I need help building a subwoofer

[voodoomelon]

Hey all,
I'm just after getting a 1000w Kenwood subwoofer from eBay for a bargain price and i want to build an enclosure for it and add it to my Creative DTT3500 5.1 speakers.

Here it is:
http://www.justkenwood.co.uk/images/kfcw1205db.jpg

Thing is, I cant power it directly from my DTT3500 amp because it only outputs 30w's.
Can anyone give me some advice on getting a car amplifier around 500w - 750w to connect to the subwoofer? I also need some advice on connecting it to my walls 240v mains socket (seeing as a car amp will run on 12v).

If this isn't possible, can I get some other kind of cheap amplifier (<$80) to power the sub that will plug into the wall?

Thanks a lot!
Voodoomelon
;)

[Azzkiller]

Thing is, I cant power it directly from my DTT3500 amp because it only outputs 30w's.
The rated power output for an amplifier does not specify if it can drive a speaker or not (unless its really low - below 1 watt or something)


Can anyone give me some advice on getting a car amplifier around 500w - 750w to connect to the subwoofer? I also need some advice on connecting it to my walls 240v mains socket (seeing as a car amp will run on 12v).
You'd need either a bench power supply, or a car battery with a trickle charger. Either would be quite expensive, and it would probably make more sense to buy a home audio amplifier.

Also, why can't you use the Creative's built in amplifier? You would have to dissasemble the speakers though.

[voodoomelon]

Hi.
I can't use the DTT3500's amplifier because, like you, I thought I could just connect the 1000w subwoofer directly to the amp's sub output.
I went to my friend's house the other day and connected a Sony Xplod 12" 900w subwoofer to the amps output, and after 15 minutes or so of music playing, the amp got extremely hot and now the amp has been damaged.

Any subwoofer that I now connect to the amp sub output just rattles and distorts instead of outputing bass.

So, what I want to do now is forget the damaged sub output, and instead use the "Line Out" subwoofer output which Creative have convieniently included. This means I can connect a powered sub, the one which i intend on building, which will amplify itself and not be dependant on the DTT3500 amplifier.

I have seen 500w-750w car amplifiers on eBay for around $50, but have no clue as to how I would connect one to the mains power....

;)

[Azzkiller]

Hi.
I can't use the DTT3500's amplifier because, like you, I thought I could just connect the 1000w subwoofer directly to the amp's sub output.
I went to my friend's house the other day and connected a Sony Xplod 12" 900w subwoofer to the amps output, and after 15 minutes or so of music playing, the amp got extremely hot and now the amp has been damaged.
The Sony woofer probably had a lower nominal impedence than the stock woofer. That would cause the amp to overheat at full volume. I would venture to say that was the reason the amplifier was destroyed.

Do you by any chance know the nominal impedence of the Sony woofer, or have a multimeter so that you can measure it's DC resistance?


So, what I want to do now is forget the damaged sub output, and instead use the "Line Out" subwoofer output which Creative have convieniently included. This means I can connect a powered sub, the one which i intend on building, which will amplify itself and not be dependant on the DTT3500 amplifier.
Well that would certainly work then.



I have seen 500w-750w car amplifiers on eBay for around $50, but have no clue as to how I would connect one to the mains power....

;)

If you see an amplifier that is rated for that much power for only 50 dollars, you are almost certainly seeing a completely overrated amplifier. In reality it probably puts out closer to 100-200 watts - or maybe even less.

Instead, why not buy a home plate subwoofer amplifier like this? http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-784

70 watts is quite a bit of power, and depending on what woofer and enclosure type and size you choose, you can get better performance than most inexpensive (sub 200 dollar) commercial subwoofers offer.

[voodoomelon]

Hello again.
It's funny that you should include that link to Parts Express, because I was looking at the exact same pages myself. I'm considering buying one of their 250w plates or maybe even one of ther 500w ones.
Delivery to me here in Ireland though is a colosal $60. But it still works out relatively cheap because of the strong Euro against the dollar.

Oh, and the Sony sub is 4ohm's i think, whilst the DTT3500's subwoofer is 6ohm's.

Would this matter if I got one of the plate amplifiers? Because the Kenwood sub i bought is rated at 4ohm's...

Thanks ;)

[Azzkiller]

Hello again.
It's funny that you should include that link to Parts Express, because I was looking at the exact same pages myself. I'm considering buying one of their 250w plates or maybe even one of ther 500w ones.
Delivery to me here in Ireland though is a colosal $60. But it still works out relatively cheap because of the strong Euro against the dollar.

Oh, and the Sony sub is 4ohm's i think, whilst the DTT3500's subwoofer is 6ohm's.

Would this matter if I got one of the plate amplifiers? Because the Kenwood sub i bought is rated at 4ohm's...

Thanks ;)

Yes, the Partsexpress plate amps are rated to drive loads as low as 4ohms nominal.

[voodoomelon]

So is that a Yes, it does matter, or a No, it doesn't matter? :)

What i meant was does it matter that the DTT3500's amp only outputs 6ohm's, whilst the plate amp outputs 4ohm's?

Thanks for your continuing help.

;)

[Azzkiller]

So is that a Yes, it does matter, or a No, it doesn't matter? :)

What i meant was does it matter that the DTT3500's amp only outputs 6ohm's, whilst the plate amp outputs 4ohm's?

Thanks for your continuing help.

;)

Yes, the amplifier can drive as low as 4 ohm loads. That means as long as the nominal impedence of the speaker is 4ohms or higher, you should be fine.

So yes the amplifier will work.

[voodoomelon]

Hey!
I just bought a Legacy LA770 1000w car amplifier from eBay.
Here it is:

http://www.audioblowouts.com/ebay/LA770.jpg

I'm gonna get my friends dad, who is the head of electronics at my local college to hook it up to a transformer to reduce a 240v mains current into 12v for the amp.

I'm then going to screw the amplifier to the rear of the subwoofer.

The amp was a steal by the way, they retail for about £200 in England, I got mine for EUR104, that's about £70! And it's brand new. Can't beat America for cheap electronics. :)

Thanks for your help ;)
Voodoomelon

[james.miller]

your gonna need one hell of a dropper for that mate lol.

I paid £45 (i think) for the denon amp that powers my sub - does me a treat :)

[voodoomelon]

your gonna need one hell of a dropper for that mate lol.

I paid £45 (i think) for the denon amp that powers my sub - does me a treat :)

Lol, i know. I'm gonna bring the amp into my local Car Audio Specialists and see what they suggest to bring the voltage down. I was thinking of using one of those standard 12v transformers with the inter-changable heads you can buy in Argos and the like, but I doubt they could sustain a constant high power output for long.

I'll see what they suggest. I'll see if they have any subwoofer ports while i'm in there...

;)

[Steven4563]

i was thinking the same thing to get a Car Sub and a Car AMP intill i get a car to put it in but i dont know the best way to go about it maybe ill just read up on your thread to see what people think and what u decide to do

The Sub i was gonna buy was a JBL 15" 1000watts peak power and the amp was a Infinity 5760A 560watt

[Quattro]

That's some nice power...
How the hell do you use that much bass.

As soon as I start putting power to my Z2200 Sub it's starts making things shake. Plus it's sitting on a wooden floor in the upstairs part of my house so it's makes the whole house vibrate.

[james.miller]

like mine then :D

http://homepage.ntlworld.com/james.miller700/Picture%207.jpg

still need to get that sub finished off :rolleyes:

[MasterCraft]

:drool:

that amp is droolage at that price, I've been a fan of legacy for awhile, holy crap what a deal

[voodoomelon]

Hey all!
Been a while, but i've finally got my 1000w subwoofer built and up and working!

I had to make a crappy Ms Word website :rolleyes: for college, so i thought i'd make it on "How to build a subwoofer". :D
Sorry about the crappyness, i threw it together in 20mins.

Heres the link : Sub Link! (http://www.angelfire.com/film/buildasubwoofer)

I'll have more pics soon, seeing as there are no pics of the finished box.

;)

[Korndog]

very nice job, looks very nice.
you made a pretty good box.
But you know, if you changed that 1/2" mdf to 1" mdf, it makes a HUGE difference, expectually for a 1000w subwoofer.
as for the legacy amp, its horrible. They are bad amps. I would look into lanzar amps if you're on the budget. But since ur using this at home, it would be better to get a plate amp and an inverter.
heres a pic of my box that i made and carpeted, still need to paint the inside though..
http://img144.exs.cx/img144/9081/smallspeakers003.jpg
its a memphis subwoofer and lightning audio amp in a 3cuft box ported to 40hz. Only 250w, but i out bass people in the 750w range at competitions :)

[voodoomelon]

I thought of using 1" thick MDF, as soon as I had actually build it using 1/2" MDF, lol. As you can see, the edges are really rough, but the finish on the rest of the box is beautiful, really smooth and glossy. (The flash really shows up imperfections).

As for the amp, I think it was an absloute bargain, can't go wrong for €100 shipped (brand new).

Here are some pics, and a pic beside an old Dell case to compare size.

http://img.photobucket.com/albums/v282/voodoomelon/DSCF0196.jpg
http://img.photobucket.com/albums/v282/voodoomelon/DSCF0198.jpg
http://img.photobucket.com/albums/v282/voodoomelon/DSCF0197.jpg
http://img.photobucket.com/albums/v282/voodoomelon/DSCF0199.jpg

Some thump!
;)

[zabomb4163]

what power supply are you powering the amp with?

[zabomb4163]

Hey all!
Been a while, but i've finally got my 1000w subwoofer built and up and working!

I had to make a crappy Ms Word website :rolleyes: for college, so i thought i'd make it on "How to build a subwoofer". :D
Sorry about the crappyness, i threw it together in 20mins.

Heres the link : Sub Link! (http://www.angelfire.com/film/buildasubwoofer)

I'll have more pics soon, seeing as there are no pics of the finished box.

;)

your video does not work

[Korndog]

it looks like an antec 350, i have something similar
its like 18a on 12v i think, its enough for a legacy.
trust me on this one, i had that amp and trashed it because it was so bad compared so other amps. Even the new PYLE amps are better.

[voodoomelon]

Lol, I know the video doesn't work, we were made throw it in as a mere formality. I got rid of it.

The power supply is an Antec 400w Smartpower, it's a very good PS and you're spot on Korndog, 18A exactly.

Well, I hope the amp doesn't go arse-up for me.... :-/

P.S. Korngod, what do want a Z3 for!? :D

;)

[zabomb4163]

Hey all!
Been a while, but i've finally got my 1000w subwoofer built and up and working!

;)

18a*12volts = 216watts. amps are usually about 50% efficient. so that gives you 108watts to the subwoofer.

[Korndog]

18a*12volts = 216watts. amps are usually about 50% efficient. so that gives you 108watts to the subwoofer.
thats true.
but besides that 1000w is the MAX. people don't get this, max means it can burp 1000w for a few seconds before blowing (this is at very low impedances)
the true rating is..
# 75 watts RMS x 2 (4 ohm load)
# 125 watts RMS x 2 (2 ohm load)
This is rated at 14.4v so its probably 50x2 rms at >12v, so you're getting 100w to it if you're running a dual 4ohm coil or about 150w if you're running it bridged on a single 4ohm. You're psu probably won't be stressing over that..
you could have gotten a profile or lanzar 400w-600w for the same price, but it will actually out put 400w-600w, but besides all that, the quality will be better, it will be cleaner.

[Korndog]

P.S. Korngod, what do want a Z3 for!? :D
;)

Z3s are sweet, but i'm starting to change my mind again.. if i have the time i might get an old 300zx and fix it up (that doesn't mean sup it up)

[Ryan T]

but besides that 1000w is the MAX. people don't get this, max means it can burp 1000w for a few seconds before blowing (this is at very low impedances)

When they do peak power rating its usually far less than a few seconds I believe. Most the time they apply the power for a fraction of a second but maybe I'm wrong.

Anyway good work on the sub voodoomelon! MDF is pretty picky when It comes to painting. I've found the only way to get a really even coat is to use primer first (a few layers and sand between coats). Since The MDF soaks up paint like a spong. But Since you made all your cuts at 45 degree angle you dont have to worry about the edge of the MDF soaking up more than the side (which is a big problem usually).


Ryan

[Korndog]

When they do peak power rating its usually far less than a few seconds I believe. Most the time they apply the power for a fraction of a second but maybe I'm wrong.

Anyway good work on the sub voodoomelon! MDF is pretty picky when It comes to painting. I've found the only way to get a really even coat is to use primer first (a few layers and sand between coats). Since The MDF soaks up paint like a spong. But Since you made all your cuts at 45 degree angle you dont have to worry about the edge of the MDF soaking up more than the side (which is a big problem usually).


Ryan
i'm just saying that because i tried it on a pyramid amp that was 500w max at 1ohm, but only 2ohm stable, wired it up at 1/2 ohm and a 14v alternator (good old german cars got big alternators ;)) at first it blew right away without playing anything, the fuse blew, so i put bigger fuse and tried it again and it lasted for a few seconds, didn't really count, it got a lot louder, but something eles blew in it after like 3 thumps at max volume. pyramid is not better then legacy, so a few seconds sounds about right.

man, i just just painted my box 2 hours ago, i totaly forgot about mdf soaking paint :-/ the metal and plastic parts came out like a car paint finish, but the wood came out spongy, lol.
fiberglass sound good right now :)

[Ryan T]

i'm just saying that because i tried it on a pyramid amp that was 500w max at 1ohm, but only 2ohm stable, wired it up at 1/2 ohm and a 14v alternator (good old german cars got big alternators ) at first it blew right away without playing anything, the fuse blew, so i put bigger fuse and tried it again and it lasted for a few seconds, didn't really count, it got a lot louder, but something eles blew in it after like 3 thumps at max volume. pyramid is not better then legacy, so a few seconds sounds about right.

Ahh, I thought you were refering to the subwoofer drivers peak power. My bad.

man, i just just painted my box 2 hours ago, i totaly forgot about mdf soaking paint the metal and plastic parts came out like a car paint finish, but the wood came out spongy, lol.
fiberglass sound good right now
Cool, What subwoofer are you building right now if you dont mind me asking. Id love to see some pictures!


Ryan

[ComPuterFreak90]

how do u build a subwoofer?

[Ryan T]

how do u build a subwoofer?

Well there are quite a few different methods. What did you have in mind?



Ryan

[voodoomelon]

Yeah, I know the Legacy isn't actually 1000w. i'm thinking of selling it anyway to some unsuspecting buyer. I'll make a decent profit as car amps go for a lot more over here than the US.

I'm in the market for a new 5.1 amp, eBay, here I come...

;)

[Korndog]

do u mean 6channel?
usually 5.1 is the 4 lefts and rights and a center channel and the .1 is for the subwoofer.
you better make sure you want 5.1 or 4.1.
i would seriously recommend a seperate amp for the kenwood. the kenwood subs have a heavy cone. although they are decent, they will not give you the best quality but they will give you decent spl (.. loudness :D) for a 1000w that is. I'd suggest getting a class D amp so its more effiecent, something thats 500w or more. Look into MTX amps. Get a car battery (cheapo one) and use it for its capacity, add a second power supply to the assembly and let it blast, you'll have the cops at your front door in no time. :)

[Mr.Guvernment]

I hope you dont plan to keep that sub that close to your tower....

[Korndog]

r u refering to the magnet doing damage to a computer? magnets do NOTHING to computers, even hard drives, you can search "pump magnet damage computer" in the watercooling section for more into on that.

If a sub was strong enough, the vibrations might damage something or screw up your burns, lol, but if it was that strong/loud, i would be more concerned about your ear drums then a computer

[zabomb4163]

nothing eh? I'll post some pictures of what my subwoofer does to my monitor if its less than 3 feet away.

[Mr. Chambers]

yep, zabomb's right - magnets do a ALOT to computers, especially if they aren't sheilded and especially ones of that size.

[Korndog]

a monitor is not a computer.. we were talking about 'towers' right?
here..
http://www.ocforums.com/showpost.php?p=1463288&postcount=9
http://www.ocforums.com/showthread.php?t=148135&highlight=magnet+damage

if you think about it a little, the ONLY thing a magnet will do is move Fe or mess with another magnets electrical field. With that said, the only things that are affect is the monitor and hard drive, but the hard drive requires such a powerful that even the adire's Parthenon wouldn't damage it. for a monitor on the other hand, my old power acoustic sub with a 270oz magnet used to make it green about 6 or 7 ft away, although i had it stored in a shelf about 2ft away from my computer. I have two JL 10" with huge magnets in the same shelf for the past 4 months and my computer has no problems. to top it off, i've had a 2lb magnet/pump running in my computer for 4 years now and nothing has happend, although i have to keep it atleast 4 ft away from my monitor so it doesn't screw up the color.

[spookeboom]

i sugest that you put a capasitor inline of your amp to save your power supply
with a 1000w sub and under powering it,
will put a lot of strain on the amp
i recommend using at least a 1/2 farad
prob 1 farad capasitor will be best though

good work on the sub box
(sugestion use 3/4 or 1in MDF when building a sub box no matter what
wattage the sub is )

[Mr. Chambers]

Hey, if you want to risk long-term exposure to a magnetic field on your hard drive full of data, feel free. Personally I'd just move the computer a few feet away for safety's sake. ;)

I know with my subwoofer, I moved my computer because I was more worried about the huge vibration it caused (the PC was also sitting on the floor with the sub).

[joethemole]

when you guys find "boxes"/encloseurs for your subs, do you use specific ones, or do you just find a box that looks nice and put it in? cause are you considering the resonant lengths and all the other physics crap?

[Mr. Chambers]

when you guys find "boxes"/encloseurs for your subs, do you use specific ones, or do you just find a box that looks nice and put it in? cause are you considering the resonant lengths and all the other physics crap?

If you want your new subwoofer to sound like complete garbage, you could skip "all the other physics crap". I wouldn't recommend it however, as the enclosure design/build is THE most important part of a setup/build.

I can't vouch for everyone, but that's my opinion. So yes, I personally calculate the correct volumes, port lengths, and other variables when building an enclosure.

Welcome to the forums by the way :)

[Korndog]

mr.c is right. my friend has the same sub i have because he liked it so much when he heard it in my car (memphis PR 250w), he got a 1cuft tube enclosure for it and it wasn't loud at all, didn't even make the seats shake much. so he ported it, it sounded like crap. Now for the physics stuff. since the box was small and was ported with a short port, the sub was basicly experiance freeair, although giving it the rated power, the sub coil was not properly coiling itself at this point and within a few min. of horrible sounds, it overheated and the coil melted. now i personlly put 400w on this sub and it worked fine.. just goes to show a sub can make a good sub sound bad and die, and a good box can make a cheap sub sound great.

[Korndog]

i sugest that you put a capasitor inline of your amp to save your power supply
with a 1000w sub and under powering it,
will put a lot of strain on the amp
i recommend using at least a 1/2 farad
prob 1 farad capasitor will be best though

good work on the sub box
(sugestion use 3/4 or 1in MDF when building a sub box no matter what
wattage the sub is )

both the sub and amp are underrated. the amp is what provides the power and the sub has no affect on that. Adding a cap will do little to nothing in this situation and in many cases little to car audio as well. You should always put ur money into upgrading the actual power source and battery before adding caps.

[voodoomelon]

Wow, haven't been on in a while.

First off, yes I am in the market for a 5.1 amp, as in 6 channels. I don't really plan to have a high powered amp for the sub, a 5.1 amp that outputs 200w-250w rms on the .1 channel will suffice, seeing as the Kenwood sub is actually rated at 250w rms.

Also, When i had the Kenwood driver within 2 feet of my monitor, it caused distortion. But no matter, as it is 5 feet away from the screen in the corner of the room, 7 feet away from my tower.

And last, I built my subwoofer enclosure using precise measurements for internal volume and external dimensions, which i calculated using online formulas. (Just do a Google).
My enlosure is within a 3% error field for internal volume, whereas up to 20% would be acceptable (Although not desireable).

;)