Expert: Cleggsan - 10/29/2008

Question
i have an old LXI series home stereo system.. and i have three
LXI series speaker cabinets that have 12" subs in them and one Realistic system 1230 15" sub woofer. all hoked up to my home stereo system.(LXI series). and every time i give the system about 40% volume it turns off the amp and then turns back on after 3 secs or so...(resets). i believe that happens because my speakers pull too much power from the amp(thus resetting it)IS THIS IS WHATS HAPPENING? AND IF SO, WHERE CAN I FEED MORE POWER TO THE AMP/SYSTEM? (could i use a 120V power capacitor) similar to car audio power caps?

Answer
It is more likely a heavy mismatch of impedance.  When you put more than one speaker on an output the impedance goes down. For example if the speaker has a rating of 4 ohms and you add another speaker that is also 4 ohms the resulting load impedance to the amplifier is now 2 ohms and most home stereo systems are not suitable for such low impedance.  The amp shut off is from too much current being drawn by the low impedance.

You really should obtain another amplifier to drive the extra speakers.  The LXI probably has an audio output which you can use to feed the new amplifier.

A medium power amp/receiver can be obtained for under $100 at BB or CC type retailers.

Best to you,
C