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Asus Xonar STX built-in amp and K701 synergy

post #1 of 14
3/8/10 at 7:49pm
Thread Starter 
This is a scientific validation as to why Asus Xonar STX built-in amp has almost perfect synergy with AKG 701 at its 64-300ohms setting.

AKG 701's maximum power input 200mw at 1hz.

Asus Xonar STX power output 3.52V @ +12dB for headphones with impedances of 64–300 ohms


• Power (P)
• Resistance (R)
• Voltage (E)

Calculate for Power (P)

P = E^2 / R

3.52V^2 / 62ohms = 0.19985 watts (199.85mw)


There you go, almost exactly 200mw (at a load of 62ohms), the maximum input power for AKG701 recommended by AKG.
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Gear mentioned in this thread:

ASUS Xonar Essence STX Virtual 7.1 Channels PCI Express Interface 124 dB SNR /...
AKG K 701 White
post #2 of 14
3/8/10 at 8:26pm
Great post, maybe you can post more tips about using the STX with the K701/2, you know like lower gain, etc.
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post #3 of 14
3/8/10 at 8:31pm
Thread Starter 
Thanks Acix. I had posted a basic guide on how to setup STX/ST software for headphone listening at computer as source section:

http://www.head-fi.org/forums/f46/as...-guide-475872/
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post #4 of 14
3/10/10 at 2:25pm
This kind of argument reminds me of a movie called "The number 23" (don't mean any offense)
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post #5 of 14
3/10/10 at 2:34pm
Quote:
Originally Posted by audiofil View Post
This kind of argument reminds me of a movie called "The number 23"
You Can't Argue With History, Or Numbers.
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post #6 of 14
3/10/10 at 2:37pm
Quote:
Originally Posted by leeperry View Post
You Can't Argue With History, Or Numbers.
Yep, numbers don't lie...... unless when used incompletely or in the wrong context (which happens A LOT), or incorrectly measured!.... (edited: not bashing the OP lol, just jargon)

Thanks to the OP for providing useful news on the other hand. I planned on building a better box and might snag this card due to your research.
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post #7 of 14
3/10/10 at 2:44pm
Thread Starter 
Quote:
Originally Posted by BryanP View Post
Yep, numbers don't lie...... unless when used incompletely or in the wrong context (which happens A LOT), or incorrectly measured!....

Thanks to the OP for providing useful news on the other hand. I planned on building a better box and might snag this card due to your research.
if there is something wrong with the calculation fix it. we'll all learn in the process, otherwise troll somewhere else.
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post #8 of 14
3/10/10 at 2:47pm
Quote:
Originally Posted by wali View Post
if there is something wrong with the calculation fix it. we'll all learn in the process, otherwise troll somewhere else.
What are you talking about? I was never bashing you... or let alone say that something was wrong with your calculation. I was referring to what he said about numbers not lying. I'm just stating that that is true and that the only times they do is when they're misused. In fact, I gave you props for the recommendation.

Don't call me a troll either. I don't recall ever saying anything negative to you.
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post #9 of 14
3/10/10 at 2:50pm
Quote:
Originally Posted by BryanP View Post
Yep, numbers don't lie...... unless when used incompletely or in the wrong context (which happens A LOT), or incorrectly measured!
now, you're being sarcastic
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post #10 of 14
3/10/10 at 2:50pm
Thread Starter 
Quote:
Originally Posted by BryanP View Post
What are you talking about? I was never bashing you... or let alone say that something was wrong with your calculation. I was referring to what he said about numbers not lying. I'm just stating that that is true and that the only times they do is when they're misused. In fact, I gave you props for the recommendation.

Don't call me a troll either. I don't recall ever saying anything negative to you.
That was my impression from your sly remakes but then I really don't take such things seriously. Its all good.
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post #11 of 14
3/10/10 at 2:53pm
Quote:
Originally Posted by wali View Post
That was my impression from your sly remakes but then I really don't take such things seriously. Its all good.
Ah I see. I apologize if I rubbed off in that manner.

I was just posting basically an observance since ironically, I'm a mathematician and wanted to sputter jargon about numbers that holds true often...

Let us not derail this useful thread due to a misunderstanding.
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post #12 of 14
3/10/10 at 3:07pm
Thread Starter 
No problem.

But in the interest of understating, how would one go about calculating the optimum output power for K701?

When AKG says maximum power input 200mw, I'm sure its not that more than will blow up the headphone drivers (i tested that) its probably to minimize negative feedback and control dumping for optimum clarity.

I tried to drive K701 at highest power output of STX which is 800mw at a load of 62ohms and the sound quality deteriorated in fact, the bass weakened and the overall presentation sounded bland with a high noise floor, the only positive was the volume increase.

My amateurish conclusion was that higher power meant more negative feedback and an increase in damping which result in drivers not working optimally/efficiently. But I could be wrong and I would like to hear what other technically inclined members have to say.
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post #13 of 14
3/10/10 at 3:10pm
correct me if I'm wrong those who are more knowledgeable, (and I'm sure this is oversimplified) but if you go past a certain point you start giving the headphone too little current for the same amount of power.
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post #14 of 14
11/26/10 at 4:46am

I agree with the above,but it is only true at 1kHz....(if that is when the maxium occured, the guy doesn't specify)

 

The maximum voltage put out by the card might be 3.52V from a 1kHz sine wave, but what is its output at 50Hz when a music track is being played?

 

There is a constant equilibrium between the output of the souce, and the sensitivity of the driver. A nice way to look at it is the graph from headroom. It shows that the HD650 should be way harder to drive at bass-y levels, as much as 475Ohm at 70Hz! But the sensitivity of the driver must be awesome at that point, because everyone knows the HD650 has better bass than the K701 right?

 

That is lesson 1 in headphone maths. It doesn't even include all the other variables; like slew rates, quality of the source, or even the mechanics of how amplifiers work; that I have no idea about. The statistics surrounding headphones are only as good as the mathematician.

 

But at the end of the day, an amplifier is an amplifier is an amplifier. Digital files can now be so close to the originals that this shouldn't come into the mix at all. The IC amplifier chips used are also great quality, I can't see humans being able to heat the difference between 0.00003% and 0.0044% THD. The differences in recordings are going to much more noticeable.

 

If the K701's do not produce as much bass as I want, I'll add some EQ to it. This is the beauty of having a computer-source-solution. The synergy that standalone amps have with headphones can be perfected or destroyed by adjusting the EQ, or simply turning the volume up on a track you really like. So i'll say it again, if I want more of something or less of something else, I'll play with the EQ and hopefully get it right. 'Current hungry headphones' is nothing the EQ in the Essence can't fix. 'High current amplifier' is how the mechanics of that amplifier react with that particular headphone. There is no reason the Essence can't power these headphones.

 

After all, the most important person to please is yourself.

 

....woo 2nd post...

 

 

graphCompare.php?graphType=7&graphID[]=703&graphID[]=853

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Gear mentioned in this thread:

ASUS Xonar Essence STX Virtual 7.1 Channels PCI Express Interface 124 dB SNR /...
AKG K 701 White
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