[Question]

Hi all

I tried my new k701s with Mbox2, with an echo indigo, and an old pioneer receiver. Probably these all three were not sufficient to feed this cans.

I feel a little bit confused in positioning k701 against 7506. One fact that I couldn’t clearly understand is, despite they share similar impedance and sensitivity   I can not get any comparable volume from k701.

 

 

[argentum]

Quote:

Many other members and I have covered this topic in other threads. Impedance is just one of the factors that we have to consider to foresee how demanding on an amp or HP output a pair of cans is. It's true that impedance on AC is not the very same as resistance on DC, but considering that many HPs have quite flat impedance curves across the frequency response, with flat phase angles, it's quite safe equaling them when speaking of HPs. Looking at things this way, it's also true that the higher the impedance the phones have, the more opposition they present against the current flow, so they seem to be needing more power. But this is not the whole picture. You need to see the heapdhone as a mechanical transducer which asks for electrical power to produce sound pressure level. And here is when sensitivity comes into play. Sensitivity tells you how loud the phones will sound when applying a mW of power on them. If you have very sensitive headphones, something like 115dB/mW, it doesn't matter what's their impedance, with very little power they'll sound loud and quite good. The higher is their impedance, the less current intensity they'll ask from the output, so they can be even easier to drive than an equally sensitive pair of phones having lower impedance. Remember that power is a function of Voltage and current Intensity. More impedance asks for more voltage being all things equal. The reason why most IEMs don't need an amp to sound good is not their lowish impedance, is their high sensitivity which in most cases is well above 110dB/mW. But this high sensitivity has its tradeoff, which is that very low voltage signals, like hums and noises in the source, will be clearly heard. As long as the sensitivity of the phones goes decreasing, you need more power to make them sound equally loud. Exactly the double of power for every 3dB you decrease the sensitivity. Hence phones rated at 97dB/mW will need 64 mW to sound at 115 dB, while the cans having that 115dB/mW sensitivity need just one miliwatt! To make matters worse, if those cans at 97dB/mW are low impedance, they'd be asking for that power more in the form of current Intensity than in voltage form. If that's clear, then it's quite easy to understand that impedance means nothing alone, since also sensitivity should be considered, and that having a combination of low impedance and low sensitivity, is quite demanding on the power source. Rgrds

I quoted Cool Torpedo's response to a clueless troll in another thread. K701 are pig to drive. AKG is low impedance can with low sensitivity. Don't let yourself be fooled by AKG specification list, which quotes sensitivity to be 105 dB/V . In dB/mW it is actually around 93, hence it is quite current hungry phone. K701 is airy, lean, neutral, somewhat bass shy, has wide soundstage. Some say that K701 needs at least 300 hours burn in , but I don't belong to this camp. Sound definitely changes, but imho it isn't as dramatic change as many people here are implying. Btw I don't consider you to be clueless troll

so there is no need to be offended.

 

[StanleyB1]

You bought the K701 and you expect miracles from it today

??? First of all, you are going to have to suffer the burn in time. I reckon till the end of this month, and possibly most of the next, before the K701 will behave like a grown up product. They say it also needs a lot of current in order to perform well. I believed that story for a long while myself, since I could only get it to sound good from the headphone output on one of my 100w amplifiers. Luckily for me I managed to knock up a far more convenient solution with a few opamps.

It is possible to drive the K701 from most headphone outputs on an integrated or pre-amp. I have a Kenwood C-2 Basic pre-amp that I can also drive it with. But first I had to modify the pre-amp headphone out. Otherwise that K701 hardly sneezes loud enough.

 

[Question]

Thanks to your replies and "K701 appreciation thread!".

Since there's that 200mw limit what could be a good voltage/current capacity for a candidate amp?
Are those Fatmans recommendable? I see one at a local store like "iTube 1xx".

Thanks in advance

Question

 

[Question]

Yesterday I remembered that I had a small sub-mixer. Connected them, and voila
 
It seems, these are capable of handling lots of bass as long as your amp feed them properly

In summary I started to like them

Q

 

[pockits]

well, look, I think you are going to be fine.. You have to wait and see.. I mean, hear.... Leave them on all night every night with a moderate output level (volume), and if you can, with an audio burn in CD, wich is for me the best way of burning in, cuz the levels don't change, is not the audio tracks itself.... Or use Densen Dmagic.
But remember, leave it ON with sound for let say, mmmm 30 days... and you'll see... I mean.. hear the difference.

Cheers