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Everyone going to canjam should be sure and find boomana and thank her for this post

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I disagree on the last part. If that was true we wouldn't have the R10/K1000/HE90. Saying you can enjoy the music the same with the K1000/HE90 /W5000 comparee to a 80.00 headphone over simplifies thing. Yes, I can enjoy music with 80.00 headphones, but the music will be less enjoyable.
Found the info I needed. Thanks
great stuff thanks
A big thanks to this useful thread!
Hey boomana, if you're still updating, maybe you can help clear up some of the common misinformation going around. I can't really think of too much at the moment, but when I keep seeing people telling others that certain headphones don't need amps because their impedance is low, that just kills me. I saw a post by Cool_Torpedo in Currawong's blog that explained things pretty well:

OK, here we go, since I can't find the thread nor the reply, I'll try to explain a bit -again- how the impedance/sensitivity thing goes.

Headphones' drivers are transducers that convert AC electricity into sound. Dynamic drivers, the most common ones, use a coil -wounded wire around a hollow cylinder- into a magnetical field provided by a magnet, to convert the AC voltage into movement which is transferred to a membrane. The membrane's movement is transferred to the air particles in front of your ear. For the frequency characteristics of that vibration, and its pressure level, your brain interprets it as sound.

The voice coil of the driver has an impedance, which is the opposition it presents to the AC source (the amp or any headphone out) to the free flow of electrons thru it. The lower that impedance, the more freely the electrons travel and the closer is the scenario to a short-circuit. This means that your source of electricity needs to pump more current intensity to correctly drive the transducer. So you can take two conclussions from this:
- What makes the AC to drive any coil is its voltage. The minute variations of voltage follow the signal originally recorded.
- The current intensity is important to keep the coil excited, and you need more current intensity the lower is the impedance. There's a relation between the current voltage and the intensity which is the power measured in watts. Power is the product of the voltage and the intensity: P=V*I. This is why amps are rated for their power output and not only for their voltage capabilites.

Up to this moment there's no relation between the impedance and how loud the transducer will sound. However there's a parameter named sensitivity which tells you how loud will a transducer "sound" for a given amount of power you're feeding it. The sensitivity is rated in dB/mW for headphones, so a pair of phones delivering a SPL of 100dB/mW are more sensitive (can sound louder) than a pair rated at 90dB/mW.

So the easy or hard to drive a pair of phones is, depends on both parameters, the sensitivity and the impedance. The worst case would be a pair of phones of very low sensitivity and also a very low impedance. Why? because they'll be asking to the source more watts to sound equally loud as a more sensitive pair, and an important part of that power will be asked in the form of current intensity, which is something that most portable players, headphone outs in receivers and players, etc. aren't designed to deliver. This is the case of cans like AKG 701 or Denon D5000.
If your cans are low impedance but are very sensitive (the case of Grados and most IEMs) then despite their asking more current from the source, they still manage to sound very loud because they need very little power to do so.

Most people tend to think that low impedance equals to louder sound, but this is plainly wrong. It all depends on the sensitivity and how much power the cans need to give a high SPL. Also take into account that not all manufacturers offer their sensitivity values and not all them do in dB/mW but do in dB/mV. It's not much of a problem, you just need to convert the mV in mW knowing the phones impedance.

Rgrds

Torpedo, if you see this, I'm assuming it's OK for me to repost. If not, my apologies.
what are the FS forums?

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 Originally Posted by dhp1161 what are the FS forums? and cans...= headphones?

FS Forums = the For Sale Forums, which are great places to buy excellent used gear.

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 Originally Posted by The Monkey Welcome to head-fi and sorry about your wallet. FS Forums = the For Sale Forums, which are great places to buy excellent used gear. And yes, cans = headphones.
haha yes i am going broke

are cans specifically the ones over the head? or they include all headphones like IEMS
Good question. I usually use the term in reference to full-size headphones, but I think "cans" arguably includes all headphones.
Quote:
 Originally Posted by The Monkey Good question. I usually use the term in reference to full-size headphones, but I think "cans" arguably includes all headphones.
thanks for helping a newbie out
just discovered a bunch of audiophile/headphone/amp forums and have been reading for hours on end researching
about 10 hours of research makes me want the cowon S9 and head direct RE2's and the E5 amp or PA2V2

i asked this on another forum but if anyone knows the PA2V2 which are 40\$ more than the E5's, is it worth it? does it increase the SQ a considerable amount?
dhp, my advice is to give boomana's first post one more read. Then head over to the various portables boards here and do some searches, and ask your question there. There's so much info, it will probably make your head spin. Good luck with your search!
Quote:
 Originally Posted by atothex Hey boomana, if you're still updating, maybe you can help clear up some of the common misinformation going around. I can't really think of too much at the moment, but when I keep seeing people telling others that certain headphones don't need amps because their impedance is low, that just kills me. I saw a post by Cool_Torpedo in Currawong's blog that explained things pretty well: OK, here we go, since I can't find the thread nor the reply, I'll try to explain a bit -again- how the impedance/sensitivity thing goes. Headphones' drivers are transducers that convert AC electricity into sound. Dynamic drivers, the most common ones, use a coil -wounded wire around a hollow cylinder- into a magnetical field provided by a magnet, to convert the AC voltage into movement which is transferred to a membrane. The membrane's movement is transferred to the air particles in front of your ear. For the frequency characteristics of that vibration, and its pressure level, your brain interprets it as sound. The voice coil of the driver has an impedance, which is the opposition it presents to the AC source (the amp or any headphone out) to the free flow of electrons thru it. The lower that impedance, the more freely the electrons travel and the closer is the scenario to a short-circuit. This means that your source of electricity needs to pump more current intensity to correctly drive the transducer. So you can take two conclussions from this: - What makes the AC to drive any coil is its voltage. The minute variations of voltage follow the signal originally recorded. - The current intensity is important to keep the coil excited, and you need more current intensity the lower is the impedance. There's a relation between the current voltage and the intensity which is the power measured in watts. Power is the product of the voltage and the intensity: P=V*I. This is why amps are rated for their power output and not only for their voltage capabilites. Up to this moment there's no relation between the impedance and how loud the transducer will sound. However there's a parameter named sensitivity which tells you how loud will a transducer "sound" for a given amount of power you're feeding it. The sensitivity is rated in dB/mW for headphones, so a pair of phones delivering a SPL of 100dB/mW are more sensitive (can sound louder) than a pair rated at 90dB/mW. So the easy or hard to drive a pair of phones is, depends on both parameters, the sensitivity and the impedance. The worst case would be a pair of phones of very low sensitivity and also a very low impedance. Why? because they'll be asking to the source more watts to sound equally loud as a more sensitive pair, and an important part of that power will be asked in the form of current intensity, which is something that most portable players, headphone outs in receivers and players, etc. aren't designed to deliver. This is the case of cans like AKG 701 or Denon D5000. If your cans are low impedance but are very sensitive (the case of Grados and most IEMs) then despite their asking more current from the source, they still manage to sound very loud because they need very little power to do so. Most people tend to think that low impedance equals to louder sound, but this is plainly wrong. It all depends on the sensitivity and how much power the cans need to give a high SPL. Also take into account that not all manufacturers offer their sensitivity values and not all them do in dB/mW but do in dB/mV. It's not much of a problem, you just need to convert the mV in mW knowing the phones impedance. Rgrds Torpedo, if you see this, I'm assuming it's OK for me to repost. If not, my apologies.
Thanks to you for reposting and insisting on this matter. I think it's very important that everyone knows how impedance and sensitivity work, so they don't make wrong assumptions based solely on their single values.

### Indeed

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 Originally Posted by Oggranak #2 is something I needed to hear back when I first came here. Sticky this indeed, lest others fall victim to the myth that portables are actually an alternative to full-sized amps...
I agree. I was buried under all the information and got confused.
But I still enjoy the gear I bought.
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