Question for experienced cab builders

[TussinBot.]

a friend of mine who builds cabs or has in the past gave me this empty cab for free and I am wondering if it is worth it to throw speakers in. I don't know a lot about the science behind cab building and havent played any of his cabs so I'd prefer to ask a larger community of experienced builders. Its a 15" 8" and horn set up with 2 ports. 35 3/4" tall x 22 1/2" wide x 16 1/2" deep. ports are 3 1/2" in diameter. and its all built out of 3/4" plywood. are these dimensions on? if so, what would you guys throw in here?

Thanks for the help

[dhomer]

Measures out to about a 6cu.ft. box, which is large by todays standards. Probably better suited for an 18/mid configuration. Two 15' Kappalites might work here, but you would have to figure space for ports and a suitable midrange - see the fEarful threads... In any case I'd figure out a way to take out the baffle and make a new one to fit what you'd need. To get more specific than that someone would have to spend a few hours w/Win ISD and plugging in different drivers

[Petebass]

How about using one Kapalite 3015LF, but using some extruded polystyrene inside the cab to bring the internal volume down to 4cu.ft without adding weight.

Or find a driver that likes 6 cu.ft. Say an Eminence Basslite C2515 or Delta 15 LFA.

Add an alpha 8 for mids, the one with the sealed back. Find a horn flare that fits the cutout and add an appropriate tweeter. all you need then is a 3 way crossover and bingo.

[rpsands]

Need bigger ports for a 3015LF. The Basslite C2515 would be decent, but realistically would want more port frontage also.

The 3015LF works fine in 6cf. Just fine. That said...

That cab appears to be made of OSB or some other chipboard like substance with no bracing. Throw it out.

[Petebass]

There is plenty of room on that front baffle for appropriate porting. And chipboard can last a very long time if you don't get it wet and look after it. Don't be such a party pooper.

[AlexanderB]

Well the guy says it is plywood...

Port surface needs to be bigger if you want to take advantage of the large internal volume. (Getting lots of loud, deep bass requires rather deep cabinet tuning = long ducts = large cross section area to avoid turbulence at high SPL.)

Any decent capacity 15" woofer will move enough air to make those existing ports huff, puff and whistle.
Rule-of-thumb is generally not a good way of doing things, but for generic woofer applications this works:
For every inch of speaker diameter, one centimeter of (circular) duct diameter is a good start.
A 15" woofer requires at least 15 cm diameter of tube diameter if a single bass port is used.

I normally use simulations software to find air speed, though...

/Alexander

[Bassmec]

Originally Posted by Petebass

How about using one Kapalite 3015LF, but using some extruded polystyrene inside the cab to bring the internal volume down to 4cu.ft without adding weight.

Or find a driver that likes 6 cu.ft. Say an Eminence Basslite C2515 or Delta 15 LFA.

Add an alpha 8 for mids, the one with the sealed back. Find a horn flare that fits the cutout and add an appropriate tweeter. all you need then is a 3 way crossover and bingo.

+Of course You can add another port and try various port tube lengths till you have something that really works, after all you have loads of space on the baffle.

[TussinBot.]

Thanks for the responses guys. Still trying to figure out which direction id like to head in...been busy with work so havent had a lot of time to screw around with it yet. avatarspeakers sells the delta 15 lf for 68 plus shipping, may look into that. A guy at a speaker store near my house said I could make it into a 215 and just double the ports i have but im not sure how that'll turn out.

[JimmyM]

Originally Posted by TussinBot.

Thanks for the responses guys. Still trying to figure out which direction id like to head in...been busy with work so havent had a lot of time to screw around with it yet. avatarspeakers sells the delta 15 lf for 68 plus shipping, may look into that. A guy at a speaker store near my house said I could make it into a 215 and just double the ports i have but im not sure how that'll turn out.

nah, it's built for a 3-way. 2 and 3-ways are an excellent way to go for bass because of the dispersion being better. i'd just make the ports bigger like rp says and try the 3015lf and a good 8" mid cone. just ignore the "throw it out" comment he added hey, it's a decent enough cab and with a little work it could turn out excellent.

[jazzblade]

That cab appears to be made of OSB or some other chipboard like substance with no bracing. Throw it out

.


To me I think that is padding your seeing not chip board or OSB in the back. Bracing should be added I would thin but that is easy.

I like what Jimmy said. Give it a try if its not too expensive (and you don't mind moving it because it is big!)

Maybe Bill will com in and have some ideas??


Good Luck. let us know what you plans are going forward.

[billfitzmaurice]

Originally Posted by jazzblade

.


To me I think that is padding your seeing not chip board or OSB in the back. Bracing should be added I would thin but that is easy.

I like what Jimmy said. Give it a try if its not too expensive (and you don't mind moving it because it is big!)

Maybe Bill will com in and have some ideas??

The dimensions are compatible with the 3015LF, but it would have to be re-ported, as they're too small, and braced, and for all the work involved you could do a fEarful 15/8 from scratch and lop off 15 pounds using 1/2" plywood. But if the weight isn't an issue you could use it.

[Petebass]

Originally Posted by TussinBot.

Thanks for the responses guys. Still trying to figure out which direction id like to head in...been busy with work so havent had a lot of time to screw around with it yet. avatarspeakers sells the delta 15 lf for 68 plus shipping, may look into that. A guy at a speaker store near my house said I could make it into a 215 and just double the ports i have but im not sure how that'll turn out.

That Delta 15LFA works best in a BIG enclosure, like 9cu.ft per driver. You could probably get a decent result as a 1x15 3-way in that cab, but I'd look at another driver if you want to go for a 2x15.