u can go to see and check on wikipedia...there is a page for
guitar amplifier..
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A combo amplifier for a guitar contains a normal guitar
amplifier and one to four speakers. A normal guitar amplifier does
not contain speakers, but is able to send the signal to a speaker
cabinet.
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Yes
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For an electric guitar you definitely need an amplifier because
the guitar on its own is pretty quiet.
If you play an acoustic guitar you can use an amplifier to make
your guitar louder and more hearable but you don't have to in order
to record it.
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Yes. An acoustic-electric guitar plugs into an amplifier the
same way a regular electric guitar does.