Driving Headphones (Impedance and Sensitivity)

[Samgotit]

K501
Efficiency 94 dB SPL/mW
Rated impedance 120 ohms

K701
Efficiency 105 dB/V
Rated impedance 62 ohms

HD 580
Efficiency N/A
Rated impedance 300 ohms

SR325i
Efficiency 98 dB/mV
Normal impedance 32ohms

I am trying to understand why the AKG 501s are so difficult to drive given the numbers above.

Notice the 3 different units for efficiency here? Is this due to some proprietary measuring. Can they be standardized? I guess measuring dB with 1 watt of power at 1 meter is out for headphones. Anyone know how they are measuring efficiency.

What other variables are important for driving headphones outside of impedance and efficiency?

I thought I could get a simple answer by looking at a couple of numbers but now I’m just confused. Is the simple answer that K501s have a low sensitivity.

Thanks,
Sam

 

[haibane]

Quote:

Originally Posted by Samgotit K501 Efficiency 94 dB SPL/mW Rated impedance 120 ohms K701 Efficiency 105 dB/V Rated impedance 62 ohms HD 580 Efficiency N/A Rated impedance 300 ohms SR325i Efficiency 98 dB/mV Normal impedance 32ohms I am trying to understand why the AKG 501s are so difficult to drive given the numbers above. Notice the 3 different units for efficiency here? Is this due to some proprietary measuring. Can they be standardized? I guess measuring dB with 1 watt of power at 1 meter is out for headphones. Anyone know how they are measuring efficiency. What other variables are important for driving headphones outside of impedance and efficiency? I thought I could get a simple answer by looking at a couple of numbers but now I’m just confused. Is the simple answer that K501s have a low sensitivity. Thanks, Sam

My guess is either the sensitivity or the impedance is off. I would get out a meter and try to find the impedance and then go from there

 

[slwiser]

Here is a good thread concerning this issue;

http://www.headwize.com/ubb/showpage...num=3&tid=6081

 

[JahJahBinks]

it's measured at the cup.

 

[Samgotit]

Quote:

Originally Posted by slwiser Here is a good thread concerning this issue; http://www.headwize.com/ubb/showpage...num=3&tid=6081

That is a great start.

Thanks

 

[fewtch]

Quote:

Originally Posted by Samgotit I am trying to understand why the AKG 501s are so difficult to drive given the numbers above.

IMO it's partially because people are trying to milk more bass (impact) out of the headphones. They aren't tremendously hard to drive if you ignore the bass frequencies.

 

[Garbz]

That doesn't make sense. It's one thing if the headphones are typically bass light, but if I have a speaker that is supposed to be flat to 20hz and my amp can't make it so that makes them hard to drive IMHO.

The Grado rating is a typo IIRC there was thread on headwize about it. It's mW.

Mind you thoes AKGs aren't difficult to drive. Ignore the numbers and use your ears. A 120ohm load doesn't draw much current. So feed it with sufficient voltage and you should be right.