[MrVitalic85]

So, what I understand from the last few post is that my presonus firebox ( 150mw, 60ohm ) is not fit to drive my akg. Nobody care but I paid my akg full price at almost 700$ 3 years ago when the akg 812 where brand new to the market. I dont hate my akg 712 , but they are so hard to understand that I still listen to my old shure 440 and will get a set of shure 840 because I need to. At first, I bought the 712 for mixing, but the are so fatiguing to my ear that they are left in the pouch.... maybe forever

 

[MrVitalic85]

My old passive yorkville ysm7 from the 90's where better (monitor, ... I know)

 

[MrVitalic85]

Nothing will be good enough for my akg..... Shure her I go.

 

[swagadelic]

So, what I understand from the last few post is that my presonus firebox ( 150mw, 60ohm ) is not fit to drive my akg. Nobody care but I paid my akg full price at almost 700$ 3 years ago when the akg 812 where brand new to the market. I dont hate my akg 712 , but they are so hard to understand that I still listen to my old shure 440 and will get a set of shure 840 because I need to. At first, I bought the 712 for mixing, but the are so fatiguing to my ear that they are left in the pouch.... maybe forever

Correct.

In your case you are getting severe under voltage there is both way to little power and way to little voltage.
Just imagine then how horrible my ur22 sounds which manages 6mw @ 40 ohm, lol.

So not only do you want roughly 100 - 1000mw @ 64 ohm (technically there is no limit, just be careful on the dial, since poor little k712 are rated for max 250mw) but most importantly you need around 8 ohm output stage (where 4-24 might be acceptable)

Sadly, nearly all interfaces and cheaper amps are no good on the k712. I can't think of a single good match for less than 500 eur

I'm sad to see you go to shure though, I had a pair of 440s a while...

 

[MrVitalic85]

Thx Swagadelic for the insight. I think I found a good match for a resonable price (199$), the burson audio play. ( cant copy/past link on my cell phone) .

 

[MrVitalic85]

For the 440, mine are shimmed to allow more space for the ears. Not ideal by any mean, but Ive been listening to them for the past 6 or 7 years... :/

 

[swagadelic]

no prob! just glad to keep spreading the truth about how hard it REALLY it finding a cheap headphone amp for these - and just how many who do own these - use them with incorrect amps/audio interfaces*) it makes me cringe and sad! and its AKGs fault!!!

anyway, the 840s are for "shure" much better than the 440s which i found was not nearly suitable for any type of mixing work.


(* nearly every single audio interface i can find, does not have suitable output impedance at the headphone output for the k712. i cant find one. so not only do they cost 250 bucks but REQUIRE an amp. and not only an amp wich much power (but honestly, they require very little power) but with decent output impedance. (since the require ALOT of voltage. much much much more than say a 300 ohm pair of cans, while technically the 300 ohm cans have much more resistance, its no longer about voltage but instead power (wattage) meaning alot of interfaces can drive nearly every 250+ ohm headphone just fine, since they are mostly above 40 ohm at the output stage - while they might be quiet instead. but rather proper sound but quiet- than fuked up sound but deafening.)



which is why the beyers 770s, 880s and 990s are so freaking popular is because they work out the box with 99% of interfaces. (while they instead might require an amp for power/volume. not for making them have accurate frequency respone, the "+3db bass boost" as promised, and the soundstage is far far smaller than they CAN be, on nearly everything below 500 eur)



god dammit, they *** around with customers creating headphones like the k712.

 

[Tshiknn]

Just dropping in here to say that that EQ i posted previously is working really, really well and that these headphones do sound nearly perfect to me at this point. I will say I resigned myself to fate and have now retained the 2kHz bump in its full glory. Seriously, if you're thinking your headphones sound a bit grainy, just try that EQ and see if it helps. It opens the treble up so much and makes it sound so much less congested.

 

[futuretrash]

I'd like to ask for some advice if I may (and thank you for all the info in this thread!)

I have a pair of K712's I use for music production and I'm trying to drive them a bit harder because when I compose -6db masters the output volume on my Motu Ultralite AVB is too low. I also understand these headphones really like a certain combinationor power / current, etc.

I'm currently building the DIYRE HC1: https://www.diyrecordingequipment.com/products/hc1
I'm powering it with a 12V DC wall wart: https://www.mouser.com/ProductDetail/553-WDU12-600

HC1 Headphone Amp Specs:

• Input Impedance: 20kΩ
• Current Draw: 10-20mA
• Gain: 0-10dB (customizable)
• Power Supply: 9 to 44VDC

I contacted Motu and after a long wait they finally tested the headphone output on the Ultralite AVB and it is: 3.8VRMS. I don't know what this means, but in another inquiry I was told the following:

"For 3.8VRMS, optimal gain is 1.0/1.8VRMS. This is very low, so I would personally opt for 1.0/2.5x to give some headroom. Source volume can always be slightly attenuated for hot signals."

So I gather this is the suggestion for how much additional power should be added tot he signal to be optimal for the K712's?

I have this kit on the way now, but as I've been reading through this thread, I understand now that it doesn't just need "power", it needs to have ceratin levels matched. So, my abilities are that I can build devices, I've made a summing amp, CAPI pre-amps (500 series) and fixed some of my synths and replaced screens, but this is mostly just following directions well.

Can anyone here suggest how I could modify the output of this amp to best match the K712's I'm making them for?

@swagadelic: Really, thank you, you're coments on this thread were like reading a small book on the subject, thank you for your contributions!

 

[swagadelic]

@futuretrash
thanks man, appreciated!

hmm whats the output impedance on that thing? thats really all that matters for these guys.
also that stuff about "optimal gain" and s*it like that, those vRMS values and all, i really dont know how much of that is actually important... at all..

if we talk about power meaning watts; then the k712 will work fine on anything . its really just volume.

but if we talk about power meaning voltage, then the output impedance is really all that matters. if its too high (desktop integrated amps and most studio interfaces; like any old hifi system or say the ur22) it will sound absolutely horrible. (and it does. its WAY WAY Too quiet while also suffering from terrible frequency response in the low end)

or; the output impedance is way way too small (0.1 and up to say 2 ohm) then they will sound horrible the other way, but at the same time will make you bleed and the drivers might pop (since they are rated at 250mw)

so yeah, output impedance is the thing here, and almost ONLY the thing.
i dont think ive ever seen a headphone be THIS picky before.
64 ohm with max rating of 250mw. its REALLY rare.
the "myth" about these being hard to drive is most certainly not a myth.

 

[futuretrash]

hmm whats the output impedance on that thing? thats really all that matters for these guys.

So, how do I figure this out, is this somethign I need to measure with my multimiter after I build it? Or is this something the DIYRE guys will just know?

 

[swagadelic]

@futuretrash
you can probably measure it, but its probably easier to just email and ask them, what the headphone ouput is set at. my guess its either something very small like 0.1-2 or something much higher like 40>.
which most amps are.

 

[futuretrash]

@futuretrash
you can probably measure it, but its probably easier to just email and ask them, what the headphone ouput is set at. my guess its either something very small like 0.1-2 or something much higher like 40>.
which most amps are.

Okay, I emailed them, I report back when I hear. TY! I've had these for a couple years now and the volume issue in my studio is driving me crazy, that and I'd like to know what these cans are really capable of.

 

[abmwinnoch]

I love my K712's, even if they are not that comfortable on my (small) head. I have found two headphone amps which bring out the best in them. My Chord Mojo and Moon 230HAD. Like others here, I found that anything less (and I tried a few cheaper amps) made them sound awful. Not just slightly disapointing, but flat and lifeless with no bass. With the right amp (there will be others I'm sure) though, they give such an effortless, natural, balanced sound -especially with vocals- that I find it hard to imagine bettering them at any price.

 

[swagadelic]

@futuretrash ill be happy to hear your update.

@abmwinnoch
chord mojo is excellent, congrats on having that
that one should indeed make the k712 sing, although not as much as the project headbox ds2b would, as its fully balanced with 3 ohm settings, allowing the k712 to sound better than hd650 with sonarworks correcitons.
sure, ill concede that out of the box, hd650 easily beats k712.

but when youve spent 500eur on a amp, and ur using sonarworks to correct the signature ; i think the k712 wins.
thats the tradeoff they made. they made them cheap, KNOWING FULL WELL they require an amp far exceeding its price.

my guess had they made them more amp friendly, the price rate would go up while still not being able to compete with hd650 out the box.
so i fully understand their business modell with these.

although i blame them for not giving out more information on what amps they REQUIRE. and the headbox i have to be perfectly clear, was the best headphone experience i had, and it was with the k712, and ive used hd650 extensively. the bt928 amp im currently using is miles ahead the ur22 output its not even comparable, i get the full frequency spectrum.
id say is a poor chord mojo.
but, with the headbox i felt they were another pair of headphones entirely. which is why the k712 doesnt really cost 250 eur. they cost 750 eur. and at that price the hd650 is an obvious choise seing its half that.