Did my subwoofer blow my reciever? - AVS Forum
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post #1 of 9 Old 07-19-2014, 04:11 PM - Thread Starter
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Did my subwoofer blow my reciever?

Hello, newbie here. Hoping I can get a diagnosis on my system that does not work anymore.

I use a small Kama Bay Class D amplifier (which I like a lot).

I recently hooked up Audioengine P4 speakers which sound great, but do not have much low end.

So, I bought a second-hand Cambridge Soundworks III passive subwoofer, which I thought would add just enough bass. BUT, after I hooked that up to test, it barely made any noise at all and was very clipped.

Then I disconnected the sub and connected my other speakers back and now they sound very clipped and do not put out much sound at all.

My guess is that the sub blew my amp, but I don't know how to confirm that theory.
If I hook up headphones to the receiver/amp it sounds fine.
I am afraid to hook up any other speakers to the amp in case the fried amp can blow the speakers.

Any ideas on how I can diagnose my amp? Is it possible for the sub to blow the amp?

Thanks for the help!
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post #2 of 9 Old 07-19-2014, 10:48 PM
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I don't know too much about electronics but I think an oscilloscope might be the only way to know for sure. It can measure the output signal to see if it's truly clipped
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post #3 of 9 Old 07-19-2014, 11:23 PM
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Was thinking about this.

Try hooking up only one speaker at a time. Try swapping speakers from left to right. The idea is to try to see if the problem follows a specific speaker, or is isolated to one amp channel

You could download some test tones, such as a frequency sweep and play that back to see if that would give you a better idea of the issue. I would have thought that a blown amp channel would not work at all though.

Try to isolate as many variables as possible, changing only one at a time. That's my usual method of trying to resolve issues

"But this one goes up to 11"
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post #4 of 9 Old 07-19-2014, 11:24 PM
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Did my subwoofer blow my receiver?
Does your receiver look happy?

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post #5 of 9 Old 07-20-2014, 10:14 AM - Thread Starter
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Isolated

MichaelJHuman, thanks.
I think I isolated it. Tried two different speakers on the left channel. Both serious clipping and minimal volume. Tried both on the right channel - both sounded near to normal. So looks like the left channel is blown.

I am guessing that the amp I have does not have a 'protector' to keep the circuits from getting fried. (like a proper receiver would.) The unit never got hot, and there was no burning smell. But I think that Class D amplifiers are know for staying cool? So it seems like it is the amp.
Still not sure if the new sub blew it out, or if powering my 4 ohm speakers with an underpowered, 8 ohm amp did it.

I am going to get a receiver, connect the 'new' subwoofer to it, cross my fingers and hope it doesnt blow up.

Thanks for your help
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post #6 of 9 Old 07-20-2014, 02:54 PM
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Quote:
Originally Posted by Duggernaut View Post
Hello, newbie here. Hoping I can get a diagnosis on my system that does not work anymore.

I use a small Kama Bay Class D amplifier (which I like a lot).

I recently hooked up Audioengine P4 speakers which sound great, but do not have much low end.

So, I bought a second-hand Cambridge Soundworks III passive subwoofer, which I thought would add just enough bass. BUT, after I hooked that up to test, it barely made any noise at all and was very clipped.

Then I disconnected the sub and connected my other speakers back and now they sound very clipped and do not put out much sound at all.

My guess is that the sub blew my amp, but I don't know how to confirm that theory.

If I hook up headphones to the receiver/amp it sounds fine.
Good first step.


Quote:
Originally Posted by Duggernaut View Post
I am afraid to hook up any other speakers to the amp in case the fried amp can blow the speakers.
If you had or could borrow a digital voltmeter, you could measure the voltage across the speaker terminals of the amp, and if it were close to zero with the power turned on, then hooking up other speakers could be reasonably safe.

Quote:
Originally Posted by Duggernaut View Post
Any ideas on how I can diagnose my amp? Is it possible for the sub to blow the amp?
This is not exactly a robust mainstream product. It might be fragile.

Ordinarily hooking up a passive subwoofer by reasonable means should not damage an amplifier.
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post #7 of 9 Old 07-20-2014, 03:36 PM
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Originally Posted by Duggernaut View Post
MichaelJHuman, thanks.
I think I isolated it. Tried two different speakers on the left channel. Both serious clipping and minimal volume. Tried both on the right channel - both sounded near to normal. So looks like the left channel is blown.

I am guessing that the amp I have does not have a 'protector' to keep the circuits from getting fried. (like a proper receiver would.) The unit never got hot, and there was no burning smell. But I think that Class D amplifiers are know for staying cool? So it seems like it is the amp.
Still not sure if the new sub blew it out, or if powering my 4 ohm speakers with an underpowered, 8 ohm amp did it.

I am going to get a receiver, connect the 'new' subwoofer to it, cross my fingers and hope it doesnt blow up.

Thanks for your help
Amp might have internal fuses. Worth opening the cover to see.
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post #8 of 9 Old 07-20-2014, 04:32 PM
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It is possible the subwoofer was connected improperly. Need a model # for the subwoofer and/or a picture
of the connection area. Passive sub means you still need another external amp to use the sub with a receiver.
Does the subwoofer plug into the wall for power?

That amp is only rated 10 watts per channel stereo maximum power. No way that is meant to power a sub.
It will drive those P4 satellites fine in a desktop layout, but yes you still need a subwoofer powered by a different amp for full sound.
You probably did blow a fuse. Please describe better how the speaker wires were connected to the CA.
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post #9 of 9 Old 07-21-2014, 02:50 AM
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Quote:
Originally Posted by Greatwhitewing View Post
Amp might have internal fuses. Worth opening the cover to see.
There are pictures online of the innards:

http://www.tnt-audio.com/ampli/scythe_sda1100_e.html



I see no fuses....
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