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Discussion Starter · #1 ·
After ALOT of thoughts on tuning, enclosure size etc... I have now decided to do something in which has an element off trial and error but should work ok and give me the flexibility that suits my needs better than with one tuning and that is 3 different tuning frequencies similar to the SVS PB13 ultra.

The two 15 cu ft subs will be powered by the EP4000 which I currently have and with a sorted fan which doesn't overheat now. The dimensions will be 24" wide by 30" deep by 48" high and will go in the same positions as the current 11 cu ft subs are now and this gives me the best position with regards to sound.

The three tunes will be 12.5hz, 17.5hz and 21.5hz. There will be 3 square ports which will be 7" x 5" by 36". All ports unblocked will give the 21.5hz tune, 1 port blocked will give the 17.5hz tune and 2 ports blocked will give the 12.5hz tune. Port velocity will be at 15 m/s max on the 21hz tune, 20 m/s on the 17hz tune and 28 m/s on the 12hz tune. I am not worried about the 12hz tune velocity as that is the same as my current subs and I don't get an ounce off chuffing at all on low stuff. This is with the EQ.2 engaged although I won't use the hpf for the low tune as I currently have no chuffing issues and that is 38 m/s at 10hz.

I can do it with three 7" round ports but this is something I have never used hence going the slotted route divided by 3.

The ports will be at the rear off the sub and I will buy some heavy duty foam blockers to block the ports with. This way I will have the best of 3 worlds. A tune for music, a tune for films and a tune for low bass tracks for when I want to have fun.

I will be using either a EQ.2 for hpf duties. I have been quoted $145 delivered to the UK for the EQ.2 which is about £100 but I can get the Reckhorn for £60 delivered but I have been advised that the EQ.2 is more accurate below 15hz so I may go for that.

The biggest problem with the Q18's is that we all know they need big boxes to be their best and not many people want 36 cu ft boxes in their living rooms so 15 cubes is a happy medium.

I will set up 3 sets of filters on the BFD for each tune to get flat.

I just need to work out how much wood to order and I will be ready to go.

cheers

Graham
 

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Discussion Starter · #3 ·
Here's an update for everyone. I have cut and finished all the bracing this weekend. I did the first set off bracing yesterday and finished the other one today. Here's a few pics to show my progress. My hands are pretty sore from sanding I have to say. I have added my son in the pic to give you and idea off size off these subs. I have tried to do a quick mock up with the sides and top added. I am planning to do the holes in the baffles next weekend and then start putting it together.

I did try some gloss black paint on a piece of mdf. It looked ok but was covered in bits off dirt so I need to find a way off keeping it clean. Suggestions for this would be appreciated. I am half tempted to leave the ports just mdf as they will not be visible as they are at the top and you won't see them. We'll see.

cheers

Graham
 

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Discussion Starter · #4 ·
Update time.....

I spent just a few hours in the garage today cutting the holes for the baffles. All done now and all the mess cleared up. Phew!

I cut the two outer baffles seperately instead off buying the 50mm straight cut bit and it came out perfect. I surprise myself sometimes.

The next pics will show some off the other parts mocked up to give you an idea off how it will look and how big these are going to be.


Cheers

Graham
 

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Discussion Starter · #5 ·
These are pics off the bracing positioned on top off the baffles. It still needs glueing which will be done next week. Wrights Carpentary did a first class job on the mdf cutting. Everything is spot on and perfect.
cheers

Graham
 

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Discussion Starter · #6 ·
These pics are to show what it looks like with the inside piece off the port added and the struts for the ports with the back on too. This thing really is big. I am going to try and use as little amount off screws this time. The titebond wood glue is pretty ace and rock solid when it drys.

cheers

Graham
 

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Discussion Starter · #7 ·
Update time....

I have now glued the bracing on both subs to the baffles. I know I said it before but I really wished I used wood glue before instead off the bond and seal as it glues so well.

I bought another clamp yesterday and some more glue and was pleased that I could get away with just 4 clamps to glue the bracing onto the baffles.

I also used the parasol base to lay on top off the sub. Made it look pretty anyway.

cheers

Graham
 

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Discussion Starter · #8 ·
I have now added some screws on the front just so it is a bit more secure and filled with filler. It now is starting to take shape. These are defo going to be big. Its now starting to get quite heavy so moving around is going to be very interesting. I have put the top on one off them but not taken a pic off that.

The wood so far all fits perfectly. Very impressed.

Next job is to fix the slots for the ports to the inside port piece and prime the inside off the ports and paint black.

cheers

Graham
 

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Discussion Starter · #10 ·
I have also routed the ports and slots and sanded down. I have glued the first one and will glue the second later this afternoon. I have to say 3rd sub build and I do feel that things are starting to become much easier and am making less mistakes. I just hope the veneering works out as good and easy as building it.

cheers


Graham
 

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Discussion Starter · #11 ·
A small update for you. I have now glued the first port piece to the bracing and baffle so I will give it a few hours before I glue the second port piece to the other baffle.

cheers

Graham
 

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Discussion Starter · #12 ·
Ive been back out in the garage again and glued the second port onto the rear off the bracing. So that is now drying. I have put a few screws in the back off the port on the other one just to secure a bit more. I have filled the holes with filler. Fingers crossed tomorrow I will add the first coat off primer to the port.

cheers

Graham
 

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Discussion Starter · #13 ·
A few more pics to show it standing up. I have also added some filler where the port exit joins the top piece to make sure it is dead flat and smooth.

I have added one coat off primer to the inside off the port piece and wet sanded down and I have also glued one off the sides on the first sub so I will do the other sub today and take some more pictures.



cheers

Graham
 

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Nice to see another huge sub build.

Hate you right now.

I will have to wait sometime before I can do my all out monsters so for now I get to watch others with envy/jealousy.:hissyfit:

I cant complain to much though I will atleast have my THT to get me by.
 

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Discussion Starter · #17 ·
Hello fella!

Yep I decided to make them a bit bigger. LOL.

Lots off priming and painting to do then just case of putting the other side and back one, then veneer.

Its sound so easy. I wish it was.

cheers

Graham
 

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Yah ....I also cant wait to hear what you think of the 18's?

They have them hear in Oznation for about half the cost of the Maelstroms so I'll see what you think of them.
 

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Discussion Starter · #19 ·
I remember you were working on a pair of dual ported malx subs weren't you. Do you remember I did some sketchup drawings for you and some graphs.

Graham
 

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Very impressive design and build. I hope you'll be giving us some REW measurements once you get this thing situated. I'd be very interested to see the performance of each tuning in room.
 
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