Klipsch SUB-12 Subwoofer (1 Viewer)

[BraveHeart123]

It won't be last InshaAllah. Hang on ... I am on the search spree for Apline 1242D. Lemme find it and I will get back to you.
Update:
I've checked with a store that carries Alpine subs but, to my misfortune, they are out of stock on this model. They do carry MB Quart PWH304, which is over $300.
No GTi series on JBL but GT4-12 and GT1502D are available.
Also, readily available is Pioneer TS-W309S4 (12" / 4 ohm / Single Voice Coil / FR: 20-220Hz / 400 RMS & 1400 PMPO). T/S parameters are also known and published on Pioneer USA website in the owner's manual at http://www.pioneerelectronics.com/PUSA/Car/Subwoofers/Champion+Series/TS-W309S4.
I think I will go with pioneer.

 

[Robert_J]

I don't like the Pioneers. The Fs (resonant frequency) is almost 40hz. The Qts is .66 which will go even high in a sealed box. Finally, the xmax (one-way linear excursion) is 10mm. The Alpine has a lower Fs, lower Qts and almost double the excursion.
Find the manuals on the JBLs and I'll take a look at them.

 

[BraveHeart123]

That's the info I pulled out on JBL subs, They are also readily available
T/S Paratemeters for JBL GT4 12" Sub
Revc = 3.56
Levc = 2.54
Sd = 82.31 Sq-Inches
BL = 14.78
Vas = 3.22 ft
Cms = 227.58
Mms = 181.74
Mmd = 174.70
Fs = 24.75
Qms = 6.46
Qes = 0.46
Qts = 0.43
Xmax = 12.5mm
T/S Parameters for JBL GT1502D Sub
http://www.jbl.com/resources/Brands/jbl/Products/ProductRelatedDocuments/en-US/BoxesandParameters/GTO%201502D%20Enclosure.pdf

 

[Robert_J]

The JBL has good specs as well. If they cost less than an Alpine, go with them. But based on swept volume, the Alpine wins. Both have similar sized 11" diameter cones but the Alpine has about 25% more excursion. Therefore it has the potential to move 25% more air.

 

[BraveHeart123]

Alpine is simply not available. There are a couple outlets, but I know they sell fake Alpine subs made in God knows where. The outlet I checked with is licenced and serves full warranty, but I will have to wait for 2-3 months.
For the time being these two models of JBL are readily available. I think the 12" model has better excursion and more air volume to displace than the 15 incher does. I wana go ahead with the 12 inch JBL sub. Pls do the initial math for me and advise on the box dimensions (internal and external) and internal bracings, if any.
Also, I need some clarification on the following; I may sound dumb, but need to ask anyway
I am using Yamaha RX-V3900 AVR, which can drive speakers at 8 ohms or 6 ohms. Also, if I buy Yamaha P5000 amplifier for this sub, P5000 gives 750 Watts per channel at 4 ohms. Can I connect P5000 with my AVR keeping in mind the impedence difference?
How would I run JBL 4 ohms sub in this setup??
Does this car sub (12 Volts DC) require external power (230 Volts AC), or will just require a signal input from P5000?

 

[Robert_J]

Also, I need some clarification on the following; I may sound dumb, but need to ask anyway

Don't ever think a question is dumb. These are all valid questions for all but people who are big into DIY.
1. Yes, you can connect the P5000 without any issue. The RX-V3900 does not see the impedance of the sub since there is different amp powering the sub.
2. It is connected to the P5000 amp. If it is a dual 2 ohm coil, then you wire the coil in series.
3. Subs don't care where you install them. Car sub, home sub, etc. are just marketing terms. The majority of the subs work well in all environments. Others that don't have a lot of low-end output work better in small spaces but I still wouldn't consider them "car subs". Your sub doesn't care if the amp is powered by 12v DC or 230v AC. The sub sees the amplified audio signal.

 

[BraveHeart123]

That's good news. Seems I dont have to worry about AC/DC conversion. So, with the 12" JBL model mentioned in previous posts, can u give me the box details?? Thanx

 

[Robert_J]

I ran the numbers and a 28.3L (1 cubic foot) enclosure is great for the JBL. Use the sealed Subduction design linked above. It only takes 250w to push the sub to its full potential so I suggest a smaller amp than the Yamaha P5000. One channel of the P2500 is just slightly overkill. Even it will run a pair of JBL subs with ease.
Physical Vb - 28.3l
Absorption, Qa - 5
Leakage, Ql - 15
Alpha, a - 2.658
Vb - 34.3l
Fb - 46.93Hz
F3 - 46.99Hz
Qtc - 0.711
Response peak - 0.00dB
Peak at - none
Basically, it's a great looking sealed sub. Depending on the size of the room, you could have significant output at 20hz.

 

[BraveHeart123]

Thanx for the input. I checked with local outlet carrying stereo amps. There are more brands readily available. Pls advise on which one to choose from the following;
1. Samson SX1200
2. Samson SX1800
3. Crown XLs-602
4. Crown XLs-802
5. Yamaha P5000
Pls bear in mind, this is not the only and last DIY sub I am ever gonna build. I will go higher in RMS output, of course with your help, as and when better sub drivers are available in the market. This DIY project is infectious and interesting so, pls suggest one amp from the list above, coz that's all what is avaiable. Behringer amps won't be available till January next year.
Now about the sub box;
1. What should be the MDF width? Is it the same in Subduction sealed design?
2. Is one cubic foot box measurement internal or external??
3. Do I need the parameters you listed or were they just used for the box measurement and I just need to follow the Subduction design now i.e. cutting the MDF to specs and join them together??

 

[Robert_J]

1. Yes, build the Subduction sealed box as shown. You will have to measure the driver for the proper sized opening. And you don't need a magnet brace as the JBL driver can be mounted vertically with no issues.
2. Internal. It's all about the volume of air. 12 x 12 x 12 = 12^3 = 1728 cubic inches.
3. I listed the simulated performance of the JBL driver in the Subduction enclosure. Just build the Subduction box.
Pick the most power for the least amount of money. Samson is great. In fact, SVS used to sell them to power their old passive subs. Crown amps are great. The Yamaha should work fine as well. All are much more powerful than you need......Also look to see if any are 2 ohm stable. They Yamaha isn't. The Samson ones may be. I'm pretty sure the Crowns are. That will allow you to build 4 subs and run them in pairs on each channel.

 

[BraveHeart123]

1. Yes, build the Subduction sealed box as shown. You will have to measure the driver for the proper sized opening. And you don't need a magnet brace as the JBL driver can be mounted vertically with no issues.

Which brace?? Vertical one along the circumfrence of the magnet OR Horizontal at the back of magent extending to the rear end of the box??
What should be the diameter of circular cuttings in braces??
What kind of input the sub will receive?? Is it single RCA or Left/Right RCA??

 

[Robert_J]

The vertical brace. Just cut the hole at 7 1/16 as shown. The magnet on the JBL is much smaller.
From the text on page 1, right side:
"the smaller holes
don't need to follow any pattern -- you
just want to have lots of holes (irregular
is probably better than regular)."
Neither. The sub is passive so it will have speaker inputs like this - http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=417 . If you really want to go high-tech, use the Speakon terminals - http://www.parts-express.com/wizards/searchResults.cfm?FTR=speakon&search_type=main&WebPage_ID=3&searchFilter=speakon&x=0&y=0 .

 

[BraveHeart123]

On page 1 of Subduction design, 3rd point says "Double front flush mounts driver" ..... what does it mean??
Samson SX1200

The convenient two rackspace design may be compact, but there's plenty of power available, with 2 x 300 watts at 8 ohms and 2 x 450 watts at 4 ohms over the full frequency spectrum, from 10 Hz to 55 kHz

Crown XLs 602

Power Output 1 kHz Stereo Mode - 380W into 8 ohms, 600 Watt into 4 ohms and 840 Watt into 2 ohms Bridge-Mono Mode

I took the excerpts from Amazon. I've shelved the idea of Yamaha P5000 on your advice and narrowed down to these two models of Samson and Crown. But Crown power offerings are at 1KHz like yamaha, whereas Samson SX1200 gives the rated RMS across entire spectrum but doesn't have 2 ohm option.
Which one do u think I should go for??

 

[Robert_J]

"Double front flush mounts driver" ..... what does it mean??

The front baffle is 2 layers thick. The outside layer is cut out slightly larger than the diameter of the driver. The inside layer is where the driver actually mounts. This is for cosmetics only. It is easier to cut the same sized hole in both layers and surface mount the driver.
Crown. Even though they only rate their power at 1khz, they can drive a 2 ohm load. This will be beneficial if you use the amp on future projects.

 

[BraveHeart123]

OK... this comes from a sub guru, so I go by your pick. I am gonna pick up Crown XLS-602. The sub will arrive tomorrow and um gonna get down with the business this weekend. I will keep posting the pictures from time to time.
Thanx truck loads and c u here soon...

 

[BraveHeart123]

I forgot to mention...I use my HT 90% for movies. I hope the enclosure u designed focuses on this aspect. Also can u pls share the fequency/spl graph of your sub building software for this sub?
I will crack on with MDF cutting tomorrow morning.

 

[Robert_J]

I'll get that posted tomorrow.
My goal is to accurately reproduce whatever signal is fed to the sub. Whether it is music, movies or a movie with music in it.

 

[BraveHeart123]

Sub has arrived. Spent whole afternoon in getting the pieces cut to required measurements. Following is the detail;
Note: The MDF is 18 mm thick. Subduction design recommended 19 mm, but it is not avaiable here. Sizes are (16/17/18/24) mm. Is it OK??
1. Front (12" x 12") with 11" dia cut for speaker.
2. Back (12" x 12"). Haven't cut the whole for binding post terminal yet.
3. All sides Left / Right / Top / Bottom (12" x 13.5").
4. Inner horizontal holy magnet brace (12" x 7.75"). The center hole is in dead center, rest all were made asymmertrically as many as the space allowed.
Um attaching the pictures for u to have a look.
All Pieces

Back

Front

Inner Horizontal Holy Magnet Brace

Left / Right / Top / Bottom

Check if this is correct. The box seems very tiny. Anyway, how do I put them together??
Do I need to glue them OR nail them OR screw them together???
Also, do I need internal tiny pyramid shaped widgets to affix in the corners where the walls meet in order to kill box resonance???

 

[Robert_J]

18mm MDF is fine. Did you adjust your cuts to account for the 1mm change? If not, shouldn't be a problem to lightly sand the overhangs to get perfect joints.
Awesome picture with the toes. I have been known to do the same thing. Another forum I belong to, it is an unofficial requirement to have toes in at least 1 picture.
Yes, the box is sort of small. Subs come in all sizes.
Tightbond II wood glue and clamps are the best. Glue and nails are great if you use brad nails and an air nailer. Glue and screws will also work if you pre-drill the holes. After everything dries, remove the screws and fill in the holes. Good wood glue holds better than screws.
You are dealing with wavelengths that are 10 feet long and longer. Putting things in the corners will have no impact at all on standing waves. Box resonance is lessened via thickness of the wood and bracing. You may need stuffing. Fiberglass works great. So does polyfil. I normally go to Wal-Mart and buy a $2.50 pillow. I'm assuming that Wal-Mart has invaded Pakistan like they have with the rest of the world. If not, a fabric store will should have polyfil. Even raw wool will work but it is expensive over here.

 

[BraveHeart123]

Awesome picture with the toes. I have been known to do the same thing. Another forum I belong to, it is an unofficial requirement to have toes in at least 1 picture.

That was a coincidence

Tightbond II wood glue and clamps are the best. Glue and nails are great if you use brad nails and an air nailer. Glue and screws will also work if you pre-drill the holes. After everything dries, remove the screws and fill in the holes. Good wood glue holds better than screws.

Does it mean screws and nails are just catalysts and they have to be removed from the final product and the box eventually stands on strong wood glue??? I hope the joins do not rip apart from immense internal pressure.

Box resonance is lessened via thickness of the wood and bracing. You may need stuffing. Fiberglass works great. So does polyfil. I normally go to Wal-Mart and buy a $2.50 pillow. I'm assuming that Wal-Mart has invaded Pakistan like they have with the rest of the world. If not, a fabric store will should have polyfil.

Thats's no problem. Would surgical cotton do the job?? It comes in a roll 6 inches wide and about 4-5 mm thick. I can just glue the strips against the wall inside box enclosure