EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: BravoV on September 04, 2013, 06:31:57 am
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Ok, I understand cap can not pass DC (AC only), thats it, but this is really a noob question, what is the pro & con on each with/without the cap for driving a speaker ?
Is it for cheaper cost by reducing just one cap ? I'm "assuming" its not just that simple right ? ???
TIA
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An amplifier with a single supply rail usually has the output biased at half the supply with no signal. Your audio signal then moves this voltage up (towards V+) and down (towards 0V). The output capacitor removes the DC offset so the speaker only sees the AC (audio) portion.
An amplifier with split (+/-) rails has the output near 0V with no signal. Your audio signal then moves this voltage up (towards V+) and down (towards V-). You don't need the output capacitor in this case as there is no DC potential across the speaker.
Make sense?
EDIT: There are also other amplifier topologies (bridge, etc) that work differently. I've kept it simple for this reply.
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Ok, I understand cap can not pass DC (AC only), thats it, but this is really a noob question, what is the pro & con on each with/without the cap for driving a speaker ?
With cap- Pro: No need of output protection. In case of short of the output devices, no DC current at the output to burn your speakers.
Con: Reduced damping factor at low Audio frequencies and inherent phase shift.
Without cap- Precisely the oposite. Need output protection (relay). And no reduction of DF, nor introduction of phase shift at the lower end of the audio spectrum.