I have decided I want to build my own sub

[highfigh]

That is of course, anechoic (1M) / field (2M) results. I don't know of any other driver at any cost that even come close to these results. In room, that is at least 118-120dB at 20Hz, from a single driver in a very undersized sealed box. I fail to see how this can not impress, since distortion is still relatively low, and very little power compression is occuring. This is simply demonstrating the driver is in a league of it's own when it comes to handling massive excursion, thermal capacity and motor linearity.

Put the driver in a more ideal enclosure, and it will easily produce far more SPL in the bottom octave. You know that a tiny sealed box results in a great deal of loss to SPL at the lowest octave. This type of arrangement is very important/useful in applications where the sub must have the smallest possible size yet retain as much performance as possible.

Here is the driver in a box using massive passive radiators:
http://www.hometheatershack.com/forums/subwoofer-tests-archived/8156-diy-tc-sounds-lms-5400-18-2x18-page-ranking-200l.html

Output, anechoic (1M), is about 116-118db for most of the range. You will come to around 130dB in an average closed room with this single driver, in an ideal cabinet type/design. Distortion/compression remains incredibly low.

-Chris

How are they achieving an anechoic space at such low frequencies?

 

[BigSkreen]

Is there a way to adjust the size and shape of the other parts that would allow you to make the smallest difference in the box's volume, so it would still work for your design? That way, you don't need to go through all of this.

I had already glued parts together. I ended up getting another piece and cutting it.

 

[BigSkreen]

I sealed the inside. I also used rope caulk around the edges of the sub to seal it. I was getting a little bit of air through one of the screw holes but not much. I tested it again and the difference is night and day. I don't get the sounds that I was. I still think the bass is a little anemic but I've just pushed it against the wall. I haven't had time to place it or adjust any of the settings.

Sometime this week maybe I'll do the sub crawl and put it in a more ideal location. Then I'll tweak the settings. It could probably use a few db in the lower end.

 

[TLS Guy]

I sealed the inside. I also used rope caulk around the edges of the sub to seal it. I was getting a little bit of air through one of the screw holes but not much. I tested it again and the difference is night and day. I don't get the sounds that I was. I still think the bass is a little anemic but I've just pushed it against the wall. I haven't had time to place it or adjust any of the settings.

Sometime this week maybe I'll do the sub crawl and put it in a more ideal location. Then I'll tweak the settings. It could probably use a few db in the lower end.

Thanks for the update. I was pretty sure leaks were your major problem. Keep chasing them down!

Remember a sealed sub will have a more subtle bass quality than a ported one.

 

[BigSkreen]

To be honest its been hard for me because I've never had a sub as part of my system and nothing in that room so I have no idea what it should sound like. I know that sounds weird but that makes it kind of hard to tune the system.

 

[lsiberian]

To be honest its been hard for me because I've never had a sub as part of my system and nothing in that room so I have no idea what it should sound like. I know that sounds weird but that makes it kind of hard to tune the system.

It should sound natural. Find your favorite piece of bass music. I suggest you start in a corner and work your way out till you get what you want. It shouldn't be boomy or thin, but clean and natural. Unless you listen to rap music a lot.

 

[MStrickland1988]

Pretty cool project. Good work.

 

[BigSkreen]

I am debating on if I should do the sub crawl today or hunt for more leaks. I know I have one around the screw hole on the sub. How air tight does this have to be. What sonic difference will I see? I know what a totally unloaded sub sounds like now. But if the sub is functioning what will a little extra loading do?

 

[TLS Guy]

I am debating on if I should do the sub crawl today or hunt for more leaks. I know I have one around the screw hole on the sub. How air tight does this have to be. What sonic difference will I see? I know what a totally unloaded sub sounds like now. But if the sub is functioning what will a little extra loading do?

It needs to be really sealed. Even small leaks will detract from performance. Getting that enclosure airtight apart from a tiny hole from the smallest drill to equalize changes in atmospheric pressure is job one for any sealed sub. Your driver's life depends on it also.

 

[WmAx]

I am debating on if I should do the sub crawl today or hunt for more leaks. I know I have one around the screw hole on the sub. How air tight does this have to be. What sonic difference will I see? I know what a totally unloaded sub sounds like now. But if the sub is functioning what will a little extra loading do?

Well, TLS is right about sealing. Address that first. After that, it may be that sealed is just not for you. You may want to go ported, which requires a larger, more complex cabinet. The driver you have is the best 15" woofer design in the world; so there is no 'upgrading' the driver - not possible - at least not for linear displacement; the LMS driver has the most linear motor in the world. You can add more power; that driver will take more power than an EP4000 can produce. A ported cabinet will double the output on the lowest octave, if you build the cabinet properly. Or you can go with a more efficient driver; more SPL is delivered per watt - though nothing will exceed the low octave output of the LMS if you have enough power to push it. It has a near textbook perfect flat motor power curve well past 30mm one way and virtually no thermal compression even with well over 1000 watts input; pretty much unheard of except for the absolute top world class drivers.

-Chris

 

[lsiberian]

Well, TLS is right about sealing. Address that first. After that, it may be that sealed is just not for you. You may want to go ported, which requires a larger, more complex cabinet. The driver you have is the best 15" woofer design in the world; so there is no 'upgrading' the driver - not possible - at least not for linear displacement; the LMS driver has the most linear motor in the world. You can add more power; that driver will take more power than an EP4000 can produce. A ported cabinet will double the output on the lowest octave, if you build the cabinet properly. Or you can go with a more efficient driver; more SPL is delivered per watt - though nothing will exceed the low octave output of the LMS if you have enough power to push it. It has a near textbook perfect flat motor power curve well past 30mm one way and virtually no thermal compression even with well over 1000 watts input; pretty much unheard of except for the absolute top world class drivers.

-Chris

Have you had the chance to evaluate a 21" Maelstrom? It looks very promising.

I wonder how it would compare to the 18" LMS. I"m sure it would lose, but I do wonder how they would compare. I really want to see a ground plane measurement on the 18" LMS in a folded port box. I know they did a P-R one that had the highest spl and lowest distortion at 20hz measured by Illka.

 

[WmAx]

Have you had the chance to evaluate a 21" Maelstrom? It looks very promising.

I wonder how it would compare to the 18" LMS. I"m sure it would lose, but I do wonder how they would compare. I really want to see a ground plane measurement on the 18" LMS in a folded port box. I know they did a P-R one that had the highest spl and lowest distortion at 20hz measured by Illka.

XBL2 is nice, but I have never seen evidence showing it was close to LMS. Now, we can look at available comparable testing that has been done to date. While the DIYCABLE subs like Maelstrom have not been tested, another popular XBL2 design has been. The 15" CSS XLB2 design is on hometheatershack's sub testing database, and the standard TC 2K motor 15" has about 50% superior performance in all ways, and the 2k is two steps down from the LMS motor (TC3000/AXIS being the intermediate).

-Chris

 

[BigSkreen]

I've gotten the sub pretty well sealed but I have a few questions. I also placed the sub in the corner unfortunately its about 1 foot away from my chair. This seemed to get the best bass besides the front corner which put the sub behind my floorstanding speakers.

1. The last leaks were the screw holes in the sub. Any suggestions on how to seal them. My first thought was some silicon inside the back of the hurricane nuts. Right now I have some rope caulk in the screw holes temporarily.

2. I put a temporary hole in the side of the box because I'm waiting for my terminal cup but after having placed the sub I would like to move the hole. Its about 5/8" (also temporarily sealed). Will wood filler or wood glue be a sufficient patch?

3. Does the sub itself have to face out of the corner? I was wondering what would spinning the sub 180 degrees do to the sound?

I really appreciate all the help everyone here has given me this certainly has been a learning experience.

 

[TLS Guy]

I've gotten the sub pretty well sealed but I have a few questions. I also placed the sub in the corner unfortunately its about 1 foot away from my chair. This seemed to get the best bass besides the front corner which put the sub behind my floorstanding speakers.

1. The last leaks were the screw holes in the sub. Any suggestions on how to seal them. My first thought was some silicon inside the back of the hurricane nuts. Right now I have some rope caulk in the screw holes temporarily.

2. I put a temporary hole in the side of the box because I'm waiting for my terminal cup but after having placed the sub I would like to move the hole. Its about 5/8" (also temporarily sealed). Will wood filler or wood glue be a sufficient patch?

3. Does the sub itself have to face out of the corner? I was wondering what would spinning the sub 180 degrees do to the sound?

I really appreciate all the help everyone here has given me this certainly has been a learning experience.

1). I would use flexible silicone sealant/caulking.

2). I would use fiber glass body patch like the body shop men use.

3). Just change the phase, so the phase switch would have to be set in the opposite direction.