Subwoofer High Level Inputs stopped working

Onelius

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Jan 27, 2013
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Hello everyone, I have a Cinema Audio Studios (CAS) sub which I can't seem to find on the internet. It has worked fine since I bought it. I woke up today and the subwoofer seems to have stopped receiving signal from it's high frequency inputs. The inputs otherwise work fine, because the signal reaches my two bookshelf speakers without a problem. I also tried the lfe input with red and white rca cables, and the sub works perfectly. Just to clarify, the sub isn't exactly not receiving a signal, it appears to be extremely low. If I turn the gain to max it doesn't make a difference. Any help would be greatly appreciated.
 

iam2thecrowe

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high level signals into a sub run through resistors (around 1000 ohms i believe) to drop the signal to the desired input level. the output speakers run in parallel, sometimes through a filter, so they can receive a signal even though the amp in your sub does not. its possible a resistor is burned out, or you have a bad connection internally causing higher resistance (and lower output to the subs internal amp) than usual.
http://www.jaycar.com.au/productView.asp?ID=AA0482
you can get a high level>line level converter really cheap
http://www.ebay.com/bhp/rca-line-out-converter
although the cheap ones may be of lower sound quality.
If your keen you could open the sub up and have a look at the electronics, but take care lots of voltage is often present in capacitors even with power disconnected.
 

Onelius

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Jan 27, 2013
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I'd like to try opening it up. How long should I keep it disconnected before it's safe to open up?
 

iam2thecrowe

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i don't think there is a "safe" period. you can check any capacitors with a multimeter to see if there is voltage in them. If you are not trained i say do it at your own risk, because i don't want to take the fall for you getting zapped. but if you don't touch anything, have a look for obvious blowouts of components. Even then, replacing anything would require soldering skill and knowledge of basic electronic components. I would say just pay out the few dollars for the line level converter. If it were me, i would open it up, look for visible signs of electronic damage, meter any resistors found and check for bad soldering/connections. But i work on electronic stuff for a living and understand the dangers and risks.