subwoofer box???

[michaelyoung]

hello: anyone here ever had any experience with madison executioner x21 subwoofer? i got my hands on one in a trade , and wanted to know if anyone has ever tried putting one in a 24in.x24in.x24in.. sealed enclosure.( 2 ft. sq. cube ) i know the driver should go in a much larger box, but just want to use it to enhance low end on home theatre system used mainly for rock and country videos , and maybe be able to play bass guitar thru it. it is a 21 in. woofer. i have t/s parameters for it, but just wanted any advice if anyone else had tried this idea. slot / vented enclosure would be ok too, if i could keep original cube design. dont have room for much more. also, will not be driving it to full power )1000w ), probably no more than 400 / 500 rms. would like to keep bass tight, so thats why i am asking about sealed enclosure vs. vented, which in my experience gives more boomy bass. thanks in advance for any advice.... mike young...

[Pete Schumacher ®]

> hello: anyone here ever had any experience
> with madison executioner x21 subwoofer? i
> got my hands on one in a trade , and wanted
> to know if anyone has ever tried putting one
> in a 24in.x24in.x24in.. sealed enclosure.( 2
> ft. sq. cube ) i know the driver should go
> in a much larger box, but just want to use
> it to enhance low end on home theatre system
> used mainly for rock and country videos ,
> and maybe be able to play bass guitar thru
> it. it is a 21 in. woofer. i have t/s
> parameters for it, but just wanted any
> advice if anyone else had tried this idea.
> slot / vented enclosure would be ok too, if
> i could keep original cube design. dont have
> room for much more. also, will not be
> driving it to full power )1000w ), probably
> no more than 400 / 500 rms. would like to
> keep bass tight, so thats why i am asking
> about sealed enclosure vs. vented, which in
> my experience gives more boomy bass. thanks
> in advance for any advice.... mike young...

2x2x2=8

That's a really large sealed box.

[billfitzmaurice]

> 2x2x2=8

> That's a really large sealed box.

Not with a .98 Qts and 14 cu ft Vas. It's really a gosh awful driver, I'd dump off on someone who doesn't know any better and get something worthwhile.

[michaelyoung]

> 2x2x2=8

> That's a really large sealed box.

yes, i know. i think t/s parameters call for 10 cu. ft. i dont know of any way to get any smaller, since the driver is 21 in. might could go 23in x3 but want to make sure i have enough room for outside mounting hardware. am thinking of making it downfiring type, so maybe wife would accept it as piece of furniture!! have to check with mfg. to see if that much cone mass could be used in that configuration. thanks for response.... mike young..

[Pete Schumacher ®]

> yes, i know. i think t/s parameters call for
> 10 cu. ft. i dont know of any way to get any
> smaller, since the driver is 21 in. might
> could go 23in x3 but want to make sure i
> have enough room for outside mounting
> hardware. am thinking of making it
> downfiring type, so maybe wife would accept
> it as piece of furniture!! have to check
> with mfg. to see if that much cone mass
> could be used in that configuration. thanks
> for response.... mike young..

With the highish Qts, especially in a smaller than optimum enclosure, a capacitively coupled input could give you the unpeaked response you're looking for.

[daryl]

> With the highish Qts, especially in a
> smaller than optimum enclosure, a
> capacitively coupled input could give you
> the unpeaked response you're looking for.

The third order sealed family does use the highest Q's but but you will have a peak if Qtc is above 1 and this thing has a Qts of 1.

You could use it third order infinite baffle.

[Pete Schumacher ®]

[Wolf]

With a cone that large the Mms is probably substantial, meaning you'll have decreased performance in the amount of xmax loss due to cone sag. I'd space it from the wall a few inches, and back-fire it to couple it to the room if you are worried about aesthetics.
Later,
Wolf

[michaelyoung]

> With a cone that large the Mms is probably
> substantial, meaning you'll have decreased
> performance in the amount of xmax loss due
> to cone sag. I'd space it from the wall a
> few inches, and back-fire it to couple it to
> the room if you are worried about
> aesthetics.
> Later,
> Wolf

thanks for that advice. i thought the cone mass would affect it too, thats why i asked. will have to get back to mr. schumacher on his advice also.... anybody else feel free to dive in with advice!! thanks.... mike young.

[michaelyoung]

> With the highish Qts, especially in a
> smaller than optimum enclosure, a
> capacitively coupled input could give you
> the unpeaked response you're looking for.

ok. now i am out of my leauge... please explain more. if you have to , email me with details. i just do this for fun, have built a few boxes for myself and friends long before t/s parameters came along. mostly for band and dj use. looked at driver, averaged out boxes containing similar drivers and just built them. no complaints so far, but for what we do with them, no one is that picky. its not like they are going to listen to bach on them. right now, my home theatre / band practice setup ( mixing board run thru harmon kardon av receiver ) i am running 4 boxes--two to each main channel-- each box contains 18in. woofer, two 5in. midranges and a 7 x 14 horn. this produces lots of bass just for the main channels, and i was looking for a way to enhance the rear channel setup, along with the lfe channel that is now only using two 10in. powered subwoofers. thats the whole reason in trying to get this 21 in. woofer with 500w amp to work. anyone welcome to send detailed ideas to my email if they want to. thanks for all advice so far. mike young...

[michaelyoung]

hello: is that like using an active equalizer on the amp powering the subwoofer???

[Wolf]

> hello: is that like using an active
> equalizer on the amp powering the
> subwoofer???

It is an active circuit, and you can program it to do what you want, but it's not a variable unit in the usual mockup. It extends the bass by shelving the frequency response, allowing you to use a smaller box. There are caveats however, that it requires a ton of amplifier power for drivers that are fairly sensitive, and immense amounts of power for drivers that aren't very sensitive. Usually in the neighborhood of 4x the power required in the lower frequencies. If your driver is highly sensitive- like 95dB plus, it might not be as bad, but the second caveat is Xmax limiatations. If the driver does not have a long stroke, it is not capable of allowing the FR to be shelved, and operate safely.
Later,
Wolf

[Pete Schumacher ®]

> hello: is that like using an active
> equalizer on the amp powering the
> subwoofer???

Sort of.

If you have an adjustable parametric EQ on your amp, or if you can add one in the signal chain, you should be able to get acceptable response from that woofer, especially if you band limit it to no more than 40Hz, using it only for the first octave of frequencies.

[unknownuser]

Get a couple of 2 x 4 or even 4 x 8 panels of plywood. Cut a hole and mount the woofer in the lower half, and just prop the whole thing up in the corner of your room. Experiment with placement.


(Originally posted by: BFB)

[billfitzmaurice]

> ok. now i am out of my leauge..

No doubt, and no offense, but you seem to have fallen into the "it's bigger so it must be better" trap, and that simply isn't the case. Before wasting any more time, money or energy you need to learn how to use a box program like WinISD Alpha Pro to accurately predict what any driver is actually capable of. You'll soon find that size is not indicative of performance. My best advice was contained in my first reply: Dump that piece of junk driver.

[michaelyoung]

> Get a couple of 2 x 4 or even 4 x 8 panels
> of plywood. Cut a hole and mount the woofer
> in the lower half, and just prop the whole
> thing up in the corner of your room.
> Experiment with placement.

ok. another thing to consider, thanks. now, what if i kept original design of 2 ft cube and just left the back open? what kind of results do you think i would get with that approach? i had thought about the infinite baffle approach, but would be too much work to install in wall and make wall sturdy enough to handle bass. wall is now just studs and 3/8 drywall. not strong at all.

[michaelyoung]

> Sort of.

> If you have an adjustable parametric EQ on
> your amp, or if you can add one in the
> signal chain, you should be able to get
> acceptable response from that woofer,
> especially if you band limit it to no more
> than 40Hz, using it only for the first
> octave of frequencies.

hello: yes, i do have eq in signal chain on main amp, and can also add another to the outboard amp that will power the subwoofer. all this being said, what do you think about just leaving the back off the enclosure entirely, with padding to absorb waves inside of enclosure? thanks for your time.... mike young...

[unknownuser]

what kind of
> results do you think i would get with that
> approach?

You don't get the flat bass you can get from a sealed or ported box of the right size, but you can get a lot of output. It all depends on how big the baffle is (the bigger the better) and how deep the sides of the "wings" are. People do this with high Q woofers, usually in stereo, as part of an open baffle system.


(Originally posted by: BFB)

[Pete Schumacher ®]

> hello: yes, i do have eq in signal chain on
> main amp, and can also add another to the
> outboard amp that will power the subwoofer.
> all this being said, what do you think about
> just leaving the back off the enclosure
> entirely, with padding to absorb waves
> inside of enclosure? thanks for your
> time.... mike young...

it would work, but padding would do very little absorbing at those wavelengths.

If you have a room, closet, something off the main listening area, you could mount the driver in a door and use the other room as the enclosure during listening.

But if you do have EQ available with enough resolution to fine tune the lowest octave, you should be able to get reasonable results, especially if you limit it to just the lowest octave, purely for reinforcement duty.

[michaelyoung]

> it would work, but padding would do very
> little absorbing at those wavelengths.

> If you have a room, closet, something off
> the main listening area, you could mount the
> driver in a door and use the other room as
> the enclosure during listening.

> But if you do have EQ available with enough
> resolution to fine tune the lowest octave,
> you should be able to get reasonable
> results, especially if you limit it to just
> the lowest octave, purely for reinforcement
> duty.

ok. yeah, i tried that a few years ago in a different hosue,( 15 in. subwoofer ), and it worked for what we were using it for. cant do that now with current setup. room has no closets or any rooms i could use that way. room is 30 by 35 ft. so i will take all the suggestions given, and work my way up from least expensive to more expensive. certinly got lots of ideas to work with. thanks to all that responded. if i ever get it to sounding good, i will post results later. again, thanks to all who responded... mike young...