Spiderbox

can i hook in a sub without using an amp?

I just got a new headunit, the kenwood kdc-x791. heres some of the specs.

http://www.cardomain.com/item/KENKDCX791?vq_id=none

biff1805

nope.....a headunit alone will not output enough watts to power a sub

u could get something like a bazooka sub with the built in amp

TheQuietThings

you will need aan amp for sure

Amoxaphobic

Uhm... technically, yeah, you could. Hook the positive and negative wires up and you will have some noise.

But notice that I said noise, it's not going to sound good and it surely won't thump. As a matter of fact, it's a very high chance that you will have so much distortion from under power that you would blow the sub... maybe even blow the rest of the speakers as well because of the power the sub would be attempting to pull from them.

In other words - it's NOT recommended.

ajayaitch

The other issue is the range of frequencies put into it by just hooking it up to the speaker outputs Subs don't like that, and in fact usually only designed to produce sounds up to 150Hz or so.
That HU you got has sub outs, so I'm ASSuming it has the sub controller built-in. The amp you buy may have it (cutoff, gain and phase) as well. Most self-powered subs have these features. My KSC-WD250 does, on a wired remote. Clicky! Clicky2!
BTW: those sub-outs are low level, and have no real power behind them. Hook those directly to a speaker and you stand a good chance of ending up with a three hundred dollar paperweight fairly quickly.

Amoxaphobic

^^^ I agree.

So, it's much better if you just buy an amp and save yourself the trouble.

Spiderbox

how much would i have to spend to get an amp and sub to match the headunit?

btw on a side note this headunit is really annoying, it keeps resetting when i'm navigating the menus or flipping thru the songs and it doesnt read the cds 1 out of every 5 times. gonna go back to the store and ask for a replacement, something is not right.

integroid

You can probably find a used amp for about $50 and then pay a shop another $50 to install it.

Amoxaphobic

You can find an amp for cheap... but keep in mind, that you get what you pay for (generally).

XBooster

You will definetly need an amp for the sub, cause like Amoxapine said, if you want sound,buy the amp, but if you want a scraching noise, don't use an amp.

I know this isn't the right thread, but, can 1 or 2 8"sub be installed in the rear hatch???

remember guys.. i'm just asking, don't pound me

UV7

Sure, if you glass an enclosure into the door, but the hatch struts are not going to hold it open. The weight would be too much for them. You may have to rig up some sort of hatch support to keep it open.

metal112524

Here is wat i got going spider, Im still missing a way to wire in to the factory HU (if someone could help thatd be great)

-First i got my sub box for $15
(1/2 MDF, Silicone, Gold terminal cup)
-Fosgate 450.4 Amp $105
(bought off Czech He still got one left for $100)
-Elemental Designs SQ10 $70
-Missing Wireing and harness for hU Est. $30

Total $220 For some thump. Note im doing all the work myself this doesnt include install prices.

UV7

So, from the looks of your list, you are in need of some LOCs...and the wiring harness. Correct? What happened to the stock wiring?
If you're in or around the Houston area and need a hand, let me know. I'd be more than happy to help you. I don't have any LOCs lying around, but they are not difficult to come buy, nor are they expensive.

Spiderbox

will this http://www.bestbuy.com/site/olspage....=1108124880979
or this http://www.bestbuy.com/site/olspage....=1108124880920
fit into this?http://www.edesignaudio.com/edv2/pro...roducts_id=463

what kind of amp would i need to match that sub?

i'm still kind of fuzzy on the how the wattage correlates to the different components, anyone care to school me? thanks guys.[/url]

XBooster

THANK YOU, I APPRECIATE THE INFO

Amoxaphobic

xbooster, yeah, the subs will fit there. I think UV7 is right with the glass enclosure. It won't be just something that you can drill holes into and stick them in hoping that they would sound good. Too much tin.

Spider... those subs will work and that box will work too. Most of the xBs that I have seen have the box in the back, so you would be a little different with the box under the seat. Obviously, you won't be completely original because others have done it, but it's a good idea at least.

Here is a very basic run down of an amp to sub... and I do mean basic!

Watts from the sub and the amp should match. Watts are generally measured in the amounts of power a sub can handle and the amount of power an amp can put out.
Subs are blown, not so much because of purely power, but distorion. You don't want to have the amp give too much to the sub... and you don't want the amp to give too little to the sub. It should be pretty close, otherwise, you will get distortion at higher levels and are liable to blow the sub.

However, IMO, if you are not going to be able to get an amp that gives just the right amount of power, then its better to have an amp give more power than an amp give too little. Subs pull power too, so at high sound levels, with your amp not being able to give enough power, you could burn up the amp. In this case, you would be out of an entire system rather than just a sub. And trust me... it's a whole lot easier (and cheaper) to buy a new sub than a new amp.

When looking at power, you will see too different measurements - RMS and Peak. Peak is nice for a good number to throw out there, but when looking into a system and what you should buy, you should look at RMS. RMS is usually going to be substantially lower than peak. Peak is the amount of power (or in this case, you can think of it as sound) that a sub or amp will put out at it's loudest or more powerful point. RMS is raw power and is the best to match. So, if you have a 200 Watt RMS sub, you want a amp that will give the sub 200 Watts RMS (NOT peak).

Here is the kicker... Ohms. Ohms are the measurement of resistance in the sub or amp. Because Ohms are resistance, for the loudest system possible, you would want the lowerest measured ohms... You can get them down to 1 (maybe lower, but I haven't seen any), but those are generally going to be pretty high dollar. 2 ohms are good as well, but again, those tend to start getting high dollar. For the most part, what you will find in best buy or wal-mart is going to be around 4 ohms, and sometimes 2.
When hooking your sub up to you amp, you want the sub and amp to not only have the right amount of power, but the right ohms. Why you ask? Because if the amp and sub match in power, but not in resistance, you will be pulling too much from the amp (making it hot) or giving too much to the sub, (making it distorted).

Think of it this way...
If you have a bottle of water, (lets say it's 100 watts), and you know that you can drink 100 watts worth of water, you would simply turn the bottle up right and down the water (hook up the amp to the sub and let 'er rip!) right?
Well, if the neck of the bottle is too small, (high ohms or high resistance), you would be sucking on the bottle trying to get the water (power out). This would crush the bottle, (burn up the amp).
If the neck of the bottle was too big, when you turned it upside down to drink it, water would get all over you (too much power to the sub... ) you getting wet = your sub being blown.

Does that make sense?

Spiderbox

thanks that cleared up alot i was assuming it was something of the sort but wasnt too sure.

reason i chose the stuff from best buy is because my buddy can get me discounts there.

how does the wattage rating apply to the headunit and speakers?
i see that my headunit specs say 22 watts x 4, what does the 4 refer to ?

Amoxaphobic

the x 4 means that it will put out 22 watts per 4 channels (front right and left, and rear right and left).

integroid

Get an eD nine.2. That will be plenty of power for a sub.

Amoxaphobic

Come on... a little more information would be nice. Do you think you could help us out by giving a link or something. Does that amp match the subs that he is looking at?