Considering a Subwoofer build and would appreciate your thoughts. - AVS Forum
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post #1 of 51 Old 08-14-2013, 05:27 AM - Thread Starter
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Hi Guys,
I've been toying with the idea of building a sub. I have two klipsch 12" woofers (I know, that's why I'm looking to build). By happenstance, a warranty issue left me with a spare amp that I would like to use. It's out of a rw-12d. The website states that it is: FTC Rated Power: 350 watts continuous @ <2% THD / Dynamic Power*: 825 watts.

I was considering building a clone of the 12d, but then thought why not do better? Looking at the drivers on parts express, I realized that I don't really know where to start. I don't want something that is enormous, but has a tight punch. I would keep the rw-12d to use alongside it.

I'm fairly handy with wood, and have all the tools that I would need.

Thanks in advance for your suggestions.
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post #2 of 51 Old 08-14-2013, 06:09 AM
 
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how big is "enormous"? What are your max box dimensions?
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post #3 of 51 Old 08-14-2013, 07:32 AM - Thread Starter
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I would say a 3'x3'x3' would be the max. I don't want a new coffee table. I don't think I'd be able to hide that from the wife.
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post #4 of 51 Old 08-14-2013, 07:47 AM
 
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that is a huge box!!! 3'x3'x'3 is way bigger than a coffee table! You could get a SI 18" and put it in a 21" x 21" x 21" sealed box.
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post #5 of 51 Old 08-14-2013, 07:57 AM - Thread Starter
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That would be my max. I had a 12" driver in my mind, but am open to othwr suggestions. Are there any plans out there that people are happy with?
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post #6 of 51 Old 08-14-2013, 08:01 AM
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Quote:
Originally Posted by mr.pope View Post

Hi Guys,
I've been toying with the idea of building a sub. I have two klipsch 12" woofers (I know, that's why I'm looking to build). By happenstance, a warranty issue left me with a spare amp that I would like to use. It's out of a rw-12d. The website states that it is: FTC Rated Power: 350 watts continuous @ <2% THD / Dynamic Power*: 825 watts.

I was considering building a clone of the 12d, but then thought why not do better? Looking at the drivers on parts express, I realized that I don't really know where to start. I don't want something that is enormous, but has a tight punch. I would keep the rw-12d to use alongside it.

If you are not married to that amp and to the idea of using the other klipsch 12 then there may be some other options you could look at, but within those parameters I would build a ported 15. Nothing wrong with using what you have though.

That amp likely has a high pass filter. You would do best to try to match the tuning of the Klipsch box (I assume it's ported) as that will work well with the rolloff of the amp.

The dayton DVC 385 15 would do well with that power as well as the JBL GTO 1514. 350w is a little shy on power for some of the bigger guns that are popular around here like the Dayton or SI 18.

A 3' cube is 27cu ft. That's bigger than an Lilwrecker. That's HUGE!
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post #7 of 51 Old 08-14-2013, 08:07 AM
 
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Originally Posted by mr.pope View Post

That would be my max. I had a 12" driver in my mind, but am open to othwr suggestions. Are there any plans out there that people are happy with?

Why 12"? 18" is better in every single way except for size of the cabinet, which you said you could do a 36" cube. a 21" cube is only one fifth of the size of a 36" cube. Sealed subs give a tight punch. I see no reason to make a sealed sub smaller than 18" unless you can't make a box that is a 21" cube.

Like nograve says, the amp might have a high pass filter, you might have to mod it or see if it can be turned off. A ported 15" would be a nice fit as well for that amp, box will be a bit bigger than 21" cube though.
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post #8 of 51 Old 08-14-2013, 08:39 AM
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Originally Posted by JWagstaff View Post

I see no reason to make a sealed sub smaller than 18" unless you can't make a box that is a 21" cube.

With that amp your returns diminish quickly. You could run a si 24 in a box smaller than a 3' cube, but it's not worth it unless you put some power behind it.
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post #9 of 51 Old 08-14-2013, 09:06 AM
 
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I wouldn't say a 3 dB loss is "returns diminishing quickly". Last time I modelled the SI I believe it was pushed to xmax with only 400 or 500 watts.
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post #10 of 51 Old 08-14-2013, 09:26 AM
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Quote:
Originally Posted by mr.pope View Post

That would be my max. I had a 12" driver in my mind, but am open to othwr suggestions. Are there any plans out there that people are happy with?

Why 12"? I think you should explain your thought process a bit.

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post #11 of 51 Old 08-14-2013, 09:39 AM - Thread Starter
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Originally Posted by JWagstaff View Post

Why 12"? 18" is better in every single way except for size of the cabinet, which you said you could do a 36" cube. a 21" cube is only one fifth of the size of a 36" cube. Sealed subs give a tight punch. I see no reason to make a sealed sub smaller than 18" unless you can't make a box that is a 21" cube.

I just figured because of the amp, I wouldn't be able to do much more than 12"
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Originally Posted by nograveconcern View Post

If you are not married to that amp and to the idea of using the other klipsch 12 then there may be some other options you could look at, but within those parameters I would build a ported 15. Nothing wrong with using what you have though.

That amp likely has a high pass filter. You would do best to try to match the tuning of the Klipsch box (I assume it's ported) as that will work well with the rolloff of the amp.

The dayton DVC 385 15 would do well with that power as well as the JBL GTO 1514. 350w is a little shy on power for some of the bigger guns that are popular around here like the Dayton or SI 18.

A 3' cube is 27cu ft. That's bigger than an Lilwrecker. That's HUGE!

I am a bit married to the amp. The reason I'm thinking of doing this is that I have the amp. It sits there saying "Use Me! Use me! Find a use for Me! The info given on what drivers the amp could handle are very useful and is very appreciated.

I don't really want to build a sub that big, but I could. The rw-12d is around the size i'd like, but I could go plus or minus. it's dimensions are 21x19x15.

Klipsch rw-12d
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post #12 of 51 Old 08-14-2013, 09:40 AM - Thread Starter
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Why 12"? I think you should explain your thought process a bit.

I just thought that's what the amp could handle. I'd love to go bigger if you guys think it would be alright. Is the premium (price) significant to go up in size?
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post #13 of 51 Old 08-14-2013, 10:10 AM
 
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Here's some graphs.
Yellow: 26" x 26" x 26" sealed SI 18" 350 W
Orange: 21" x 21" x 21" sealed SI 18" 350 W
Blue: 21" x 21" x 21" sealed SI 18" 1000 W

With a 12" driver say this one http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-466 it's only $70.00 cheaper than the SI 18.
Pink: 14" x 14" x 14" sealed 350 W
Purple: 15" x 15" x 15" ported 350 W with 2nd order 20 hz highpass and 3" diameter port 15" long tuned to 30 hz.



As you can see it does a few dB better above 20 hz if you triple the power. All these SPL charts are at or below maximum excursion. The 18" clearly destroys the 12" for only a bit more money.
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post #14 of 51 Old 08-14-2013, 10:29 AM
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I wouldn't say a 3 dB loss is "returns diminishing quickly". Last time I modelled the SI I believe it was pushed to xmax with only 400 or 500 watts.

...With sine waves in a big box. 800-1000w is needed to really make use of the extra excursion. With 350w of amp and program material the 18, due to the greater surface area, will have about 2db on a good, efficient, inexpensive 15 but at 2.5 times the cost. I'm not aware of a cheaper 18" option that would be a good match for that power, hence the diminishing returns. 2db is still 2db though so the op can weigh his options.
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post #15 of 51 Old 08-14-2013, 11:20 AM - Thread Starter
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...With sine waves in a big box. 800-1000w is needed to really make use of the extra excursion. With 350w of amp and program material the 18, due to the greater surface area, will have about 2db on a good, efficient, inexpensive 15 but at 2.5 times the cost. I'm not aware of a cheaper 18" option that would be a good match for that power, hence the diminishing returns. 2db is still 2db though so the op can weigh his options.

Do you have an example of a good efficient 15? I like seeing what I get for my money. As you say, if that 2db costs me quite a bit of extra money, then it may not be worth it. I rarely get to work out my system as it is. (wife and kids).

As an aside, when I was interested in simply building a clone of the a fore mentioned sub, I called klipsch. The 12" driver is available fro $110.
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post #16 of 51 Old 08-14-2013, 11:30 AM
 
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Originally Posted by nograveconcern View Post

...With sine waves in a big box. 800-1000w is needed to really make use of the extra excursion. With 350w of amp and program material the 18, due to the greater surface area, will have about 2db on a good, efficient, inexpensive 15 but at 2.5 times the cost. I'm not aware of a cheaper 18" option that would be a good match for that power, hence the diminishing returns. 2db is still 2db though so the op can weigh his options.

just look at the chart above your post. Yeah the SI does better with more power. What 15" are you suggesting that makes the 220.00 shipped SI 2.5 times the price?
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post #17 of 51 Old 08-14-2013, 11:34 AM
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The dayton DVC 385 15 would do well with that power as well as the JBL GTO 1514.

Either can be had for $99 shipped if you are patient. The DVC graphs < 1db below the SI 18 w/ 1w.
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post #18 of 51 Old 08-14-2013, 11:43 AM
 
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yea for that cheap the 15" is a bit better value with 350W.
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post #19 of 51 Old 08-14-2013, 12:02 PM
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I just thought that's what the amp could handle. I'd love to go bigger if you guys think it would be alright. Is the premium (price) significant to go up in size?

A larger woofer doesn't immediately indicate worse sensitivity. I can see where/why a person could think that because it seems causal. The design tools typically used can allow you to try a bunch of designs based upon a given input. In your case..fix your 350W and play around.


P.S.. A woofer box DOESN'T need to be a cube..especially sealed. You could make it 2x higher and shave the other dimensions accordingly.

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post #20 of 51 Old 08-14-2013, 12:14 PM - Thread Starter
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Yes. I assumed we were using cubes just for academics. I will just keep the internal volume the same. Thoughts on down firing vs side? I want to make it look nice and not having to make a grill would simply things a bit. Wife accwptance factoe would go up with no visible drivers. I took the grills off if all my speakers once to poor fanfare.
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post #21 of 51 Old 08-14-2013, 12:27 PM
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Yes. I assumed we were using cubes just for academics. I will just keep the internal volume the same. Thoughts on down firing vs side? I want to make it look nice and not having to make a grill would simply things a bit. Wife accwptance factoe would go up with no visible drivers. I took the grills off if all my speakers once to poor fanfare.

A cube has the best surface area to volume ratio short of sphere, which is hard to build. Other than that, there is no advantage to a cube...all of which is academic.

Down firing has some advantages. It filters out some harmonic distortion. I also find it more stable, and thus less energy is wasted, to have the axis of the driver going in the same direction as gravity. If you can't build dual opposed subs then down firing is the next best thing.

I built my boxes 24" wide and 20.5 high with 3.5" legs so they look like a 24" square. It's aesthetically pleasing and requires no grill.
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post #22 of 51 Old 08-14-2013, 12:35 PM
 
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yea I'm just using cubes just because it's easier to say the same 3 numbers haha
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post #23 of 51 Old 08-14-2013, 01:09 PM - Thread Starter
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yea I'm just using cubes just because it's easier to say the same 3 numbers haha

Yeah, me too. :-)
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post #24 of 51 Old 08-14-2013, 04:13 PM - Thread Starter
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Either can be had for $99 shipped if you are patient. The DVC graphs < 1db below the SI 18 w/ 1w.

I am patient. What do I need to look for? Does parts express have many sales or do I need to sign up for a mailing or similar? Or is there another place I should be watching?

Thanks again for all your help. I appreciate. it.
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post #25 of 51 Old 08-14-2013, 04:24 PM
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"Sealed subs give a tight punch."

not sure where that comes from. ported and horns can give tight punch too.

http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012

"I was considering building a clone of the 12d, but then thought why not do better?"

one reason is that the amp probably has digital signal processing to add equalization, high pass filtering, and the rest of it in order to protect the driver from damage while maximizing performance. just plopping some other driver in some other cabinet and then applying the klipsch amp dsp may or may not result in success.

Listen. It's All Good.
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post #26 of 51 Old 08-14-2013, 06:43 PM - Thread Starter
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^^^
I was wondering about that. I have the ability to shut all of that off. But your point is well taken. I may not have great results with that amp. If that's the case, I can always replace the amp later.
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post #27 of 51 Old 08-14-2013, 07:33 PM
 
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oh I totally agree ported can be tight and give punch, most do. It is possible for ported to sound sloppy and loose if it's not built/designed right, but I find with sealed it's basically impossible to not be considered "tight".
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post #28 of 51 Old 08-14-2013, 07:45 PM
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blue = dvc 15" 4 cubic foot sealed (to keep driver from over excursion)

red = si 18" 10 cubic feet sealed

green = dvc 15" 8 cubic feet, ported and tuned to 18hz

all with 350 watts and all dsp disabled. the ported would require a high pass filter though.

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post #29 of 51 Old 08-14-2013, 07:51 PM
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this form factor is front firing with a slot port. it is a little smaller than 8 cubic feet, but that is a 15" driver and might give you some ideas... :-)



that one is the old mfw-15 subwoofer. google images has several pictures of what can be done with it.




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post #30 of 51 Old 08-15-2013, 05:54 AM
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Quote:
Originally Posted by mr.pope View Post

I am patient. What do I need to look for? Does parts express have many sales or do I need to sign up for a mailing or similar? Or is there another place I should be watching?

Thanks again for all your help. I appreciate. it.

Right now the 385 is $129. It was $99 last holiday season.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-455

Also, I got my first one on deal of the day (under sales and offers tab) for $116. You got'a watch that every day though.

The GTO is $117 right now. I paid $107 for mine and I've seen it for $99. Add it to your wish list and watch the price.

http://www.amazon.com/JBL-GTO1514-Die-Cast-Single-Voice-Coil-Subwoofer/dp/B001UJGUQS/ref=sr_1_2?ie=UTF8&qid=1376571182&sr=8-2&keywords=gto+1514

The dvc preforms real similar to the MFW that LTD02 used in that beautiful slot port box. I don't think you can get the MFW anymore though.
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