2245 Ports

[sekess]

I recently swapped in my pair 2245's into my existing subwoofer boxes. These boxes are somewhere between 14 and 14.5 cu. ft. internal volume (after subtracting for corner bracing, driver volume and port volume). I have 3 precision ports in each box (4 inch diameter, 17 inches long, and flared on all ends). The boxes are tuned to 18.50 Hz or so. I made these for a pair of Avalanche drivers.
These boxes came out nice. But, constructing cabinets is very tough for me. So, I'd like to use these for my 2245's if it's possible. My question here is about the port lengths.
Currently, I have a 20Hz highpass (2nd order)(to protect against too much excursion down low) and I've been alternating between 60Hz and 80Hz lowpass (2nd order). To optimize these boxes for my 2245's, what would be a good length for three 4 inch ports ber box? They sound nice now. But, I think this is too low of a tuning for the 2245's. I see that most are using smaller sized boxes for these drivers. But, I dread having to go through constructing another pair of cabinets this large. So, any help in adapting these guys to my 2245's is much appreciated.

Here is a pic of the cabinets with the 2245's inside.
The 416's above them are sitting in some old cabinets I picked up. The 2 small drivers in the 416's cabinet are not active. They are just in there to plug up the openings.

Thanks in advance for any suggestions,
Steve

32783

[sekess]

Oh yea,
In case anyone asks, those are just the grill covers to the 416 boxes. I placed them in front of the TV (middle of the pic - between the two 416's) so as not to get glare from the flash in the pic.

Steve

[SMKSoundPro]

Dear Steve,

Can you send the outside dimensions of the sub cabinets?

I can run the numbers through Bass Box Pro 7 and see what it recommends.

Are the cabs made of 3/4" material throughout? or a thicker baffle...

Scott.

[sekess]

Hey Scott,

Thanks, that would be great.

The boxes are 3/4" all the way around. All the inside edges have 1.5" x 1.75" studs -- I sliced 2x4's in half (actual cross section of 1.5" x 1.75")and used them on all the inside edges to reinforce the whole thing. So, they occupy the volume of all the inside edge lengts x 1.5" x 1.75". Plus, there are three 17" long 4" diameter ports. And of course, there is the volume that the 2245 takes up.

Thanks a lot Scott,
Steve

[sekess]

Now for the dimensions:

The external dimensions are : 48" x 24" x 28"

The edge bracing is a total of 358" long x 1.5" x 1.75" = .544 cu. ft.

So, those are the external dimensions. But, you'll have to subtract .544 cu. ft. from the internal volume to take into account the edge bracing. And of course the port volumes and the driver volume.

Thanks again Scott,
Steve

[johnaec]

Bass Box Pro 7Errr - isn't 6.0.20/21 the latest?

John

[yggdrasil]

I entered your data into WinISD, and it seems you have a 18,5Hz tuning.

If you cut the vents at 10", your tuning would be 23,3Hz.

Gray line is your tuning, yellow is alternative tuning.

[sekess]

Thanks Johny,

Ok -- 10" sounds good -- that's what I was guessing -- somewhere around there. I hate to cut up my precision ports unless I'm certain those are the lengths I'm going to stick with. I've been trying to come up with some temporary port setup. This way, I can cut different lengths and actually hear the differences -- maybe a temporary sheet of MDF or plywood with three holes that line up with my existing holes. Then I could affix different sized PVC pipes to that. When I'm done, I could cut my Precision Ports to the lengths I need. I have to think on it a little.
But anyway, 10" sounds like a good place to start.

Thanks,
Steve