[Dulalala]

"Current drive limited means the limit of minimum current right?"

Limit of maximum current allowed to flow through.
 

"akg is hard to drive since low impendance need more power. i'm confuse because like fidelio x2 is 32ohm and it easy to drive"

How hard it is the drive a headphone depends on sensitivity and resistance.
 

"V=(Vpp/2)/sqrt2"

The correct formula is V_rms=V_p/√2 
 

"a new question is what is the different SPL/mW and SPL/V on that calculator? since mW is P and V is in different unit? V unit is Vrms right? i use SPL/mW for beyer, and the result is correct to this formula 10^(14/10) but i use SPL/V because in akg website it write 105db SPL/V"

P=VI so if you know any 2 values in this, the last one can be derived so you can calculate the end result in dB SPL either way. 
 

"3.46 Vrms is about 4.89 V
3.46 Vrms=4.89V how is the formula?"

V_average=2√2 x Vrms/π
 

"3.46 Vrms, it will only give you 11.5 mA rms
3.46 Vrms=11.5 mA rms what is the formula?"

185 mA rms per channel, you are only going to get 2.96 V rms.
185 mA rms=2.96 Vrms ?

https://en.wikipedia.org/wiki/Root_mean_square

 

[Benn Beckman]

 
Quote:

 Limit of maximum current allowed to flow through.
 

oh ok i kinda understand this
 

 The correct formula is V_rms=V_p/√2 

yes i use Vpp because on fiio spec it only give us Vpp information
 

 P=VI so if you know any 2 values in this, the last one can be derived so you can calculate the end result in dB SPL either way. 

mW=Vrms X mA
kinda like this:
ir will produce 96db if we give that 1mW
on the other hand at k702 specs it will produce 105db if we give that 1Vrms?
mm i confuse since i don't know what is formula to relate it with db. i mean in this formula !0^(14/10) i don't know where 10 come from. 
 

 V_average=2√2 x Vrms/π

what is "n"?
in this formula too √(ΣV2/n)
so now i know
to convert from Vrms to mW use this formula (Vrms^2)/R
to convert from Vrms to V use this formula  V_average=2√2 x Vrms/π
 
i still don't know to convert from Vrms to mA vice versa

 

[Dulalala]

what is "n"?

Number of values.
 

i still don't know to convert from Vrms to mA vice versa

Look at the Wikipedia page I posted earlier.

 

[Benn Beckman]

  Number of values.
 
Look at the Wikipedia page I posted earlier.

hihi is hard to me to learn from that wikipedia, it is in english and to much formula i must learn, SPL/V, how to relate mW or mA to db, and relating it with Hz. i will ask this to my friend who study at science major.
at least from you i learn
Vpp to Vrms
Vrms to mW
because of you i can understand this:

  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.

thank you mate for give me the detail explanation, especially ^ and sqrt2 which i don't know what it mean in the first place. so i can use the Vpp on spec list to find Vrms
thank you, cheers

 

[Benn Beckman]

 

man seriously what is the different beetween SPL/mW and SPL/V
i try to use akg impendance (62 ohm) and sensitivity (105db SPL/V) to the audio calculator you gave me, the result is, it needs:
V: 1.78 Vrms  I: 28.71 mA but it needs P: 51.1mW 
it isn't too big? the power it needs?
since fiio e17k has 2.75 Vrms so i try to use this formula (Vrms ^ 2) / R *1000 the result is 121.97mW @62 ohm, am i wrong? it isn't too big?
 
but the guy who told me to use this http://www.innerfidelity.com/images/AKGK702.pdf 
and teach me this:

  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.

he says that fiio e17k @67 ohm can produce power around 95mW, if i use Vrms to mW formula it has 112mW @67 ohm
and its kinda weird since the official akg web says it 62 ohm but on thus site it is use 67 ohm
since akg specs use 105db SPL/V i can't use this formula 10^((110 - headphone sensitivity) / 10) to find how much power need by the headphone right? is there any other formula for SPL/V?
 
i can use the technique he gave me, but it can be use if the headphone exist on that site. if i want to calculate a brand new headphone that isn't write on that site i can't use the technique he gave me..
i'm confuse

 

[Dulalala]

man seriously what is the different beetween SPL/mW and SPL/V
i try to use akg impendance (62 ohm) and sensitivity (105db SPL/V) to the audio calculator you gave me, the result is, it needs:
V: 1.78 Vrms  I: 28.71 mA but it needs P: 51.1mW 
it isn't too big? the power it needs?

How many dB are you looking at? dB SPL/mW and dB SPL/V are the same. They are both sensitivity, but one is how much sound is produced with 1 mW and the other is with 1V.
 

he says that fiio e17k @67 ohm can produce power around 95mW, if i use Vrms to mW formula it has 112mW @67 ohm
and its kinda weird since the official akg web says it 62 ohm but on thus site it is use 67 ohm
since akg specs use 105db SPL/V i can't use this formula 10^((110 - headphone sensitivity) / 10) to find how much power need by the headphone right? is there any other formula for SPL/V?
 
i can use the technique he gave me, but it can be use if the headphone exist on that site. if i want to calculate a brand new headphone that isn't write on that site i can't use the technique he gave me..
i'm confuse

It's a good thing you are trying to learn for yourself how to do things, but really, if you want to understand any of this, you need a background in maths and physics. Unless you are willing to put the effort into learning it, I don't think you'll be able to understand it. You can always just ask the people around here for help to confirm if a certain equipment is viable for your needs instead of trying to figure it out yourself. We won't bite don't worry. 
 
However if you are willing to learn about it, I will link some sites that will be able to explain it better than I can and in much more detail. If you have any questions you can always post in the sound science section as I think it's getting a bit off topic now.
https://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law (read this one first)
https://www.allaboutcircuits.com/textbook/semiconductors/chpt-1/from-electric-to-electronic/
http://nwavguy.blogspot.com/2011/09/more-power.html
http://nwavguy.blogspot.com/2011/02/gain-and-headphone-ampsdacs.html

 

[Benn Beckman]

  How many dB are you looking at? dB SPL/mW and dB SPL/V are the same. They are both sensitivity, but one is how much sound is produced with 1 mW and the other is with 1V.
 
It's a good thing you are trying to learn for yourself how to do things, but really, if you want to understand any of this, you need a background in maths and physics. Unless you are willing to put the effort into learning it, I don't think you'll be able to understand it. You can always just ask the people around here for help to confirm if a certain equipment is viable for your needs instead of trying to figure it out yourself. We won't bite don't worry. 
 
However if you are willing to learn about it, I will link some sites that will be able to explain it better than I can and in much more detail. If you have any questions you can always post in the sound science section as I think it's getting a bit off topic now.
https://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law (read this one first)
https://www.allaboutcircuits.com/textbook/semiconductors/chpt-1/from-electric-to-electronic/
http://nwavguy.blogspot.com/2011/09/more-power.html
http://nwavguy.blogspot.com/2011/02/gain-and-headphone-ampsdacs.html

for now i just want to know how to match headphone with amp. thats it
this is what i want to know:
-  is this 10^((110-sensitivity) / 10) formula can be applied to all types of headphone to know how much they need power even if that spec use SPL/V? or there is other    formula to convert them to  SPL/V first?
 
- if i use db SPL/V on that calculator, for example akg k702 105db SPL/V and 62 ohm
  it needs V: 1.78 Vrms  I: 28.71 mA  P: 51.1mW is this correct result? i mean it needs power too big (51.1 mW) compare when i use SPL/mW
  then can i use these formula Vrms=(Vpp / 2) / sqrt2 then (Vrms ^ 2) / R *1000 to know how much power that an amp can produce?
  for example fiio e17k has Vpp: 7.8 then the Vrms: 2.75 then i convert that to mW the result is 121.97mW at 62 ohm. is this correct? since k702 needs 51.1mW at 62     ohm, so it can drive k702  right?
 
- on the other thread it said fiio e17k at 67 ohm can produce P: 95 mW and V: 2.5 Vrms
  but i try to calculate with the formula we discuss, at 67 ohm fiio e17k can produce 112.87mW
  why is it different? 
 
seems like what you teach to me is usefull, but in the other thread it different iam confused.
man i thank you and appreciate you for giving me those site. i will ask my friend, but for now i can't meet them since they study at different university on different city.
so for know i just want to know a simple math to determine which amp that i need. if its only simple math like i try above its very simple, but what make me confused is one says this and the others says different.
if it use like sin cos tan and the other stuff like that then i give up. and if theres varible more than what we discuss above i will giving up too. but since it only formula and i just apply the number on that formula, i think i can do it.

 

[Dulalala]

  if it use like sin cos tan and the other stuff like that then i give up. and if theres varible more than what we discuss above i will giving up too. but since it only formula and i just apply the number on that formula, i think i can do it.

There will be logarithm involved in the equation.

 

[Benn Beckman]

  There will be logarithm involved in the equation.

so then i give up, if i can't use that simple formula to determine which amp that can drive certain headphone
if ask here on head fi, theres too many recomendation based by individual experience, or maybe they just read somewhere and give me recomendation. i read so many thread about beyer and one says this amp and the other that amp, some says it needs certain expensive++ extra amp to drive the headphone properly, about harmonic dynamic combo a combo b bla bla. i'm just sick of it. i just want to know that an amp i buy will give sound loud enough. thats it
i'm not serious listener, i just want a headphone that make me enjoy music movie and playing fps
ok one last question, first i want to buy dt990 250 versionand buy fiio e17k to drive them, since dt990 250 has a spike treble and i can set the treble on e17k. it cost around $285 and i buy them seperately.
but i heard the 600 ohm version is more clear at bass, a little bit forward at mid, and more soft on the treble and i saw a bundle of dt990 600 ohm version with fiio A5 and it cost only 279. what do you think?

 

[Dulalala]

  so then i give up, if i can't use that simple formula to determine which amp that can drive certain headphone
if ask here on head fi, theres too many recomendation based by individual experience, or maybe they just read somewhere and give me recomendation. i read so many thread about beyer and one says this amp and the other that amp, some says it needs certain expensive++ extra amp to drive the headphone properly, about harmonic dynamic combo a combo b bla bla. i'm just sick of it. i just want to know that an amp i buy will give sound loud enough. thats it
i'm not serious listener, i just want a headphone that make me enjoy music movie and playing fps
ok one last question, first i want to buy dt990 250 versionand buy fiio e17k to drive them, since dt990 250 has a spike treble and i can set the treble on e17k. it cost around $285 and i buy them seperately.
but i heard the 600 ohm version is more clear at bass, a little bit forward at mid, and more soft on the treble and i saw a bundle of dt990 600 ohm version with fiio A5 and it cost only 279. what do you think?

Don't worry about the 600 Ohm version. Just buy the 250 Ohm version or if you can find it, the 32 Ohm version. The differences between them, if any, are very small and you can achieve the same/similar thing with good EQ. The Fiio E17K can run it loud enough if that's all you care about. The Dragonfly Black/Red will also be able to run it if you want another option. 

 

[Benn Beckman]

  Don't worry about the 600 Ohm version. Just buy the 250 Ohm version or if you can find it, the 32 Ohm version. The differences between them, if any, are very small and you can achieve the same/similar thing with good EQ. The Fiio E17K can run it loud enough if that's all you care about. The Dragonfly Black/Red will also be able to run it if you want another option. 

if i set the treble on e17k can the treble on 250 ohm smooth as 600 ohm version? can i set the treble at e17k if i use it just for amp, not dac?

 

[Dulalala]

  if i set the treble on e17k can the treble on 250 ohm smooth as 600 ohm version? can i set the treble at e17k if i use it just for amp, not dac?

Well I've never heard the 600 ohm version so I wouldn't know but EQ still works using line in (only amp).

 

[Benn Beckman]

  Well I've never heard the 600 ohm version so I wouldn't know but EQ still works using line in (only amp).

i ask you once again, will fiio A5 drive dt990 600 ohm to the level "enjoy" listening for me who aren't serious listener? i mean without losing soundstage bass etc. i don't know what it means thin, full body, harmonic, dynamic, sybilant etc since i new on audio
seems like it will be a great deal, dt990 600 ohm(arround $200) + fiio A5 (arround $120) + 64gb lexar micro sd (i don't know$)  only for $279
rather than dt990 250 ohm ($150-$178) and fiio e17k (arround $100)

 

[Dulalala]

  i ask you once again, will fiio A5 drive dt990 600 ohm to the level "enjoy" listening for me who aren't serious listener? i mean without losing soundstage bass etc. i don't know what it means thin, full body, harmonic, dynamic, sybilant etc since i new on audio
seems like it will be a great deal, dt990 600 ohm(arround $200) + fiio A5 (arround $120) + 64gb lexar micro sd (i don't know$)  only for $279
rather than dt990 250 ohm ($150-$178) and fiio e17k (arround $100)

I highly recommend you not to buy the DT990 600 ohm for use with a portable amp. Will it be able to drive it, probably. It really depends on how loud you listen to things but pushing the amp too much will create distortion regardless. Portable amps are not designed to run very high impedance headphones. 

 

[Benn Beckman]

  I highly recommend you not to buy the DT990 600 ohm for use with a portable amp. Will it be able to drive it, probably. It really depends on how loud you listen to things but pushing the amp too much will create distortion regardless. Portable amps are not designed to run very high impedance headphones. 

hihi i was tempted by the price and when I get a job, I plan to build a gaming pc, that's where i spend lot of money to buy good amp and the others for gaming. that's what I think right now.
ok i will think it again wheter to buy 250 or 600 ohm version. i will wait 1-2 month, if i got a job, i will buy 600 version but if not, i will buy 250+e17k instead.
if i buy the 250 ohm version, which one do you advice, pro or premium 250 ohm?