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So after contemplating, I'm wondering what drawbacks there might be to building a pair if 8-9' cabs. 22X12X57 internal vol before any bracing, fill, or driver displacement. Probably around 8' net. I would mount a 2269 on the 22" 'side'. One each behind my Acoustat Monitor 3..(perfectly hidden), after I may be done listening to the York U15s whose bottom end needs extension, imo. How much does it matter the dimensions and/or placement of the driver? TIA. :)
If you're going with a 2269 why not copy the SUB18 box?Quote:
Originally Posted by gasfan
It is a simple square box nothing special about it, at about 11.25 cubic feet - if you're considering 9' ...
When doing boxes you must consider the ports - number of and length - as this will influence the size (depth) of the box and achievable tuning frequency. Ports also take up baffle space - more than you think.
You don't want to find yourself in a situation where you have to consider bending a port as the length to the desired tuning frequency is longer than the depth of the cabinet.
I think the point is to avoid typical large looking big square boxes... I know I would hate a pair of big square boxes in my listening room.Quote:
Originally Posted by christo
Regarding the tube length, the port tubes can equally go on any side of the six sided cabinet. I have not looked into this, but if the length is too long for the 12" deep side, it could go on the 22" deep side, or even the 8' plus side, so I don't think a curved tube will be needed.
That said, you do need to follow the basic rules about being near adjoining sides or the rear of the cabinet's interior.
Widget
Right. Those dimensions will fit neatly out of the way. It's about space. The Sub18s are just too massive for my space.Quote:
Originally Posted by christo
Did I calculate wrong? Height would be 60", 57" internal. 22X12x57 internal yields 8.7'. So with a bit of eq i should be able to get them down to 22hz with room gain? I have a Driverack 4820 to mate with the 2269s and the U15s.Quote:
Originally Posted by Mr. Widget
No, well, maybe, but I didn't bother multiplying your dimensions. I must have mistaken your 8 cu ft for an 8' tall column.Quote:
Originally Posted by gasfan
Regardless, the answer is essentially the same. You can make them any dimensions that work for you as long as the volume is correct. There are basic rules about standing waves etc., so avoid cubes and simple relationships of even multiples. You don't want a 1' by 2' by 4' interior dimension if you can help it.
Widget
Remember to account for the volume occupied by the port inside the enclosure.
You may have accounted for the following. But l will put the following out there for the uninitiated.
I have not simulated this particular driver.
If you look at the original JBL drawings for the 2245H Subwoofer Project that would be a good starting point to realise a practical box. You could put the woofer on one end of the enclosure or one of the sides. Mounting the port on one end will possibly give you enough port length with three 4 inch ports.
Those ports will use up in the order of 18L of enclosure volume. The woofer volume is about 8L and the bracing can be assumed to 24L. So your gross enclosure volume of say 250L ends up being 50L less of used volume. That leaves 200L of volume remaining behind the woofer.
Then allowing for the fibre glass wadding on the enclosure walls this will add around 5- 10% volume or 20L to the internal volume of THD enclosure. The net enclosure volume might look like 220L. But that’s 30L less than your target volume.
Box losses can also unfortunately impact on your net enclosure volume.
A unity box loss call QL=7 on your simulator assumes a fairly rigid box with no leaks. The rule of thumb is the bigger the enclosure the more it will typically flex, shake or leak and dissipate energy as a loss. However to much bracing will make the box impracticable to lift and move.
So your best option is to oversized the enclosure by 10-15 % and tune the ports according to your modelling for the desired low end F3.
This is just a FYI to take on board after looking at your simulations. It used to do my head in working this out. Simply over volume your box a bit after running your simulation to be on the safe side!
Be careful on the depth of the cabinet - looking at the 2269 specs in the library the depth of the driver is 12.5"Quote:
Originally Posted by gasfan
I hadn't paid attention to that either. It will probably still fit since part of that 12.5" depth will be taken up by the baffle. That said, I would never have the back of a woofer even remotely close to the rear of the cabinet as the reflected midrange (upper bass) will come back through the cone.Quote:
Originally Posted by christo
If this was something I was serious about, I would build a test cabinet before diving in.
Widget
That’s not good for the environment.
Another tree chopped down so you can get it right and then another when your serious. Get real. Where will all the squirrels and the bears go? Even chopping it up and burning in the backyard will confuse your neighbors who will think it’s another lithium Ford EV catching fire.
In addition to post #6, JBL also has a rule that any cab dimension must not be more than three times any other. Moreover, high power drivers must have sufficient clearance behind woofer back vent and rear of enclosure. The latter also applies to vent clearance vs rear of box.
That kind of kills your proposed dimensions, sorry. I think you will have to use one of the usually accepted box ratios (proportions), such as the Golden ratio, the Acoustic ratio, or one of the other such ratios mentioned in Dickason's Loudspeaker Design Cookbook, and in Weems' Designing Building ... Speaker Systems.
The rest of the phrase on the pic is: three times greater than the shortest dimension. (JBL document)
Richard
What would/could the consequence be? The driver on the 22" side 10" up from the bottom, the ports up top.Quote:
Originally Posted by RMC
Did you consider the aesthetics (WAF?) of a 5 foot high box? See the far end of the room. https://cimg0.ibsrv.net/gimg/www.cor...58107c6978.jpg
Here’s a visual perspective of the cabinet you're propsing vs. the SUB18 – not really much difference in size…Quote:
Originally Posted by gasfan
The 2245 is mounted on a 23.5” baffle close to your 22”.