Ish, when you are taking the negative (-) from the left output channel and the positive (+) from the right output channel you are not connecting the amplifier in series nor in parallel. The two channels still work independently, however by using the (+) of one channel and the (-) of the other you are able to get substantially more power. However, as I mentioned in an earlier post, doing this only takes care of the output stages. You also need to wire the input of the two channels correctly. As you said, you were only using one channel to power the subwoofer and that the other channel was disconnected. That means that the output of one channel was NOT connected to any speaker. How about the INPUT of this non-used channel? Was there an RCA cable going to it? If it was, then disconect it and let it hang there because it is NOT going to be used again.

In order to bridge the two channels of the amp, you should first put them in MONO mode. This is usually accomplished by a switch. Now in your case there is no such switch so you have to do this manually. This is where that Radio Shack cable comes in. You will need a cable that has ONE FEMALE RCA plug on one side and TWO MALE RCA plugs on its other side. This cable takes the input from the female RCA plug and splits it into the two male RCA plugs. (This is a small cable aproximately 6 inches long with three plugs hanging from it and if I remember correctly it is either black or grey in color). The Radio Shack guys should know what you are talking about.

Connect these two male RCA plugs of the Radio Shack cable to the inputs of the two channels that you are going to bridge.
Also connect the female RCA plug of the Radio Shack cable to the RCA plug that you had attached to the channel that was driving your subwoofer before.
Thats it. Of course, if you have not already done so, you will also need to connect the negative (-) output of the LEFT channel to the (-) of your subwoofer and the positive (+) output of the RIGHT channel to the (+) of the subwoofer.
Now your amp should be bridged and you should be able to get way more power than before.

Again, I need to caution you. This is the way that MANY but NOT ALL amps in the market get bridged. Some amps have different output stage design and bridge differently. Some others do not bridge at all. That is why I keep insisting that you should contact Kenwood's technical support and find out in what way your amp gets bridged. However if you want to experiment yourself do as I am describing above and you will PROBABLY be fine.

Finally as far as measuring the output power of the amp, well this is done in the following way: The amplifier's output is not connected to the speaker but instead it is connected to a dummy load (this is a load comprised of non-inductive resistors that have a total resistance equal to the impedance of the speaker, in this case 4 OHMS). Then the amp is driven with a sinusoidal wave of a known frequency (obviously a frequency that the amp can produce) and the input level is raised to the point where the amplifier JUST starts clipping. It has to be at this exact point nothing more nothing less. At this point the voltage at the output of the amp is measured and then the power is calculated by the formula I gave in the beginning of the previous long post, (Voltage squared over resistance).
This is nothing very difficult, however it requires the use of an oscilloscope in order to be able to determine the EXACT point were the amp starts clipping. I assume that you do not have such a scope handy but if you do then you can calculate the power by using the above steps.

[Edited by public enemy on 04-25-2001 at 02:04 AM]