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Discussion Starter #1
Hello All!

So I've been reading a bunch of the builds on this woofer along with others. I've played around with WinIsd and feel a bit overwhelmed. I have a few questions that might seem retarded, but i'm stuck.

-Xmax is listed at 33mm with a Xmech of 40mm. which number should i be more conscious of? when i've been modeling, i try to stay just below 33mm which usually occurs around 10hz.

-Pmax is 1500w yet i see people running much more using crowns or 2500's. what would be the right amount of power to put through this woofer and maintain reliability.

-i see people running different sized sealed units. it seems that the smaller the box, the less excursion you get given the same amount of input power. is this correct? if so, what is the benefit to running a 150L box versus say 225L box?

-given room constraints, i am thinking of building one box with opposing drivers. possibly to cancel out any vibration, if there is any. this would be instead of building two sealed boxes. the thought being that i could maybe stack my tv on the big box and hopefully not experience any tv vibration.

-i can eq with my SMS-1 which has helped lots in playing around with phase, slope, etc. so i do have the ability to tune things even if the sub doesn't go in a great spot.

any and all help is appreciated :)

thank you,

joe
 

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I would try to model with Xmax rather than Xmech which is the mechanical limit of the Driver in relation to excursion, even though the Driver will not bottom above 33mm it will not sound very good either :T

As for power the reason people run huge amplifiers is for the headroom they provide, most of the time listening to music or watching a movie the actual power being sent to the sub is probably very little (about 50 watts) however why there is a large explosion the sub is suddenly sent more power. The reason for a larger amplifier than is needed is becasue larger amplifiers will not clip when there is an explosion or a loud noise becasue they have more power reserve so to speak. Although some do not agree with a sealed sub i would recomend buying the most powerfull amplifier you can afford, A good example would be the EP1500 vs the ... EP2500, you are much better getting the EP2500 for the extra $50 becasue it provides more headroom and does not have to be run as hard to provide reference levels, even if the EP1500 will drive the sub to Xmax.

I have never blown a woofer, ever... Even in my car i have run 100watt RMS subs on 1000Watt amplifiers and never had problems becasue im not stupid. Listen to your speaker, if its exceding Xmax and is starting to sound distorted then turn it down. The only real reason for a dead speaker is when it is used for a purpose other than intended. If you have a huge room and try to get reference levels with a single 8 then chances are it will not survive very long becasue you will over drive the speaker casue mechanical or thermal failure.

Now coming to the box size. The larger a sealed box the slower the roll off. This means that a larger sealed box will have a slower roll of in the lower frequencies then a smaller box. For home theater a sealed box needs to be much larger than for Car use. Always aim for a maximum QTC of 0.7 and the lower the better. As a sealed box gets larger the air suspension behind the woofer gets lower meaning there is less pressure behind the subs in the box. This means that the subs will have more excursion for a given level of input power and therefore less power handling. Do some general reading here to find out more :daydream:

A box with opposing drivers will work and you shouldnt have too many problems with TV vibration providing the box is well build and braced.

Have a read here to for some simple but good information on subwoofers http://www.audiopulse.com/know-how/

:whew:
 

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Discussion Starter #3
thank you very much! good thing this stuff isn't addicting ;)

with box size are you saying lower than .7 or as close to it as possible?

:)
 

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thank you very much! good thing this stuff isn't addicting ;)

with box size are you saying lower than .7 or as close to it as possible?

:)
It depends on the aplication, is it movies only or music too? I personally build to 0.7 becasue you can add stuffing to lower the QTC of the box. For example i think a box with a QTC of 0.7 can be stuffed down to 0.6 with polyfill or pillows or whatever...

I find that a QTC of 0.7 provides the best balance of low end and power handling. Not to mention the volume needs to increase significantly to get a lower QTC in which case your better of with a LLT

I vote a box with a QTC of 0.7, using the WinISD file here for two maelstrom's i get a internal volume of 402L or 14ft^3 :T That gives you a F3 of 30Hz which is really good (means the box will be 3db down at 30Hz) and with 2000 watts you will not reach Xmax until 4Hz meaning no subsonic filter is needed :bigsmile: Very Very nice sub for either Home theater or music...
 

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Discussion Starter #5
It depends on the aplication, is it movies only or music too? I personally build to 0.7 becasue you can add stuffing to lower the QTC of the box. For example i think a box with a QTC of 0.7 can be stuffed down to 0.6 with polyfill or pillows or whatever...

I find that a QTC of 0.7 provides the best balance of low end and power handling. Not to mention the volume needs to increase significantly to get a lower QTC in which case your better of with a LLT

I vote a box with a QTC of 0.7, using the WinISD file here for two maelstrom's i get a internal volume of 402L or 14ft^3 :T That gives you a F3 of 30Hz which is really good (means the box will be 3db down at 30Hz) and with 2000 watts you will not reach Xmax until 4Hz meaning no subsonic filter is needed :bigsmile: Very Very nice sub for either Home theater or music...
i primarily watch movies but do enjoy music too. where did you determine the F3? i think i might try and modify the cut list neo-dan did for the single driver box for one dual with opposing drivers. it is really easy to get wrapped up in the tweaking and over think the project.

i didn't mention it but will probably do my build out of a quality veneered plywood.

i'll have to look up LLT out of curiosity even though the sealed is the way i'd go.

i appreciate your advice! :)
 

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No problem glad i could help :)

The maelstrom is a great driver, have a read on LLT's, its a sticky in the Ported and Sealed forum. As for the f3 in WinISD below the box volume there is something called Fsc which is the -3Db point for the enclosure, for most woofers its about 35Hz so having an f3 of 30 is great but that is a function of the large enclosure

Just to throw it out there (puts on Steve's hat) you could probably achieve something similar with a single driver in an LLT... probably larger though but like i said just to put it out there

Can you give me a link for Neo Dans design... wouldnt mind a look
 

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Discussion Starter #7
how cool, this site is optimized for my iPhone! The build can be found on the diy sub forum under user builds. It is the 225L build. The cut sheet is on the first page. Sorry no cut and paste :(
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so if i go with a dual driver box, here is sorta what i'll be basing mine off of... http://72.9.159.100/avs-vb/showthread.php?t=1059962&page=2

i have also been thinking of doing two separate enclosures or even one enclosure with both drivers facing in the same direction. so i have a couple questions...

1) on the single driver design, i'm thinking of doing something around 24x36x18 (hxwxd) would there be any issues regarding this tower design moving around on me if i centered the driver towards the middle of the 24x36 face? of the three subs i have, none have ever rattled or moved on me even during high excursion. but this design would be tall and relatively narrow.

2) if i do one box with both drivers facing forward... like the one shown in my link, but with both drivers facing in the same direction. would i need to worry about the box shaking even though it will be made of plywood and heavily braced.

3)i'm thinking of my amp options and i noticed lots of people go for the ep2500. any thoughts on the crown or qsc? i don't need eq as i have a sms-1.

any thoughts would be appreciated.
 

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1) on the single driver design, i'm thinking of doing something around 24x36x18 (hxwxd) would there be any issues regarding this tower design moving around on me if i centered the driver towards the middle of the 24x36 face? of the three subs i have, none have ever rattled or moved on me even during high excursion. but this design would be tall and relatively narrow.
You should be okay. I can't see such a large and heavy cabinet as you are building moving or tipping over from the movement of the driver.

2) if i do one box with both drivers facing forward... like the one shown in my link, but with both drivers facing in the same direction. would i need to worry about the box shaking even though it will be made of plywood and heavily braced.
Again, I don't think you'll have any issues. You will have double the force on the front baffle so a double baffle and bracing would be a good idea. Dual opposing as you eluded to at the beginning of your post would be the best idea.

3)i'm thinking of my amp options and i noticed lots of people go for the ep2500. any thoughts on the crown or qsc? i don't need eq as i have a sms-1.

The EP2500 is picked for it's value. It's well built and can't be beat for power to price. QSC and Crown build very good stuff as well. Some of the newer amps have built in facilities for crossovers and eq as well.
 

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The Mal-X in my single box form is incredibly inert and barely even moves at full onslaught...

I can place a drink on my box and it barely shows signs of vibration..... I used NeoDan's sealed cut sheet and added 1 extra center brace and 2 in the back to stabilize the rear wall.

Something like this.... I forgot to take pics of the inside of the box before dropping in the driver, I was a bit excited to get them running.... :D

These are of the TC2K box, but the Mal-X's are very close to this design...

 

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Discussion Starter #12
that looks sweet! i was checking out your build thread the other day. did you just glue the pieces together or did you also screw/nail?

well, i'm committed as my two drivers were ordered today! :) i've been playing around with lots of different dimensions, but keep ending up back at neodans tower. i'll have to build it taller, but i think i won't change much else... except a little more bracing.

did you end up using stuffing of any sort?
 

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The box is already pretty much build to optimum specs for the driver, so I didn't stuff it, but lined it with egg crate foam to break up the sound waves... I'm very happy with the results so far, and my 3rd driver gets here today, but I haven't started building that box yet... hope to get it up within a week or so...

All Glue no screw.... Solid as a rock and sealed inside with silicone caulk and I used speakon connectors...
 

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Discussion Starter #14
speakon connectors? Where did you get those? I'll check your build threads to see the process.
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Discussion Starter #17
probably, but size gets to be a bit of an issue. as it stands, this beast is going to be 29wx52hx20.5d. sealed is just the way for me to go because of simplicity. if i had a dedicated theater, maybe.
 

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as it stands, this beast is going to be 29wx52hx20.5d. sealed is just the way for me to go because of simplicity. if i had a dedicated theater, maybe.
WOW! That's one big sealed your going to build there:hsd:
 

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Discussion Starter #19
tell me about it. I was thinking of doing two smaller ones, but they would still be pretty big. So I figured I'd go up instead. 402l isn't easy to hide but I have 3700 cubic feet to fill. Hopefully this creation will dominate my current setup: vtf3ho and dual ufw12's. I'd be curious to see how a sealed m-x would compare to a dd18
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