[genclaymore]

Modding the cable wasnt the first thing that came into  my mind when  I got these, it was their sound signature then the deal i saw them for when i got them.

 

[AudioA]

Are you guys serious about the fiio E-9?  Really? After all the reviews about how difficutl to pair a the 701 with a amp. E-9 powerful enough?

 

[jcx]

E-9 specs are OK for K 701 drive - the TPA6120 has the current output ability, the 600 Ohm spec and users manual verbage about "power converter module" suggests the 15 Vdc supply is being inverted for a dual rail internal supply so there's no shortage of V output either
 
(the performance is verified in another review you can find online)

 

[Arleus]

The E9 will put 80mW into 600 ohm headphones, and a full Watt of power into 16 Ohms.
 
NwAvGuy wrote a very good article on calculating power requirements on his blog (google it). With the sensitivity of the 701 at 105dB/V, and the RMS voltage output of the E9 at ~7.07Vrms (he states that the peak to peak swing is approx. 20V), the 701 and E9 combo should, according to my very rough calculations, reach an extremely deafening 121-122dBspl of volume. Even with music with very large dynamic ranges of 30dB, the quiet bits will still be at 91dBspl - still plenty loud enough to cause hearing damage over a long period.
 
Power isn't the problem - it's the output impedance that's the issue here. At 10 Ohms, we've got a damping factor of 6.2, a little on the low side. This might lead to 'tizzy highs', as Tyll likes to call them, or uncontrolled bass. The output impedance might also have an effect on the frequency response of the headphones. Looking at the impedance curve of the 701 on innerfidelity (Tyll's site), the impedance starts to shoot upwards after about 6kHz. It's pretty flat before then. 
 
An increase in impedance at 6kHz should mean that the headphones get delivered more voltage than they 'should do' at frequencies above this, since the higher impedance of the headphones is a larger proportion of the voltage divider formed with the output impedance. Assuming I've got this the right way around (someone correct me if I'm talking rubbish), maybe this is why a lot of people find the 701 very bright, and others don't mind so much. Maybe those that find it bright use amps with high output impedances? Hmm, that's an interesting (though possibly totally wrong) theory.
 
With all that said though, I own a 702 and an E9, and find them to sound very satisfying together, so I don't see what's wrong with recommending it as an inexpensive amp to go with the AKGs.

 

[genclaymore]

There isnt nothing wrong with suggesting it, it just people judge it for its price and not how it performs. I seen it a few times around this forum. That people judge it because it affordable. But I betting if it cost more then what it cost now people wouldn't be so quick to judge it. The only reason i got the E9 is because of it performs for the price and I was on a budget. I enjoying it even more now because I finally got around to getting the tools needed to open it up and change its opamps.
 
 

 

[Willakan]

 
Quote:

 
Power isn't the problem - it's the output impedance that's the issue here. At 10 Ohms, we've got a damping factor of 6.2, a little on the low side. This might lead to 'tizzy highs', as Tyll likes to call them, or uncontrolled bass. The output impedance might also have an effect on the frequency response of the headphones. Looking at the impedance curve of the 701 on innerfidelity (Tyll's site), the impedance starts to shoot upwards after about 6kHz. It's pretty flat before then. 
 
An increase in impedance at 6kHz should mean that the headphones get delivered more voltage than they 'should do' at frequencies above this, since the higher impedance of the headphones is a larger proportion of the voltage divider formed with the output impedance. Assuming I've got this the right way around (someone correct me if I'm talking rubbish), maybe this is why a lot of people find the 701 very bright, and others don't mind so much. Maybe those that find it bright use amps with high output impedances? Hmm, that's an interesting (though possibly totally wrong) theory.
 
With all that said though, I own a 702 and an E9, and find them to sound very satisfying together, so I don't see what's wrong with recommending it as an inexpensive amp to go with the AKGs.

Prettymuch. I wonder how many people, who own monstrously expensive audiophile amps with high output impedances, concluded that the headphone was unlistenable after coming from higher impedance 'phones such as the Senn' HD650s - assuming that their amplifier couldn't possibly be at fault. 
 
 

 

[grokit]

Uncontrolled bass on a K701 is something I would like to hear.

 

[Mad Max]

plug it straight into an ipod?

 

[grokit]

Oh, that clipping sound 

 ?

 

[Mad Max]

clipping?
no lack of control?
All of my headphones would suffer a lack of bass control (among other things) to some degree when I ran them straight out of my ipod.

 

[DomieMic65]

.... I enjoying it even more now because I finally got around to getting the tools needed to open it up and change its opamps.
 
 

...and what opamps do you suggest for the E9 with the K701s???
Another very good upgrade imho would be a better regulated power supply.. the one that comes with the amp is rubbish!!!

 

[AudioA]

Very interesting. A review that finally talks about the technical part. I am so tired of reading about how someone finds music to be low, great, fluid like and just really opinion. But at the same time trying to understand what the specs are really talking about is like learning a different language. But when you understand science behind the music it will help you understand what your really being sold/told. the 701  I am having just as much fun listening to the music as learning how it works. So farther down the rabbit hole i go.  Still need an AMP. The 701 are 62ohm 105db max input power 200mW , What does it all really mean? But i need it explained  like you would to a child.

 

[Mad Max]

 
Quote:

...and what opamps do you suggest for the E9 with the K701s???
Another very good upgrade imho would be a better regulated power supply.. the one that comes with the amp is rubbish!!!

OPA602B kills all.  It will require 2x1 adapters.

 

[genclaymore]

The only problem is normal adapters will not fit, you will have to make a dual to single 8dop adapter that will fit in the headphone output's Dip8 socket. Because it pretty close to the 6.3 output connector. I tried OPA2107AP,OPA2111AM and LT10364 in the Fiio E9. Try some of those or some other kind and see which ones you like.I was gonna use 2x LT1028ACN8 my self but the adapter I had didnt fit. I also wondered if a OPA-Earth would fit on it side in it.
 
Edit: the Screws on the E9 needs a Torx T5, the Plus screw driver on the rear is screwed into the pcb RCA connector of the pcb it self. Also you may have to use  a angle tool to lift the opamp out if you cant movve the E7 connector board and dip out the way to pull the pcb out to get full access to the E9 pcb.

 

[grokit]

 
Quote:

clipping?
no lack of control?
All of my headphones would suffer a lack of bass control (among other things) to some degree when I ran them straight out of my ipod.

I just use IEMs for the most part straight out of an iPod, but I have tried a few full-size headphones with medium-powered portable amps and the HE-5 and K701 would both clip out in the same way, when pushing the volume during complex dynamic passages.