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View Full Version : Cutting into walkway glass? (Subwoofer port)


Brian B
06-14-2011, 08:27 PM
I'm seriously considering cutting a "slot like" port into the port side glass where the walkway is to port my subwoofer into the cab area. Before you get excited, I will have it professionally done, and will wrap the edges in matching vinyl for a stockish look.

What I'm concerned about is the integrity of the hull and wondering if I'll compromise any structural strength by doing this......

MariStar-Man
06-14-2011, 08:56 PM
I didn't know there was such a profession as "Professional Stereo Installer." Lol

I assumed they all just slapped it in making holes wherever they pleased, and splicing into any wire close by...

Brian B
06-14-2011, 08:58 PM
I didn't know there was such a profession as "Professional Stereo Installer." Lol

I assumed they all just slapped it in making holes wherever they pleased, and splicing into any wire close by...

I dont even know where to begin and will kindly not respond. Thanks for your input though.

Gabe63
06-14-2011, 09:42 PM
I am not sure a professional stereo installer knows much about compromising the hull. I have seen speakers cut into these areas though. Am I an engineer and can I say if it would compromise the hull???

I would hate to see you do it and find out the port did little to help with base. Is the boat a beater? I would not do it on a boat with value.

Brian B
06-14-2011, 10:18 PM
Not a beater at all. In fact, its cherry. 01 x10, 140 hours. Thats why I'm willing to spend the money with someone who specializes in glass/boat work......

I have also seen it done where most of the glass was cut away on an XStar. And I'm 100% positive that it will help with the sound. It sounds perfect with the observers seat open.........

MIskier
06-14-2011, 10:21 PM
There is a u shaped bracket in the wakeway that provides most of the torsional rigidity, but I still would not recommend doing this. Unless you plan on keeping the boat for the next 20yrs you will find that it will have a pretty negative affect on the resale value.

Thrall
06-15-2011, 02:56 AM
Why not spend the $ on a better sub/amp instead?
I have a single Boston 12" sealed enclosure sub w/tuned radiator under the dash, no "port" into the boat and it is very loud.
I'd upgrade your sound system before cutting the boat. While I'm not an expert, there's alot of subs that are completely concealed, even down firing that sound great. Doesn't take an open air window too hear the sub.
You could get some good automotive components, sub and amp for probably $500 if you shopped carefully that would make the boat really thump.

agarabaghi
06-15-2011, 08:01 AM
x2 on better sub amp. Didn't you get some kicker sub / amp put in the ski locker? Why not get a small sealed box under the dash? Also how quiet is it? I have a JL 10" in the stock location running off 220w JL amp and it sounds perfect... Could be your tuning ...

EarmarkMarine
06-15-2011, 09:17 AM
Brian B,
I'll only address the acoustic side and what is actually occurring. A subwoofer concealed within a locker can easily lose 10 dB as compared to a direct radiating sub. That can be a 10 times power differential. That means you are driving the subwoofer and sub amplifier much harder. IMO, the subwoofer system that always sounds the best is by far the one that is operated most conservatively. Some will compensate for the losses by using far more leverage in the way of larger subs and more power. You are still consuming alot more current. Acoustically, that works to a degree. You can still get lots of boom and rumble from within a sealed compartment but you definitely lose alot of the tonal construction in the way of midbass articulation and transient response. While you won't recover the entire 10 dB with a vent, it will make a substantial difference. Optimumly, you would like a smaller locker and a larger vent. There is less impetus for the bass radiation to exit from a large and compliant air space through a tiny opening. So, you would like to have a vent that at least approximates the total radiating surface area of the woofer and bass-reflex port if applicable. Its still not a free ride with a vent. The large locker and adjoining cavities constitute a major and separate air mass that is very compliant thus stores and releases acoustic energy with a different phase response from the woofer itself. So the reflected energy from the locker and the energy direct from the woofer do not exactly arrive at the vent in phase. This in itself creates losses and creates an uneven frequency response as various frequencies are either passed or filtered differently. But the lesser of the two evils by far is using a vent to freely pass the bass radiation.
In some cases a good route would be to couple the woofer/enclosure directly through the wall. For example, in a bench seating console you would sandwich the wall between the woofer and sealed enclosure. It would appear to be a factory-like infinite baffle sub.

David
Earmark Marine

bturner2
06-15-2011, 10:11 AM
I didn't know there was such a profession as "Professional Stereo Installer." Lol

I assumed they all just slapped it in making holes wherever they pleased, and splicing into any wire close by...

That's how the "professional installers" the PO hired to install the stereo upgrades he purchased did it. They did such a professional job that they put all 4 Wet Sounds tower speakers on the same channel. Took me close to a week to fix their "professional" installation.

rspiecha
06-15-2011, 11:55 AM
What size sub is it??? The X-10 boats come with a hole already cut under the dash for a sub. If the sub wasn't installed, they carpeted over the hole. Or is that already installed and you are adding another sub???

Rob

rspiecha
06-15-2011, 11:58 AM
Nevermind, looking at your other thread, you already have a speaker installed in the under dash location.

Rob

Brian B
06-15-2011, 01:19 PM
Alright guys! Thanks for the input!

I recently installed my system and have an incredible sub/amp combo

http://www.mastercraft.com/teamtalk/showthread.php?t=41450

The thing absolutely rocks with the observers seat open. It pounds. Close the seat and it nearly blows it back open, and all the seat cushions in the bow flutter and rattle like a mofo.......

Brian B
06-15-2011, 01:22 PM
Brian B,
I'll only address the acoustic side and what is actually occurring. A subwoofer concealed within a locker can easily lose 10 dB as compared to a direct radiating sub. That can be a 10 times power differential. That means you are driving the subwoofer and sub amplifier much harder. IMO, the subwoofer system that always sounds the best is by far the one that is operated most conservatively. Some will compensate for the losses by using far more leverage in the way of larger subs and more power. You are still consuming alot more current. Acoustically, that works to a degree. You can still get lots of boom and rumble from within a sealed compartment but you definitely lose alot of the tonal construction in the way of midbass articulation and transient response. While you won't recover the entire 10 dB with a vent, it will make a substantial difference. Optimumly, you would like a smaller locker and a larger vent. There is less impetus for the bass radiation to exit from a large and compliant air space through a tiny opening. So, you would like to have a vent that at least approximates the total radiating surface area of the woofer and bass-reflex port if applicable. Its still not a free ride with a vent. The large locker and adjoining cavities constitute a major and separate air mass that is very compliant thus stores and releases acoustic energy with a different phase response from the woofer itself. So the reflected energy from the locker and the energy direct from the woofer do not exactly arrive at the vent in phase. This in itself creates losses and creates an uneven frequency response as various frequencies are either passed or filtered differently. But the lesser of the two evils by far is using a vent to freely pass the bass radiation.
In some cases a good route would be to couple the woofer/enclosure directly through the wall. For example, in a bench seating console you would sandwich the wall between the woofer and sealed enclosure. It would appear to be a factory-like infinite baffle sub.

David
Earmark Marine


Thanks for your input David!

Here is my box......

http://i28.photobucket.com/albums/c250/ultimatuc2/IMG_0099.jpg

By leaving it down firing within the storage compartment and porting the glass, wouldnt I essentially be creating a bandpass effect? What would be better, porting the compartment like we've discussed? Or mating the box up to the walkway and firing the sub outward?

EarmarkMarine
06-15-2011, 04:55 PM
Brian B,
A bandpass is two carefully tuned acoustic circuits (one in the front and one to the rear of the driver). You can have a well-damped design where the two circuits are tuned at different frequencies and provide more output over a broad bandwidth. This would be more of the SQ version. Or, you can have a higher output version where the two circuits are tuned at a coincidental frequency. This would sound like a single note resonator but would hit like crazy at that frequency. Trouble is that everything, whether a bass drum or bass guitar, sounds like that frequency and has a carry-over ring to the bass.
Bandpass enclosures also have a filtering byproduct where you trade greater output over a narrower bandwidth in exchange for less output outside of that narrow bandwidth.
Although you have placed an enclosure within an enclosure, your scenerio has little in common with the principles of a bandpass. The front enclosure with the added vent is a massive displacement and its only impact wthin the audio bandwidth will be the negative filtering effect. But, just as you clearly hear more output and a little more articulation as you raise the observer's seat, you will get a similar increase once adding the vent while the seat remains closed.
You have some nice equipment and a nice looking job. It will only provide improvement when you add a vent.

David
Earmark Marine

Brian B
06-15-2011, 06:08 PM
Thanks David. If you were me, would you face the sub out, or leave it downfiring and port the walkway glass?

EarmarkMarine
06-15-2011, 07:36 PM
Brian B,
I would do a custom vent on the port locker pass-through surface. It would be a white vinyl bolster that surrounded the stainless steel mesh vent. I would install the identical but mirror image bolster on the opposite side wall to encase a storage net or pocket. This way everything would appear plausably factory and would not detract from the appearance or value of the boat in any way.
I know its a little late but I just saw the driver's under helm photo. I definitely would have found a way to integrate the sub there in a direct-radiating fashion and avoided all this.

David
Earmark Marine

Wake2004
06-18-2011, 01:24 PM
Here is a picture of my cut walk way, previous owner had it done as I am not sure that I could have cut it. But I am glad that it was done as it works very well. I added the Rockford grill with a small white grill under it.

Brian B
03-21-2012, 01:06 PM
So I ended up putting a small, rectangular vent in the walkway down low. The sound has improved greatly! I will post some pics and vids next time I have the boat out!

Thanks for all the input!

agarabaghi
03-21-2012, 02:58 PM
I wanna see video!