Confusion about AC and DC concerning headphones/Amplifiers

[N3XED]

So I'm rather confused about how AC and DC operates in headphone amplifiers and headphones. From what I've gathered, headphones and speakers use Alternating currents (amps) and not DC. But then how does DC comes into play? Is AC carried "through" DC? Why do we measure headphone output power by volts (or volts RMS) or milliwatts instead of milliamps or something of that nature? I can wrap my head around everything else.. But not this one dilemma


P.S Idm a complex answer!

 

[71 dB]

So I'm rather confused about how AC and DC operates in headphone amplifiers and headphones. From what I've gathered, headphones and speakers use Alternating currents (amps) and not DC. But then how does DC comes into play? Is AC carried "through" DC? Why do we measure headphone output power by volts (or volts RMS) or milliwatts instead of milliamps or something of that nature? I can wrap my head around everything else.. But not this one dilemma


P.S Idm a complex answer!

Electric power is current times voltage. DC means you have steady voltage and current. AC means they alternate at say 60 Hz. Current can change depending on load, so talking about current is misleading.

 

[N3XED]

Electric power is current times voltage. DC means you have steady voltage and current. AC means they alternate at say 60 Hz. Current can change depending on load, so talking about current is misleading.

I do know about the current changing based on voltage! Well that much at least. But you didn't really answer the entirety of my question. Do headphone amps use DC and then produce AC out of the headphone jack? Or something similar?

 

[sander99]

I do know about the current changing based on voltage! Well that much at least. But you didn't really answer the entirety of my question. Do headphone amps use DC and then produce AC out of the headphone jack? Or something similar?

You are mixing up things. One thing is how an amplifier gets its power. For example from a battery (DC) or from the (built in or external) power supply. A power supply generally takes in AC from your wall outlet and supplies the actual amp with a DC voltage.
The other thing is what the amp outputs at the speaker terminals or the headphone jack. And that is of course the amplified input signal.
I don't think you should say an amp produces AC out of the headphone jack, a signal generally is a complex thing containing different and changing frequencies, AC power is just a constant sine at one frequency.

 

[71 dB]

I do know about the current changing based on voltage! Well that much at least. But you didn't really answer the entirety of my question. Do headphone amps use DC and then produce AC out of the headphone jack? Or something similar?

Sorry about my very bad quick answer I made just seconds before leaving home!

Headphone amps can be AC or DC powered. Regardless of which one, the power source generates DC voltage(s), for example plus and minus 5 volts for the amp to operate and it uses it to output music, which is kind of "AC" if you will of course (various frequencies).

This is a simple thing, but surprisingly difficult to explain, maybe because this is the first time I am ever explaining this to anyone!

 

[N3XED]

I do know about the current changing based on voltage! Well that much at least. But you didn't really answer the entirety of my question. Do headphone amps use DC and then produce AC out of the headphone jack? Or something similar?

That makes sense. I actually forgot about source input current. So you get something like AC from the wall the PSU converts that into DC. Then through the countless resistors capacitors, amplifiers it finally makes it out as AC. Or in this case a sine wave?

 

[N3XED]

You are mixing up things. One thing is how an amplifier gets its power. For example from a battery (DC) or from the (built in or external) power supply. A power supply generally takes in AC from your wall outlet and supplies the actual amp with a DC voltage.
The other thing is what the amp outputs at the speaker terminals or the headphone jack. And that is of course the amplified input signal.
I don't think you should say an amp produces AC out of the headphone jack, a signal generally is a complex thing containing different and changing frequencies, AC power is just a constant sine at one frequency.

Right I can get behind that. So basically the internals of the amp function as DC, and for the output we say it's AC because of the *similarities* between it an a sine wave?

 

[sander99]

Right I can get behind that. So basically the internals of the amp function as DC, and for the output we say it's AC because of the *similarities* between it an a sine wave?

From:
https://en.wikipedia.org/wiki/Alternating_current

From this I take it that strictly speaking alternate current really means a constant sine wave.
A more flexible interpretation could be simply alternating between positive and negative in whatever pattern or form, in that sense an audio signal would fit the description.

But I sense that in fact you want to know something else, like how does an amplifier work, or how do headphones work?
Maybe someone here knows a website that explains the basic concepts in a simple way?

 

[ctjacks336]

This is all still so confusing to me. I have been into the hobby for about 3 years now and I am getting into different power supplies,cords and what not. Very confused about AC/DC also even after reading this post which everyone did amazing at explaining. So Thankyou,but I still need some help. I have the geshelli lab j2,which is a 12v power supply. It is being power by the ifi silent ipower2 12v power supply. Is this ok? Nothing has started popping so I figure it is fine. Also was lucky to grab the Schiit piety and would like to use the same power supply on that as well. This is what it uses-

• Protection: Standard failsafe DC power input and muting relay
• Power supply: “Wall wart”-style 14-16VAC transformer, 1A

If I got the 15 v ifi would it work? Thanks and happy holidays

 

[SoundAndMotion]

If I got the 15 v ifi would it work? Thanks and happy holidays

No, according to Schiit.

According to the manual: "Magni’s wall-wart is AC output. Most AC adapters are DC output, and will not work with Magni. Magni works with a 14-16VAC, 1-2A output adapter only." Didn't it come with a manual?

 

[ctjacks336]

No, according to Schiit.

According to the manual: "Magni’s wall-wart is AC output. Most AC adapters are DC output, and will not work with Magni. Magni works with a 14-16VAC, 1-2A output adapter only." Didn't it come with a manual?

Thanks so much. I don’t receive the Schiit amp until Friday.

 

[Mark200]

This is all still so confusing to me. I have been into the hobby for about 3 years now and I am getting into different power supplies,cords and what not. Very confused about AC/DC also even after reading this post which everyone did amazing at explaining. So Thankyou,but I still need some help. I have the geshelli lab j2,which is a 12v power supply. It is being power by the ifi silent ipower2 12v power supply. Is this ok? Nothing has started popping so I figure it is fine. Also was lucky to grab the Schiit piety and would like to use the same power supply on that as well. This is what it uses-

• Protection: Standard failsafe DC power input and muting relay
• Power supply: “Wall wart”-style 14-16VAC transformer, 1A

If I got the 15 v ifi would it work? Thanks and happy holidays

It is not a good idea to use an external power supply brick other than what the manufacturer specifies. Some devices can operate fine using a range of DC voltages using different external brick power supplies (and may allow the audio component to output more power on the backend line level or speaker level if the DC voltage is higher), but that is not the case for all of them. The component manufacturer will tell you what your options are (if any) for external power supply bricks.

Also, the DC voltage that is output by the external power supply brick into the electrical audio component requires a certain amount of amperage, and not all external power supply bricks supply the same amperage even if the DC voltage is the same.