Guitarhacker
You know.... While it's easier to buy something off the floor of a store, it's also a ton of fun to build something.
 
In the day, I have built or been involved in more than one speaker cab build. The interesting thing is store bought speakers come in all sizes and dimensions, so I'm thinking it's pretty hard to go wrong on a guitar cab design/build. Build it to the size you want for the number and size of the speakers you plan to load it with.
 
the main thing is to use good quality wood/plywood, and brace it and glue it so it can survive the bumps and drops and won't start rattling and buzzing over time.Nothing sux like a buzzing cab on those resonate low notes.
 
I was partial to EV 12" speakers. They are highly efficient.... giving a nice SPL for a given wattage input, and crisp and clean sounding with a nice bright sound to them. Power handling is not as critical with a good speaker like the EV, but getting a clean bright efficient sound is. I had EV's in a number of my rigs and in the PA too.

From time to time I have wanted to build a guitar cab. If/when I do, I will build the EV ported cab (plans can be found with a search) designed for the EVM 12L" speaker.
 
My first cab (I had been using the cab/speaker from my old Yamaha combo amp with a JBL in it) was a 4x12 used Carvin. They are easy to find used, built well and very inexpensive. I found one with 4 working 12" speakers for $200. It was inexpesnive enough that I could not make one for less (with speakers).

Whether a speaker or speakers move in or out on the first pulse is irrelevant once you are past that first move of the cone.... it then simply becomes a note of music or a sound.   Once that cone is in motion, it doesn't make a hill of beans what direction it moved first.
 
Phase is critical with multiple speakers since you do want them all working together as a team. Swapping the polarity on the leads does nothing that is audibly different since the sound you are hearing is AC.
 
If there is a difference, I believe it would be psychological to the ear of the person who knows the polarity is different.... kind of like how your car seems to run better after it's been washed and waxed.

Well I am glad I started his thread because now after all the input I am not sure I want to take this on.
Especially if I were to do two speakers in a cab.
Phase etc.
hmmm

Anytime you use more than one speaker you should check phase.
 
Anytime you use more than one amp you should do the same.
 
It's kid stuff... don't let that persuade you to not have some fun.

Yes, my JBL speakers are so old they are a negative system. But anyone who tells me that you can not hear the difference whether the speaker is moving out or in with the system to me is well - just plain wrong. I think it does make a difference but each to their own. (at least it does to me whether the speaker moves out with first punch or not.)
 
Two speakers are not a worry at all, hook them up for 4 ohms and in parallel. It's the 4 speaker cabinets in series and parallel (to get 8 ohms instead of 4 depending on the ohms of the speaker in the first place) that end up having 2 speakers move out and 2 speakers moving in with first punch (at least to me wired that way like well about all of them are wired that way. (because series means positive to negative lead of a speaker and parallel means positive to positive of the speaker to the input jack). But then there are 16ohm speakers and all of that so perhaps all the speakers in a 4 speaker cabinet are moving all out at first punch also.)
 
 

 
But think of all the fun building cabinets designed by yourself. (and perhaps headaches)
 
And I did not know that about the convention back when of the industry doing the connections on the speakers that way. I thought someone was having a really bad day making speakers or something like that. Well, still learning something even now.
What kind of idea was that in the industry??? Goofy to me.
 
And in this context, I am not talking about very loud re-production, just the normal loudness in a small or medium venue of re-production. In any case the music shall be probably played on.