Question about connections between head unit (HU), amp, and sub

[kanihoncho]

Okay I am seeing two possible ways to connect a sub with HU and amp depending on their construction (there maybe more but I'm a newb). I also have not researched subs/connections yet so forgive my ignorance . . . I have attached images below . .

a. HU dedicated sub preamp cord out > into AMP > 2 wires out > into SUB
b. HU 2 RCA sub preamps out > into AMP > 2 wires out > into SUB

1. Is one of these connections from the HU better than the other ( 1 cord vs 2)?
2. Does the dedicated sub cord carry both L and R signals that are separated out by the amp for delivery to the sub?
3. If the HU has a dedicated sub cord out, what connection is used on the amp (L or R)?

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[Doxquzme Premium Member]

You have 2 different HU listed but they both have dedicated subwoofer outputs.

Anytime you have the option to use a dedicated preamp output from the HU to the amp, it is preferable. Use the dedicated sub out to the amp. It will allow you to control frequency and volume from the HU prior to amplification. This assumes you do not have a processor/eq/dsp/LOC inline between the HU and the amplifier(s).

 

[kanihoncho]

The second HU was used to show the two RCA connectors from the HU to the amp. The first HU where it is labeled <subwoofer preout> is only showing one connector type unless it chose not to show the second one for brevity in the diagram . . .

 

[Doxquzme Premium Member]

One or two, they are still subwoofer outs and are mono summed signals from both left and right. Even the 2 RCA subwoofer pre-outs on the 2nd one are both subwoofer, mono summed signals. Pre-out low level options are also the cleanest signal too. Having 2 is just a bonus should you have dual inputs as most subwoofer amplifiers do. In a single out, I would slipt that at the amp and run a y-splitter to the amplifiers inputs should that be the configuration. While the frequencies are not impacted, leaving one of the dual inputs open on an amp unused/opened also lowers the input signal and the overall volume of the sub amplifier if both inputs are not used.