15in 300w 8ohm vs 12in 300w 4 ohm

Question

I have a 15in 300w 8ohm subwoofer with a paper cone and a 12in 300w 4ohm with a plastic cone. I don't understand too much about audio systems, so I'm wondering which of these would end up being louder or sounding better, the 12in is JL and I can't find any info on the 15in one

Answer 1

If those are passive subwoofers, you pick the one matching the impedance of the amp. If they are active subwoofers, they should already be impedance-matched to their respective amps. In that case, the 15in subwoofer has a better pitch at producing clean low basses at volume. Whether it actually does so depends on the quality and strength of its magnets, bearings, coil, membrane, the size and build of its enclosure and its respective walls. Not to mention the amp.

In short, all other things being equal there might be reason to pick the 15in, but very clearly not all other things are even remotely likely to be equal.

Answer 2

Those specifications aren't really enough to say which one will be louder. The info you're missing is the speaker's efficiency: how loud it will be when you feed it with an 1 W signal.

Without knowing this figure: a 15" sub needs more energy to move the cone than a 12" (bigger area->more air resistance), so if the design were identical, the 15" would be less efficient.

Next to consider is the enclosure: this can cause a peak in the output, depending on the enclosure design. To build a good enclosure, you need to know the speaker parameters. These allow you to calculate the optimum enclosure size and type.