Okay I have a Sony Xpold 1000w 2/1 channel amp. Here are the specs.

• 1000W max power
• 165W x 2, 20Hz - 20kHz, @ 0.04% THD + N, at 4 Ohms
• 200W x 2, 20 - 20kHz, @ 0.15% THD + N, at 2 Ohms
• 400W x 1, 20Hz - 20kHz, @ 0.1% THD + N, at 4 Ohms
• OTL (Output Transformerless) circuit
• Pulse power supply
• Line & High Level Inputs
• .3-6V Level Adjustment Control (RCA Pin Jacks) 1.2-12V (High Level Input)
• 80 Hz, -18dB/octave Low Pass Filter Switch

I had a 1000 watt kenwood Sub, rated at 400rms hooked up like this.

Here are the specs for that sub

Model KFCW3012 Speaker Type Subwoofer Speaker Sensitivity 86 dB @ 1V Speaker Frequency Response 39 - 300 Hz Speaker RMS Handling 400 Watts Speaker Peak Handling 1,200 Watts Speaker Impedance 4 ohms Speaker Depth 6-3/16 Inch Speaker Size 12-inch Voice Coils Single Voice Coil Sealed Enclosure Volume (Cu Ft) 1.25 Displacement Volume (Cu Ft) 0.157

I have a Kenwood Double Din Deck with 2v sub preouts.

I have a single 12" fox box.

My sub blew up the other day, and i am not quite sure why. Ive been doin some research and found that the gain on the amp should be set to match the preout voltage on the HU. I didnt do this I just set it to where it sounded the loudest, which I think was around .5 volts.

Is this why the sub blew? Im not sure wether its hooked up 4ohm or 2 ohm or what. any advice would be great thanks.

Also I would appreciate sub recomendations as well, Dont want to spend more than about 120$

 

It looks like to me you had the sub hooked up at 4ohms, which with the amp was fine. I dont think the voltage of the preouts matters too much for the average consumer, I think that is for the crazy high end guys who wanna hook up a million subs and need to worry about signal strength.

My only other thought is about a crossover. Im not sure what you have on that amp or HU, but if for some reason the crossover was set incorrectly the sub could have been playing highs and lows, and that can definitely damage it. It sounds like you got a nice HU, there should be a sub out crossover setting on it somewhere, you may wanna check that. If that's not it, you got me as to why it blew.

 

I was just looking around on the HU, and the LPF X-over for the sub was set to "through" I did set the HPF for my component speakers so that they limited the low frequencies coming out of them but never messed with the X-over for the sub because it sounded good. Maybe that was it?

and there is a switch on the amp that Lets it play the highs, but that switch was not on. It was set to LPF

 

Your sub could have blown from a number of things actually, but I'm willing to bet that your issue was with clipping. If you overpower the amp by sending it too much signal(gain) then the amp with begin to clip with distortion most of which you actually cannot hear. This transforms into heat at the voice coils on the subwoofer causing the sub to bear the brunt of disaster.

Here's how you can tune a sub for proper gain control within close accuracy most of the time....All your sub EQ setting should be flat and at 0 and bass boost needs to be off.....Find your max HU volume setting and set it at 80% of that. Gain on amp must be at lowest right now. Then you want to play a frequency note or music that will give you the loudest ouput possible. You turn up the sub gain until the loudness peaks at it's cleanest. After a certain point, the sub just provides distortion while not getting any louder. You want to turn the dial back 1/8th turn from it's peak output arises.
You can match the the output voltages and achieve similar results but you need to measure the HU voltage and cannot just go off the owners manual. Like my Pioneer is rated at 4v and was measured at 2.4v.
If your HU is as lows as .5v, i would think about picking up a line driver to boost that signal with very little added distortion. I ran one until I began using a sound processor RF360.2
I've always tuned by ear and never once had issue's.

The reason for using 80% on your HU is because higher than that generally means dramatically rising distortion on 70% of the HU's out there. This means that when you are listening to music you cannot turn it much higher than 80% volume or you will incurr distortion at your speaker voice coils: however, your door speakers will be much quieter than your probably used to. So, if that is the case i would reccomend tuning with the volume control to where the loudest you listen to your door speakers at and tune the sub at that level(this cannot be max regardless of HU or you will eventually cook speakers)

Your amp controls should be set at flat for HPF/LPF if you dont have a flat, then set if to LP, but flat is prefferred this way you have full control at your HU to go between 40hz, 60hz, 80hz...etc rather than flipping between setting on the amp to see what sounds better.

 

Dirtydog is right. And in all honesty, if you want a little better sound, upgrade your HU to one with a little higher preouts, like mine has 6.5 tested at 4.8. And I can definitely tell the difference from my HU that had 4v preouts. Another thing, make sure your amp and sub are properly matched as well, you want an amp that is meant to power your sub or a similar sub, mostly power ratings for the best sound. Like I have a 12" rockford fosgate p3 and an alpine 400 watt rms amp, the amp is slightly underpowered for the sub, but its about the closest I could get my hands on at the time. My sub is rated at 500 watts rms at 2 ohms and my amp is 400 rms at 2 ohms. Those are the numbers you want to look for when matching amps to subs. If you have an amp that is not powerful enough you can blow your sub from underpowering it, if its to high of power and you use that power on your amp, then you blow it from overpowering it. Those are the most common reasons why people blow subs in my experience.

 

Well, my amp pushes 400wrms at 4ohms, and the sub says it is rated at 400wrms. Is it bad if these numbers are equal? i understand that you never want to have an amp that has a higher RMS than your sub, but not sure what a setup with equal values would do.

 

Actually you are better to have an amp that runs higher power than what your sub is rated for than to run one that is too low. 100 watt range is usually safe.

 

alright then, If I get a 1000w, 380WRMS Xpold sub that would actually be better than my 400WRMS kenwood i had? Ive always been told the opposite... that underpowering wasnt a problem, but if your amp was more powerful than your sub then your asking for it.

 

Whoever told you that is way off, because you can always run an overpowered amp at lower power to match your sub, but you cant turn an underpowered amp up to match the power handling that your sub needs to move it, if that gives you an idea.

How much power do you really like to have out of your sub? Lots, or just a little? My suggestion if you like lots of bass is to go with another kenwood, just make sure you get excelon, or you have a few different options for subs, kicker if you dont care much for tone and just want volume, diamond, or rockford if you want quality and quantity for a decent price, alpine is quality, but not a whole lot of volume. It all just depends on what you are looking for. Sony doesn't care much about their car audio, its such a small portion of what they do, so dont count on getting something real amazing out of them. And to be honest, another great sub that I have had, is phoenix gold, not very well known, but good quality products nonetheless.

 

My subs call for 800 RMS / 1600 max and thats exactly what my amp puts out also. I matched them that way. I play them hard and never an issue. But I have installed for years so I know what Im doing. I love my FB but I do wish it was a tad bit bigger.