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Car Subs for my new theater - Page 2

post #31 of 65
Quote:
Originally Posted by flexinator View Post

I turned the sub level on the receiver all the way up. I even got the speaker to clip a little bit with the amp gain all the way up. I'm pretty sure its being driven pretty hard...

Your line level signal might be clipping. Not your speaker level. Go to Guitar Center and get line level RCA to XLR powered bump box. Most likely you will need this.
post #32 of 65
Quote:
Originally Posted by braveheart123 View Post

If you look at the WinISD sims posted by Mrkazador up in the posts, you can use your current subs for a ported box tuned to 25Hz and that's close to the resonant frequency of these drivers. I don't know if that simulation is with 2 drivers or one. If it is one driver, then you can make another identical box using other driver and add 4-6 dB of extra output. You will get enough SPL down to 20Hz depending on where you place the subs in your room. It will serve your movies/gaming and music needs considerably and very cost effectively.

DIY isn't that difficult and anybody can learn unless of course you don't want to get your hands dirty wink.gif


The sim is with 2 drivers. If flexinator can wait a day or so I can create a ported box for him in google sketchup. That will take all the guess work out of building the box but I would need to know if he has any size restrictions.

 

 

Quote:

Originally Posted by Jinjuku View Post


Your line level signal might be clipping. Not your speaker level. Go to Guitar Center and get line level RCA to XLR powered bump box. Most likely you will need this.

 

I have the same receiver as he does and it can output enough voltage for my EP4000.

post #33 of 65
Thread Starter 
What kind of size restrictions? I have a 18ft room by 13.5 ft wide. There is plenty of room for whatever size box. I am planning on using this box as well as another powered sub I have someplace else in the room
post #34 of 65

What do you think of a 18 x18 x32" enclosure?  That will be big enough for the two drivers in a ported enclosure tuned to 25hz. If you do go ported, you will need a high pass filter to protect the driver below 25hz. What other sub do you have?

post #35 of 65
Thread Starter 
i think i have a polk audio psw10. I have a polk audio setup of a pair of monitor 70s, a cs2 front, the bookshelf speakers x4 for surrounds, and the psw10. I decided to use this stuff to start the theater, then upgrade over time if I want something better.

Since I happen to have the sub box from my car, I decided I'd use it rather than throw it away since I need my trunk more than louder music in my car.

The amp has a 30hz high pass filter i can enable, I assume that would be ok?

if 18 x 18 x 32 will bang, I'm willing to try it.

I looked through the stickies, but didn't see a general building thread. I'm sure its an easy question to answer, but what is the best way to build? What kind of board, then I'm sure you glue and screw all the joints.

I'm a total newb with speaker building, but I like to make stuff, so this will be a fun project.
post #36 of 65
Thread Starter 
The specs on the speakers say 1cu ft for a ported box. Is that a problem if I make a bigger box
post #37 of 65

I'm not familiar with the amps highpass filter but I assume it will work fine but you will lose some output at 25hz compared to a highpass set at 25hz. I made a sketchup of the enclosure and port, it measures 18 x18 x34".

 

 

I will attach the sketchup file so you can upload to Google Sketchup. From there you can use the measuring tool to get the exact measurements.

 

 

You need to extract the zip file with Windows, then load it up in Google Sketchup.

flexinator 25hz.zip 106k .zip file

 

 

Download Google Sketchup and install.

http://www.sketchup.com/intl/en/product/gsu.html


Edited by Mrkazador - 4/25/13 at 1:35am
post #38 of 65
Quote:
Originally Posted by flexinator View Post

The specs on the speakers say 1cu ft for a ported box. Is that a problem if I make a bigger box


You can follow the manufacturer's enclosure but that is usually for car audio with a high tune and small enclosure. Better to simulate the drivers in software like Winisd.

post #39 of 65
Thread Starter 
That looks very easy to build. Nice weekend project. Can you point me in the correct direction for materials?
post #40 of 65

3/4 MDF, 3/4 Arauco, or 3/4 Birch. Those are probably the 3 most common woods people use on their builds. You can find them in a lumber yard or some home centers. You can use glue only if you have lots of clamps or glue and screws. Titebond II is preferred if you can make accurate cuts. PL Premium is best if your cuts aren't perfect because this glue will expand slightly filling any gaps.

post #41 of 65
I would opt for a round port instead of a slot. Reason being fluid mechanics. Cylinderical shape of round ports pose less resistance to the flow of air as compared to its slot counterpart. Slot ports have bigger coefficient of drag against it walls than the cylinderical round ports. You will have smooth flow of air and have more output at the tuning frequency. I myself built a slot ported sub and that's the first thing I noticed. Um building dual Dayton HO 15 subs, but this time with round ports. It's easy but requires more precision.

Also, it will be a killer deal if you can manage to return EP4K and swap it with iNuke 3000 DSP for your needs. It has a built-in DSP and you can use it to set your HPF around 23-24hz. Setting HPF on EP4K at 30Hz will literally suck life out of your subs. Coz below 30Hz is the main business area in movies, which is what all the DIYers actually shoot for. Happy building
post #42 of 65
Thread Starter 
I can always just shut off the high pass filter...
post #43 of 65

If you shut off the highpass filter theres a high possibility that the driver will be damaged by over excursion from below its tuning point (25hz).

post #44 of 65
driving ferrari at full throttle without brakes eek.gif
post #45 of 65
Quote:
Originally Posted by braveheart123 View Post

I would opt for a round port instead of a slot. Reason being fluid mechanics. Cylinderical shape of round ports pose less resistance to the flow of air as compared to its slot counterpart. Slot ports have bigger coefficient of drag against it walls than the cylinderical round ports.
It's not the drag coefficient that is to be worried about, since they may very well be the same in square or circular ports. The idea is to minimize surface area because of its negative impact on smooth air flow to maximize laminar flow and minimize the turbulence entering/exiting the port with large port flares.

Sometimes folks increase the drag coefficient in order to keep more air right along the surface of the port to hold it there and create a buffer between the port wall and the fast moving air in the middle of the port.


post #46 of 65
Quote:
Sometimes folks increase the drag coefficient in order to keep more air right along the surface of the port to hold it there and create a buffer between the port wall and the fast moving air in the middle of the port.

It means we are reducing the port surface area, which further means the tuning frequency goes higher than what the port was actually tuned at. I think that's bad.
post #47 of 65
Thread Starter 
Just wanted to update this thread. I built the box Mrkazador suggested. Many thanks for the plans.
The interesting part, before I built it, I spent many hours trying to diagnose the problem with the subs. It turned out that the wire going between the two subs (since they were wired in series) was faulty. They speakers would work, but most of the power was not going through. I don't know how or why, but when I rewired the old box internally with new wires, boom, it worked. In any case, even with the old box working, I set out to build a bigger one. Here is the finished product.
post #48 of 65
So how does it sound?
post #49 of 65
Thread Starter 
It sounds great! Very loud... I need some help with the rattles in the glass light fixtures I installed. Thats the only thing in the room that rattles...
post #50 of 65
Thread Starter 
I am building some bass traps as well for the corners... here is the start...
post #51 of 65
Thread Starter 
I think I may have wrecked one of the subs. I was working on something else and I walked by my box and pushed on the woofers a bit. One is smooth and nice as it should be, the other feels a bit scratchy now. I've blown other subs before, so i know where this story goes. My question is, why? I dont think I over drive them. I have an opportunity to buy a new matching sub pretty cheap. What have I done wrong that it broke after only 2 movies. Was it ready to go perhaps? Help appreciated.
post #52 of 65
Quote:
Originally Posted by flexinator View Post

I think I may have wrecked one of the subs. I was working on something else and I walked by my box and pushed on the woofers a bit. One is smooth and nice as it should be, the other feels a bit scratchy now. I've blown other subs before, so i know where this story goes. My question is, why? I dont think I over drive them. I have an opportunity to buy a new matching sub pretty cheap. What have I done wrong that it broke after only 2 movies. Was it ready to go perhaps? Help appreciated.
That scratching is the voice coil coming apart, probably from overpowering. Drivers that are designed to operate in small boxes and small listening areas just don't fare well when put into larger boxes and larger spaces.
post #53 of 65
Thread Starter 
overpowering ie too much wattage? If that is the case turning down the gain will not help? Or perhaps over excursion? I've wrecked a sub once before doing that on accident, gain too high, over excursion for a short time, it only took a month or so before it was dead...
post #54 of 65
Did you have a high pass filter set up? If not you could have hit some low frequencies and it wouldn't take too many watts to send that speaker flying all over the place...
post #55 of 65
Thread Starter 
Yes. The amp has a 30hz high pass filter.
post #56 of 65
They probably just can't handle the power. I hooked 2 old 12" sony xplods to an ep4000, didn't last long.
post #57 of 65
Quote:
Originally Posted by doodoobutter View Post

I hooked 2 old 12" sony xplods to an ep4000, didn't last long.
They were aptly named, though. rolleyes.gif
post #58 of 65
Thread Starter 
They say they handle 350w rms. so 700 power handling for 1000w of output. Should I replace one sub with another I found on Craigslist? Or what kind of sub should I look at to handle the watts?
post #59 of 65
Seems rather odd that those Infinity's would just fall apart like that... Tons of people run the 1260 series Infinity's in a multitude of sub designs for home use. I'm running some Power Acoustik 15"s each in a 7 ft3 17hz box. "Car subs" can work just fine for home use...

How much does the replacement woofer cost? The 10" reference drivers cost the same as the 12" models, so not as good of a value, but they're still cheap and would work in your box. i wouldn't recommend powering them with a bridged amp.

http://www.amazon.com/Infinity-Reference-1062w-High-Performance-Subwoofer/dp/B0028ARP1W/ref=sr_1_1?s=automotive&ie=UTF8&qid=1374198924&sr=1-1&keywords=1062w

If you really want to step up the power handling, these RS265's would probably be your best bet. They will work great in your box, even with a 30hz HPF.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-463
post #60 of 65
Quote:
Originally Posted by Bill Fitzmaurice View Post

They were aptly named, though. rolleyes.gif

Well to be fair, I intended on "xplod"ing them, and I won. They were pretty damn loud in a house above 40hz with music. Then I hit em with a movie and literally put cracks in the cheap plastic cones. I don't know if they still make them out of plastic these days but wow, plastic. They were in my basement from the highschool box building days.

I don't remember what kind of power I was giving them 10 years ago, but I'll have to say I was pretty blown away for about 20 minutes with what they could do on a berry... until the berry blew them away.
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