Deiz
100+ Head-Fier
- Joined
- Apr 6, 2007
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I've been searching for budget headphones for a friend. Likely to be driven by an iPod in the short term, and a Fiio E5 after that.
I extrapolated off of figures given for the Fiio E3: 70 mW @ 32 ohms, 12 mW @ 300 ohms.
Formula being: Output mW = 70 - (Resistance - 32) * 0.21641.
I realize it's a gross oversimplification, as output is likely nowhere near that linear (And if you exceed 356 ohms in my model, you start generating power.) but it should work for rough estimation.
My main question is, does impedance play into SPL when you're basing things off of sensitivity?
Let's take two headphones, the PX100 (32 ohms @ 1 kHz, 114 dB @ 1 mW) and the HD650 (300 ohms @ 1 kHz, 103 dB @ 1 mW)
Given that to increase the dB by 10, you must exponentially increase the power, the output of the headphones would be 124 dB and 113 dB @ 10 mW, respectively.
Now, the Fiio E3 is capable of supplying 12 mW @ 300 ohm, so the HD650 would, if my math is correct, output 113 dB + (12-10) / 90 * 10 dB = 113.22 dB, an utterly imperceptible increase.
On the other hand, the PX100 @ 32 ohm would receive 70 mW, and 124 dB + (70-10) / 90 * 10 dB = 130.67 dB, a substantial increase.
I am unsure of whether this makes sense, but from anecdotal evidence I'd say the HD650 outputs between a quarter to a third of the PX100's SPL at the same volume setting.
Also, the headphones I'm likely pointing him to are the 66 ohm, 99 dB sensitivity ATH-AD500s - I'd assume they'd receive 62.6 mW from the Fiio E3 and thus end up with a peak SPL of 114.84 dB, which again makes sense to me because while their impedance is drastically lower than that of the HD650, they're markedly less efficient.
I extrapolated off of figures given for the Fiio E3: 70 mW @ 32 ohms, 12 mW @ 300 ohms.
Formula being: Output mW = 70 - (Resistance - 32) * 0.21641.
I realize it's a gross oversimplification, as output is likely nowhere near that linear (And if you exceed 356 ohms in my model, you start generating power.) but it should work for rough estimation.
My main question is, does impedance play into SPL when you're basing things off of sensitivity?
Let's take two headphones, the PX100 (32 ohms @ 1 kHz, 114 dB @ 1 mW) and the HD650 (300 ohms @ 1 kHz, 103 dB @ 1 mW)
Given that to increase the dB by 10, you must exponentially increase the power, the output of the headphones would be 124 dB and 113 dB @ 10 mW, respectively.
Now, the Fiio E3 is capable of supplying 12 mW @ 300 ohm, so the HD650 would, if my math is correct, output 113 dB + (12-10) / 90 * 10 dB = 113.22 dB, an utterly imperceptible increase.
On the other hand, the PX100 @ 32 ohm would receive 70 mW, and 124 dB + (70-10) / 90 * 10 dB = 130.67 dB, a substantial increase.
I am unsure of whether this makes sense, but from anecdotal evidence I'd say the HD650 outputs between a quarter to a third of the PX100's SPL at the same volume setting.
Also, the headphones I'm likely pointing him to are the 66 ohm, 99 dB sensitivity ATH-AD500s - I'd assume they'd receive 62.6 mW from the Fiio E3 and thus end up with a peak SPL of 114.84 dB, which again makes sense to me because while their impedance is drastically lower than that of the HD650, they're markedly less efficient.
