[bcwang]

With 300 ohm impedance, and all the talk of needing an AMP to drive the HD800, I'm surprised it's as sensitive as it is.

It's louder at the same volume setting than the K701 by quite a bit it. In fact it seems close to grado volumes at the same volume setting.

It's also so sensitive, just touching the jack tip to something grounded, I hear a loud buzz in the headphone. None of my other headphones has this phenomenon, which I notice every time I'm changing jacks with the HD800. Remember, this is with only one positive side touching something grounded, nothing is completing the connection. It just buzzes.

 

[xnor]

According to the specs, if my calculations are right, the HD800 is about 3.8 dB louder (at 1 kHz, 3.3mW) than the AKG701 (which has only 62 ohms) at equal power drain. However, due to the higher impedance you need higher voltage but also less current (1V, 3.3mA for the HD800 versus 0.45V, 7.3mA for the AKG701 from my example).

So 3.8 dB difference, which is like 2.4 times higher efficency.

Btw, comparing PX100 with HD800 the little sennie is 2.3 dB louder.

edit: and the difference to the Grado is even lower with 1.2 dB

 

[krmathis]

Pleasant surprise it seems. Nice!

 

[xnor]

Also note that many people seem to think that "the higher the impedance, the lower the efficiency", which is a generalization that has no basis in physical fact.

 

[bcwang]

I created a spreadsheet and posted in another thread "Headphone Sensitivity / Power Requirements Compared" to compare sensitivities of different headphones based on their specs and normalized. It seems like the HD800 is one of the least sensitive headphones on the market actually. It just happens that the K701 is much less sensitive. The HD800 is the 3rd least sensitive headphone on the list.

 

[xnor]

Quote:

Originally Posted by bcwang /img/forum/go_quote.gif I created a spreadsheet and posted in another thread "Headphone Sensitivity / Power Requirements Compared" to compare sensitivities of different headphones based on their specs and normalized. It seems like the HD800 is one of the least sensitive headphones on the market actually. It just happens that the K701 is much less sensitive. The HD800 is the 3rd least sensitive headphone on the list.

Maybe on your list, but there are a lot of other HPs out there.
The DT770/880/990 or K271 also need more power, K601 more voltage and many others higher current.

 

[logwed]

Quote:

Originally Posted by bcwang /img/forum/go_quote.gif With 300 ohm impedance, and all the talk of needing an AMP to drive the HD800, I'm surprised it's as sensitive as it is. It's louder at the same volume setting than the K701 by quite a bit it. In fact it seems close to grado volumes at the same volume setting.

Loudness is not equivalent to high fidelity sound.

 

[wali]

Volume is determined by sensitivity, impedance, and driver design.

HD600 for example will play loud even from a weak source but it will sound completely like a different headphone because its not getting the voltage required and the voltage swing it needs. Secondly, if there is no voltage swing it will sound off... The same applies to HD800.

K701 is a completely different animal. Its sensitivity and impedance does not reflect its volume requirement, so the only variable left is the driver design. why K701 is not loud enough has a lot to do with the way K701 drivers are designed.

Then K701 has a flat impedance frequency ratio which means if its driven at anything more or less than 64ohms its going to mess up its frequency response... at higher voltage it sounds plasticy and fatiguing bright. at low voltage the bass goes away and the sound is plain boring.

all the misinformed rumors spread here that K701 requires a powerful amp is nonsense. in the back of the K701 box its clearly put, maximum input power 200mw. just to give you an idea the maximum power input of Shure SRH440 is 500mw!

So, when I'm getting the best synergy possible at 64-300ohms setting using Xonar STX built-in amp some noob comes and tells me he does not understand how a "cheap" soundcard amp could drive K701 when more powerful amps fail... well noob, the reason is quite simple, those powerful amps make K701 sound like crap because its above spec power... amps are not magical devices, their job is to amplify the signal and drive the headphone at just about right power requirements...

anyway... its all good.

 

[xnor]

uhh slow down a bit

Quote:

Originally Posted by wali /img/forum/go_quote.gif HD600 for example will play loud even from a weak source but it will sound completely like a different headphone because its not getting the voltage required and the voltage swing it needs.

Where's the logic behind this? As long as there is no clipping...

Quote:

K701 is a completely different animal. Its sensitivity and impedance does not reflect its volume requirement, [...]

Why? The specs clearly show the low sensitivity.

Quote:

[...] so the only variable left is the driver design.

Again, where's the logic. If that were the case the specs would be those of a different driver?

Quote:

Then K701 has a flat impedance frequency ratio which means if its driven at anything more or less than 64ohms its going to mess up its frequency response...

That makes no sense at all.

Quote:

all the misinformed rumors spread here [...]

Sorry, but this is just *ouch*

Quote:

in the back of the K701 box its clearly put, maximum input power 200mw. just to give you an idea the maximum power input of Shure SRH440 is 500mw!

I'd love to see those Shures playing at 132dB.
Jeez, everyone (with the slightest clue) in the audio world knows that such "peak" values are meaningless marketing numbers...

Quote:

well noob, the reason is quite simple, those powerful amps make K701 sound like crap because its above spec power...

So you're saying that powerful headphone amps can't drive 62 ohms...

*sigh*
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Hope it's all good now