Cab Dimensions set---how to decide on speaker configuration?

[chriscrob]

I have a sealed cab that I plan on re-purposing for use with a bass. From what I've read it will take a good bit of figuring and reconfiguring to get it to sound good.

I'm posting this because I haven't found many resources online that are of any help to someone starting with a specific cabinet and willing to be flexible about speaker configurations. The current configuration is 4x12 so unless I did a 2x12 (and sealed the other two holes) or a 4x10 (I would try real hard to find a way to adapt the current baffle before I removed it) I am probably going to have to replace the baffle anyway (which is going to be a chore).

The cabinets internal dimensions are 25x25x13.125. (around 4.74 cubic feet - - the real number is actually a little bit lower because of a 5.125"x.75" brace and 4 10" round .625" thick raised wooden blocks behind each speaker.)

My questions are:
1. given those dimensions what speaker combination would yield the best result?
2. how much does the shape of the volume matter vs total volume---the cab is not very deep---is there some way to determine which speakers will perform best with the shape of this cab? (None of the calculators I've been looking at deal with the shape of the cabinet---they just find the volume from the speakers stats)
3. Is there any reason to port this cabinet?


My ideal (and possibly workable I think) cab would be a 15" on the bottom and two 8"s on top (i.e. the cabinet would be divided into two cabinets) for biamping with my 800rb. (With 1/2 an inch of wood between them I could get a 15.5x25x13.125 (2.94 cubic feet---not sure if there are 15"s that will work well in this small of a space) on the bottom and 9x25x13.125 (1.7 cubic feet) on top. If not that I would go with 1x18, 2x12, 4x10 and 1x15 (in that order) if given the choice...but I'm willing to do whatever will yield the best results. I just don't really know how to figure that out.

I understand that this sort of thing is not for the faint of heart and may or may not yield great results...but I think I'll enjoy the process either way.

 

[will33]

Don't put the cart before the horse.

Figure out the cabinets internal volume first. External doesn't matter, it's the internal space the drivers have to work with. Then start looking at possible driver compliments that will do what you want in there.

Are you the guy who posted a thread about putting bass speakers in a guitar sealed 412? I noticed that thread pass by, but figured there'd be enough people saying "get a bass cab".

As a speaker building lesson and possible workable result....fine. I'd say lets sort of keep it that way, learn a bunch along the way, stick with inexpensive drivers, get a result that sort of works, then apply all that knowledge gained to arrive at the conclusion of "meh....get a bass cab".


No offense....just sayin'. I learned a lot by diving headlong into it too. If you want to do it, take the measurements and start figuring. This would be a good place to start. Invalid Link Removed

Search up " WinISD Pro Alpha" and familiarize yourself with that as well.

 

[chriscrob]

Yeah, that was me. I think everybody people just waited for someone else to tell me to get a bass cabinet...but nobody did. So here I am, lol. But I sort of knew what I was getting into. I think if I can be patient before I start ordering drivers I should be able to make something work. Those measurements were internal...the cab is exactly 25"x25" inside and 13.125" deep---I have yet to do the math to remove the volume displaced by the wood inside though (some of which will be changed if I change the baffle.) The other dimensions mentioned were based on a possible division of those internal measurements.

That link looks awesome! I've got a lot of reading to do...but I had to get the ball rolling because I can't buy drivers until I sell the ones that came loaded in the cab. Plus, this was the only of the few cabs I was willing to get available in Atlanta right now and I couldn't possibly wait---even though it won't be playable as a bass cab for awhile now....

Thanks! I really appreciate it!

 

[will33]

4.75 cu.ft. gross. Says 212's or 410's that can give good bass. Or an 8ohm sealed cab using SVT replacements. The 4 in a square positioning isn't the best idea when starting from scratch, but folks do sell them like that everyday. The shallow depth could possibly give some cancellations in the wrong places but it's not all that far out of line. Happy reading.

 

[chriscrob]

2x12 is appealing because it would be the least destructive option. I had a beautiful epifani t212 that still makes me a little misty-eyed when I think about the fact that I let it go...

I was hoping to use Carvin speakers because they offer a good blend of quality and price...but using the diyaudio box calculator I come up with [Invalid or Expired Link Removed] speakers wanting a 2.8 cubic feet of space...I think I read somewhere that making calculations for each speaker and then doubling it was the best way to find the number for multiple speakers...Adding in speaker volume would make the cab too small by nearly half a cubic foot. I can't add volume but I can take it away.

I'm not really sure what speakers to look at elsewhere. I've been to usspeaker---the beta 12a has a recommended volume between .9 and 1.25 cu. ft---if adding them together is the right way to find the number for multiple speakers I could theoretically use 4x12"s? (of course the diy calculator yields 3.11 cu. ft.)

The PSC 18-8 returns 3.59 cu ft. and the PS 15C-8 returns 3.76 although it seems like the depth would be more of an issue with a bigger speaker.


Reading the recently revived "mixed speakers" thread tempted me to make it as similar to my 1x15 as possible (even if that meant making the working volume of this cab smaller to emulate the other cab and getting identical drivers suited for that form factor---not sure the exact internal dimensions on that cab, I need to measure it).

After reading most of the links posted---I understand that there is a whole lot I don't understand. I mostly need to figure out what size speakers I'm going to be using so I can truly begin the search for drivers.