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raeggis

Ac or Dc to speakers?

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Do the speakers get direct current or alternating current from amplifier?

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AC. DC can/will damage speakers if of significant amplitude or duration. Sometimes a small battery is used to test what polarity makes the cone move forward and backward.

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3 hours ago, raeggis said:

Do the speakers get direct current or alternating current from amplifier?

 

 

The speakers are ONLY supposed to get Alternating Current at all times. If you turn your amp up to loud, you can Clip the amplifier.  Clipping the Amplifier means you have run out of headroom and instead of a round wave of Alternating Current, the tops and bottoms of the wave are Clipped off meaning they are flat, straight, or cut off. These flat spots are DC, both positive at the top of the wave and Negative voltage at the bottom of the wave. These flat spots of Direct Current are exactly what heats up your voice coil and can blow your speakers. A lot of good amps starting around 1980 had two RED L.E.D.'s, one for each stereo channel and they would start to light up when you started running your amp into Clipping. Kind of like an idiot light on your car!  ...

 

Roger

 

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10 minutes ago, twistedcrankcammer said:

 

 

The speakers are ONLY supposed to get Alternating Current at all times. If you turn your amp up to loud, you can Clip the amplifier.  Clipping the Amplifier means you have run out of headroom and instead of a round wave of Alternating Current, the tops and bottoms of the wave are Clipped off meaning they are flat, straight, or cut off. These flat spots are DC, both positive at the top of the wave and Negative voltage at the bottom of the wave. These flat spots of Direct Current are exactly what heats up your voice coil and can blow your speakers. A lot of good amps starting around 1980 had two RED L.E.D.'s, one for each stereo channel and they would start to light up when you started running your amp into Clipping. Kind of like an idiot light on your car!  ...

 

Roger

\

That is a good explanation and one which should behoove one.

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A clipped sine wave does not have a dc component.  I would be more concerned with a SS amp which has a very high dc offset.  The latter is easily measured.

 

 

Maynard

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15 hours ago, raeggis said:

Do the speakers get direct current or alternating current from amplifier?

Music is an AC signal. There should be no DC on your speaker in theory. As Maynard said SS amps are the ones you have to check for DC offset being that most tube amplifiers do not have any dc because they use a transformer that stops DC from reaching your speakers. In reality there are very few SS amplifiers have zero DC on speakers. Optimally you check for 50mv or less. I would not worry if one of my SS amps has 100mv or less. Some receivers and amps do not have adjustment for dc offset so less than 100mv is acceptable . If you have too much dc on a speaker you risk your speaker coils heating up and destroying themselves. Think electric stove. 

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9 hours ago, henry4841 said:

Music is an AC signal. There should be no DC on your speaker in theory. As Maynard said SS amps are the ones you have to check for DC offset being that most tube amplifiers do not have any dc because they use a transformer that stops DC from reaching your speakers. In reality there are very few SS amplifiers have zero DC on speakers. Optimally you check for 50mv or less. I would not worry if one of my SS amps has 100mv or less. Some receivers and amps do not have adjustment for dc offset so less than 100mv is acceptable . If you have too much dc on a speaker you risk your speaker coils heating up and destroying themselves. Think electric stove. 

 

 

My Nakamichi amps have a anti DC protection circuit to shut the amps down if to much DC output is present. The Adcom GFA-565, 300 watt mono blocks I ran way back when did not and roached a few woofers as they went bad.

 

Roger

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