volts, the power will not be there. I remember the first Aura drivers have too much BL and they had to re design their motors and reduce the size of the magnets and their sub made more bass!

Quote:
Ricci wrote: View Post
Nice stuff. I can't wait to see your patent as it pertains to linear motors. When will the patent application documents be available to read? I think that the move to Rohacell will be a good one and I'm actually happy to see it. You are right about making LMS owners jealous. I have another one lined up but I'm hesitating because I don't want to have buyers remorse when the 09 model comes out. I can already see myself selling the 2 older versions to upgrade to the newer versions.

Thanks Ricci, it was a lot of fun to do but a lot of work also. The exciting part is it has even more efficiency than lms and xbl^2. No products planned yet, sorry. As far as the lms’s, wait for the 09’s they have undercut t-yokes and 3 shorting rings, and 11” spiders, ya I want one too!

Quote:
annunaki wrote: View Post
This is exciting stuff!

It is great to see that even when someone appears to be down, they are not out, but actually regrouping to come back stronger than before!

I love the fact that you are not just sitting back and saying "it is good enough". It is great to see that you have found areas to improve.

I don't have much direct experience with your drivers, but I am well aware of how the designs work. I do plan to gain some experience with them in the near future.

One question, with using such a long throw design, have you had issue with surrounds "puckering" at high excursion?

Also, based upon the BL curves I have seen with some of your drivers, it appears as though they are linear right out to the limits of excursion. I assume a tight manufacturing tolerance needs to be in place so as not to have motor force exceed the mechanical limits.

I also noticed that your designs to drop off motor force near the limits of the woofers excursion. How much overhead is allowed in the suspension to allow for manufacturing variances to prevent possible damage?

Sorry, one more question, how are you controlling the suspension linearity with such long throw? Tighter tolerance in the gap requires very linear suspension. Is the suspension design also improved in this case?

I eagerly await your patent drawings to see what innovations you have come up with.

Yes, puckering occurs and its one of the things we are working on changing, not sure it will make the 09 production, but like everything it’s a tradeoff. We’re hoping to use foamed rubber which is light, but still durable. Straight foam will fix the problem, but its also stiffer and far less durable long term. We have two tall rubber surrounds a thick and a thin. The thin is what we use for the drivers and that will dimple at high excursion. Hopefully we can improve that down the road. The thicker one has no issues at all, but its very heavy – perfect for the VMP and it will be used for the 09 VMP’s. The mechanical limits of the big LMS were increased so it won’t bottom any more (surround limited) well… I’m always surprised how much things stretch so it will at least be very difficult to bottom now. 4.00” peak to peak is what it will see now, you’ll need a Labgruppen to do that.

The spiders were stiffened up from the tc to the audiopulse change and we already shaved 0.018” off the former ID. And we tooled a new spider for the big LMS (almost 11” now)

Last edited by kyle_k; 02-21-09 at 05:23 AM.
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