Building a 2X12 cab - opinions needed on design

brewhound

Member
Messages
80
I’m a noob to cabs, but I want to build my own 2X12 anyway. I know that by the time I factor in the time it takes, any economy from doing it myself will be lost, but this way it’s a lot easier to fly under the wife’s radar until I have to buy the speakers for it at the end. Plus, it’ll be fun.

Anyway, I want to build a front ported / detuned style cab – it’ll be closed back, fairly deep, and have a couple pretty large ports. I plan on making it about 14 inches deep, but I’m also considering 16 inches for convenience because I can get 0.75 X 16 inch wide nice edge-glued pine boards at Lowes that I think would make excellent top, bottom & side panels. The baffle and back will be 0.75 inch thick birch plywood.

I’ve come up with two different baffle designs, shown below. One is based loosely on the Freda 2X12, and the other is something I came up with using a 24 X 24 square that’s intended to be sort of a mini-4X12. The larger circles shown are the speaker perimeters (cutouts will be slightly smaller diameter), and the smaller holes are open ports. The surface area of the rectangular ports is approximately equal to the area of the 6 inch diameter circles for the square design. I used 6 inches because that’s the largest port tube that parts express sells to make a nice finished appearance (I would just cut off most of the “tube”). For the rectangular ports I would just wrap the tolex.

I’m looking for opinions on what possible sound differences there would be between these designs assuming the cab volumes are roughly equal. I’m curious about whether speaker arrangement and port shape makes much difference in terms of sound dispersion and spread. I would like full, punchy sound but with a nice wide, relatively even soundstage in front of the cab rather than the directional beam of a pure closed-back design. I want it to sound “big”.

I’m thinking of loading the cab with Eminence GB128’s because I like the greenback sound but could use a little more power, plus the price is great. I’ll be using this cab with my 50 watt Peavey Valveking so I need 16 ohm total. I plan on adding a Marshall-flavored head in the future. I play 80’s-style metal and classic rock.
2X12-baffle_1.png


2X12-baffle_2.png
 

gooma

Member
Messages
450
Glad to see your going to have a shot at building one yourself, good for you!!:BEER

I think the top design will have more low end due to the positioin of the ports, speakers and shape of the box.

Kevin Oconnor has a great book on quite a few dfferent designs too so that may be worth a look. I cant remember the name of it off the top of my head, do a google search for Kevin Oconnor`s London Power and something should show up.

If you have enough materials on hand you could even try both of those baffle designs and see which you like best.

Good luck
Brad
 

CitizenCain

Member
Messages
4,819
I'm interested in the responses you get on this because I've been thinking along these same lines myself. Actually, my current plan is to get a Lopoline 2x12 diagonal cab, which is a 24x24x14 closed back cab, and run one speaker in it for a detuned effect. Oddly enough, the speaker I have for it is a Emi GB12 :D This is very close to your square cab design.

It'll go under a JTM45 clone head.

2x12diagbaffle.JPG
 

bosstone

Member
Messages
3,396
O'Connor's book is "DYI Speaker Cabinets for Musecal Instrument Applicatons".
It has lots of info on speakers, cabinets and sound in general, plus all the dimensions and building methods for a wide range of speakers. I built a single 12" detuned cab thinking I would build a 2 X 12" cab one day. Now, I can see that with that design, I don't have a need for a second speaker.
 

Axeplyr

Platinum Supporting Member
Messages
2,279
I built a 2x12 cab a couple of years ago using 3/4" birch ply all around. The cab looked great but did not sound great! After doing a bit of research, I discovered that I had overbuilt the baffle. I cut grooves in the four pieces of wood (top, bottom, sides) that mate up to the baffleboard. That, and the use of 3/4" baffleboard, resulted in an extremely stiff, constricted sound.

In the end, the cab could have fallen off a cliff and not sustained damage. Unfortunately, since I built the baffleboard into the cab, there was no fix for the problem. guess I could have jigsawed it out of the cab, but I digress.

My advice from this experience is to go easy on the baffleboard. Consider using 1/2" ply instead, and don't overdo the coupling to the adjacent cabinet structure. You want the cab to resonate. In fact, consider 5/8" ply for the cab and 1/2" for the baffleboard.
 

brewhound

Member
Messages
80
Thanks for the replies.

I've heard about Kevin O'Connor's book, but I haven't checked it out yet. What I've heard is that if you follow his design you get a great cab that is very large. I thought I would borrow from some designs where others have already made some successful compromises for the sake of portability.

Also, I realize that for my situation a good detuned 1X12 would be plenty, and I may get back to that before I actually start building, but 2X12's just seem cooler.
 




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