[satasha]

This site really confuses me with all the contradictory opinions. Anyway, here is something simple I need to know: If a portable device (iaudio m3) says it has an output of 16 ohms, and a headphone such as the Sennheiser PX100 says it has an Impedance of 32 ohms Does that mean that they will be vastly underpowered? What about the Sennheiser HD 555 which has an impedance of 120 ohms? Amps are so expensive, often more than the headphones! I just want to buy a headphone or 2 that would work with this player (one for home and one for street use). This should be a simple thing! Anyway, thanks to anyone who can answer my question!

 

[commando]

We're all confused here...

... and the answer to your question is plug it in and see how you like it. The only thing that matters really is if you enjoy the music.

 

[satasha]

Umm.....commando, I am not sure you answered my question. Are you saying that the headphones will produce sound under those conditions but not as loud or driven?

 

[commando]

I'm not really sure about the technical aspect, but it should be fine. Cheap headphones like that can be driven by pretty much any portable device. What I really meant was try it and see, but if you can't it should work fine anyway.

 

[satasha]

Ok, thanks. I guess I'll wait for a more technical explaination from someone around here.

 

[Jorg]

It depends on the player. My one my Sony CDP produced enough volume with 120 Ohm hps, another very quiet and there were a lot of distortions, another produced quiet sound with no distortions (I guess it's sound was limited by engineers so one couldn't hurt hearing).

So better choose the headphone and then try it with the player.

BTW If the specs of the player show that it's output power is more than 20 mW, than it's ok with hps around 150 Ohm max.

EDIT:And the volume depends not only on the impedance but more on the sensetivity.

 

[Reck45]

Yea right...creative says the jb1 has a lot of output(100mw) and it can't drive the 555s for ****. They need an amp esp for portables. Sure you'll get sound but it's will have no body at all. I don't recommend using anything but 32Ohm phones without an amp....

 

[satasha]

Hmm... the specs say: Output 16 Ohm earphone : 20mW+20mW

 

[Rempert]

The impedance at the output of a player vs. the impedance of the headphones is not enough information to say whether the player can properly power the headphone or not. In practical terms, I don't think this information tells us much at all. For instance, if I recall correctly, Sennheiser HD600 is only intended to be used with very low output impedance, even though they are high impedance cans. We would need more information about the power output capability of the source, and also the sensitivity of the headphones, to say anything based on numbers.

Something like PX100, being fairly low impedance and clearly designed for portable use, is probably a safe bet to at least drive to listenable levels out of your player.

 

[satasha]

What is sensitivity measured in? I looked at the specs on those phones and I don't see anything that looked like sensitivity.

 

[Anders]

Link to Head-Fi's sister (brother?) site with information on impedance and other useful things.

http://headwize.com/articles/hguide_art.htm#sens

 

[JaZZ]

Quote:

Originally Posted by satasha Hmm... the specs say: Output 16 Ohm earphone: 20mW+20mW

16 ohm is the impedance of the earphone with which the amp will provide 20 mW per channel. With a 32-ohm headphone it will provide something like 10 mW per channel. Solid-state amps, even such built in the headphones outputs of portables, have quite low output impedances (between 0 and say 5 ohm), but these numbers don't say anything about the recommendable headphones anyway. If an impedance is mentioned in the context of a power indication, it's usually just to give a reference for the latter.

 

[satasha]

Thanks for the replies!

"Sensitivity (loudness): A measure of headphone efficiency in dBs SPL per milliwatt of input.........When shopping for portable headphones, look for a sensitivity rating of 100 dB or greater."

Is this the same as SPL? HD 555s have 103dB max and characteristic Spl, the PX100 has 114dB. I am theorizing that I won't need an external amp given the above information, but what most of you are telling me is that it varies a lot.

 

[TCC-2k7]

Basically, for any sort of portable, unless you want to lug around an amp, you're not going to be driving any Senns besides the PX100/200s, or anything really above $100 in price. The sound and output you'd get just wouldn't be what you'd want. I'm not knowledgable on the science behind this stuff, but I do know for a portable audio device, go for portable headphones. I have an iPod, and I have used both the Senn PX200s and the Koss PortaPro2s with it. The Senns are great, but kind of placement sensitive; bass response is dependent on getting the phones EXACTLY in the right spot (i've heard this isn't an issue with the PX100s, or is less so). The Koss' are a good for a portable given their *sarcasm* outrageous price of $35 USD. Both are easy to power though and sound great for the price.

 

[satasha]

Right on TCC-2k7. I guess I could fork over some money for a small cmoy type amp for home use. I realize it isn't by the standards of this board, but It just seems excessive to me. Maybe I could route the M3 through my stereo which seems to have no problem with my AKG 240's.