sub upgrade

[chpthril]

the shape of port does not matter, just the same volume?

Exactly, within reason. We can round, rectangle, square or even triangle. What matters is the port opening sq2. Too small and the port will weez and huff. Too large and you likely never get a port length that would all for the tuning Hz.

if you look at the enclosure section it says the volumes below are gross internal volumes, driver and vent displacement has been accounted for

No worries, just deduct the volume consumed by the port. if my math is correct, the 4" x 20.5" would deduct .17, so no the woofer's volume is down to about 1.08 ft3. Using a wood slot port constructed from .75" wood rather then 3/16 thich ABS, is going to take up way more space then .17.

so with these specs do you still its 40 hz in the thiele parameters Fs =32.4hz in the enclosure section it says Fb/F3 (hz) 40/34
with these I thought the box would need to be 32 hz. Yes/NO

The woofer's Fs is not the same as the tuned frequency of the enclosure. DA likes 40hz for this woofer and I wouldnt argue with that in a boat unless I was more intimate with this woofer.

[dukesofhazzard]

awesome,
thanks very much.

[dukesofhazzard]

one last thing before I start this box build, is a 1.5" slot opening good, or smaller or bigger, just thought an 1.5" wide would look good. maybe even 1". so much thanks

[chpthril]

1" is too narrow IMO for a 12" woofer, but keep in mind, if you change the width of the port, it effects the tuning frequency, which forces a change to the height and length of the port, which then changes the net woofer volume, which changes the tuning frequency once again.

[dukesofhazzard]

thank you sir, do you recommend 1.5 or 2" then, from there I will start to design the box. Mike thank you for always helping out, it is so much appreciated.

[chpthril]

Remember back when you were working to figure out why the 12 x 1.5 has a much longer port then the 4" round? Its the surface area. If you go up to a 2", i think you will find the port length to be unworkable if you maintain the 40Hz. if you then adjust the length to fit the box, then that tuned frequency will then change.

[dukesofhazzard]

Hi Mike, thanks for helping me like you have been,
I am confused though, I am pulling the 10" ws free air sub out, there are 4 wires going to the sub and only 2 going into the amp,
are they spliced somewhere, traced back a few ft, don't see a splice. Not sure now how to wire new 12"dvc diamond audio sub up.
What am I missing.
I did do the bridge on channel 5/6 on the amp before like you recommended so that is where I stand with that end
thanks again

[chpthril]

Regardless of the woofer being a single voice coil or a dual voice coil, there should only be a single pair of wires leading away from the woofer. Brown and yellow IIRC. If it is a DVC woofer, those 2 short jumper should be short and go from one coil directly to the other. Tige only wires the boat with a single pair of sub wires.

[dukesofhazzard]

no I have two sets of wires going to the sub, grey and blk x2, have checked back through the wall under the steering wheel and can't find a splice, however there is only one set of wires going to amp grey and black. That's why I am confused. I snapped a pic I will post it up
subwire.jpg

[chpthril]

That parallel connection should be right there close to the binding posts on the left in that pic. If you can find that connection, then clip off those ends on the left side coil and tape them up.

[dukesofhazzard]

thats the thing that was confusing me, I can't find that connection, it is hidden somewhere farther away so I thought I was missing something, so safe to just tape up the shorter leads and just use the longer ones then? correct?
thanks again mike.

[chpthril]

yes

[dukesofhazzard]

okay I know everyone likes pics, especially when someone is cutting up there expensive boat. Well the scary part is over, got the hole cut to fit the sub box in under the helm. I used a bosch flush cut saw, went fairly well. Hopefully next few days can start the box build, not sure why it rotates it, but anyhow, will build a new front to cover the hole of the 6.5" to try and get as factory look as possible.
helmhole.jpg

[dukesofhazzard]

hey mike, gonna start the box today, got my dimensions all set etc. however when I plug my dimesions into a couple diff port tuning programs it def comes up diff from what I orig. have.
with a round 4" port d.a. recommends 20", when you plug that into the programs it comes out at around 38hz. so very close.
with a rect. port, slot port, with my box volume, hz etc the programs come out to 1.5" x 8" x 13". that is with 3 diff. prog. and they are all within reason of each other.
the surface area is roughly the same for both ports, but why is the length so diff. that's the part I don't understand. really wanna get going on this.
thanks

[dukesofhazzard]

hey mike, gonna start the box today, got my dimensions all set etc. however when I plug my dimesions into a couple diff port tuning programs it def comes up diff from what I orig. have.
with a round 4" port d.a. recommends 20", when you plug that into the programs it comes out at around 38hz. so very close.
with a rect. port, slot port, with my box volume, hz etc the programs come out to 1.5" x 8" x 13". that is with 3 diff. prog. and they are all within reason of each other.
the surface area is roughly the same for both ports, but why is the length so diff. that's the part I don't understand. really wanna get going on this.
thanks
ps
I just used the kicker app and plugged in the 1.25 cu ft, port height 8, width 1.5, length then equals 16", so I think that is what I will go with.that is workable and orig. what I had my box designed for.