Subwoofer Question

I am trying to upgrade the subwoofer to add a little more low end on my boat... Part of the problem is finding access because its hidden under the helm seat I believe. Judging by the rest of my system i'm pretty sure the subwoofer in the boat is a Rockford Fosgate PM210S4 4-ohm subwoofer.

My question is... If I swap the subwoofer for a 2-ohm speaker what will happen? My subwoofer amplifier is a PBR300X1 which is rated at only 75 watts RMS on a 4-ohm speaker but is rated at 150 watts RMS on a 2-ohm speaker (and it actually states in the manual its rated at 300 watts RMS for a 1-ohm speaker also, but I can't find any 1-ohm subwoofers). By getting a more efficient speaker I should be hearing a lot more bass, no?

Wont likely find any 1 ohm woofers, but rather you would look for a 2 ohm DVC that would be wired to 1 ohm at the amp.

I honestly dont see a real return on your investment to buy a 2 ohm woofer to just get 75W more watts. Yes, thats 2X what its getting now, but this is a 10 woofer, not a full range coaxial. Id jump at a chance to go from 75 to 150 W/rms on an in-boat speaker though.

I think your money would be better spend with a new amp that will drive the current woofer in the 300-400W range. Once thing to consider though, an amp change may require upgrading the cabling.

Now, before suggesting new gear, I always like to make sure any existing gear is working to its potential. IS the amp tuned correctly? Is there a bass level knob hooked and hidden somewhere? Is the input source from the head unit proper? Is the woofer radiating directly into the cabin or is is closed in an insulated cavity? A few little things that can greatly impact bass, without spending much, if any money, but mostly just time to double check. Then, if bass is not enough, we now have a baseline to go from.

I believe the amp is tuned correctly, it’s set for low pass and I increased the gain a little. The source is the head unit and the RCAs are set to “subwoofer”. The only subwoofer control is on the head unit itself and is set to max. I’m going to get in to where the subwoofer is and figure out exactly its placement in there, all I can say is that it’s entirely enclosed, you cannot see any part of the subwoofer, I’m not even 100% sure where it is. I also want to see if sea ray used a cheapo subwoofer and if they did I don’t mind spending a couple hundred for a nicer one, or maybe increase the size of the hole and put a 12” subwoofer in.

Cross-over filter and gain are part of it. The actual cross-over point will greatly impact the woofer's performance. From the head unit, i prefer a full-range signal and let the amp's cross-overs do the job. Altering the signal pre-amp can get you into a tug of war between the source and amp. 99 of 100 factory installed amps are bolt in and rarely tuned by the manufactures suggestions.

The rockford marine woofers are pretty good, if thats what they are. A more expensive 10" woofer wont necessarily yield any better results. The size is the greatest determining factor for output. Two same size woofer with the same amp and enclosure will have nearly identical output.

Going from a 10 to a 12 is about a 35% increase in surface are. Thats noticeable. However, 75W rms is SOOO low for a woofer in an open air environement like a boat. Heck even 150 is low. Not to mention a woofer is closed up in a cavity.

I think I’ll open up the helm seat to check out what I’m dealing with then go from there. Assuming I’ve got a 4 ohm 10” Rockford subwoofer I think I may try to install a 2 ohm 12” subwoofer, doubleing the power to 150rms and increasing the surface area. Also I may see if there’s a way to ventelate or port the area where the woofer is to let some of the bass exit better. I want to stay away from increasing the size of the amp for a few reasons, wire gauge being one of them. Another being the draw on the batteries while the engines are off.

Also, I didn’t think about the head unit and the amp both trying to filter high signals out... I’ll try changing the head unit to deliver a full range signal and let the amp filter out the highs on its own like you said

I’m also curious what setting on the amps crossover I should be using for the 6.5” speakers. I believe it’s set to high pass right now, they’re full range speakers, I may try setting it to all pass to see if I get any added bass.

If they wired the amp for its potential output, there are 400-500 watt rms @ 2 ohm amps that are the same size and will draw no measurable more battery current.

There are means to vent closed cavities.