But the sub has two SUB connections..
Do both the sub sockets need to be connected?
Should the sub be connected to the speaker output?
Connecting a Sub
Adding a sub woofer to you android head unit will allow the unit to bring more bass sounds to the music. Typically in car speakers are quite small in physical size meaning the bass response – low frequencies tails off too soon. Connecting a SUB can make up for this lack of sub-bass from the front and rear car speakers.
There are separate controls for the sub output giving much for control over the sound your android head unit gives you. You can tune just the sub output to make the sound just as you want. A graphic equaliser is a great way to achieve this. Picking an android head with with a DSP can also help adjust the sound stage to perfection.
If you have two SUB OUT RCA connectors on the rear of your android head unit, then connect these by those RCA/Phono cables to the two SUB IN connections on the sub.
If you have only one SUB OUT on your android head unit but your sub has SUB_IN_L and SUB_IN_R or just two RCA sockets then how do these connect?
Not the speakers
Don’t connect your sub to the android head unit speaker cables unless you have no SUB_OUT, then this is your only option.
If you have one SUB_OUT on the android head unit you want to use this connection to get the extra level of control that the head unit can deliver to the SUB. If you only connect one RCA cable you won’t get the full benefit of your sub.
The trick to connecting the single sub output to the two subwoofer inputs in a simple one. Use a RCA type splitter that will share the single SUB_OUT with the two SUB_IN connections. A typical RCA splitter is shown below and will allow the android head unit with only one sub output to feed a dual input sub.
The single RCA plug will fit the single SUB OUT of your android head unit. The other end of the short patch splitter lead has two SUB OUT connections. These will accept the RCA plugs and the leads that will take the signal to the sub. You have easily turned a single sub output to a dual sub output.
Adding a splitter to your android head unit to run the sub won’t affect the sound quality if good cables are used. Cheaper cables are easily damaged during a tight fitting installation. There in no degradation of the signal as it travels through the simple splitter. Having your SUB_IN_L and SUB_IN_R driven by a single, combined output on the android head unit will sound better than only connecting one lead.
Why split at the head unit end?
Splitting at the head unit end is preferred for two reasons. If the android headunit being fitted is replacing an install that use the two input sub, there should be two sub leads that the head unit end. Secondly, if this is a fresh install of the sub, running two cables in just as easy as running one cable. It is so much better when the android head unit gets upgraded in the future to a two sub output version and the cables are already there. It won’t make any difference to the sound level or sound quality and does increase the number of cables fitted. But we see this as an investment for the future upgrades.