subwoofer redisign?

[philip_g]

since I've got the bug pretty bad.. and there's all these sub threads... I'm looking at my current sub and thinking maybe I should try and improve on it.
right now I've got a shiva II with a 250w plate amp in about a 2.0 cu ft sealed enclosure (it's an exact knockoff of the adire rava)
it has served me well for years, since about 2000 or 2001 anyway, so I'm trying to decide if I should just live with it as is, or try and put the amp and sub in a new enclosure.

Space is a bit of an issue because of the funky room layout, I have infinite space by the television but it's a terrible location for the sub

anyway, what do you guys think? leave well enough alone, it's not worth it, or try something else? Might be an inexpensive project to keep me occupied this winter.

[JonMarsh]

If you want to get higher output levels at low frequencies, you could go with a design like the Aerial SW12- a largish ported enclosure will definitely increase your output capability if done right. Adire EBS alignment.



But, you cite space being an issue because of your layout. If you can't go to something larger like this, then there's really no reason to mess with what you have already. Hoffman's Iron law dictates sensitivity and output capability is a strong function of enclosure, regardless of the driver.

~Jon

[philip_g]

If you want to get higher output levels at low frequencies, you could go with a design like the Aerial SW12- a largish ported enclosure will definitely increase your output capability if done right. Adire EBS alignment.



But, you cite space being an issue because of your layout. If you can't go to something larger like this, then there's really no reason to mess with what you have already. Hoffman's Iron law dictates sensitivity and output capability is a strong function of enclosure, regardless of the driver.

~Jon

Heck, I can always make room
the problem is my room is open on one side to a diningroom and kitchen, so it has to go in a corner behind the table sort of, I can put it by the tv but it sounds terrible.
The current box is 1.5x1.5x1.5 so my memory has failed, it's actually closer to 3 ft. Do you think moving to a larger, ported enclosure is worth it?
I'll research designs at work tonight, I'm sure there's no shortage of good shiva plans out there.

[ThomasW]

If you port it you'll get more output at the tuning frequency, and you won't be running out of suspension travel as quickly.

The large ported Adire designs work well.

[philip_g]

BTW, the box it's in is probably the same you played with

http://www.htguide.com/forum/showthread.php4?t=3177&highlight=shiva

I can't for the life of me remember who I ordered it from, but at the time I thought it was a deal for 100 bucks.

Maybe after I tie up the 3 projects I have in mind I can kick the speaker ug for awhile!

[ThomasW]

That's the Woodstyle small sub box. I used to buy them direct from Woodsyle (500 lb min for truck shipment.).

Madisound and Speaker City sell them

[SteveCallas]

Do you find anything lacking with your current design or do you just want to build something?

[philip_g]

Do you find anything lacking with your current design or do you just want to build something?

mostly just want to try something new.

[philip_g]

That's the Woodstyle small sub box. I used to buy them direct from Woodsyle (500 lb min for truck shipment.).

Madisound and Speaker City sell them

the WS120, that's exactly what it is.

[philip_g]

Here's my room, this is why space is a problem, even though it's a fairly large room.
See the "media niche"? the TV, mains, center are in there, there is a nice big gap for a sub but it's so incredibly bad in that corner.

my other options are along that wall to the left, either in the top right corner or at the bottom edge, just before the hallway (where it lives now because I haven't run wires yet)

When I built the house I figured enough bass could overcome poor placement, boy was I WRONG. Worst room for a theater ever. There are no dimensions, it's about 20'x18'
don't even get me started on rear surrounds.

[ThomasW]

Put in a ceiling mounted IB sub......

[philip_g]

Put in a ceiling mounted IB sub......

I could do that!
hard to adjust the gain though

[ThomasW]

You don't put the amp in the attic......

http://ibsubwoofers.proboards51.com/

[philip_g]

You don't put the amp in the attic......

http://ibsubwoofers.proboards51.com/

Why not, keep 'er cool in the winter time!

actually this amp overheats if I drive it hard for long, next project when I get some $$ is to build a bunch of class D monoblocks. Guess I need to learn to read a schematic better first.


actually....
when they built the house the idiots put a freakin return RIGHT over my sofas, I could move that return out away from the viewing area to quiet things down and use the existing hole and grate for a sub.

[Bent]

Philip, I like that floor plan! (in spite of it being HT difficult.)
could I trouble you to send me a full res drawing of it? (or link)
(that is unless you paid a draftsman for it - I wouldn't feel right about asking for somethimg for nothing).

We are probably going to do a new house soon, I'd like to see if that design could lend itself to a basement underneath.

[philip_g]

Philip, I like that floor plan! (in spite of it being HT difficult.)
could I trouble you to send me a full res drawing of it? (or link)
(that is unless you paid a draftsman for it - I wouldn't feel right about asking for somethimg for nothing).

We are probably going to do a new house soon, I'd like to see if that design could lend itself to a basement underneath.

have at it, it's a cookie cutter design from one of the big box home builders, sent you a PM.

[Bent]

Thanks they have lots of stuff to look at - I wish I wasn't on dial-up.

[philip_g]

does anyone have the adire shiva design PDF?
they've either moved it, or deleted it, used to be at

http://www.adireaudio.com/Files/VentedShivaApplications.PDF

but gone now :M

I could be really down and dirty and cut a port into my 3 ft box using their example here

http://www.adireaudio.com/Files/ShivaTechSummary.PDF

[ThomasW]

You need to learn about the Wayback Machine....

http://web.archive.org/web/20041018181326/www.adireaudio.com/Files/SealedShivaApplications.PDF

http://web.archive.org/web/20041018182844/www.adireaudio.com/Files/VentedShivaApplications.PDF

[philip_g]

You need to learn about the Wayback Machine....

http://web.archive.org/web/20041018181326/www.adireaudio.com/Files/SealedShivaApplications.PDF

http://web.archive.org/web/200410181...plications.PDF

haha, that works too!

[philip_g]

Yeah, I can make this work.

the current box is 18x18x18 roughly, and on a 3" pedestal, the 142L design is 22.5 all around, with 3.5" feet, so it's just over 2' tall, I think it'll fit under my corner table
So the question is, will the performance be worth it.

if I port my existing box I'd basically have the 85L ported with:
FB 20hz
in room f3 22.4hz
IR F8 16.3
in room > 105 db SPL 14.5

if I build the 142L box I'll have
Fb 18.1 hz
F3 16.3
F8 13.7
>105 13.7

current setup is
in room f3 of 27hz and 123db SPL (according to the shiva whitepapers)

should I bother?

[ThomasW]

One uses the internal dimensions to calculate the volume of the enclosure. Your WS120 box is considerably smaller than a 18" cube. It's gross internal volume is closer to 68L.

And......

It's necessary to subtract anything that displaces air inside the box. So the driver itself, the port, any bracing etc., is subtracted to get the net volume. That's what the programs use when they say a build a box of 142L. They're talking 'net' internal volume not gross internal volume.

To figure the real size of box you build, start with that 'net' volume, add in the amount of air displaced by the port, the driver and the bracing. Next add in the wall thickness of the cabinet doubled. Now you have the outside dimensions of the box you actually have to build.

[philip_g]

One uses the internal dimensions to calculate the volume of the enclosure. Your WS120 box is considerably smaller than a 18" cube. It's gross internal volume is closer to 68L.

And......

It's necessary to subtract anything that displaces air inside the box. So the driver itself, the port, any bracing etc., is subtracted to get the net volume. That's what the programs use when they say a build a box of 142L. They're talking 'net' internal volume not gross internal volume.

To figure the real size of box you build, start with that 'net' volume, add in the amount of air displaced by the port, the driver and the bracing. Next add in the wall thickness of the cabinet doubled. Now you have the outside dimensions of the box you actually have to build.

You think so?

we're talking 18x18x22 (adire's design) with bracing (outside dimensions) vs. vs 18x18x18 with no bracing, I would have thought they'd be quite close.

the 142L figure of course comes from adire's plans.

Oh well, what the heck, I can build the cab for 20 bucks and try it out anyway, I'll try the BIG ported box, why not.

[ThomasW]

You think so?

WS120 box isn't an 18" cube.

The OD measurements of the box are 17 7/8" wide, 17 3/4" deep and 15 7/8" tall. Subtact 1.5" from each of those to get the interior dimensions. That gives 16 3/8"X 16 1/4" X 14 3/8" So my questimate was off, there's really ~62L, actually 61.89. Then subtract for the volume displaced by the woofer.

[philip_g]

you think it's worth using the adire FP4 flared kit (14 bucks) or should I just use some PVC and add the appropriate length mentioned in the plans?

[ThomasW]

Yes use flares...

[philip_g]

Yes use flares...

ahhhh crap, there go my hopes of getting it slapped together this weekend. Guess I can try it without the port to see how bad it sounds :T

gotta figure out if my brad gun can shoot anything long enough to assemble this beast, build a saw board (thanks for the idea! got it here) and start cuttin'

[philip_g]

Box is done, need the port to come in and to cut a hole for the amp, then seal it up. Should hear it by the weekend anyway.

[philip_g]

well, got it together, used some PVC pipe just to test. Glad I did, listened to it on the depth charging scene in U-571 and am just not happy with it. Doesn't quite have the impact that I'd like I'm afraid. Guess I'll go back to my old box
that really sucks. The materials ran me about 75 bucks.

I'd let the sub break in but it's been in use for 4 years, the amp too :P
one good thing, in the sealed box the amp would overheat, it runs much cooler in this enclosure.

[ThomasW]

Ok I'm now officially confused. You ported the WS120 box? If so what tuning did you use. Adire has no plans for a 56L ported box.

Also it's unrealistic to think that a single 12" in a small box is going to reproduce depth charge explosions in a room as big as yours.

[philip_g]

No, I built the adire EBS alignment, 146L ported.

[ThomasW]

That's a very popular design and gets good reviews. My guess is that it's a function of room placement and the size of the room.

Might want to do some measurements (both nearfield and listening position) to see what's happening

[philip_g]

That's a very popular design and gets good reviews. My guess is that it's a function of room placement and the size of the room.

Might want to do some measurements (both nearfield and listening position) to see what's happening

I can do that, though it's in the same location as the previous box has been. Plan is to put it in the corner with some glass on top and use it as a table :P

It's braced well and there is little vibration felt on the cabinet.
Man I don't look forward to moving it, it's about all I can do to pick the thing up by myself.

[ThomasW]

Why move it at all?

Do a nearfield by placing the mic/meter 1"-2" from the dustcap.

[JonMarsh]

Don't forget to measure the port output, too- that's where most of the stuff below 30 Hz will come from. The main driver output should show a strong null at the cabinet tuning.

~Jon

[philip_g]

Don't forget to measure the port output, too- that's where most of the stuff below 30 Hz will come from. The main driver output should show a strong null at the cabinet tuning.

~Jon

that's a lot of work :P

I also do not have a data cable for my meter.

[philip_g]

Ok, I take back at least half the things I said.
Reset the gain and watched solaris on TV, it has some really deep parts for some reason, anyway it sounds good, smooth is the only way I can describe it.

[JonMarsh]

that's a lot of work :P

I also do not have a data cable for my meter.

DIY is a lot of work. That's why there's a "Y" in it.


Contrary to urban myth, you don't get into DIY to save time or save money....

[cjd]

Contrary to urban myth, you don't get into DIY to save time or save money....

Correct. Just money. It's a way to spend time and save money. Well, sort-of save money. You may not spend as much on the speakers, but the other gear, tools and toys...

C

[JonMarsh]

Correct. Just money. It's a way to spend time and save money. Well, sort-of save money. You may not spend as much on the speakers, but the other gear, tools and toys...

C

Add up the power tools, microphones, software, computers, etc... Save money? Hah! Bah, humbug!

But you can have a lot of fun, and once in a while, build something performing "out of class" in a particular project...

You don't become an artist just because you want a few pictures hanging on the wall, either, and don't want to spend the money buying someone elses art.

[philip_g]

Correct. Just money. It's a way to spend time and save money. Well, sort-of save money. You may not spend as much on the speakers, but the other gear, tools and toys...

C

SAVING money?
what a novel idea :T

Was talking yesterday about the lack of fill in the cab, scanned the adire PDF again and this is the only place they mention anything about fill in their designs. Searched the PDF for fill, poly, and dacron and there is no further mention, so there is nothing in the cab at all.