Subwoofer Setup Help

[chpthril]

.75" gap minimum would make me comfortable.

Theres ok material, good material and great material for enclosures, but you get more mileage from the construction method. Sounds like you are looking past the material and looking at the condition of the material and the condition of the construction, so you guys are on the right path with looking into a new box.

That amp will be fine

[EricU]

MDK and I were looking at the box today and he mentioned that it didn't look like the correct material type and when you knock on it, it doesn't have the dead sound a box should have. Also the design of the box is horrible. It has cracks that aren't sealed and the wires are run through a hole rather then a terminal point on the outside. Also as discussed earlier the depth is to shallow. The only thing that seems to have been right is the cubic feet.
Speaking of depth what do you think the minimum depth should be for this box?

I built a sealed box last year for my Moomba and a 12" JL W6 wired for 2 ohm. I used some 3/4" birch that is used for making cabinets. I coated the inside and outside with 2 part resin and fiberglass, then used a sealer primer and then paint (both primer and paint were rattle can). That box I had my buddy who does auto interiors on the side help me out and I covered the whole thing with marine vinyl.

I sized the box using some basic audio calcs and on line calculators, used Chpthrl's and Earmark's help and that thing ROCKED! powered it and the inboats with a Kicker IX amp.

If you have access to some basic woodworking tools and some time, it's pretty easy to get good results. I asked a lot of questions and these guys never made me fell dumb (though they probably thought it more than once!). I am going to throw that sub and enclosure in the new boat for the rest of this season, then build it into the helm with a two piece box during the offseason.

[EricU]

Or hell, just throw one in the walkway like I did lol!

BTW...HOLY CR@% that is SWEET!! I now have JL envy

Now we know what's causing those Kansas winds!!

[Yokes]

So had some issues with my amp purchase so I wanted to revisit this with the audio guys on here (received a 4 channel so returning). So I'm planning on running a 1ohm stable amp these are the two I am looking at but I'm not sure if the 1200watt is to big.

I have the Memphis 2 DVC 300rms subs. I assume this means that all 4 voice coils can handle 300rms. 1200/4= 300 and 750/4=150 plus the 80% efficiency. I was thinking what the heck might as well go big! What are your thoughts? Am I thinking of this completely wrong?

Amp A
1200watt x2 at 1ohm 80% efficient
http://www.rockfordfosgate.com/produ...tails/m1200-1d
(Just would use one channel?)

Or

Amp B
750watt x2 at 1 ohm 80% efficient
http://www.rockfordfosgate.com/products/details/m750-1d

[chpthril]

Yokes,

Opening post, you noted having Memphis M1104D subs, is that correct? Specs posted indicate they come in either a single 4 ohm or a dual 4 ohm. Knowing exactly what you have here is crucial. Not only for a good power match but so the amp runs in its comfort zone.

300W rms would be for the sub as a whole, not each coil. In the opening post they are listed as a 300W rms / 600W peak

Lastly, what problems did you have with the amp, and what amp was it, the MTX listed on the first page? Knowing this is important in order to not repeat with the new amp.

[Yokes]

I was not aware that the coils were 300 total. So the 750 mono wired to 1 ohm is what I want.

My current amp is this one: http://item.mobileweb.ebay.com/viewi...353&cmd=VIDESC

I have no idea how it works as it is. The coils are wired in parallel and each sub has its own wires coming back to the amp. Then one set (positive-negative from one sub)is wired into the terminals on speaker 1 and the other is speaker 2. So if they are parallel inside the amp it would be 1 ohm (not one ohm stable) unknown watts maybe 300? or series inside the amp they would be a series/parallel circuit and be 4 ohms 100 watts. Divided across all 4 coils either way is under powered. So I could triple my output with that new amp with 150-190 at each.


So my issue is my subs hardly move unless the volume is completely cranked and I want some base with my rev 10s (which are insane). Also the amp went into protect mode. Didn't see a light but I assume that is what happened, after about 3 hours of pounding (the volume was cranked pretty high) the amp was crazy hot and no more output. Worked fine the next day again.

I will have to work late tomorrow most likely but if I get time I can run down to the boat with my meter and ohm some wires to verify.

Thanks for all the help on this boat stereo project. I appreciate it!

[chpthril]

Reading back through this thread this AM. Based on the past info, your subs are dual 4 ohm coils. Wired parallel/parallel/parallel is netting a 1 ohm load at the amp and that amp is not 1 ohm stable. This is likely the cause of the amp going into protect mode and shutting down. This is one reason why you needed another amp, and the other is the lack of watts output to those subs. Your current amp will only deliver 200W rms total @ 2 ohm. Since its not 1 ohm stable, we can only guess to what its 1 ohm output is to your current setup.

My suggestion, as noted before, is to run those subs @ 4 ohm at the amp as opposed to 1 ohm. There are plenty of mono amps that will run stable @ 1 ohm, but with the power needs of those subs, there are plenty of 2 chnl amps that will deliver the watts rms when bridged with a 4 ohm load and tons of mono amp that will deliver what is needed @ 4 ohm as opposed to loading it down to 1 ohm.