Will a fiio e7 power an AKG K702? (To reasonable levels)
May 15, 2012 at 10:21 PM Thread Starter Post #1 of 20

MaximumSandvich

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I am considering getting an AKG K702 after having to send my DT990 premiums back to the seller because of a defective driver. I heard these are more difficult to drive than the DT990s.
 
I'm not looking to push them to the absolute max, and I don't need extreme volume. In fact, the dt990 250 ohm variant sounded loud enough to me from my laptop/ipod alone, so I'm not a major volume nut. I Just want it to sound somewhere near its true sound quality.
 
May 15, 2012 at 10:38 PM Post #2 of 20

fabio-fi

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Nope, the E7 as amplifier is not powerful enough to drive the AKG.
 
May 15, 2012 at 10:51 PM Post #4 of 20

mikeaj

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FiiO E7 is limited to about 50 mW into the ~62 ohms of the K702 (1.7V).  That's probably more than any laptop except rare exceptions.  At higher impedances it's still limited around 1.7-1.9V.  Taking the least sensitive of the K701 and Q701 sample data on InnerFidelity and rounding down, that would be around 104 dB SPL maximum from the E7 with those headphones, pretty loud for a lot of recordings.
 
If you look at the sensitivity data for DT 990 250 ohms, assuming the Pro isn't quieter than the Premium, at a given voltage, the DT 990 250 ohms should be quieter than the K702:
http://doctorhead.ru/images/misc/catalog/beyerdynamic/dt_990_pro/fr.png
http://doctorhead.ru/images/misc/catalog/akg/k702/fr.png
 
And the voltage an E7 can supply to the K702 exceeds what a typical laptop or an iPod could put into a DT 990 250 ohms (or any headphone).
 
So the K702 with E7 will be louder than DT 990 250 ohms with a laptop / iPod.
 
May 15, 2012 at 11:00 PM Post #5 of 20

tdockweiler

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IMO the K702 isn't really worth using with 90% of the portable amps out there.
I don't even really suggest it with the E11. I only think that's a good combination if you get some additional power from your player and don't use the LOD.
 
One portable that does a good job with the Q701 is the Total Airhead. Love that thing.
 
I hate to admit it, but I used the K702 for 2 years with that thing when I didn't have a clue. Sounded pretty good actually!
If I recall it was an Ipod Video with a 3.5mm cable.
 
I did have a decent receiver that could drive it, but no desktop amp.
 
May 16, 2012 at 12:29 AM Post #7 of 20

theeyealtering

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I've found that the K702 can get loud enough on most things, but just doesn't sound right unless its run off a pretty decent desktop amp. It's amp requirements are totally different from higher impedance headphones, where the concern there is mainly about getting the volume.

Unless you're planning on forking out for an amp, I'd definitely go with the Shure.
 
May 16, 2012 at 1:10 AM Post #8 of 20

MaximumSandvich

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Quote:
I've found that the K702 can get loud enough on most things, but just doesn't sound right unless its run off a pretty decent desktop amp. It's amp requirements are totally different from higher impedance headphones, where the concern there is mainly about getting the volume.
Unless you're planning on forking out for an amp, I'd definitely go with the Shure.

 
Alright, since I'm mostly looking for sound quality I will probably end up not getting the AKGs as I don't have $300+ for an amp
 
May 16, 2012 at 1:18 AM Post #9 of 20
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I'm sure you don't need anywhere near $300 to make the AKGs sound good.
 
May 16, 2012 at 1:25 PM Post #12 of 20

IEMCrazy

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Quote:
+1 on the O2. It's a great amp, and has absolutely no problem with the 702s...even on battery power.

 
+2 on the O2.  Almost as neutral as a Phonitor, plenty of power to spare even on batteries.   K702 + a neutral SS amp like O2 is an analytical detail-freak's dream!
 
 
Quote:
I've found that the K702 can get loud enough on most things, but just doesn't sound right unless its run off a pretty decent desktop amp. It's amp requirements are totally different from higher impedance headphones, where the concern there is mainly about getting the volume.
Unless you're planning on forking out for an amp, I'd definitely go with the Shure.

Quote:
FiiO E7 is limited to about 50 mW into the ~62 ohms of the K702 (1.7V).  That's probably more than any laptop except rare exceptions.  At higher impedances it's still limited around 1.7-1.9V.  Taking the least sensitive of the K701 and Q701 sample data on InnerFidelity and rounding down, that would be around 104 dB SPL maximum from the E7 with those headphones, pretty loud for a lot of recordings.
 
If you look at the sensitivity data for DT 990 250 ohms, assuming the Pro isn't quieter than the Premium, at a given voltage, the DT 990 250 ohms should be quieter than the K702:
http://doctorhead.ru/images/misc/catalog/beyerdynamic/dt_990_pro/fr.png
http://doctorhead.ru/images/misc/catalog/akg/k702/fr.png
 
And the voltage an E7 can supply to the K702 exceeds what a typical laptop or an iPod could put into a DT 990 250 ohms (or any headphone).
 
So the K702 with E7 will be louder than DT 990 250 ohms with a laptop / iPod.

 
The trouble with that figure is, while it will drive it loud, it will not drive it loud across the entire frequency spectrum and leads to some measure of frequency shift especially at the upper range.  K702 has wildly non-linear impedance as frequency goes up.   Well above that 62ohm rating at the center.   Planars on the other hand are famed for linearity, so they rarely go out of step with the frequency response.  K70x gets really wierd when it gets frequency shift.
 
But you don't need a $300 amp either.  O2 and the like should do fine.  Maybe (maybe?) even a cMoy or E11, but that's a little more questionable.  Despite its amping needs, K70x is a great deal right now for the level of detail and soundstage it provides (assuming you dig analytical sound) at its price point.   It's sort of a really, really, really cheap HD800 (an exaggeration, but it's on the same quest for neutrality.)
 
Jun 27, 2012 at 4:30 AM Post #13 of 20

Ampeezy

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Dude the Fiio E9 will serve you well with the K702. That's the setup i use and the bass on these supposedly bass-anaemic cans is quite good. the E9 should be about $100 on Amazon.
 
Jun 27, 2012 at 6:05 AM Post #14 of 20

genclaymore

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The E9 is a good amp, but the Default OPA2134 isn't a good match for the AKG 702. I used to own a Fiio E9 and the AKG 702 my self, tho mine E9 had the socket. The newer models suppose to have the opa2134 fused with the pcb directly making it unchangeable. But I had to swap out the OPA2134 inside the Fiio E9 I had to another op-amp before I became happy with the setup.
 
Granted the E9 will power the AKG 702s, but you might not like the sound signature of the E9 with the AKG 702's.
 
Jul 12, 2012 at 12:59 AM Post #15 of 20

Ampeezy

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Quote:
The E9 is a good amp, but the Default OPA2134 isn't a good match for the AKG 702. I used to own a Fiio E9 and the AKG 702 my self, tho mine E9 had the socket. The newer models suppose to have the opa2134 fused with the pcb directly making it unchangeable. But I had to swap out the OPA2134 inside the Fiio E9 I had to another op-amp before I became happy with the setup.
 
Granted the E9 will power the AKG 702s, but you might not like the sound signature of the E9 with the AKG 702's.


I love my setup, but i guess its because i haven't heard better. I'll upgrade my amp in due time though. Will the Schitt valhalla be a good fit?
 

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