Matt- Thanks for sharing. I am of a different opinion based upon my knowledge and experience with the physics and electrical principles involved. Things are very different in a bow rider boat in that you need the direct radiation from the woofer but want it to sound deep and kick you in the butt. 4th order bandpass is out, ported is not optimal unless ported into the cabin along with being direct radiating, which leaves sealed or free air. I am of the opinion that a properly fitted sealed enclosure with direct radiation will sound best.
I'm not really sure what you're getting at, the woofer in either situation would have the same placement on the inside of the boat. What happens behind the mounting point doesn't change the radiation pattern.
The physics of low frequency waves is that they bend around corners more than high frequency. So you don't need to be in front of a woofer, but you do need to be in front of a mid or tweet. So I think I'm not tracking that logic. It's certainly true that opinions on what sounds good vary.
Yeah the oscilloscope may be a bit over the top but if I can figure out how to get a clean and safe signal that is even 10 percent stronger going into the amp and then the amp multiples at a fixed rate of lets say 10x based upon the same gain then I will get 10 percent more power to the speakers and my system will be more efficient on the power consumption side when not using full volume in a class D amp. Keep in mind I have done bunches of electrical projects that needed my old military surplus oscilloscope. It took up too much bench space so I sold it and got a robust portable 4 channel with 2 digital inputs, 2 analog inputs, and a logic tester. As for tone generation I could use the oscilloscope but using the same input device as you do for music is better so I have a app for the tone gen that will run on my source device. Being able to attenuate the tone to normal recording levels for music is a big plus and also a miss by lots of folks who tune systems with a tone generator.
All a scope will do is tell you when your sound starts to clip. If you set the deck to 50% you could just turn up the amp's gain to get to the point of the amp clipping. Or if you set the deck to the max before clipping, someone said 95% (I doubt that, but ok) you would still just turn up the amp's gain until it starts clipping. The advantage of the latter isn't that you get more volume, it's that you get less noise in the signal because the source to the amp is greater. So better SQ, but not more volume. The amp can only do so much. Also adjusting the gains doesn't in any way impact the efficiency of an amp. Conservation of energy after all. If power conservation was/is a priority then IB and a high eff woofer is the only way to go. Most high eff woofers are probably not going to hold up to water though.
I'm not really sure what you're going to use for the source of the test tones, but the dynamics of music are going to be a lot different than test tones. I don't mess with this so it sounds like you know a lot more about the process.
Again thanks for sharing your thoughts and opinions and I am by no means flaming you. I am just of a different opinion and thats ok. I will post photos and results. I have been very honest in posts where things don’t come out how I wanted so you can count on it being accurate even if that means I end up looking stupid for wasting time and money for no gain.
I like projects like this too, and I've run aground on things, so I can relate to doing it and learning as you go. Good for you. I won't badger you anymore about it, other than please post pics.
I think the problem here is low Fs woofers are hard to come by in today's world (at least car audio wise). There is really too many variables to say what will play lower (well, with authority). My IB10 on the boat plays down in the 28hz region (based on a common song I test), but it has zero output, I can just watch it try lol. I install a ton of manufacturer loaded enclosures tuned around 40hz, that can play into the the under 30hz region and still be respectably audible. I run the ID8 in my Charger IB, simply because it was lowest Fs 8 I could find. That plays low notes well, but overall output is just enough to blend in to the factory Alpine system. If I put it in a sealed box, I doubt it would get as low, but output would increase. I ran two 15" Dayton HF's IB in my Challenger, while it sounded great... there is no doubt in mind a sealed box would have been louder. Maybe if I get super bored this weekend I can do some trial run's on random woofers in WinISD.
I really think we are on the same page here. Getting a marine woofer with a low Fs is probably even harder than a car. Still IB will be more efficient and lower than sealed.
I wonder if the enclosures you mention are in a boat or a car. There's tons of "room gain" from a tiny car at low frequencies and so they sound much lower. Comparing an enclosure in a car to the same enclosure in a field is completely disappointing.
Also comparing the enclosures that have different amps and speakers is really hard to fairly do. WinISD sounds familiar. I've used several programs dating back to 1997 and I never really found them that useful because I always either used the biggest sealed box I could (bigger is lower) or later went fully IB. One thing that I do think helps a sealed box in a car is that you get more loading in the trunk from the small volume in the trunk. The trunk starts to act like a bandpass box. I remember people with 4th gen Cameros would face the sub down into the "hole." That was the best orientation because it used the "hole" like a ported bandpass box. The same exact setup pointed up or forward wasn't nearly as loud.
I won't badger you anymore either. I'll just add that two 15 IB's in anything auto must have been impressive. I've also scaled back from my youth of two 12" or one 15" to just the one 10" in my Lexus. It's not wake the neighbors loud by any means, but it sounds much more like my home HiFi.
Good on you both. I may someday justify this in my old boat, but for now I can only bench race.
