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Discussion Starter · #1 ·
Firstly, hello. :) I've been lurking here for years, and finally decided to jump into slowly building my HT setup.


I've been using an older 2005 model RE XXX 15" in my car for years(2100w [email protected]), and have grown to not really care for car audio anymore. So logically, I decided to use the sub for my home theater.


I ran across the T/S parameters:
XXX 15
FS 28.0HZ
RE 1.9DVC
QMS 4.68
QES 0.55
QTS 0.49
SD CM2 810
VAS 123.3
XMAX 32mm(1 way)
BL 17.1
SPL 1W/1M 88.7
RMS 1600W
MAX 2500W


I'm new to WinISD, so please go easy on me. I've uploaded a couple WinISD tables to see what you guys think.


I plan to pick up an EP4000 and use that with the XXX 15 in place of my HTIB(Onkyo HT-S894) 230w powered 10".

I'll be going slow at first, but I believe that a second EP4000, and two 18's(FI BTL's maybe) will be in my future as well as whatever surrounds/center channel sets I can build to keep up with the 18's.
 

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Discussion Starter · #2 ·
Oops, I forgot to mention the XXX is a dual 2ohm model.


Also, the WinISD calculations made the SPL 86db, while it's really 88.7db. I changed that in the parameters tab, but I didn't notice a difference on the graphs so I didn't take any updated screen shots.


Also, that port air velocity is probably going to be a problem, right?
 

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Looks ok. My modeling looks even better with the same parameters so something is a bit odd about yours. The hump above tune specifically. LE maybe? Either way that should be fine. Not bad for just starting with winisd. You'll want a hpf below 15hz to remove that content and prevent the sub from bottoming below tune. A behringer MIC2200 is cheap and effective for that. The port airspeed looks high with 2000w dumped into it but in real world use it will be fine.
 

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Discussion Starter · #4 ·
Thanks for the help. Yeah, I don't know enough about frequency graphing to say anything at first, but I couldn't do anything to get rid of that hump in the 30-34hz area. I've always just heard "flat response" over and over again, but I figured that it was low enough HZ-wise to not be an issue.

I'm not sure what LE is and WinISD didn't calculate that value after I input the other TS parameters.


I think I've added a 12db/octave filter at 15hz like you suggested, if I did it correctly. I read something about "2nd order=12db/octave" in the WinISD program. I'll definitely pic up that MIC2200.

The specs are still as follows:
11ft³ net tuned to 18hz with an 8" port, roughly 32" long. Input power=2400w(EP2500 or EP4000).

Here's some graphs of the changes.
 

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I found the problem, some of your parameters are wrong, Re is 3.8 ohms as it's a dual voice coil sub. Vas is 123 liters which is 4.34 cu.ft. SPL should be 88.7. Under the signal tab it should be the default value of 0.100 for series resistance as this is not referring to the voice coils.

11 cu.ft. tuned to 20 hz looks good with 2000 watts input power and a hi-pass filter at 18 hz. Port air speed is under 33 m/s with a 8" diameter port.

Here's the project file, save it to the Projects folder in WinISD.

View attachment XXX 15 2005.wpr


xxx15.JPG
 

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That looks more like it.

You can still go with your original plans of 11ft and 18hz tune with an 8" port and a 15hz hpf. It is only marginally different from what Mike posted.

GL with the build. We expect pictures around here. :T
 

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Discussion Starter · #7 ·
Thanks Mike and Ricci, you guys are awesome!


So being that i'm coming from the car audio world, I pretty much have no idea what tune would be best in a HT environment. I've taken Mike's file and ran tunes at 18, 20 and 22hz, each with a [email protected] All in the same 11ft³ net box with 2000w.

So looking at the SPL graph, the 22hz tune is 3-4db louder in the low to mid 20hz region than the 18hz tune while not quite as loud in the mid to upper teens. That should be a significant difference, right? Then there's the "happy medium" 20hz tune, which I'm sure makes Mike say "well no duh dude, that's why I gave it to you".. lol

Am I over analyzing this?

Sorry for all the graphs, but you give me a new toy and I have to play with it. :coocoo:
 

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Am I over analyzing this?
No, you're doing your homework. :T

Your cone excursion is too high in my opinion, adjust the HPF's to bring it down to 1.4" As for tuning, what the graph doesn't show is room gain which will boost the bottom end. With room gain the 18 hz tune would give you a flatter response then the 20 hz tune which would have a hump in the response around 20 hz. Lots of people go for a flat response, I like a "heavier" bottom end.
 

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Discussion Starter · #9 ·
Oooh, I just can't choose. lol Although, I'm leaning towards the "happy medium" 20hz tune.


You referenced the 1.4" mark for the cone excursion, I changed the setting to show the excursion in mm's and if I'm correct 1.4" is roughly 36mm. Isn't that a problem since my drivers xmax is 32mm? Or does that play into the xmech of the driver, and exceeding xmax is okay since it's unlikely to mimic the graphs 100% in real world conditions?


11cubes net, 2000w.
Yellow=18hz tune, 17hz HPF
Green=20hz tune, 18hz HPF
White=22hz tune, 19hz HPF
 

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Your cone excursion is fine. That's with all of the power that your EP4000 amp has dumped into the driver. You won't encounter that very much and the HPF and natural losses will keep you ok. I personally like the 18hz tune. I like to be able to get to 16hz with authority, but the 20hz tune would be fine too.
 

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Discussion Starter · #11 ·
Gotcha. Plus with the 18hz tune, I can just trim the port to raise the freq if I wanted to.


Hmmn.. Okay, i'm going for it. The only setback I have in the build is that I can't remember the 2005 XXX models displacement. It's been four or five years since i've build a box for it. I want to say it's somewhere in the 0.24-0.25 range? Since it's close to the Tumult, I could search for its displacement also right?
 

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Discussion Starter · #12 ·
Wow, just got lucky and found my long lost account on termpro from 2003. One of my old posts lists the displacement as 0.21ft³..



<------Happy camper!
 

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Nothing completed yet, I'm likely going to do a sonotube build and i've yet to locate a local supplier.

This is what a pre-2006 model RE XXX 15 looks like.
http://www.whitecap.com/

find the closest one if you can. Make sure to go and get them to cut the tube for your and get the port while you are at it. They have tools that do the job easily. That just leaves you some routing drilling and gluing.
 

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Discussion Starter · #17 ·
The good news is that there's one about a mile away from my house.

The bad news is that whitecap doesn't list sonotubes on their site, they have "Ceme-Tube's" made from recycled HDPE plastic.
 

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I'm using 10" cemetube for ports in my latest build. I got it from my local White-Cap. It is a little expensive but i probably won't use anything else for large diameter ports anymore. They did have regular cardboard concrete forming tube at the one i went to.











 

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Discussion Starter · #20 · (Edited)
Sorry, i've been MIA lately.


I just ordered an EP2500, MIC2200 and a pair(I think it includes two) of RCA to 1/4" adapters from audiolines.
I'm not sure what the cable is that comes from the onkyo AVR to the powered sub, so i'll likely pick that cable or adapter up locally from radioshack or guitar center. I want to say it's a 1/8" on the sub end, but will confirm when I get home from work.

I've yet to really look for a sonotube locally, but i'll get on that in the next couple days.


I'm hesitant to get the HDPE ceme-tube because that material isn't very porous at all, and I fear that gluing it to MDF won't bond well. Another issue I see is that by using the 24" diameter tube(4ft tall), the 32" port length might run into issues being too close to the driver after the flares, bottom(triple 3/4") sub mount and the top cap/port area(double 3/4") are taken into consideration.


I plan to utilize the services of a local CNC-lathe shop I found that does custom work to cut out all the circular parts and see about designing a couple port flares also. They charge $55/hr for most design/engraving work, so I figure cutting circles shouldn't take very long at all. LOL
 
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