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post #1 of 65 Old 04-14-2012, 09:41 AM - Thread Starter
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I'm starting the designing phase of a DIY project for a decent home subwoofer.

I've been using a couple of RW-12D Klipsch subs which are not that bad for the money I spent on them, but they leave me wanting much more.

From what I've gathered, the Klipsch do great from 25 Hz on up and are limited to 85 db around 20 Hz.

As my title states, I'm limited to 24" X 24" X 46" of space. I'm also wanting to keep the cost under $750. $500 would be even better.

I would like to get the most out a sub for my money. I've modeled the dayton titanic 15" and it looks pretty decent. I've also modeled the Mach 5 18.2.2

I still haven't decided on an amp, but I would like to go digital with dsp. I've been looking at the inuke and drivecore.

Here is my first cut at a design using Google sketchup:
http://sketchup.google.com/3dwarehou...2f40cbc69e723d

Any suggestions welcome to help me with this project.

Thanks
LL
LL

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post #2 of 65 Old 04-14-2012, 10:15 AM - Thread Starter
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I've done a little bit of playing around with WinISD.

I've thrown in a 17hz tuning and a 19.57 tuning on the dayton.

I've included the 18.2.2 for good measure.

It looks like with my limited space, I should stick with my near 20 hz tuning with the dayton. The 18.2.2 seems to need more space to work at its optimum.

All are graphed with 500 w.
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post #3 of 65 Old 04-14-2012, 10:26 AM - Thread Starter
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I need to figure out the following also:
- best speaker terminals ?
- best method to cover the front? Thinking speaker cloth grill and doing plain carpeting on box.
- Best way to mount sub? hurricane nuts or other?
- Should I stick to 1" mdf or go with 3/4"?
- How much bracing do I need with 1" vs 3/4"?
- Flare ports internally/externally or not?

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post #4 of 65 Old 04-14-2012, 12:07 PM
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For a box this large you might want to consider plywood, mdf will make it ridiculously heavy. Thicker is always better, especially on the baffle. Place a window brace front-to-back above and below the driver cutout, and tie in another window brace to the top and bottom of the box from the front/back braces. Run a couple side-to-side dowel rods behind the depth of the woofer. I use #10 screws with no issues into plywood. Take a round over bit to all port edges including your internal 90 degree bend.
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post #5 of 65 Old 04-14-2012, 03:11 PM
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"Take a round over bit to all port edges including your internal 90 degree bend."

why?

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post #6 of 65 Old 04-14-2012, 05:04 PM
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Same reason you flare a round port. Decrease the possibility of noise by smoothing the transition of airflow.
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post #7 of 65 Old 04-14-2012, 06:22 PM - Thread Starter
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Quote:
Originally Posted by Jay1 View Post

For a box this large you might want to consider plywood, mdf will make it ridiculously heavy. Thicker is always better, especially on the baffle. Place a window brace front-to-back above and below the driver cutout, and tie in another window brace to the top and bottom of the box from the front/back braces. Run a couple side-to-side dowel rods behind the depth of the woofer. I use #10 screws with no issues into plywood. Take a round over bit to all port edges including your internal 90 degree bend.

You make a good point about the weight. I am a bit wary about using plywood instead of mdf. I may split the difference and go with 3/4" mdf with some tic tac toe type bracing.

Assuming I do go with 3/4" mdf, what is today's chosen method for joint construction. In the past, I've always used countersink bits and screws along with glue and silicon in all of the joints. I'm hearing some say using screws is a bit overkill and proper gluing gets better results..... without the risk of splitting which mdf likes to do.

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post #8 of 65 Old 04-14-2012, 11:50 PM
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"Same reason you flare a round port. Decrease the possibility of noise by smoothing the transition of airflow."

if you look inside of just about any horn loaded sub, you will see 90 degree unsmoothed bends (and many times several 180 degree bends), yet they don't produce the effect/noises that you are talking about.

flaring a port to the outside of the sub is completely different because of the dramatic transition in cross sectional area. that one has been described and measured.

do you have any data to support your claim?

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post #9 of 65 Old 04-15-2012, 12:19 AM
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"In the past, I've always used countersink bits and screws along with glue and silicon in all of the joints. I'm hearing some say using screws is a bit overkill and proper gluing gets better results..... without the risk of splitting which mdf likes to do."

pl premium is an expanding adhesive that while a mess to work with will fill in most small air gaps/voids in your joints.

fast forward to the 4 minute+ mark for measurements
http://www.youtube.com/watch?feature...&v=IY7hkCexNVY

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post #10 of 65 Old 04-15-2012, 12:58 AM
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Do you have data to support your claim, other then referencing a non ported design? It is a common practice that is easy to do. It literally takes a minute to put a round over on the port before adhering it to the cab. Will it be audible? Maybe, just like many of the other common practices you see.

A better place to question this may be the easy button build threads, that's my reference.

Quote:
Originally Posted by LTD02 View Post

"Same reason you flare a round port. Decrease the possibility of noise by smoothing the transition of airflow."

if you look inside of just about any horn loaded sub, you will see 90 degree unsmoothed bends (and many times several 180 degree bends), yet they don't produce the effect/noises that you are talking about.

flaring a port to the outside of the sub is completely different because of the dramatic transition in cross sectional area. that one has been described and measured.

do you have any data to support your claim?

Not exactly the most serious claim
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post #11 of 65 Old 04-15-2012, 01:28 AM
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"Do you have data to support your claim..."

the reason that i mention tapped horns is because they blow major air around all kinds of 90 and 180 degree bends. for example:



they blow as much air as a ported enclosure, yet nobody seems to complain of the effects that you are talking about.

i used to suggest the same thing, but now, i am wondering what the practical benefit is. having searched around and never seeing any data makes me suspect. if you have some data that shows that it matters, please post it.

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post #12 of 65 Old 04-15-2012, 02:24 AM
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Do you not see the size difference between the throat of a horn and a slot port? Again you're comparining apples to oranges. Ported and horn do not work the same... Coupling vs resonating.
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post #13 of 65 Old 04-15-2012, 02:46 AM
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"Do you not see the size difference between the throat of a horn and a slot port? Again you're comparining apples to oranges. Ported and horn do not work the same... Coupling vs resonating."

what does the throat of horn have to do with anything?

the point was and still is all the 90 and 180 bends that you suggested make noise as air moves through them. the air velocity through such bends is similar to a ported enclosure, so it is apples to apples.

not sure why you are going all off topic. i was simply asking for any evidence that 90 or 180 degree bends, sharp edges vs. routed, have any audible impact. if so, just link them up...

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post #14 of 65 Old 04-15-2012, 02:48 AM
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Oh the hypocrisy done
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post #15 of 65 Old 04-15-2012, 03:14 AM
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av, for a couple of other options, the jbl w15gti and the alpine 15swr might be worth having a look at. 15gti is a better driver, not sure about the alpine.

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post #16 of 65 Old 04-15-2012, 06:28 AM - Thread Starter
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On the topic of ports....

I'm planning a 3.25" X 22" slotted port. I would like to make it smaller.

Should I be concerned about air velocity at this size? Also, any reduction I can make in the port will give me more internal volume, so I guess I'm looking for the minimum port area.

I could lower the tuning more easily if the port was smaller, but I don't want to give up too much as my overall power handling goes down. More volume makes this power handling worse in my winisd models also.

How much more velocity can I handle if I flare the external port?

Would I benefit by changing to a PVC pipe over a slot port? I'm thinking the reduced weight may be a beneficial reason to change.

At what point does the SPL of the system mask the port noise...does it? 110 db @ 20hz?

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post #17 of 65 Old 04-15-2012, 12:51 PM - Thread Starter
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I've made an idiotic error. I was looking at ft/s instead of m/s. This changes things quite a bit.

I can now go from 9 --> 11 ft^3.

I've now included a model using the dayton and mach5 18.2.2 and dropped my tuning from 19.57 to 17 hz

I think I'm leaning toward the 18.2.2

I've already sent an email to Mark asking how long the current wait is for these.

If you have any new ideas with my newly found volume, let me know.

Now to work on a new sketchup design with the different port and sub...
LL

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post #18 of 65 Old 04-15-2012, 02:33 PM
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An option at the top of your price range would be the 18sound 21LW1400. Looks impressive with the O-Audio 500 watt plate amp. Shown with 25hz filter and 400w (driver re is 5ohm).

http://www.data-bass.com/data?page=driver&id=42
LL
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post #19 of 65 Old 04-15-2012, 03:16 PM
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Quote:
Originally Posted by Jay1 View Post

An option at the top of your price range would be the 18sound 21LW1400. Looks impressive with the O-Audio 500 watt plate amp. Shown with 25hz filter and 400w (driver re is 5ohm).

http://www.data-bass.com/data?page=driver&id=42

I have one of the 18Sound 21s for sale if you choose it for your build, it is actually the driver Ricci tested.

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #20 of 65 Old 04-15-2012, 03:16 PM
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"I think I'm leaning toward the 18.2.2"

that's a good choice.

"Would I benefit by changing to a PVC pipe over a slot port?"

i don't think that there is any practical advantage there.

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post #21 of 65 Old 04-15-2012, 03:47 PM - Thread Starter
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Latest box design attached. I'll have internal bracing too..just too lazy to model it.

Found a plug-in for cutsheets I figured I'd share with sketchup. Its "cut list 4.11". Image attached.

I'm still researching a bit more on possible drivers. Thanks for all of the input.
LL
LL

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post #22 of 65 Old 04-16-2012, 06:37 AM
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Full Disclosure: I work for Alpine

While there was a post about the R15s, I'd suggest looking at the new S15's, actually using a pair of them in that box.

They are fully new design, a different take on things in the "budget" category. They are an underhung design with a clean 15mm Xmax (one way) 36mm Xmech so you can beat the snot out of them. 500W RMS, but they are quite efficinent, so no need for crazy power.

Here is a sim of 2 S15's in your 11cf box.

A nice benefit with a pair other than headroom, you could mount both woofers on the face for a nice imposing presence, or you could try to mount them opposing for a vibration free design. I'm planning my build to have 4 24" cubes dual opposing at each corner of the room (but sealed). I'm still a few months out yet on it, but since your box size fit one of the vented sims I had done while brainstorming, I figured I would post this up.
LL

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post #23 of 65 Old 04-16-2012, 07:22 AM
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hey there Jim, got a link to those alpine subs you where talking about?

quick Google doesn't show anything "new" under s15 alpine.

My first DIY project. A dual, dual opposed setup

www.avsforum.com/avs-vb/showthread.php?t=1345494
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post #24 of 65 Old 04-16-2012, 08:28 AM
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John,
Did you not read the big JBL research paper on port performance? Flaring does show some advantages in lowering air noise and allowing higher airspeeds (higher output) before the core slug of air goes fully turbulent.
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post #25 of 65 Old 04-16-2012, 09:07 AM
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Quote:
Originally Posted by Audiophile34 View Post

hey there Jim, got a link to those alpine subs you where talking about?

quick Google doesn't show anything "new" under s15 alpine.

Presumably he's referring to the SWS-15d2/d4 introduced in 2012:

http://www.alpine-usa.com/company/pr...b-box-program/
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post #26 of 65 Old 04-16-2012, 04:00 PM - Thread Starter
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Quote:
Originally Posted by Jim Walter View Post

Full Disclosure: I work for Alpine

While there was a post about the R15s, I'd suggest looking at the new S15's, actually using a pair of them in that box.

They are fully new design, a different take on things in the "budget" category. They are an underhung design with a clean 15mm Xmax (one way) 36mm Xmech so you can beat the snot out of them. 500W RMS, but they are quite efficinent, so no need for crazy power.

Here is a sim of 2 S15's in your 11cf box.

A nice benefit with a pair other than headroom, you could mount both woofers on the face for a nice imposing presence, or you could try to mount them opposing for a vibration free design. I'm planning my build to have 4 24" cubes dual opposing at each corner of the room (but sealed). I'm still a few months out yet on it, but since your box size fit one of the vented sims I had done while brainstorming, I figured I would post this up.


I'm interested in researching this a bit, but I can't find any T/S information to put into winisd. Does anyone know where I might be able to find this information or point me to a pair of drivers which could model similarly in 11 ft^3?

Thanks

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post #27 of 65 Old 04-16-2012, 05:52 PM
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Correct, they are the 2012 Type S subs. Models are SWS-15D4 & SWS-15D2.

Right now, info on them in non-existent outside of the press release. The website has been made and will be live soon, but feel free to ask any questions. I did a info thread on DIYMA for some 8s that we did a while ago and it was a lot of fun geeking out with audio guys.

Some basic T/S params to get you going, I'll have to get the rest of them tomorrow at work, this is a what I remember.

Fs 28
Qes .49
Qts .46
Vas 102L
Re 1.8
Sd 775cm^2

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post #28 of 65 Old 04-16-2012, 06:20 PM
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"Did you not read the big JBL research paper on port performance? Flaring does show some advantages in lowering air noise and allowing higher airspeeds (higher output) before the core slug of air goes fully turbulent."

yes. no question about the benefits of flaring.

i was asking about the 90 and 180 degree bends inside the cabinet and what, if any, effect they have on the port functionality.

i've become suspect of the 'common wisdom' that roundovers and smooth bends are necessary inside of an enclosure for a slot ported enclosure because the measured response for a horn with a lot of folds measures quite close to the model in hornresp which has no folds. if air was getting turbulent and making noise, then the impedance and frequency response would move around significantly and folks would complain their their horns are making internal chuffing sounds. not having to worry about 90 degree bends makes slot ported designs much easier to build.

----

jim, thanks for dropping in and i like how you were right up front about your affiliation. the new s series sounds *very* interesting...15mm linear, 38mm xmech, underhung... is the 500w rating sine waves, aes pink noise, or something more like a rough suggestion for amplifier matching?

since it will eventually be asked, do you have a klippel or dumax type report?

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post #29 of 65 Old 04-16-2012, 06:37 PM
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John,
Ahhh...Ok. I wasn't following the conversation well.
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post #30 of 65 Old 04-16-2012, 06:42 PM
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Quote:
Originally Posted by Jim Walter View Post

Correct, they are the 2012 Type S subs. Models are SWS-15D4 & SWS-15D2.

Right now, info on them in non-existent outside of the press release. The website has been made and will be live soon, but feel free to ask any questions. I did a info thread on DIYMA for some 8s that we did a while ago and it was a lot of fun geeking out with audio guys.

Some basic T/S params to get you going, I'll have to get the rest of them tomorrow at work, this is a what I remember.

Fs 28
Qes .49
Qts .46
Vas 102L
Re 1.8
Sd 775cm^2

Thanks for dropping in Jim...If I might diverge slightly from the present conversation...I recently was talking with another industry fellow who asked if I knew about or was testing to the CEA-2031 standard for mobile audio. I had never heard of it ( I use CEA-2010 which is a separate deal for outdoor testing of subwoofers.) I now see that Alpine has it listed in this press release. Could I trouble you for the abbreviated version of what this new standard covers?
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