The DIY Guitar Cab Rabbit Hole

[CipherHost]

I really know nothing about cab design, so it has been interesting experimenting with building a cab(s) for my pair of F12-X200s. Cab design can become quite the rabbit hole. I have looked at cab builders, but I can't seem to get my head around spending $500+ for an empty cab. I know there's a lot that goes into building a cab, but at the end of the day, it's an empty wooden box. Excluding my time, my costs for the speakers, wood, and everything else in the 2x12 passive unfinished cab has been less than $400. I would probably end up spending around $600-$700 to complete two nicely finished 1x12 passive cabs designed for the X200s, not retrofitted for them. Maybe I should just buy two Egnater Tweaker112X Extension Cabinets for $500, swap out the speakers, and call it a day. Actually, I have one already, so just $250.

I didn't find much difference between using a completely closed cab and using the port recommended in Celestion's F12-X200 Cabinet Plan (YMMV). I know this because I made a removable port I used in the same cab.

I currently have them in a home built, closed back 2x12. Yes, I'm using two types of wood in the same cab. All the boards are 23/32" thick. I'm not a wood expert, but I think the the short sides and back are pine (30 year old shelving, I'm a cheap bastard), and the long sides and baffle are maple/pine plywood. It looks like crap at this point, but I'm experimenting, so pretty isn't the priority. Everything is snug, but not glued in order to make modifications. The speakers are wired in parallel for a 4 ohm load and I'm pushing it with a PS 170. It's plenty loud.



I've posted two videos below that I found interesting, but a little confusing. Phillip says closed back cabs cut down bass frequency. Alex says open back cabs cancel out low frequencies. WTF? The rabbit hole gets deeper.

The REFORMER 112 in the Barefaced video looks like it has thinner walls than I'm using in my project. That might be why it only weighs 22 lbs. I don't know how much of a difference a 1/2 inch board would make compared to a 3/4 inch board of the same wood type tone wise. The V30 is ~10 lbs by itself, making their cab about 12 lbs. The X200 is ~9 lbs. I find a 21 lb passive cab desirable, if it sounds good.

Phillip McKnight's open vs closed back video:


Alex's Barefaced video:

 

[artzeal]

Not to forget size matters in terms of the resonant frequency. Whether open or closed or ported: knowing/calculating the Theile/Small parameters will show up the response of the low end. I've built a few cabinets in my day (not just for myself), usually because something larger than standard dimensions was required to get an extended low end. The value of a ported cabinet is that you can control the low end frequency of the cabinet by specifying its Helmholz resonance by the size of the port. The value of an open back is that you have sound going out the front and back and bouncing around off various surfaces for a more complex reverberant sound: the value of a closed back is that it blasts you in the the face with a focused beam of sound. Which do you prefer? To each their own. I've had the most call for semi open back cabinets - larger than a port but not wide open for balanced bass and less ambient wash. Too small of an enclosure will sound boxy and screw up the mid response because it can't fulfill the low resonance of the speaker. The wave guide approach of the referenced Barefaced Cabinet makes great sense. Note that the Barefaced has more depth, and therefore more volume and deeper bass than your garden variety narrower cabinet. The back also serves to stiffen the sides, top and bottom. The stiffness - not thickness of the walls is what its all about: and if one can stiffen thinner stock, or design with bracing or support to save weight: good call. Also: the reason some closed backed cabinets impede low end response is if its small and well sealed so it impedes the excursion of the speaker trying to move enough air to reproduce those frequencies. Conversely a cabinet that is too open doesn't contain air movement enough to create a substantial low end cabinet resonance frequency. Can of worms: to be sure, but more fun than most.