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My sub overheats and shuts off?

T

thegearhead

New Member
Hoping that someone here will be able to help me out here. I have a Cerwin Vega sub, CLSC-12S 250 watt powered subwoofer. The problem with it is that it overheats constantly and shuts off, even at low volume levels. The output is also extremely weak for what I would think a 250 watt 12" sub should be. I have to turn all my other speakers almost all the way down and the sub all the way up (in the reciever) as well as the gain almost all of the way up on the sub to really hear / feel any bass.

I have also noticed that after a quiet spot in a song / movie with little or no bass, the first thump is MUCH louder for a split second then the volume cuts WAY back, almost like it isn't getting enough power.

I have pulled the amp out of it several times and inspected the circuitry looking for anything burnt or just something that looked bad, but have found nothing yet. Even when it sits there at idle or during regular TV listening with almost zero bass it will still overheat sometimes and shut itself off.

Anyone have any idea for some help here?


Thanks in advance!
 
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what is the cut off on it,in other words at which point does it takeover the lower frequencies?
 
IMO, something definitely wrong with the unit, like bad bias, poor power supply regulation or voltages, or failing capacitors which control voltage levels. Also, any active circuitry that is not functioning right may cause excessive voltage or current readings that would send the unit into protection, if that is what is happening.

Overheating is usually a sign of excess current draw - if this is a solid state push-pull complementary symmetry type amp, if some of the output transistors are wonky, or the offset (from the input transistors in the front end) are not balanced, either the DC offset or the current draw will cause the amp to go into protection, or trip a breaker, or shut down.

Best to get the owner's manual out and/or service manual/schematic and see what fault condition would cause this behavior.
 
Powerful amps running a light load and overheating usually means its lacking a sufficient power input. Like if you are in a 120v area and its getting 105v. This can stress the internal power supply because its trying to compensate for the lower input voltage by cranking the voltage regulators. Overworking voltage regulators = heat. And lots of it.
This is especially true for active speakers.
 
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qdrone said:
what is the cut off on it,in other words at which point does it takeover the lower frequencies?
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The cutoff is variable from 40 to 120 Hz, and it doesn't matter where I have it set as far as the volume goes, but the cutoff does work properly.



The owners manual is long gone as the sub is now about four years old, but from day one almost it wasn't as loud as I thought it should be, but it has just gotten worse over the years.


I just wish something would finally actually give out and leave a visible trace as to what it is so I can replace it, but no such luck so far.
 
89grand said:
Put it out on the curb and buy something else. Subs can be found cheap all over CL.
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I have been looking, but haven't found anything yet in my price range. I don't have a super high end setup, so I really don't need a $500 used sub, which for some reason is all I have found on my local CL :no:
 
You could keep the box and the driver and just replace the faulty amp. Check partsexpress.com - they have replacement sub plate amps for reasonable money.

jblnut
 
thegearhead said:
I have been looking, but haven't found anything yet in my price range. I don't have a super high end setup, so I really don't need a $500 used sub, which for some reason is all I have found on my local CL :no:
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Hmmm, I bought a Velodyne for $90 and a BIC for $45. Maybe I just have better deals around my parts. Where are you located?

The BIC I bought for $45 is only about $175 new.

http://www.amazon.com/BIC-America-430-Watt-Down-Firing-Subwoofer/dp/B0000Y2WYS/ref=pd_cp_e_3_img


There's a Polk model that I've seen all over the place for about $100 shipped.

http://www.amazon.com/Polk-Audio-10-Inch-Monitor-Subwoofer/dp/B0002KVQBA/ref=pd_cp_e_1_img
 
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I am in the Mid Michigan area, I checked my local CL again yesterday and the only subs I found were a passive Bose and a few junk 6" RCA and Sony home theater in a box type subs. I did find a Velodyne a few weeks ago, but they guy wanted $500 for it...
 
I just read a great article on Audioholics.com about setting up your subwoofer. They recommended setting the crossover control point on your subwoofer up as high as it can go (say, to 140 Hz) and then using your receiver or pre/pro's digital crossover control to set the crossover point as low as your speakers can comfortably go (e.g. around the low frequency limit at +/- 3 db).

Of course, I'm presuming you're using an AV receiver that can do this. If you can't, then this point is moot.

I just did this with my system (earlier, I had the crossover point set on the subwoofer set at 80 Hz and the crossover set in my AVR at 80 Hz, the THX recommendation). So, just on a lark, I followed the plan recommended in the audioholics article, and turned up my sub's crossover control to 140 Hz and dropped the receiver's digital crossover frequency to 50 Hz (my speakers in front bottom out - at +/- 3 db - at 42 Hz, and my rears at 52 Hz).

It was amazing what a difference it made. The system sounded good before, but now sounds so much more cohesive.

Here's the article: http://www.audioholics.com/tweaks/get-good-bass/basic-subwoofer-setup
 
cwall99 said:
Here's the article: http://www.audioholics.com/tweaks/get-good-bass/basic-subwoofer-setup
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In case there is any confusion, this article is NOT saying you should run your sub up to 140hz. It's simply recommending that you use a crossover point appropriate for your main speakers and that you use your HT receiver to do this instead of a plate amp crossover. The "high as possible" setting is to effectively disable the plate amp's crossover if you have no bypass switch.

cwall99, if you did exactly what you describe but keep the receiver setting at 80Hz, you will actually be following THX more closely (because the low and hi pass contour will match at 80Hz, while it probably didn't before). Nothing wrong with going lower than THX though. Based on those numbers you gave, I would go for 60 or 70 on the receiver setting, but hey you're the one that can hear it.

Gearhead, check out parts express sub kits, and also their plate amps.
 
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I did check out the Parts Express plate amps and found what looks to be basically the same amp already in my Cerwin Vega sub, a Dayton 240W amp. Most of the reviews on it looked VERY good, but I did find a lot of them that said the amp likes to shut off during extended playing at high volumes. It is a great deal at only $99, but at the same time I don't want to be in the same boat I am now with an amp that ends up overheating and shutting off even when it works right.
 
thegearhead said:
I did check out the Parts Express plate amps and found what looks to be basically the same amp already in my Cerwin Vega sub, a Dayton 240W amp. Most of the reviews on it looked VERY good, but I did find a lot of them that said the amp likes to shut off during extended playing at high volumes. It is a great deal at only $99, but at the same time I don't want to be in the same boat I am now with an amp that ends up overheating and shutting off even when it works right.
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Well, I think this generates the question. "is the Cerwin Vega shutting down working as designed or is it in need of repair?"

If the Cerwin Vega is working as designed, it could be shutting down due to thermal overload or perhaps some other safety feature.

In an earlier post, I asked if you had measured the voice coil's DC resistance. If the coil has some damage, it could cause the amplifier's protection circuit to fire. This would be a repair problem.

I still think the problem has to be determined in order to recommend a repair of a possibly broken sub or that you drive it way too hard and that you'll need something much bigger to play at the levels you like.
 
It has pretty much always not met my expectations of how loud it should be, but over the years has gotten weaker and weaker. Yes, during parties or other extended periods of loud volume it shuts down from overheating protection, but it seemed to happen much faster then I think it should. Lately, it is at the point where even with the gain on the sub turned all the way up, the level in the receiver set to +10 on the sub and -5 for the other 5 channels, you can barely hear it. The coil seems to be fine (no, I still have not tested it with my multimeter) as there is no scratching noises during play or moving the cone by hand also I can hook it up straight to my receiver and it plays just fine. I am 100% certain the problem is the amp.

I do agree though that I need to find a bigger toy to play with here. I listen to a variety of music (rock, country, and bass cranked, window shaking hip hop, dance / club type music) and I watch a lot of movies. I don't always need a lot of bass (especially when listening to country, which I often do) but when I do want to rattle my windows I want to be able to do it at any moment. In case you are wondering though, my house is in the middle of nowhere so no, I am not "that guy" that blasts his music / bass in the middle of the night keeping all the neighbors up.... I do have respect :yes:

Basically I just know that I shouldn't have to have the sub literally turned up to max just to feel a little rumble while watching Gone in 60 Seconds :thumbsdn:
 
dumptruck said:
cwall99, if you did exactly what you describe but keep the receiver setting at 80Hz, you will actually be following THX more closely (because the low and hi pass contour will match at 80Hz, while it probably didn't before). Nothing wrong with going lower than THX though. Based on those numbers you gave, I would go for 60 or 70 on the receiver setting, but hey you're the one that can hear it.
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My choice of setting the x-over at 50 Hz was based on the options my AVR presented. I was choosing between 50 and 80 Hz. There are other options, too, but they're all much higher. In my AVR's menu structure, there are no x-over points between 50 and 80 Hz.
 
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