Is it safe and okay to run single voice coil subs in series to the amp? I've heard different things about this, but i want to get a real answer. My speakers are 2 15'' 4 ohm single voice coil that i want to run in series but i'm not sure if i should or not. Any help appreciated.
Running in series is better than running in parallel as far as the load on your amp is concerned.
It is definitely safe. As Wuzzzer mentioned, the higher impedance is less load on the amplifier. The key as with any speaker hookup is to make sure they are phased properly. You can check the specs on your amplifier to see what power it will deliver into an 8 ohm load. If the speakers are identical then they both should have the same SPL output level. If they are not identical then odds are that one will be louder than the other.
Now do you think it will be able to produce louder bass running in series rather than bridging?
Not sure you are using the correct terms. Speakers get connected in either Series or Parallel. Bridging is related to the amplifier. A bridged output is where a Stereo Amplifier is connected in Bridge configuration which means that when the output on Channel 1 goes up then output on channel 2 goes down. In Bridge configuration, the speakers are connected between the red terminal of channel 1 and the red terminal of channel 2. This allows you to get twice the swing voltage that you would get when not in Bridge configuration. The limiting factor is always the current that the amplifier can supply. Twice the swing voltage is going to require twice the current into the same impedance load. Typically your amplifier will state in its specs what power it can deliver into various load impedances. That is what you need to look at. Or post the make and model number of your amplifier and one of us can check it for you.
Okay so my amp is a kenwood kac929 1000 watt. I have the speakers ran parralell and have them bridged to the amp . My soeakers are kucker comp 15s with a max rating of 500 watts each. They are single voice coil. Should I run them in series to get more bass out of them or keep them how they are?
OK, didn't realize we were talking about car amplifier.
Here is the deal. The specs on the Amp do not give numbers for Bridging the Amp into 2 ohms. They specify Bridge into 4 ohms at 460 watts. They also specify stereo mode of 230 watts into 4 ohms each. The safe thing to do is to run the amp in stereo mode with one speaker connected to each channel and then use a Y adapter to parallel the inputs of the amp. That way you get 230 watts into each speaker. If you are willing to live with distortion the max power rating in that configuration is 300 watts per channel. I doubt you could hear the difference between 230 watts each and 300 watts each. Bridging the amp doesn't seem to help since with speakers in parallel the load becomes 2 ohms and I don't think the amp will like that. Putting the speakers in series puts the load up to 8 ohms the amp has no 8 ohm specs so we can only guess and do some basic math to figure what you might get and that again looks like 460 watts or 230 watts for each speaker. So, my recommendation is to run it in stereo mode driving each speaker individually and parallel the inputs.
As a side note, you asked which is louder. For most people a 3db change in volume is needed to be able to perceive that change. That 3db change would require a doubling of the amplifier power level. So once you get up over 100 watts, you can see that it takes a lot of power to move to the next perceived level. That is why I said going from 230 watts to 300 is not really going to be noticed other than producing distortion which you might hear.
Hope this helps.