Lancer,

Forgot to add something, back in the days Im talking about there where amps that put out what they where listed at plus more, they where called cheater amps and from memory Fosgate was known for them . At same time though could buy a 1000 watt amp at pawn shop that put out very little wattage. Im unsure if Majestic is still around or not but the Majestic 500 was a good cheap amp that could push 15's cheaply and effeciently.

Justin

 

Well I know when they test the amps, alot of companies used to, and I dont know if they do it anymore, but when they tested the amps, they did so at a higher voltage, like 15 volts or something like that so that it could of course provide the power it claimed. However, most cars alternators only charge at around 13 volts or so, so we cant get the actual claimed power out of the amp.

 

REMOVE ur spare tire and get a box done there

 

I understand and appreciate all the input. I'm keeping the box.

I have another problem though. The amp that was given to me didn't even have LPF so obviously it sounded horrible and making me think for other ways to improve sound.

I just received my Jensen 300watt 2 channel amp with LPF and upto 18dB bass. The thing is, I can't get it to configure properly. Amp on and off isn't making much difference in depth of the bass but if I turn the bass up it starts distorting. I played around with input levels and can't understand them for the life of me, I'll probably get a multi-meter and test how much my cable is putting out.

The way I have it right now, which is sounding horrible is as following;
X-over frequency - 80Hz (it's recommended of ported subs as far as the manual goes)
EQ Bass on Amp - 11dB
Input level - 1.2 (0.3v to 8v is available)
Sub bass on head unit - 9dB

At these settings sub is making some bass upto volume level of 18, anything past that and of course depending on the song too, it starts to distort. If I turn some of these settings down a bit there's almost no difference in bass.

My head unit is a kenwood something something with bluetooth and Mosfet power and whatnot and it puts out 50w X 4 - My rear speakers are Kenwood 500watt 6x9 5 way mounted from under the shelve using dynamat. My speakers are not powered by the amp but they sound amazing for both highs and lows.

One thing to note, the speaker wire I'm using for the subs is the left-over wire that came with my kewood speakers. I just didn't get a chance to research what kind of wire my subs would need.

My sub box is a Jensen ported box that came with the jensen subs so I'm assuming they are up to spec. Although, the box had fibreglass front, which I took off and cut the box slightly to make it slanted against the back of the seat, so save space of course.

Did I ruin the box by doing that? I didn't modify anything inside the enclosure so my assumption was that I'll be ok by cutting the front portion off.

So what am I doing wrong now?

 

Ok ok ok. Hold on here. What is the RMS wattage of both the subs and the amp? Is that amp claiming 300 max wattage? #2, make sure you hook the subs up correctly in that the positive goes to positive and negative goes to negative or else you'll be running the sub in reverse. Do you have the LPF activated? Alot of amps use a switch to go between the two. Can you hear the actual music coming through your subs? Can you post pics of your box so I can see what you mean when you say you cut it? It sounds like you may even have a blown sub. Here are two ways Ive used to test for blown subs. 1. you can push in the sub well it has no power going to it and it doesnt go back and forth smoothly. you can kinda feel like its scraping against something down inside the magnet. 2. If the first method doesnt do anything for you, as in it still feels smooth, hook it up to power and play a song and push the sub in and see if it starts bumping as long as your holding it in. Ive found many a blown sub in my past using these two methods. Hope thats not the case but its always worth a try. If you can, try to get your hands on another sub or someone elses sub to make sure its not your amp causing you problems. Oh and the amp should have a light on it to tell you if it goes into protect mode. Make sure that protect mode isnt activating on you.

 

give me the product numbers and models of your amp, subs, and head unit. in 5 minutes I can tell you what settings to be at and how to wire the subs and everything will be good.....as long as the subs and your new amp are compatible that is...and yeah post pics of the box please!!

 

I don't think Rockford Fosgate got into doing that as much. I seem to remember Orion and their HCCA amps being the most heralded "cheater" amps. Basically they were rated at 25x4 or 50x2 depending on the model at 4ohms, but they were like 1/2 ohm stable, maybe even 1/4 ohm stable for one of them. So each time you halved the load by doubling the speakers sttached to them, the power they produced doubled or tripled. So 50x2 at 4 ohms translated to 250x2 at 1/2ohm or more, I can't remember. So guys would enter in the 1-250 watt class and be able to out pound guys with 1000+ watt systems. Good times.

 

The first time you typed that, I thought it was a typo and you meant 80. But I have to ask, what model is this 800x4 amp? It must be ginormous, and have 1/0 gage terminals - or that's just some weird peak rating and it really only does like 100x4 (or less) RMS.

 

Its an Infiniti Reference series 7540a which has an RMS of 111X4. I have a really bad habit of typing the claimed wattage sorry. Heres a pic of it mounted. Not really that big. My uncle bought it for me for a graduation present along with a set of 'Verge' 12s. Obviously the amp was the only worthwhile thing. I didnt feel comfortable using it for a sub as I only wanted one sub in my car and felt it was a waste to use a 4 way amp for a single sub. So I used it to power my doors and bought another amp for my sub. Still needing to buy a class D though. Really would be worthwhile I think. My sub requires 400 watts RMS at 1ohm. so its going to be spendy. Or do you guys have a suggestion that would require less money such as some sort of 'cheater' amp that would be good to buy?

 

Thats what he meant by cheater amp. Splitting the ohms. I get it now lol. Took a bit and a little more reading than what I was doing before.

 

RMS wattage is 60 x 2 on the amp. I have no idea what the subs are rated as there are no stickers or markings on them.... other than "Made in China"

I'll go take some pictures and post them up.

As for tests, I did test the subs, they seem ok. Polarities and other wiring are ok too, I checked and double checked. No porective mode on amp.

When I say distorted, I probably meant to say too much bass for the subs to handle. I'll be back with some pics.

Amp: Jensen JPA260
Head Unit: Kenwood KDC-BT838U
Speakers (Rear): Kenwood KFC6982ie

 

Take some of the subs AND the amp. Do you have it hooked up in four ohm or two ohm? Are your subs dual voice coil or single voice coil?

 

Ok so for the subs to work on that amp (be wired correctly so as not to stress and overheat the amp), they need to each be single 4 ohm, or dual 2 ohm, 60 watts RMS. you must unscrew one sub and look on the back, usually on the magnet, and it should say more detailed specs. if it is NOT dual 2 ohm or single 4 ohm, either get new subs or return that amp and get another amp. but if a 60 watt amp is distorting subwoofers, those subwoofers might as well be thrown out.....now i know why you got them for free haha...also, on the amp, the input level setting needs to be set to 2.5V...why? your radio's pre-outs (RCAs) are 2.5 volts (which is actually not bad ) and you have to match the level here and DO NOT change that setting...use only the gain to increase or decrease the bass.

but in the end, i suggest getting new subs and a new amp. you can get some shallow subwoofers, and make a VERY skinny, tall box, taking up virtually NO room at all and still have decent bass. look on www.sonicelectronix.com for some good deals.

 

There's only one place to plug in the cables, if you're asking about running it in bridged mode, no, they are running on two seperate channels.

@yitzac1990 - If RCA output is 2.5v, wouldn't it get less after 25 feet of RCA cable? I thought I have it set at 1.2v, I'll set it to 2.5v. And like I said before, the magnet has nothing but Made in China sticker on it, but I suppose I can look again when it's light out.

Anyways, here are some pictures of my system.

Third picture is to show what kind of cable i'm using, which I'm sure is wrong if it was designed to run a 6x9.

 

first of all, that wire is fine for subs, especially only 60 watts haha. take out the sub and try to see if they are 2 or 4 ohm subs, or at least single or dual voice coil. sometimes it'll say the ohm load on the terminal on the sub itself, like on Kickers. also, voltage is not lost along the RCA. the part of the box that you cut off...did that use to be sealed off completely so you couldnt see the subs? also, in a system where the subs are in the trunk, they will sound like garbage if faced the way you have them...towards the front. for optimal sound quality and performance, face them towards the rear.