Headphone impedance

[fieldframe]

I'm looking at buying a new set of headphones for mixing. I'm considering the Beyerdynamic DT 770 Pro, which is offered in 80-ohm and 250-ohm versions. The Sony MDR-7506 pair that I'm using right now is only 65 ohms, and when I have them plugged into my audio interface, I have to keep the headphone volume knob very low, otherwise the volume is too high for comfort (and safe extended use). This also makes it difficult to adjust, as moving the knob only a small amount changes the volume significantly.

It's been awhile since my physics classes... But higher-impedance headphones should require more current to get the same sound levels, right? So a 250-ohm pair should let me use the interface with the headphones volume set higher, for the same effective volume?

[MrFigg]

Yep. The audio interface is strong enough to drive the 250s. If you want to use them to listen to music on your phone as well though get the 80ohm ones .

By the way, I’ve got the 770s 80 ohm and there’s no problem with volume from my audio interface with those ones. They’re just easier to drive.

[Boombastix]

Higher impedance means lower distortion typically so it is preferred, but you need a head phone amp to drive them.
So, a 250ohm won't work in a phone, it will be too quiet, so you have low impedance headphones for that, but lower quality sound. Trade offs...

[fieldframe]

Thanks!

It’s interesting that high-impedance doesn’t seem to be all that common, at least among the entry- and mid-level reference headphones I’ve been looking at. The AKG K series is ~60 ohms, and even the Shure SRH1840 falls in that range. The only manufacturers I’m seeing with sets in the 200-300 range are Beyerdynamic and Sennheiser.

[Boombastix]

Good headphone amps cost more to make, so more likely to be found in pro equipment. And entry level stuff needs low impedance, and cater more to users looking for cheaper headphones.
You can see the same diff with XLR vs 1/4" jacks, pro vs consumer level.