I play a cajon in a band with a few guys. Some gigs are in a pub and some are outdoors and it can be difficult to be heard. Any suggestions on what type of sound equipment to buy so that it could be easily heard? An amp or a PA?
Last time I saw a cajon live the player brought his own Shure Beta 91A.. It's a flat box-shaped kick mic that fits perfectly inside a cajon, it sounded great but it's not the cheapest option. It probably helped that he stressed to the soundie that he wanted the bass frequencies exaggerated.
I have a cajon at home and when I record it I use my beta 56a right in the sound hole and get pretty good results. Definitely look at mics designed for kicks or toms.
I've always used a Sure Sm57 with the tip of the mic just inside the sound hole. It doesn't cause feedback and picks up the nuances pretty well. I also play with brushes on some songs and it picks that up too. The mic is then put straight through the PA and sounds great. I'm thinking of trying a Bass amp to have more control over my sound levels as often I can't hear myself well if it's a loud gig and the pa speakers are forward.
Piezo clip on pickup maybe. I've heard they can be used on almost any instrument and they are really cheap.
A very practical way to mic a cajón is with a boundary microphone. You don't need any mic stand, gooseneck support etc., just put the mic in the box and you're set!
For amplification, a PA is definitely the best thing; certainly if it's also used for other instruments or vocals. If there's no PA, the next best option I'd consider would be to use a bass amp. Acoustic bass amps often have some kind of extra input, and even in a normal electric-bass amps it is possible to achieve this with a small mixing console (best used in the effects loop).
Only if there is no bass amp would I consider it worthwhile to use a dedicated amp for the cajón alone. Make sure it is a universal-purpose / acoustic-guitar amp, electric guitar amps are very badly suited for percussion. AER, Schertler and Fishman are three brands you should check out. Alternatively, a single general-purpose fullrange PA box will also do the trick, though you'll probably need an extra mic preamp (or small mixing console) then.
I have used a regular SM58 connected to the mic input on a Roland AC60. AC30 should work fine too.
When I have to, I usually mic it with a kick mic near the hole and an sm57 on the front, to have a mic for the very low sounds and another for the rest. I really think this combination can't fail.
Hope this helps!