Headphone Amplifier HELP

[Pepper81]

Hi Guys, I need Your Help

I've an ALL IN ONE Ampli+Dac by FX-AUDIO
The model is FX-AUDIO X6MKII
Taking a look at the specs I've found this:

No chance to find The Output impedence of The Amplifier,I've find This

Output Power 940 mW @ 16 Ohms, 900 mW @ 32 Ohms, 700 mW @ 64 Ohms, 450 mW @ 120 Ohms, 200 mW @ 300 Ohms.

My question is: Is this Amplifier capable to drive HD600 safely?

I'm using this calculator

HD600 Power Needed

Safe 85 db 0.07 mW
Moderate 100 db 1.98 mW
Fairly Loud 110 db 20.01 mW
Very Loud 115 db 63.08 mW
Painful 120 db 199.69 mW

If I f I have correctly interpreted the numbers, to manage the Peaks of Volume, I need 199.69 mw
My amp is able to manage 200mw at 300 ohm
Is it correct?

Thanks

 

[solderdude]

Is this Amplifier capable to drive HD600 safely?

YES.

120dB SPL peak in the bass is not painful.
Peak SPL is not the same as average dBA numbers on those familiar plots.

Output resistance is 22 ohm or 33 ohm (difficult to see) and thus no issue here.

 

[Pepper81]

Thanks for your reply
A value I don’t understand is VOLTAGE

Safe 85 dB SPL 0.14 Vrms
Moderate 100 dB SPL 0.77 Vrms
Fairly Loud 110 dB SPL 2.45 Vrms
Very Loud 115 dB SPL 4.35 Vrms
Painful 120 dB SPL 7.74 Vrms

Is it the capacity of the Power Supply?
Is it enough a power supply stock 5V?

 

[AnalogSteph]

If you want to output 7.74 Vrms ~= 22 Vpp, you need internal power supplies of at least +/-11 V, probably a bit more. The DAC-X6II comes with a 12 V (up to 1 A) power supply, so it likely has an internal DC/DC converter to generate -12 V from that, this is quite a common approach. This basically gives you +/-12 V at a bit under 0.5 A each. Peak supply current at 940 mW into 16 ohms is ~0.34 A, probably limited by the TPA6120A2 first (which is not too happy driving <60 ohms anyway). Hope that explains your question.

 

[DVDdoug]

A value I don’t understand is VOLTAGE

Power (watts or milliwatts) can be calculated as voltage squared/resistance. This is why it's "hard" to drive high impedance headphones.

This is the RMS voltage which is 0.707 x peak or .354 x peak-to-peak. (The peak and peak-to-peak is limited by the power supply.)

Amplifiers are essentially "constant voltage", which means the voltage doesn't change (or doesn't change very much) when you change the load impedance. The voltage does drop if the load impedance drops too low (relative to the amplifier's source impedance) and the amplifier can't put-out the "calculated" current or power with the particular load.

 

[solderdude]

Thanks for your reply
A value I don’t understand is VOLTAGE

Safe 85 dB SPL 0.14 Vrms
Moderate 100 dB SPL 0.77 Vrms
Fairly Loud 110 dB SPL 2.45 Vrms
Very Loud 115 dB SPL 4.35 Vrms
Painful 120 dB SPL 7.74 Vrms

Is it the capacity of the Power Supply?
Is it enough a power supply stock 5V?

The voltages behind the dB numbers are the output voltages of the amplifier that are required to reach the SPL value next to it.
The max. output voltage of an amplifier is always limited.
The max. output current of an amplifier is always limited.

How high the output voltage of an amplifier can be reached depends on internal voltage rails and the used circuits and whether or not it is balanced or not.

The power supply voltage of an amplifier can but doesn't have to be an indicator of the max. output voltage. This depends on the circuits used inside the amplifier. Portable amps for instance can have a USB input plug (5V) yet can have internal voltage rails of +/- 12V.

The only way to know how much output voltage and current is available, and thus to know how loud a particular headphone can go is to look at the output power in 300 ohm and in 16 ohm (when given) and when one knows the sensitivity (dB/V) of the used headphone.