Help with a Dual SA8 box?

[SuperDaveTX 0]

Sorry for the multiple post. I wanted this in the Sundown section, so reposted here...

My son really likes the SA8s and wants to upgrade his stereo system.

Can someone help with a box design? I assume someone has done this already and has posted a box design of what they did. I've been looking but have found some crazy installs.

We only want to do two subs. Ported since that is the recommended design. If going sealed does not hurt that much, then that would be an easier build.

This will be our first sub project together so want to do something on the easy side. We built a pirogue so have skills.

BTW, he will be powering these with a Cadence ZRS-2002 going with 2 channel, 2ohm loads.

http://a248.e.akamai...C_4-ohm_2ch.jpg

Input is greatly appreciated!

Dave

[trevorb9 2]

I would go with a ported box in 1.6- 2.0 cubes tuned to 33 hz with 25-30 sq inches of port..

You need to post the max dimensions of the vehicle your going to be putting this box in, to get more help

[RAM_Designs 25]

Your link isn't working.

[SuperDaveTX 0]

Meant to add this is for back of trailblazer. Not at home so can't measure. Will do that soon

[SuperDaveTX 0]

Link was just wiring details

Fixed link...

http://a248.e.akamai.net/pix.crutchfield.com/ca/learningcenter/car/subwoofer_wiring/2DVC_4-ohm_2ch.jpg

Edited September 4, 2011 by SuperDaveTX

[SuperDaveTX 0]

Usable area is 45" x 30"

[phillipathman 1]

25w X 12h X 15d with a 1.5" port using 3/4 mdf just use this link http://www.reaudio.com/box.php and just put in these dimensions or make your own but the recomendations for the sa-8 are .6-1 cube ft per sub and have a .1 cube displacement and sugested around 35 hrz tuning so go between 1.4-2.2 cubes total hope this helps iv used it for a few boxes iv built for the sa-8's

Edited September 4, 2011 by philla

[SuperDaveTX 0]

Wow... Thanks philla. This helps a bunch!

Using your dimensions, I get a tune down to 30Hz with an 8" port length... using a port length of 1 I can get to 34.5 Hz.

I will talk to my son about the tune freq. I would go with something close to 30Hz.

I'm still trying to find all the recommendation posts from Jacob, and also still learning... so, I'm a bit noobish.

Edited September 4, 2011 by SuperDaveTX

[CrazyKenKid 64]

If I was you I would pay RAM design 12$ to give you. the best design

[SuperDaveTX 0]

Well, it is hard to learn if you don't do it yourself, but I may look into that.

Not sure where you got $12.00 from. Site shows $20.00 for baseline.

Edited September 5, 2011 by SuperDaveTX

[ssh 924]

Wow... Thanks philla. This helps a bunch! Using your dimensions, I get a tune down to 30Hz with an 8" port length... using a port length of 1 I can get to 34.5 Hz. I will talk to my son about the tune freq. I would go with something close to 30Hz.I'm still trying to find all the recommendation posts from Jacob, and also still learning... so, I'm a bit noobish.

Do not use the RE calculator, it's a joke. Also what type of music does your son listen to? Unless he listens to a bunch of rap / dubstep electronica, I would tune higher. Personally I'm tuned around 35hz and my next enclosure will likely be higher, just depends on music material.

If I was you I would pay RAM design 12$ to give you. the best design

Completely agree, not trying to drum up business for anyone, but he does make some kickass designs, you clearly need a design, and it's not very much dinero, plus you get a cutout sheet I believe, makes everything very easy for constructing.

[ssh 924]

Well, it is hard to learn if you don't do it yourself, but I may look into that.

If you do decide to do it yourself,

Plug in enclosure dimensions, I recommend using 3/4" mdf or similar wood, put in 0.75 for thickness, then you can find your gross volume.

http://www.the12volt.com/caraudio/boxcalcs.asp#rec

Then if you decide to do a double baffle (two panels of wood glued together where speaker is mounted to), subtract the extra sheet from the above volume.

Subtract each subwoofer's displacement from your enclosure volume.

Download Winisd,

http://www.linearteam.dk/default.aspx?pageid=winisdpro

Grab the T/S specs for your drivers, create a new driver in winisd with those specs.

Make a new project, plug in a volume (won't really matter, just use gross volume), go the vent / port tab, start adjusting port width and port height until the vent mach is green, then you know you have enough port area and won't have any port noise.

Then you can use the port tuning calc here,

http://www.the12volt.com/caraudio/boxcalcs.asp#porsq

Don't forget about port displacement.

[duanebrow 6]

This is the latest version of winisd.

http://www.linearteam.org/download/winisd-07x.exe

It works well with Windows 7. If you want to do this for yourself, please let me know and I'll help you out. It has some issues with the way you enter the specs for your driver. This is a pain until you figure it out.

I can design a box if you want, just send me a message.

Edited September 5, 2011 by Duane

[SuperDaveTX 0]

Thanks stefanhinote

It is my nature to do things myself and learn about it. I am engineer, btw. I actually had this software and just got the newer version.

Anyway, my son does listen to mostly rap. So, is the L port design not good? Or is it just the dimensions etc? I compared the math of the 12volt calc vs the RE box site.. It make me wonder if the RE site has adjustments for the sub included or something.

I actually had a beta of winISD and was looking into that.

Where do i plug in the volume? Is that the volume of the driver itself and on the Dimensions tab as Dvol? Let me know.. I heard this was about .1 per driver.

I assume I also go to the volume tab and put in the desired volume I want a well? right now, the volume is 25.98 liters

Also.. how do I tell when the "vent mach is green" ?

Edited September 5, 2011 by SuperDaveTX

[ssh 924]

Thanks stefanhinote

It is my nature to do things myself and learn about it. I am engineer, btw. I actually had this software and just got the newer version.

Anyway, my son does listen to mostly rap. So, is the L port design not good? Or is it just the dimensions etc? I compared the math of the 12volt calc vs the RE box site.. It make me wonder if the RE site has adjustments for the sub included or something.

I actually had a beta of winISD and was looking into that.

Where do i plug in the volume? Is that the volume of the driver itself and on the Dimensions tab as Dvol? Let me know.. I heard this was about .1 per driver.

I assume I also go to the volume tab and put in the desired volume I want a well? right now, the volume is 25.98 liters

Also.. how do I tell when the "vent mach is green" ?

L Port design is fine, it's just the port length that changes the tuning.

in winisd,

click "new", select "own drivers", pick the driver, press next

pick amount of drivers, press next, box type: vented, press next.

Now a box will popup, click on "Box" tab, Front Chamber(only chamber in this case), input your gross volume (this really doesn't matter since were just finding the vent (port) mach.), Pick your tuning, I guess for rap you could do something in the low 30s.

Click on "vent" tab, Click on the shape until it looks like a box, have the number: 1 (since your doing a single port), then adjust the two vent boxes, width and height, you should see the vent mach box change. The more port area you have, the lower the vent mach will go, keep making the vent area larger until the vent mach is green.

Also, you can click on the measurement type and convert it from metric to standard if that's easier for you.

[ssh 924]

Since your already in winisd, you could try adjusting the enclosure volume and see how it effects the spl graph.

[SuperDaveTX 0]

Thanks again...

So, I also assume that by selecting 2 drivers everything works out properly. I hope I have all the driver parameters correct. I saw one set of numbers on Woofers etc for the SA8, DVC4 ohm. Then I saw a post from Jacob about the DVC2 ohm and he said the 4 ohm would be similar, but the numbers are not that close...

I would love to have the winISD file for the SA8 DVC4.

I will try to figure out what you mean.. I dont even know what vent mach is... I was thinking you meant match... but, maybe it is a fluids/dynamics thing.. or ASE thing. I used to work at NASA, and am familiar with mach in terms of jets, but didn't think it was used in dealing with speakers... Come to think of it, since speakers are about moving air, I guess this could make sense..

[Duran 387]

Indeed. The excitement of air, and coupling it with it's surroundings is the purpose of the port. Vent mach is the velocity of the air in the port. I tend to use the displacement capabilities of the woofer(s) being used to determine the port you need, rather than looking at the vent mach.

[SuperDaveTX 0]

So, I am starting over with WinISD so I can figure out what part is supposed to be green in the program.. So far, I can't tell if it is a graph or something else, but the numbers I use, even very large ones has no affect.

So, now I am wondering if my driver data is wrong somewhere. When I load the driver, it is saying that it fails the driver integrity check... so, I am thinking I must get this right before moving on?

[trod2902 26]

Check to see if u accidentally entered a unit along with the numbers, the units are already accounted for on the side of the blank

[SuperDaveTX 0]

Hmmm. I was going to post my SA8 page 1 data, but can't figure out how to paste a pic in here..

I may have found one thing wrong. Are the voice coils for a DVC in series or parallel?

Edited September 5, 2011 by SuperDaveTX

[SuperDaveTX 0]

I just got a great tutoring by Duane on WinISD. Thanks!

[SuperDaveTX 0]

One question... What parameters affect the cone excursion?

I have 16.5 on the driver, but my plot to 13.5. Is this ideal or should I change something to get more?

[SuperDaveTX 0]

Anyone..... Bueler?

[ssh 924]

One question... What parameters affect the cone excursion?

I have 16.5 on the driver, but my plot to 13.5. Is this ideal or should I change something to get more?

xmax would be excursion, Vd would be xmax * Sd (effective cone area), Vd is the amount of air being displaced at max excursion.

Not sure what "16.5 on the driver" is referring to.