Understanding amp output

[Hyunato]

Hello everyone,

 

I've been researching headphones and amps and there's a lot of information out there.  So much so, that I can't find the specific answer to my question. Probably because of my lack of understanding electricity in general. 

That's why I wanted to ask my specific question on a forum like this in the hopes I can finally sleep at night.

 

My example: I'm interested in the Sennheiser GSX 1000 amp/dac combo. I want to know how far this amp can take me if I want to buy a higher end headphone in the future. For now I'm interested in the Sennheiser HD 569 closed back headphone to pair with this amp. With, like I said, maybe a higher end headphone in the future. 

 

I've got a fairly good grasp on the concept of impedance and sensitivity. My next question is if I know the ohms and sensitivity of a headphone, how does that compare to the power output of the amp? 

The specs of the GSX say max output: 1 V RMS @ 32 ohms. I have no idea what this means. The definition of RMS is as far as I've come so far. How does this translate back to 23 ohms and 115 sensitivity? 

 

I'm dying to know, thanks in advance! 

[mahyar]

rms is short for root mean square voltage or effective voltage of a sine wave

[Tigerleon]

2 hours ago, Hyunato said:

Hello everyone,

 

I've been researching headphones and amps and there's a lot of information out there.  So much so, that I can't find the specific answer to my question. Probably because of my lack of understanding electricity in general. 

That's why I wanted to ask my specific question on a forum like this in the hopes I can finally sleep at night.

 

My example: I'm interested in the Sennheiser GSX 1000 amp/dac combo. I want to know how far this amp can take me if I want to buy a higher end headphone in the future. For now I'm interested in the Sennheiser HD 569 closed back headphone to pair with this amp. With, like I said, maybe a higher end headphone in the future. 

 

I've got a fairly good grasp on the concept of impedance and sensitivity. My next question is if I know the ohms and sensitivity of a headphone, how does that compare to the power output of the amp? 

The specs of the GSX say max output: 1 V RMS @ 32 ohms. I have no idea what this means. The definition of RMS is as far as I've come so far. How does this translate back to 23 ohms and 115 sensitivity? 

 

I'm dying to know, thanks in advance! 

If you want a DAC/amp which will be great for higher end headphones and were you've got sofware for it then get the soundblaster X3 or G6.

[Derkoli]

2 hours ago, Hyunato said:

Hello everyone,

 

I've been researching headphones and amps and there's a lot of information out there.  So much so, that I can't find the specific answer to my question. Probably because of my lack of understanding electricity in general. 

That's why I wanted to ask my specific question on a forum like this in the hopes I can finally sleep at night.

 

My example: I'm interested in the Sennheiser GSX 1000 amp/dac combo. I want to know how far this amp can take me if I want to buy a higher end headphone in the future. For now I'm interested in the Sennheiser HD 569 closed back headphone to pair with this amp. With, like I said, maybe a higher end headphone in the future. 

 

I've got a fairly good grasp on the concept of impedance and sensitivity. My next question is if I know the ohms and sensitivity of a headphone, how does that compare to the power output of the amp? 

The specs of the GSX say max output: 1 V RMS @ 32 ohms. I have no idea what this means. The definition of RMS is as far as I've come so far. How does this translate back to 23 ohms and 115 sensitivity? 

 

I'm dying to know, thanks in advance! 

Luckily, this is actually very simple to calculate.

 

If the GSX is outputting 1V RMS @ 32 Ohms, a pair of 32 ohm impedance headphones will get 0.031 watts of power, or 31 milliwatts. As it is 1 volt (V), every amp (A) is a watt (W)

 

If that same amplifier outputs to a 23 ohm load, it will produce 0.043 watts, or 43 milliwatts.

 

If the headphones have a "115" sensitivity, this is 115dB/mw, so if the headphones are given 1 milliwatt, they will produce 115dB SPL (The weighting of this should be A, but some companies measure differently)

 

So, if you feed those headphones with 43 milliwatts, they will get well in excess of 130dB. This is incredibly loud and will ruin your hearing fairly quickly.

 

These are the agreed dB exposure limits by NIOSH and CDC:

 

 

So as we can see, if you feed your headphones 1mw, (43 times less power than the amp can give them!), they will ruin your ears after about 30 seconds.

 

These are some quick calculations I've done before:

 

At the SPL you could produce, you could ruin your hearing after 0.46 seconds.

 

 

 

[Hyunato]

I think I understand. 

 

Example: 

GSX 1000 maximum output is: 31,25 mW 

Using an online tool for a Audio-Technica headphone that is 44 ohms and 101 dB/mW I would need roughly 25 mW to drive them "very loud" and 80 mW to drive them "painfully". Therefor the GSX would be good enough. But for the HD 800 S I would need 66 mW to drive them very loud and I would be short on power. 

 

Is that about right? 

 

[Derkoli]

3 hours ago, Hyunato said:

I think I understand. 

 

Example: 

GSX 1000 maximum output is: 31,25 mW 

Using an online tool for a Audio-Technica headphone that is 44 ohms and 101 dB/mW I would need roughly 25 mW to drive them "very loud" and 80 mW to drive them "painfully". Therefor the GSX would be good enough. But for the HD 800 S I would need 66 mW to drive them very loud and I would be short on power. 

 

Is that about right? 

 

The HD800S' are fairly happy on alot of sources. They'll be happy with 12-15 milliwatts. They prefer good quality power over lots of power.