Driving headphones properly

[NDRQ]

Thanks.
Can you give me link to your measurements and amp designs?

 

[solderdude]

here
and
here

 

[NDRQ]

Thanks.

 

[Sharur]

There seems to be a controversy surrounding the HIFIMAN Susvara where people claim that higher peak power gives better sound quality at the same SPL. How does this make sense if the power output is equal?

 

[b407driver]

When the amp has a Wattage > 100mW in 300 Ohm it has enough output voltage to drive most high impedance headphones.
When the same amp also has a higher wattage > 0.5W in 30 Ohm it can also provide enough current.

I know I'm turning some dirt dredging this thread up, but for people researching headphones vs. the capability of their amps, I'm wondering what the headphones in your second sentence would be referred to, as a generality? For the first sentence you used most 'high impedance headphones' (I know you are generalizing, of course). I believe the answer for #2 is 'low sensitivity' (requiring more current), but it seems like most headphone discussions focus mainly on impedance... OR less often sensitivity. As I understand it after reading, only after considering both the voltage and current requirements can you determine if a headphone is 'hard to drive', correct? In which case, low impedance/low sensitivity is the worst case scenario, requiring an amp that is specifically designed to drive said headphone (I assume a 'high-power' setting?

Are high sensitivity/high impedance headphones also difficult to drive, but in a different way (I'd guess easy to fry)? Sorry if this all is elementary (I'm no EE), but after all the reading I've done lately I'm surprised by how many 'articles' address mostly impedance when talking about headphones and resultant amp requirements. I do realize that is why Amir measures at both 30/300 ohm, but all this is not intuitive for a newb.

Cheers in advance...

 

[solderdude]

Generally the high impedance headphones are low sensitivity and low impedance headphones are higher sensitivity.
Sensitivity is how loud it plays when a certain voltage is applied (dB/V)

High sensitivity headphones are usually very easy to drive and require little voltage.
High sensitivity/high impedance headphones draw very little current, high sensitivity/low imp headphones draw a bit more current at the same output voltage level.
Most gear (incl. portable) can easily drive high sensitivity headphones, regardless of the impedance.

Low impedance, low sensitivity requires a higher voltage and higher current and thus requires a beefy amplifier.

Power rating determines how easily you can fry them (combined with efficiency = dB/mW)

How much power you need (in which impedance) is basically determined how loud you want the headphone to go (shortest peak power in music when momentarily listening to the song at an unusual high level.

For this you need to know the SPL you need to reach, how much EQ you need in the bass (depends on frequency response and target), sensitivity of the headphone and impedance of the headphone.

So even when one would normally only draw 1mW on average you may need 100mW, or even 1W to satisfy the above 'peak power' conditions.

There are no 'hard to drive' headphones. There are low sensitivity and low impedance headphones that require a LOT of power to reach loud peaks. But even these headphones, at normal listening levels require just 30mW or so.

 

[b407driver]

Generally the high impedance headphones are low sensitivity and low impedance headphones are higher sensitivity.
Sensitivity is how loud it plays when a certain voltage is applied (dB/V)

High sensitivity headphones are usually very easy to drive and require little voltage.
High sensitivity/high impedance headphones draw very little current, high sensitivity/low imp headphones draw a bit more current at the same output voltage level.
Most gear (incl. portable) can easily drive high sensitivity headphones, regardless of the impedance.

Low impedance, low sensitivity requires a higher voltage and higher current and thus requires a beefy amplifier.

Power rating determines how easily you can fry them (combined with efficiency = dB/mW)

How much power you need (in which impedance) is basically determined how loud you want the headphone to go (shortest peak power in music when momentarily listening to the song at an unusual high level.

For this you need to know the SPL you need to reach, how much EQ you need in the bass (depends on frequency response and target), sensitivity of the headphone and impedance of the headphone.

So even when one would normally only draw 1mW on average you may need 100mW, or even 1W to satisfy the above 'peak power' conditions.

There are no 'hard to drive' headphones. There are low sensitivity and low impedance headphones that require a LOT of power to reach loud peaks. But even these headphones, at normal listening levels require just 30mW or so.

Thanks so much for that, I really appreciate it, and cleared it up for me. There seem not to be many online sources of information (like ASR) that don't lead one astray with the variability of technical explanations. I'm thankful for the resource @amirm has created, even if it is a bit daunting to new users (been in the HT/AVR arena for awhile, but never dug too deep beyond effectively using Audyssey MultEQ 32XT).

Thanks!