2x15 cabinet volume

[Austin Duggan]

I apologize in advance if this particular question has been addressed, or if it is too simplistic for this forum. I am not an expert, but need some advice. I will be building a 2x15 bass guitar cabinet. The "recommended enclosure volume" for the eminence deltapro 15a's reads as 57-133 ltr/2-4.7 cu. ft. I've been doing a lot of reading and understand why the volume of my ported enclosure will be so important. That's why I'm confused. If I have read these specs correctly, eminence is saying that a volume of anywhere between 57 to 133 liter airspace is appropriate. First off, this strikes me as rather small, considering the size of most of the 2x15 bass cabinets that I've seen. Also, it seems a bit of a wide range of values for such an important aspect. If 57-133 ltr is the correct volume range for my cabinet, is there a magic number in there somewhere, and if so how might I calculate it. Thankyou.

[Brett]

There is no magic number, just a long scale that shades grey. Look to the 3015 or 3015LF. More actual output in a sensible size cab. The Eminence suggested datatsheets look good. Just choose driver and cab volume and go.

[Austin Duggan]

Thankyou Brett. I had actually planned on using the 3015's, due to the impressive frequency response, and the light weight of the neodymium magnets. But I'd read so many forums of people raving about the deltas. I'll again reconsider. Another question. How do I calculate the loss of air volume from the handles, speaker baskets, etc?

[Austin Duggan]

I actually have another two questions. How do I calculate the size of the ports? And is the "golden ratio" of 1:1.6:0.6 as important as people say it is?

[Brett]

Originally posted by Austin Duggan
I actually have another two questions. How do I calculate the size of the ports? And is the "golden ratio" of 1:1.6:0.6 as important as people say it is?

First q: the same way as with a hi fi speaker. Get the T/S, decide on a box size and f3 and juggle values until you get something you like. I use WinISD to get a SBB4 size box and ports, then plug that into Unibox and tweak. Both programs are free. Google them.

Q2: golden ratios are nowhere near as important as made out, especially for a bass cab. More important is the form factor, ie can you move it and get it in/out of your vehicle, up staircases and through small doorways.

PS: design it with the right driver and you may only need one. Volume displacement determines SPL, not just cone size or number of them.

[sreten]

Hi,

I'd recommend splitting it into to two cabinets for a self build.
The advantages should be obvious.

/sreten.

[Brett]

Originally posted by sreten
Hi,

I'd recommend splitting it into to two cabinets for a self build.
The advantages should be obvious.

/sreten.

I couldn't agree more.

[Austin Duggan]

Thanks for the recommendations. I've considered separating the chambers, but not making two separate boxes, as portability is never an issue for me.

[Brett]

Originally posted by Austin Duggan
Thanks for the recommendations. I've considered separating the chambers, but not making two separate boxes, as portability is never an issue for me.

If it's in a fixed location, or seldom moved, kepp it all as one chamber and brace the hell out of it to reduce panel resonances.