[Benn Beckman]

 

Power is measures in Watts (W) or milliWatts (mW)
ok i kinda understand now
 
You can read Innerfidelity sheets, there you can find how much voltage is needed for 90dB for each headphone.
You need some math to know how much current is needed, but it's not a very useful piece of information anyway since very little amps talk about how much current they can supply.
i found fiio A5 and dac/amp like e17k Vpp so we can use it to calculate total power they can produce right?
 
Me x3: There's no explanation of mine on that thread as I can see, but the math on your examples is not working fine.
DT990 Pro needs 1mW to reach 96dB at 500Hz
HD600 needs 1mW to reach 97dB at 1000Hz
K702 needs 1Vrms to reach 105dB at 1000Hz
So you are comparing green apples, with red apples, with oranges. Not a good idea.
 
Here's comparable info:
DT990 Pro needs 1mW for 94dB at 1000Hz
HD600 needs 1mW to reach 97dB at 1000Hz
K702 needs 1mW to reach 88dB at 1000Hz
 
nah i still don't understand if it related to Hz? can you explain that? how to determine if we give 1mw it will produce 94db at 1000Hz i still don't understand this since on spec list it only write 96db SPL/mW
and what is the different between SPL/mW and SPL/V?

 

[Me x3]

  Power is measures in Watts (W) or milliWatts (mW)
ok i kinda understand now
 
You can read Innerfidelity sheets, there you can find how much voltage is needed for 90dB for each headphone.
You need some math to know how much current is needed, but it's not a very useful piece of information anyway since very little amps talk about how much current they can supply.
i found fiio A5 and dac/amp like e17k Vpp so we can use it to calculate total power they can produce right?
 
Me x3: There's no explanation of mine on that thread as I can see, but the math on your examples is not working fine.
DT990 Pro needs 1mW to reach 96dB at 500Hz
HD600 needs 1mW to reach 97dB at 1000Hz
K702 needs 1Vrms to reach 105dB at 1000Hz
So you are comparing green apples, with red apples, with oranges. Not a good idea.
 
Here's comparable info:
DT990 Pro needs 1mW for 94dB at 1000Hz
HD600 needs 1mW to reach 97dB at 1000Hz
K702 needs 1mW to reach 88dB at 1000Hz
 
nah i still don't understand if it related to Hz? can you explain that? how to determine if we give 1mw it will produce 94db at 1000Hz i still don't understand this since on spec list it only write 96db SPL/mW
and what is the different between SPL/mW and SPL/V?

The thing is you need some math and physics basis to fully understand this topic.
It's not quantum mechanics but not completely straight forward either.
 
FiiO A5 drives HD600, DT990 and K702 with ease.
 
You can measure how loud is a headphone with 1mW of power using a 500Hz test tone, or a 1000Hz tone, or whatever tone you prefer. You should not compare sensitivity measurements made with different tones.
 
The information I provided is derived from third party measurements.
 
dB/mW means how loud it is when you feed the headphone with 1mW
dB/V means how loud it is when you place 1V at the headphone jack.
 
Again, if you don't know what does Voltage or Power means as Physics concepts, then trying to understand these measurements of sensitivity won't be easy. It's like trying to learn how to multiply before learning the numbers.
Once you understand what's voltage, power, current, impedance, frequency, frequency response, loudness and few other concepts, as well as how they are related then this topic about amplification is very straight forward and even easy. But we are talking about several pages on a physics book, so it's hard to teach you all these stuff on a forum post.

 

[Benn Beckman]

  The thing is you need some math and physics basis to fully understand this topic.
It's not quantum mechanics but not completely straight forward either.
 
FiiO A5 drives HD600, DT990 and K702 with ease.
 
You can measure how loud is a headphone with 1mW of power using a 500Hz test tone, or a 1000Hz tone, or whatever tone you prefer. You should not compare sensitivity measurements made with different tones.
 
The information I provided is derived from third party measurements.
 
dB/mW means how loud it is when you feed the headphone with 1mW
dB/V means how loud it is when you place 1V at the headphone jack.
 
Again, if you don't know what does Voltage or Power means as Physics concepts, then trying to understand these measurements of sensitivity won't be easy. It's like trying to learn how to multiply before learning the numbers.
Once you understand what's voltage, power, current, impedance, frequency, frequency response, loudness and few other concepts, as well as how they are related then this topic about amplification is very straight forward and even easy. But we are talking about several pages on a physics book, so it's hard to teach you all these stuff on a forum post.

ok, so this calculator http://www.digizoid.com/headphones-power.html won't help since we don't know at how much Hz is?
and we can use how much power needed on this insted http://www.innerfidelity.com/headphone-measurements to determine the right amp?
so how do i calculate the correct amp to drive k702? i mean i want to know how the simple thing i can use to choose the right amp? what is the first i look?

 

[Me x3]

  ok, so this calculator http://www.digizoid.com/headphones-power.html won't help since we don't know at how much Hz is?
and we can use how much power needed on this insted http://www.innerfidelity.com/headphone-measurements to determine the right amp?
so how do i calculate the correct amp to drive k702? i mean i want to know how the simple thing i can use to choose the right amp? what is the first i look?

I would use innerfidelity, look at the power needed for 90dB SPL.
In the case of K702 is 1.56 mW
 
Then as a simple rule, double the power = add 3dB
So here we go:
 
1.56 mW = 90dB SPL.
3.12 mW = 93dB SPL.
6.24 mW = 96dB SPL.
12.48 mW = 99dB SPL.
24.96 mW = 102dB SPL.
49.92 mW = 105dB SPL.
99.84 mW = 108dB SPL.
 
With 105dB SPL you're fine the vast majority of time (if you listen to music at normal levels, read always)
Keep in mind (1) normal listening levels tend to stay below 100dB
Keep in mind (2) enough power is not all you need to drive a headphone properly (Two amplifiers with the same power can sound different, although both will sound similarly loud)
 
If you want to see this from a Voltage perspective, look at the voltage needed for 90dB  SPL
In the case of K702 is 0.322 Vrms
 
Then as a simple rule, twice the voltage = add 6dB
So here we go:
 
0.322 Vrms = 90dB SPL
0.644 Vrms = 96dB SPL
1.288 Vrms = 102dB SPL
2.566 Vrms = 108dB SPL
 
If you don't know how much power or voltage certain amp can provide into the desired load (in the case of K702 67 Ohm) just ask around here on headfi, maybe some of us can help.

 

[Benn Beckman]

 Keep in mind (2) enough power is not all you need to drive a headphone properly (Two amplifiers with the same power can sound different, although both will sound similarly loud)

i don't know what you mean "properly"? to find an amp with correct sound signature?
 
ok in that case
fiio A5 has 14.96Vpp so (14.96 / 2) / sqrt2 = 5.28 Vrms 
fiio e17k has 7.8Vpp so (7.8 / 2) / sqrt2 = 2.75Vrms
so it means fiio A5 and e17k can drive k702 properly?
what is the formula to find how much power at 67ohm? i try use this formula (Vrms ^ 2) / R *1000 but the result is too high i think
 
and in the case i can't find the headphone on the link you gave me? such as dt990 is doesn't exist on that website, so i must googling how much power that it need at 90db SPL? SPL/V or SPL/mW?

 

[Me x3]

  i don't know what you mean "properly"? to find an amp with correct sound signature?
 
Me x3:
You can have an amp with enough power but high THD, or high output impedance, etc. Power is not the only variable in the game. As long as you are considering quality solidstate gear you shouldn't worry much about things like THD or output impedance. If you start digging into unkown brands or tube amps then you should take more considerations besides power.
Even when considering quality solidstate gear, a FiiO A3 won't sound the same as a FiiO A5 and a FiiO A5 won't sound the same as a 1700usd Schiit Ragnarok, that's to be expected. Even if they all can drive the headphone properly.
 
ok in that case
fiio A5 has 14.96Vpp so (14.96 / 2) / sqrt2 = 5.28 Vrms 
fiio e17k has 7.8Vpp so (7.8 / 2) / sqrt2 = 2.75Vrms
so it means fiio A5 and e17k can drive k702 properly?
 
Me x3:
I've tried both with the K702 and both worked well to my ears. If you enjoy listening tu music at VERY loud levels you'll be pushing the E17K to its limits, in particular with very shy recordings, otherwise it's more than enough. For my normal listening levels and the vast majority of recordings I don't even have the need of switching to the highest gain setting on the E17K. As I've said before, headphones like K702 scale with better and better gear, so if you use E17K along with K5 for example, you'll get even better sound quality than using just the E17K alone, although the E17K alone will make the K702 sound very well if you like the headphone's signature. Pick a Phonitor X and you might get slightly better sound than E17K+K5 (but it's also MUCH more expensive)
 
what is the formula to find how much power at 67ohm? i try use this formula (Vrms ^ 2) / R *1000 but the result is too high i think
 
Me x3:
There's no formula for that. E17K power @ 67 Ohm should be around 95mW
 
and in the case i can't find the headphone on the link you gave me? such as dt990 is doesn't exist on that website, so i must googling how much power that it need at 90db SPL? SPL/V or SPL/mW?
 
Me x3:
DT990 250 Ohm is very similar to DT880 250 Ohm which is there on Innerfidelity. You can use DT880 250 Ohm as reference.

 

[Benn Beckman]

  You can have an amp with enough power but high THD, or high output impedance, etc. Power is not the only variable in the game. As long as you are considering quality solidstate gear you shouldn't worry much about things like THD or output impedance. If you start digging into unkown brands or tube amps then you should take more considerations besides power.
Even when considering quality solidstate gear, a FiiO A3 won't sound the same as a FiiO A5 and a FiiO A5 won't sound the same as a 1700usd Schiit Ragnarok, that's to be expected. Even if they all can drive the headphone properly

ok, i kind understand what you mean, each amp can make sound louder, but expensive amp will make the sound even better
what is Total Harmonic Distortion means? and ouput impedance on headphone spec list, its usually a little ohm right? like 2.2ohm etc. i mean what they function is?

 I've tried both with the K702 and both worked well to my ears. If you enjoy listening tu music at VERY loud levels you'll be pushing the E17K to its limits, in particular with very shy recordings, otherwise it's more than enough. For my normal listening levels and the vast majority of recordings I don't even have the need of switching to the highest gain setting on the E17K. As I've said before, headphones like K702 scale with better and better gear, so if you use E17K along with K5 for example, you'll get even better sound quality than using just the E17K alone, although the E17K alone will make the K702 sound very well if you like the headphone's signature. Pick a Phonitor X and you might get slightly better sound than E17K+K5 (but it's also MUCH more expensive)

for now i just need a portale amp or dacamp till i got a job and i could spend more money to buy a proper amp
you said in page one if you switch gain it will add 6db right? what does it means? i know gain is for hungry power headphone, but i want to know the mechanism

 There's no formula for that. E17K power @ 67 Ohm should be around 95mW

so you aren't using formula to calculate that?how do you know it will around 95mW?

 DT990 250 Ohm is very similar to DT880 250 Ohm which is there on Innerfidelity. You can use DT880 250 Ohm as reference

in case there is a new headphone, what will you do if it isn't write on that site?

 

[Me x3]

  ok, i kind understand what you mean, each amp can make sound louder, but expensive amp will make the sound even better
what is Total Harmonic Distortion means?
 
https://en.wikipedia.org/wiki/Total_harmonic_distortion
 
and ouput impedance on headphone spec list, its usually a little ohm right? like 2.2ohm etc. i mean what they function is?
 
You should read about the Damping Factor
 
for now i just need a portale amp or dacamp till i got a job and i could spend more money to buy a proper amp
 
Q1 is a very nice affordable DAC/Amp
 
you said in page one if you switch gain it will add 6db right? what does it means? i know gain is for hungry power headphone, but i want to know the mechanism
 
Higher gain normally means more available volume. Selectable gain is useful when using headphones with very different sensitivity (for example IEMs and DT990)
 
so you aren't using formula to calculate that?how do you know it will around 95mW?
 
It's quite complicated, you should know if the amp is voltage or current limited for the desired load. These FiiOs are not current limited with 67 Ohm load as far as I recall, then you can work out some math knowing they can provide over 2.5 Vrms.
 
in case there is a new headphone, what will you do if it isn't write on that site?
 
It really depends on the published data and other third party measurements

 

[Benn Beckman]

 Q1 is a very nice affordable DAC/Amp

Q1 vs e17k which one better? 
I am confuse, in the begining i want to buy dt990 premium 250 ohm (178$) and then buy fiio e17k for ($107)
but i saw someone sell a budle dt990 600ohm bundled with fiio A5 for 279$

 

[Me x3]

  Q1 vs e17k which one better? 
I am confuse, in the begining i want to buy dt990 premium 250 ohm (178$) and then buy fiio e17k for ($107)
but i saw someone sell a budle dt990 600ohm bundled with fiio A5 for 279$

DT990 Pro is said to have more bass than DT990 600 Ohm
E17K has more features than Q1 and it's normally a tad more expensive.
E17K is slightly better here and there, although I like the analogue volume control on the Q1 more.

 

[Benn Beckman]

 
DT990 Pro is said to have more bass than DT990 600 Ohm
E17K has more features than Q1 and it's normally a tad more expensive.
E17K is slightly better here and there, although I like the analogue volume control on the Q1 more.

i read somewher the 600 ohm version is more soft on the high and little bit forward on the mids
this is why i'm confuse, the other hand if i pari 250 or pro with e17k, i can set the treble
pro is the same like premium 250 ohm right? i like the design of premium version, beside pro versien is coiled cable
so you suggest me to buy 250 ohm version and buy e17k instead bundle 600ohm+A5?

 

[Me x3]

  i read somewher the 600 ohm version is more soft on the high and little bit forward on the mids
this is why i'm confuse, the other hand if i pari 250 or pro with e17k, i can set the treble
pro is the same like premium 250 ohm right? i like the design of premium version, beside pro versien is coiled cable
so you suggest me to buy 250 ohm version and buy e17k instead bundle 600ohm+A5?

I would pick the DT990/600 + A5
Some people miss the bigger bass on the Pro version when using the 600 Ohm Premium, but FiiO A5 has a quality Bass Boost anyway in case you need it for some recordings.

 

[Benn Beckman]

  I would pick the DT990/600 + A5
Some people miss the bigger bass on the Pro version when using the 600 Ohm Premium, but FiiO A5 has a quality Bass Boost anyway in case you need it for some recordings.

you sure A5 will drive 600ohm to the level "enjoy" listening? i don't care and don't know about harmonic dynamic etc what i wanted is enjoy listening, watching movie and playing fps
i think it's a great deal too, dt990 600 ohm + fiio A5 + lexar micro sd 64gb for $279 rather than buying dt990 250 ($178) and fiio e17k ($107) seperately.

 

[Me x3]

  you sure A5 will drive 600ohm to the level "enjoy" listening? i don't care and don't know about harmonic dynamic etc what i wanted is enjoy listening, watching movie and playing fps
i think it's a great deal too, dt990 600 ohm + fiio A5 + lexar micro sd 64gb for $279 rather than buying dt990 250 ($178) and fiio e17k ($107) seperately.

Yep, the A5 is a powerful amp.

 

[Benn Beckman]

 
Yep, the A5 is a powerful amp.

ok thank you man for your recomendation