QuestionQUESTION: I have a 10" Kenwood sub (500W Peak) in a bandpass box, running from a 340W Peak Clarion amp, and when i cranked the music i smelt something funny and when i opened my trunk a big puff of smoke came out and my sub box was smoking, my nieghbor told me its probably a fried coil but my sub still works perfectly, so i called the place where it was installed and the guy told me that because it is a bandpass box i cant tell when its distorting causing it to overheat... who is right, and what do i need to do to fix this problem?! i really want it to hit hard!! Thanks
ANSWER: Hi Ryan,
It definitely sounds like you're over-powering the sub. If there's smoke coming from the sub, then something is clearly overheating; and the only thing that can cause a sub to overheat is too much power. You may not have fried the voice coil, yet; but damage has probably occurred to either the wire coating, or the adhesives that hold the various parts of the sub together. If the adhesives are vaporizing, then sooner or later the subwoofer will suffer a mechanical failure...basically, it will start to come apart under stress.
A few things to keep in mind:
-You should always look at "RMS" or "continuous" power ratings when you're matching an amp with a sub. Peak ratings are usually meaningless. If the sub's RMS power rating is 150 watts, you don't want to match it with an amp that's rated higher than 150 watts RMS.
-Keep in mind that any amplifier can produce more than its rated power if you drive it into clipping. If the amp is rated at 150 watts RMS, that means it can produce 150 watts of output without audible distortion. It may also be able to produce 250+ watts of power with lots of distortion. The sub doesn't care if the audio signal is distorted or not; but if you're sending 250 watts into a 150 watt sub, it's likely suffer damage before long.
It's true that a bandpass enclosure can mask the noise produced by a sub or an amp that's being pushed past its limit. So if you are over-driving the amplifier, you might not notice a problem until the damage is done.
Unfortunately, all you can do with your current system is turn it down. Switching to a sealed or ported box might make it easier to hear if you're pushing it too hard, but you'd probably lose the "boomy" sound you're getting now. If you can't get the volume you want without overloading the sub, then your only option is to upgrade to a larger subwoofer system, or one with more power capacity.
If you like the sound of a bandpass enclosure, I'd suggest finding one that's built specifically with a particular sub in mind. Many manufacturers offer subwoofers pre-matched and loaded in a bandpass enclosure. I wouldn't suggest buying a bandpass box, then picking out a subwoofer to use with it. You can do that with sealed or ported boxes, but not bandpass.
Hope this helps!
Brian
---------- FOLLOW-UP ----------
QUESTION: i looked some specs up on both my amp and my sub, the amp is 90-160
RMS, and the sub's recommended RMS is 160, so now i'm really stumped.. im
going to attach the links to where i found the information,
-http://www.weisd.com/store2/KENKFC-W2503.html
-http://www.onlinecarstereo.com/CarAudio/ProductDetail.aspx?
ProductID=18818#
I bought the sub second hand from an auction so i dont know what they did
with it before, but i had it professionally installed so i really don't know what
to think right now, Thanks alot
ANSWER: It does look like your amp and sub are well matched. Remember, though, that your amplifier can produce more than 160 watts if it's pushed into "clipping". You might not be able to hear the effects of the clipping because of the bandpass enclosure. The bottom line is that your subwoofer isn't able to handle what your amp is pushing right now (at least, not when you turn it up).
I'd suggest turning off any bass boost or "loudness" control that you have on your head unit, and if the bass settings are turned up, turn them down too. Listen closely to the sub and see if it sounds distorted at your maximum listening volume. If it does, you may need to turn the amplifier's gain control too.
If you're not able to get the volume you want without distortion (or smoke), then really your only option is to upgrade your sub.
A bandpass enclosure has two sections: one sealed, and one ported. This is a long shot, but if the "magnet" side of the sub is in the sealed portion, then you might try turning it around so that the magnet is in the ported half. (This might not be possible, depending on the box size and the port length). The advantage to this is that it might allow more cooling for the sub's motor structure, since the heat can escape through the ports instead of being trapped in a sealed box.
I hope some of this helps!
Brian
---------- FOLLOW-UP ----------
QUESTION: Ok, last question :P, so say I was to upgrade my sub, what RMS would you
recommend to suite my amp nicely? and what brand would you recommend that
would last me? I want to stick with bandpass because I like the sound and i
already have the box, so i was wondering on what i should be looking for.
Thanks so much
AnswerRyan,
Your original amplifier link didn't work, so I didn't look closely at the amp you're using. However, for your latest question I did some researching and it looks like you have the Clarion APX2181, or something similar.
I assume you're using the amp in "bridged" mode. If so, that amp is actually rated for 320 watts, not 160. The "160-watt" rating is for 2-channel, 2-ohm mode, not bridged mode. Bridging the amp is the best way to use it with a subwoofer, but that would explain why your 160-watt Kenwood is getting over-powered.
For your next sub, you'll want to look for something rated at 300 watts or higher (RMS rating), with a single 4-ohm voice coil or dual 2-ohm voice coils. A good choice would be an Alpine 2-ohm Type S subwoofer, model number SWS-1022D or SWS-1023D. The trouble is that it's impossible to say whether any subwoofer would work well with your existing bandpass box. It's very difficult to get good results matching a generic bandpass enclosure with a random subwoofer.
Your best option, though more expensive, would be to buy a bandpass enclosure/subwoofer combo. JBL makes one that would match up well with your amp. The model number is GTO1204BP.
Brian
