[haloshredder]

I am running them through an id14 audio interface and playing music directly from my Daw.

The way I understand impedance, the lower it is the less power the cans need to be driven right?


Why is the exact reverse happening with my headphones where the HD650 at the same headphone output level sound much louder and 'driven' than the Sundaras? Do I have a defective Sundara? Can someone please explain this in layman language please :S

 

[ScornDefeat]

I am running them through an id14 audio interface and playing music directly from my Daw.

The way I understand impedance, the lower it is the less power the cans need to be driven right?


Why is the exact reverse happening with my headphones where the HD650 at the same headphone output level sound much louder and 'driven' than the Sundaras? Do I have a defective Sundara? Can someone please explain this in layman language please :S

The Sundara is, for a headphone, fairly low sensitivity; 35 or so ohms doesn't require much voltage, but its only 94db a 1mw. The HD650, on the other hand, is a higher sensitivity headphone around 105db for the same 1mw. Long story short, if all things are equal (and they never are with amps....), it takes more mw of output power to get to the same 105db of output power.

Many factors influence this; some amps (OTL tube amps) put out more power at high impedence than low, other amps (SS designs) out out more power at low impedance. So the ohm rating isn't the be-all-end-all, and neither is the sensitivty rating.

Sundaras are pretty current-hungry and lower sensitivty and it's recommended to have ample amplification to get the best out of them.

 

[genck]

The Sundara has lower sensitivity, lower sensitivity = lower volume. Impedance also plays a role as you note, it's just that in this case the low sensitivity and low impedance of the sundara outweighs the higher sensitivity and higher impedance of the hd650.

 

[haloshredder]

Thank you so much for educating me. I appreciate it.

 

[ProtegeManiac]

The way I understand impedance, the lower it is the less power the cans need to be driven right?

No. There is only a very indirect correlation between impedance and power, and it's the other way around. Traditional driver designs typically need to have higher impedance in order to need less power. This is why when you compare the old reference Sennheisers and Beyers to their AKG peers the 300ohm and 250ohm headphones have a higher sensitivity than their 62ohm counterparts. This is not universal though since you can have a Grado at 32ohms and have the same sensitivity as a Beyer from around the same era.

HiFiMan only seems to follow that rule but given it's an electrostat making 150ohm versions of those may not necessarily result in any sensitivity gains.

At the same time higher impedance means higher damping factor. This isn't as big of a consieration now when you have so many high power (and still running in Class A) headphone amps with 5ohms or lower output impedance, so you can still maintain the very general of keeping a roughly 8:1 ratio of nominal load impedance to amplifier output impedance.

Why is the exact reverse happening with my headphones where the HD650 at the same headphone output level sound much louder and 'driven' than the Sundaras? Do I have a defective Sundara? Can someone please explain this in layman language please :S

Focusing on this particular example though you have a 37ohm headphone with a 93dB sensitivity, while the HD650 has I think 97dB sensitivity. Taking impedance out of the equation for a moment, that means that if you have xxxmW going into the Sennheiser, you need around 1.333(xxxmW) to match the output level on the Sennheiser.

Where impedance comes in is affect how much power the amp can put into a given nominal load (among other things). In some cases you can have an amp that makes 150mW into 32ohms, then drops to 25mW at 300ohms. So even if you need 1.33X the power the HiFiMan can be louder on such an amplifier. In your case it's possible that the Sennheiser sounds more "driven" not merely because of high sensitivity but because you're getting some distortion and clipping on the Sundara if you cranked it up depending on the effective damping factor at the Sundara's impedance level if not already outright clipping, so tendency is to not crank it up any higher.

 

[Johnny Golden]

As outlined above Planar dynamics need more wattage over voltage compared to high impedance dynamics.

As a result even when you are getting the headphones to a suitable volume you'll find they lack things in comparison to higher powered amps.

For example, my Sundara's reach a suitable volume for me out of my Drop O2 but start to sound thin and peaky. When I plug them into either of my Burson amps which range from 2 watts to 8.2 watts the bass solidifies and the peak is lost. Planar's can handle a lot of power and will almost always benefit from amps with over 1 watt of power.

Your interface is likely to have around 500mw or even less as many interfaces barely broach 200mw. My recommendation would be the Schiit Magni 3+ or Heresy.