| Originally Posted by JohnD /img/forum/go_quote.gif There are no AKG K501 on eBay right now. Frankly speaking I don't want to wait. I have nothing against buying used online: I bought used L - lens several times more expensive than the discussed headphones. But I don't want to wait. As of my budget while I earn money for living I am reasonable and flexible. I have completed my photo inventory (for instance, carbon tripod or 30" S-IPS monitor included), so I may spend something . J&R have replied with $350 for HD650. |
| Originally Posted by boomana /img/forum/go_quote.gif The 501 and 701 can sound really thin without some serious power. |
| Originally Posted by Acix /img/forum/go_quote.gif I can highly recommend the Kontrol 1 sound card combo with the K702...NATIVE INSTRUMENTS : Products : AUDIO KONTROL 1 The K70X are low impedance...so, they don't really need a lot of power to drive them, like the 650. what they need, is a clean SS amp that is good with low impedance hp's. And yes, there is members here that try to drive the K-701 with a powerful tubes. And they just don't get it why the K701 sound start to crack...
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| Originally Posted by boomana /img/forum/go_quote.gif It's not the impedance of the 70Xs that make them a demanding headphone, it's the sensitivity. I've heard them with many different amps and sources, and without a powerful amp, they simply don't cut it. That's not to say you can't enjoy them, but you're really not getting the sq they were designed to give. They require some serious juice, and are one of the most amp dependent headphones I know. |
| Originally Posted by Cool_Torpedo /img/forum/go_quote.gif 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 |
| Originally Posted by grawk /img/forum/go_quote.gif I'm sorry, you're just wrong. Impedance and sensitivity are related but not synonymous. And the SPL phonitor isn't exactly a low end headamp. |
