Help me understand this.

[wafflebird]

I am a little confused as to why a sub has a R&L input (RCA style) I understand why you would feed R&L speaker wires into the sub, the sub uses these signals to sample and get the low frequency out of the signal. I also understand that the sub can be used as a cross-over and be adjusted for the main speaker outputs. The sub plays the down low stuff and sends out the frequency you have selected (and above say 80 Hz just for example) in the crossover to the main R&L speakers. SO if you have a digital out on a receiver (only one) does it make sense to use a Y-splitter on the back of the sub? You are only sending in one signal. And if you do use the splitter does the sub actually play right and left signal. And I think that is another main question I have is 1 subwoofer able to play R&L bass signals independently? I have wondered about this a while and your input is appreciated. Thanks.

 

[majorloser]

Well, first you don't want to send a "digital" signal to the subwoofer. Only analog signals should be hooked up to the sub's RCA connections.

The LFE or subwoofer output on the back of the receiver is an analog signal that is a summed total of ALL bass frequencies for all channels. If you run the R&L signals (receiver pre-outs) to the sub, the sub will combine the signals and only use the bass frequencies from both channels. The R&L outputs from the sub are adjustable so only frequencies above the setpoint will return to the receiver (pre-ins).

Some receivers (even older ProLogic) will allow you to designate the "size" of the front speakers in your system. If you are using the R&L outputs you can set the front right and left speakers as "large". This will make sure all the bass frequencies are sent to those channel RCA pre-outs.

 

[wafflebird]

Oooops.....

Although I knew the sub out on the receiver is analog for some reason I said digital... duh. But the sub would combine the signal whether it comes ib two rca's or not right? Do you actually get any more performance coming out of one RCA from the receiver and the running the splitter into the sub for R&L? The "General" concensus is that you do, but why?

 

[markw]

Although I knew the sub out on the receiver is analog for some reason I said digital... duh. But the sub would combine the signal whether it comes ib two rca's or not right? Do you actually get any more performance coming out of one RCA from the receiver and the running the splitter into the sub for R&L? The "General" concensus is that you do, but why?

The thinkng behind this is that you are feeding the signal to two inputs instead of one input so that it essentially since two signals is greater than one, it sees a stronger overall input signal.

But, since there ain't no such thing as a free lunch, when you split that signal, each side only gets one half of the original signal anyway.

 

[MDS]

But the sub would combine the signal whether it comes ib two rca's or not right? Do you actually get any more performance coming out of one RCA from the receiver and the running the splitter into the sub for R&L? The "General" concensus is that you do, but why?

You get a stronger signal because you are doubling the voltage. Instead of 1 volt with a single rca input you effectively get 2 (minus any miniscule loss caused by splitting) and they are summed together by the sub. You often hear it said that it takes twice the *power* to get a 3 dB increase in SPL (10*log(100/50) =3.01 dB). Well twice the *voltage* will give you a 6 dB increase in SPL (20*log(2/1) = 6.02 dB).

 

[Hi Ho]

Most people use the splitter because without it, as in my case, the auto-on feature on thes sub won't work correctly at lower volumes. The splitter definetly increases the audio level. When I added a splitter I had to turn down the sub.