Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: Amplifier for 600 Ohm headphones (Read 6405 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

Amplifier for 600 Ohm headphones

I did some search on this query but not much info comes out, ....
What would be the required 'driving' voltage of an amplifier to drive Beyerdynamic T1 ? These headphones have nominal impedance of 600 Ohm BUT their impedance, when having to generate bass frequencies, is about 1430 Ohm, centered on 80Hz. -www.innerfidelity.com/images/BeyerdynamicT1SN3964.pdf
Would 12 Volt driving voltage be enough to have bass, volume-wise, in line with the mid frequencies ?...or 15 ?...

T1 -
Volts RMS required to reach 90dB SPL: 0.436 Vrms
Impedance @ 1kHz: 683 Ohms
Power Needed for 90d BSPL 0.28 mW
Sensitivity: 102 dB SPL/V

Amplifier for 600 Ohm headphones

Reply #1 –
Quote
These headphones have nominal impedance of 600 Ohm BUT their impedance, when having to generate bass frequencies, is about 1430 Ohm, centered on 80Hz.
Don't worry about that!    Headphones are designed to be driven from a "constant voltage" source.    Of course, the voltage isn't constant with real audio signals but "constant voltage" means that the voltage doesn't change when the load impedance changes (within specs and within reason).    So, if you are testing frequency response and you drive the headphone with 1V @ 1kHz, you also drive it with 1V @ 80Hz.    The headphone will take less current and less power from the amp at 80Hz, but the frequency response will be "correct".

With low impedance headphones and poorly designed headphone amps, this impedance variation can be an issue, but with 600 Ohm headphones (or a decent headphone amp) it's not an issue.

There is some conflicting information in those specs...  90dB at 0.43V does NOT agree with 102dB @ 1V. 

So, lets take the Beyerdynamic published spec of 102dB @ 1mW (600 Ohms nominal).  (I only found the German language spec sheet, but the specs are fairly easy to figure out.)

Power is (Voltage squared)/Impedance.    So, 0.77V gives you 1mW and 102dB.

Decibels relative to voltage are calculated as 20Log(Voltage/Voltage Reference).    20 x Log(12 / 0.77) = 23.8dB.    That means about 24dB louder than the 102dB reference or almost 126dB SPL at 12V.    (Beyerdynamic's specs also say 126dB is the maximum).


P.S. 
It's also handy to know that if you double the voltage you get +6dB (or -6dB if you cut the voltage in half).    Or, 4 times the voltage is +12dB, etc.   

Power ratings (mW) aren't that useful with headphones (we want to know the voltage), but a doubling of power is +3dB.  When you double the voltage, you are getting 4 times the power (+6dB) because you are also doubling the current (assuming the same impedance).

Amplifier for 600 Ohm headphones

Reply #2 –
I pretty much like the O2+ODAC. It can pretty much drive every dynamic headphones.

Here's the specs: O2+ODAC

 

Amplifier for 600 Ohm headphones

Reply #3 –
Quote from: Aldem on
I pretty much like the O2+ODAC. It can pretty much drive every dynamic headphones.

Here's the specs: O2+ODAC



The specs are unfortunately indirect, so I use a little spread sheet to put them into more standardized terms:

Code: [Select]
power    impedance    Voltage
0.633    33    4.570448556
0.355    150    7.29725976
0.088    600    7.26636085


In comparison the Topping NX-1 is rated at 3 volts output, while your typical portable digitial music player and PC headphone jack runs around 1 volt.