# How To Wire 6 Speakers to a 4 Channel Amplifier ### Do you have 6 speakers in your boat? ### Do you only have a 4 channel amplifier? ### Would you add additional speakers if you knew you could wire them to the amplifier you currently have? If you have more speakers than amplifier channels, you can still wire them to the amplifier that you have and use the gain settings on the amplifier to ensure that you have balanced sound throughout your boat. The most common setup we see with this is boats that have 6 or 8 speakers, but they only have a 4 channel amplifier. This often happens adding tower speakers or adding an addition set of tower speakers to your boat's stereo. This is very common and not a difficult problem to solve. ## 6 Hull Speakers to a 4 Channel Amplifier ### Is Your Amplifier 2 Ohm Stable? In order to wire 6 speakers to a 4 channel amplifier, 4 of the speakers will have to be run off of 2 channels. Most full range amplifiers are 2 ohm stable but you will want to ensure that the amp you have is in fact 2 ohm stable before proceeding. If it isn't 2 ohm stable, it will either go into protect mode or even worse, it will overheat and break. ### Yes, my amplifier is 2 ohm stable If you are mounting all 6 speakers in the hull and they are all the same size, choose whether you want to group the "Middle" speakers with the front or the rear. Whichever you choose, it doesn't matter, it is a matter of personal preference and there is no wrong answer. ##### There are two ways you can do this 1. Connect the positive wires for BOTH speakers on the left to the LEFT (+) terminal on the amplifier. Next, connect the positive wires for BOTH right side speakers to the RIGHT (+) terminal on the amplifier. Repeat the same process for the negative terminals. 2. Connect the positive wire on the LEFT side of the amplifier to the (+) terminal on the LEFT speaker, closest to the amplifier. Do the same thing for the RIGHT side. Next, connect the negative wires to the negative terminals for both speakers. Next, instead of running speaker wire from the amplifier to the second pair of speakers, run speaker wire from the first set of speakers to the second set of speakers. Connect the positive terminal from Speaker 1 on the left to the positive terminal on speaker 2 on the left. Connect the negative terminal from speaker 1 on the left to the negative terminal on speaker 2 on the left. Do the same thing for the right side. 3. Connect the remaining two speakers to the two un-used channels in parallel. Positive to postive and negative to negative. ## Setting Your Gains When you drop your amplifier down to a 2 ohm load, the power output on the amplifier changes. On many amplifiers, this will double the power output. eg. 50W x 4 @ 4 Ohms, 100W x 4 @ 2 Ohms. You have twice the power for the channel at 2 ohms, but you have twice the number of speakers. It should still be the same at 50W to all 6 speakers as the 100 watts is spready among 4 speakers instead of 2. For amplifiers like the Rockford TM400x4ad which have a constant power circuit the power rating is 100W x 4 @ 4 Ohms and 100W x 4 @ 2 Ohms. When you connect 4 speakers to 2 of the channels, you end up with 100 watts going to 2 speakers and 50 watts going to 4 speakers. When you have off balance power like this, you adjust the gain so that the volume of all 6 speakers is at the same level. You would adjust the gain for the 2 speakers down to match the volume of the 4 speakers. Rarely do you have the gains maxxed out for every channel. Also, the actual output of that TM400x4ad ends up being closed to 150 watts RMS per channel which is way more power than most speakers can handle anyway. When you don't have your gains maxxed out, your amplifier also doesn't get as hot which lessens the chance of it cutting out due to overheating.