I have a 15" JBL GTI sub that i want to use for my main room/TV/Music/Movies system. I'm modelling a box in the 8-9 cubic foot range with approximate exterior dimensions of 49" tall, 21" wide 19" deep. I like the winisd curve tuned at 25hz so far but would like any and all input.
I am considering casting concrete or using braced MDF. For MDF i can get 1.125" thick for $85 cut to my specs. My dimensions allow me to build this with only one sheet of MDF. Or i could use two .75" sheets for about the same cost.
I want this to by cheap, DIY, and great.
Concrete would be cheaper and the weight is not a problem.
Its currently powered by a 1400 watt jbl car amp, in a 4.7' box with two GTi subs. The box they came in is very poorly made (particle board) and i want to go down to just one sub as two is really too loud. I figure one sub in a great box with more power will be superior to the two subs in a junk box.
I am considering casting concrete or using braced MDF. For MDF i can get 1.125" thick for $85 cut to my specs. My dimensions allow me to build this with only one sheet of MDF. Or i could use two .75" sheets for about the same cost.
I want this to by cheap, DIY, and great.
Concrete would be cheaper and the weight is not a problem.
Its currently powered by a 1400 watt jbl car amp, in a 4.7' box with two GTi subs. The box they came in is very poorly made (particle board) and i want to go down to just one sub as two is really too loud. I figure one sub in a great box with more power will be superior to the two subs in a junk box.
Today i've been thinking about a curved slot port design and curved top. Walls would be MDF, top curved concrete. See crude MS paint design. I'm thinking i can use tempered hardboard to form the curves and fill with some concrete to make it very dead. Please comment and make recommendations.
Also if you think i should stick with a simple round port let me know.
Also if you think i should stick with a simple round port let me know.
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A 9 cubic foot box/225lt, tuned to 20Hz, with a 8" port, looks really good!
It will handle 1Kw, if you use a HPF at 19Hz, it seems to have a very flat response, and gives around 115db@ 20Hz.
I would leave out the concrete, 1" MDF well braced will be fine. Slot ports are great too, I just think round ones are easier and look better!
John.
It will handle 1Kw, if you use a HPF at 19Hz, it seems to have a very flat response, and gives around 115db@ 20Hz.
I would leave out the concrete, 1" MDF well braced will be fine. Slot ports are great too, I just think round ones are easier and look better!
John.
8 cubic feet tuned to 23-25Hz is fine too, at 23Hz a 8" port only needs to be 26" long, so with the 8" clearance you should have around the port, you would need a dimension of around 34", either height or depth.
I only suggested 20Hz because its a nice round tuning for your needs,20-25Hz is perfect for this sub, and the box size you want. Will you use a power amp?
I only suggested 20Hz because its a nice round tuning for your needs,20-25Hz is perfect for this sub, and the box size you want. Will you use a power amp?
I have a JBL GTO 14001 car amp and a power supply to run it. The amp is rated to produce 1500 watts rms at 2 ohms and 1200 at 4 ohms. I have enough DC current to expect about 600 watts true rms. If that is not enough i can get another supply and a capacitor. The amp's frequency response is 20hz-330hz and has a highpass filter. Does that usually mean it won't play below 20hz at all or just a steep roll off?
I'm trying to fit two 6" ports now since i really want front facing ports. I'm going to have to make the box bigger.
I'm trying to fit two 6" ports now since i really want front facing ports. I'm going to have to make the box bigger.
Latest design:
49" tall, 24" wide, 26.25" deep. 1.125" MDF, a full sheet is used for the four walls. Top, bottom, and bracing will be .75 MDF.
14.122 internal volume, subtract 1.25 for the ports, .135 for the driver, and i have 12.737 cubes. I'm thinking two 6" ports 20" long. So depending on bracing volume the tuning will between 22.5hz to 23.25 hz.
This won't be too much cubic feet right?
WinISD says i'l have a max port velocity of 28.74 meters per second at 800 watts. By 30hz its only 10.5 meters per second. Will I likely hear any port noise out of dual 6" ports? I'm thinking not.
49" tall, 24" wide, 26.25" deep. 1.125" MDF, a full sheet is used for the four walls. Top, bottom, and bracing will be .75 MDF.
14.122 internal volume, subtract 1.25 for the ports, .135 for the driver, and i have 12.737 cubes. I'm thinking two 6" ports 20" long. So depending on bracing volume the tuning will between 22.5hz to 23.25 hz.
This won't be too much cubic feet right?
WinISD says i'l have a max port velocity of 28.74 meters per second at 800 watts. By 30hz its only 10.5 meters per second. Will I likely hear any port noise out of dual 6" ports? I'm thinking not.
What kind of power supply? You'd have to have something seriously beefy to supply enough current to satisfy that amplifier.
Car batteries with hundreds of amps of current capability are very hard to duplicate in a power supply.
Err.. what??
Yep, much stiffer than mdf and stiffer than baltic birch too. Should be internally damped with a coating though.
Here's a pic of what i actually built.
It ended up being 2 layers of .75" MDF for the front, and 2 sheets for the top/bottom with bracing for the rest. The box took nearly 2 full 4x8 sheets and a It is slightly more than 12 cubes, port was a bit more than 8" tuned between 21hz and 22hz.
Power supply puts out 35 amps at 15 volts or about 525 continuous watts. The amp is not getting all the current it wants but it still can produce 120 decibels at 3' distance without distortion. I could beef up the DC current but this gets it more than done.
It ended up being 2 layers of .75" MDF for the front, and 2 sheets for the top/bottom with bracing for the rest. The box took nearly 2 full 4x8 sheets and a It is slightly more than 12 cubes, port was a bit more than 8" tuned between 21hz and 22hz.
Power supply puts out 35 amps at 15 volts or about 525 continuous watts. The amp is not getting all the current it wants but it still can produce 120 decibels at 3' distance without distortion. I could beef up the DC current but this gets it more than done.
At least 567 L vented to a 16 Hz F3, so will need some room gain to get it 'flat'.
Not familiar with Earthquake subs.
GM
Here's a pic of what i actually built.
It ended up being 2 layers of .75" MDF for the front, and 2 sheets for the top/bottom with bracing for the rest. The box took nearly 2 full 4x8 sheets and a It is slightly more than 12 cubes, port was a bit more than 8" tuned between 21hz and 22hz.
Power supply puts out 35 amps at 15 volts or about 525 continuous watts. The amp is not getting all the current it wants but it still can produce 120 decibels at 3' distance without distortion. I could beef up the DC current but this gets it more than done.
When using a power supply like this, does it make sense to put a large cap or SLA battery in parallel? I'm also looking to run a car amp off a power supply.
That thing must be heavy.
The box alone took two people and a dolly to get up the stairs. I could add a capacitor but like i said, for home theater use, its plenty. I don't usually turn it up high enough to dim the lights on the amp. It plays lower than i can hear, shakes all different parts of the house, and probably can be heard from the adjacent houses as is. A cap, battery, or even second supply could be installed parallel for more current. I probably would have built it smaller if i did it again today, but this huge box is amazingly efficient. I bought the subs from a guy who had TWO in 4.2 cubic feet sharing a port. He thought they sucked, but it was his box! I also designed this so that i could convert it to a dual sealed box by enlarging the port. However i think i'l use the second GTI in my car or something as i'm happy with what this can do.
I'm sure it's pretty awesome. I have a long throw 15" in about 4 cubes for my truck, and it's actually pretty flat response wise that size enclosure, but not tuned nearly as low. Based on the datasheet, looks like the jbl needs a bigger box and low tune to have a flat response.
I would throw in a cap just for peace of mind. I'm not sure what a lack of current during transients would do, maybe a voltage droop that could push the amp into clipping? I'd look into it.
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Does anyone know the difference between 15W GTI MK II with:
Silver "JBL" dustcap
and
Black, White, Orange "JBL 5000WATTS" dustcap?
JBL - W15GTi MkII - 15" Subwoofer with Kevlar®-impregnated-paper woofer cone and Dual 6-ohm voice coils
Silver "JBL" dustcap
and
Black, White, Orange "JBL 5000WATTS" dustcap?
JBL - W15GTi MkII - 15" Subwoofer with Kevlar®-impregnated-paper woofer cone and Dual 6-ohm voice coils
Power supply
I used a car amp for my subs (a car crossover too) and kept blowing power supplies.
I was using Pyramid 0-14V, 35 amp power supply (MCM-$125) for a 300 watt amp, that lasted 6 months and smoked.
It was a class D amp and should have had no problems with a 35 Amp power supply. Also, the speaker impedance was limiting it to closer to 200 watts.
After the second power supply smoked, I bought a 1 Farad cap and put that in parallel with the power supply.
What a difference, it sounded tighter, way better and the power supply lasted 10 years until a crappy wiring job shorted it and it smoked.
.
WARNING SECTION:
I finally just brought an old car battery inside so I could have music.
With nothing hooked up to the battery, no amp, no charger....BOOM.
I was not home when it happened and have no idea why it happened.
It blew acid in a line all the way up one wall, across the ceiling and down the other wall.
It left a puddle that dissolved my industrial tile and was just a disaster.
Don't ever try it, even just for that one afternoon when you need something to power your amp.
A word to the wise is sufficient,
Dave
I used a car amp for my subs (a car crossover too) and kept blowing power supplies.
I was using Pyramid 0-14V, 35 amp power supply (MCM-$125) for a 300 watt amp, that lasted 6 months and smoked.
It was a class D amp and should have had no problems with a 35 Amp power supply. Also, the speaker impedance was limiting it to closer to 200 watts.
After the second power supply smoked, I bought a 1 Farad cap and put that in parallel with the power supply.
What a difference, it sounded tighter, way better and the power supply lasted 10 years until a crappy wiring job shorted it and it smoked.
.
WARNING SECTION:
I finally just brought an old car battery inside so I could have music.
With nothing hooked up to the battery, no amp, no charger....BOOM.
I was not home when it happened and have no idea why it happened.
It blew acid in a line all the way up one wall, across the ceiling and down the other wall.
It left a puddle that dissolved my industrial tile and was just a disaster.
Don't ever try it, even just for that one afternoon when you need something to power your amp.
A word to the wise is sufficient,
Dave
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