Frequency range is the low to high value that you can hear typically measured in Hz cycles. The human ear can hear 20hz to 20Khz. Instruments fall into a relative hz cycle range (audio frequency) that they can reproduce; certain instruments the hz cycle output (loudness of a particular tone) might be emphasized to support the instrument.
Zytrax Tech Stuff - audio introduction, frequencies of 10 octaves, frequencies of common sounds and instruments, table listing frequency ranges, overtones and undertones for many instruments. American Standard Pitch, Internation Standard Pitch, equal tempering and equal temperment.
www.zytrax.com
Guitar speakers support the guitar audio range frequency and bass heads support a bass's audio frequency response needs. So as I read above you are trying to drive a guitar speaker with a bass head for use with keyboards and vocals. They don't match up, so the results will be sketchy at best and if by some miracle it actually turns out to sound good it is only because you got lucky. I would be hesitant to build a speaker "system" with components that don't match well; your likelihood for success is low. I'd rather do the homework, understand frequency audio range, frequency boost, cabinet structure, quality of components and make an educated design spec. It is somewhat comparable to people who complain that their luxury car doesn't take cornering at fast speeds like their sports car. That's because the suspension on the sports car is vastly different than the suspension on a luxury car. They all have the same components (springs, shocks/struts, ball joints, etc.) but each one is built for a different purposes; the sports car can corner better at high speed because it is stiffer but rides rougher where the luxury car doesn't handle cornering as well but has a much smoother ride. A comparable theory goes toward speaker cabinet building. There is a folded horn design, bass reflex, sealed, etc.. Each one serves a different purpose and each one will yield different results audio results. Also, what should the size of the port be, 2", 3", 4"; how long should the tube be that is inserted in the port, 2", 6", 9"? And this is just the speaker cabinet design. Then there are the components: which type of speaker, what frequency response, what size speakers? So many variables. I've built a few dozen speakers cabinets and sourced components for them over the years; it's indeed a calculated science. Typically the type of speaker cabinet (enclosure) needed and its related specs (port size, tube size, if ported), type of enclosure to be assembled, cubic feet of the enclosure needed to support the speaker is based on the speaker to be used in the system and not the other way around.
This document may help you:
Again, based on what you're doing, bass head into a guitar speaker, and playing keyboards and vocals, the odds of miraculously getting it right are against you. Good Luck....
