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AKG K712 Pro Review (Headphone)

Robbo99999

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Do you know the Chinese and Austrian versions use identical pads (when new) though?

If your goal is to test whether there's a difference between the two headphone versions, you can't make that assumption.
Good point you make to Luke, but we don't know the answer to that unless we research it. Previously when I looked into Chinese vs Austrian on the K702 side I came to the conclusion that they were the same headphone specification, I'm assuming that's the same for the K701. If that's a reasonable assumption then it does make sense to use the same newer pads on both K701's to remove the pad wear variable, at which point you'd just be assessing unit to unit variation. To be honest I'd probably expect Amir to measure both headphones with the pads that are already attached due to simplicity & ease, and it would also take into consideration your warning points you made. Either way would be good to see the K701 measured on this site, I'd prefer to see the K702 measured, but still the K701 is also good to see.
 

Snarfie

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I am looking for the AKG K514 MKII headphone measurments. The cost to sent it here from Holland does not make much sence but it would be great if some body could sent Amirm such sample from the States.
 
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bracko

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I simply adore equalized k712 :)
 

Mechanic

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This is a review and detailed measurements of the AKG K712 Pro open back (gaming?) headphone. It is on kind loan from a member and costs US $327 on Amazon.

I find the K712 cute and cheerful:


View attachment 166565

The huge cups (64mm inside diamater/24mm deep) fit over my ear fine. But I thought the cups didn't compress enough and after a while, I could feel their slight pressure on head. Ditto for the headband. I would rate it as 90% comfortable.

Plastic components help keep the weight lower:
View attachment 166570

A mini XLR socket is provided which you can use to create balanced or unbalanced connection. I used the aftermarket nice twisted cable the owner had supplied.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few kilohertz so keep that in mind as you read these tests. If you think you have an exact idea of a headphone performance, you are likely wrong!

The large cups made an easy job of mounting them on my fixture and getting good measurements on first try.

AKG K712 Pro Measurements
Let's start with our usual frequency response measurements:

View attachment 166571

Compliance with our target is only in the 200 to 500 Hz (I calibrate to 420 Hz). Very hard to imagine what they were thinking in the response between 500 Hz and 5 kHz. There is massive shortfall. We also have the usual bass droop.

Relative response shows that we need very large compensation at 4.5 kHz:
View attachment 166572

Distortion is very good at lower levels:

View attachment 166577

View attachment 166578

Impedance at 1 kHz is same as advertised but is variable:

View attachment 166579

Bass tuning is at 100 Hz and hence the reason response drops below that.

View attachment 166580

They are not very sensitive so you definitely need a headphone amp:
View attachment 166582

Group delay is reasonable in balance:

View attachment 166581

AKG K712 Pro Listening Tests and Equalization
I only listened for a minute before reaching for EQ. It sounded very closed and improper to me out of box. EQ development is a bit challenging due to troughs not matching the shape of a parametric filter. Still, I lucked out and with just three filters massively improved the response:

View attachment 166583

High level of filter amplitude causes easy clipping so I had to pull the overall levels down which means you need even more drive from your amplifier. I also could not push the bass enough as distortion would set in. As is, deep bass was good with EQ.

I really enjoyed the spatial qualities that equalization brought to these large drivers/cups. Turning off the EQ made this collapse. As usual, this is caused by lack of energy in the 2 to 5 kHz without EQ.

Conclusions
I was very surprised at the response of this headphone. I looked up the announcement data and it was 2013. I think Harman had already performed its headphone research by then. So I have to think the AKG folks were not on board with it in development of K712 Pro as it doesn't remotely comply with their preference curve. And if any headphone needs to comply with that standard is the K712. It is impossible to make a case that you want to filter out all the music spectrum in 1.3 and 3.4 kHz!

I can't recommend the K712 Pro without EQ. With EQ, I am not super happy with deep bass response but spatial qualities are good enough to push me to put it on my recommended list.

-----------
As always, questions, comments, recommendations, etc. are welcome.

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It seems to me from the graph that the dip is more at around 3.5 k not 4.5. Btw, I have those headphones (lucky enough i found them at 100$ used). I think that the dip coresponds to a higher sensitivity of the ear in that region so you won't really hear it.
What i found using those headphones for the last 1.5 years is they're very amp dependent. I tried 5 amps before finding one that i like with those: a vintage Luxman L190 speaker amp. With this one, it has better bass and no sibilance at all. About eq-ing, i tried and except for the bass, the 712 sounds better uneq-ed. Eq-ing seem to mess with their tuning in a bad way. For the bass, yes, they do lack sub-bass, but i wouldn't add more then 3-4 db. Above that, the lack of speed in the bass becomes too obvious.
 
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tifune

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. I tried 5 amps before finding one that i like with those: a vintage Luxman L190 speaker amp. With this one, it has better bass and no sibilance at all.

30W at 8 ohm into headphones? Yes, I would expect "better bass"
 

bracko

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30W at 8 ohm into headphones? Yes, I would expect "better bass"
Do you mean that Luxman outputs 30W through its headphone output?
 

Jimbob54

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Ah I see the HP out now; no I find that highly unlikely
But its likely got a high output impedance that could shift the FR of the 712
 

staticV3

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But its likely got a high output impedance that could shift the FR of the 712
It doesn't:
Screenshot_20220820-211359_Chrome.png
source
 

Mechanic

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30W at 8 ohm into headphones? Yes, I would expect "better bass"
30W at 8ohm, but the 712 has 62 ohm. there is also an aditional resistor on the headphone output. i can't say what is the actual output of the headphone out
 

bartosso

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Hello guys, it's my first post here and I'm not an expert on audio, so please excuse any silliness resulting from ignorance : )

I've recently bought the AKG K712 pro and I must say none of the measurements apply 100% to my pair (not to mention how inconsistent they are among themselves).
I have been working on an EQ preset making them as close to a compromise between the harman target and my personal preference as possible. I personally find the sound very dynamic, spacious and detailed with my EQ preset, but this is also the most expensive pair of headphones I've owned (still have my Senns HD518 around, though). As mentioned by amirm, the spatial qualities are mostly gone without the 2-4.5 khz boost.

You can check it and let me know if this makes the headphones sound neutral to you:

Preamp: -7.2 dB
Filter: ON LSC Fc 20 Hz Gain -4.1 dB Q 1
Filter: ON PK Fc 30 Hz Gain 7 dB Q 0.4075
Filter: ON PK Fc 200 Hz Gain -0.5 dB Q 1.4
Filter: ON PK Fc 1350 Hz Gain 4 dB Q 2.4
Filter: ON PK Fc 1850 Hz Gain -1 dB Q 10
Filter: ON PK Fc 2250 Hz Gain -4 dB Q 3.4
Filter: ON PK Fc 2850 Hz Gain -2 dB Q 9.3
Filter: ON PK Fc 3379 Hz Gain 7 dB Q 2.3
Filter: ON PK Fc 3700 Hz Gain 1 dB Q 3.1
Filter: ON PK Fc 5200 Hz Gain -1 dB Q 7.8
Filter: ON PK Fc 6000 Hz Gain -4 dB Q 8.3
Filter: ON PK Fc 6500 Hz Gain 2 dB Q 10
Filter: ON PK Fc 7000 Hz Gain -8 dB Q 5.8
Filter: ON PK Fc 7700 Hz Gain 6 dB Q 11.9
Filter: ON PK Fc 8400 Hz Gain -4 dB Q 10
Filter: ON PK Fc 10000 Hz Gain -1 dB Q 7

Also, if you'd add/modify/delete any filters, let me know.

Here's the resulting EQ curve:
1662233927409.png
 
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Robbo99999

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Hello guys, it's my first post here and I'm not an expert on audio, so please excuse any silliness resulting from ignorance : )

I've recently bought the AKG K712 pro and I must say none of the measurements apply 100% to my pair (not to mention how inconsistent they are among themselves).
I have been working on an EQ preset making them as close to a compromise between the harman target and my personal preference as possible. I personally find the sound very dynamic, spacious and detailed with my EQ preset, but this is also the most expensive pair of headphones I've owned (still have my Senns HD518 around, though). As mentioned by amirm, the spatial qualities are mostly gone without the 2-4.5 khz boost.

You can check it and let me know if this makes the headphones sound neutral to you:

Preamp: -7.2 dB
Filter: ON LSC Fc 20 Hz Gain -4.1 dB Q 1
Filter: ON PK Fc 30 Hz Gain 7 dB Q 0.4075
Filter: ON PK Fc 200 Hz Gain -0.5 dB Q 1.4
Filter: ON PK Fc 1350 Hz Gain 4 dB Q 2.4
Filter: ON PK Fc 1850 Hz Gain -1 dB Q 10
Filter: ON PK Fc 2250 Hz Gain -4 dB Q 3.4
Filter: ON PK Fc 2850 Hz Gain -2 dB Q 9.3
Filter: ON PK Fc 3379 Hz Gain 7 dB Q 2.3
Filter: ON PK Fc 3700 Hz Gain 1 dB Q 3.1
Filter: ON PK Fc 5200 Hz Gain -1 dB Q 7.8
Filter: ON PK Fc 6000 Hz Gain -4 dB Q 8.3
Filter: ON PK Fc 6500 Hz Gain 2 dB Q 10
Filter: ON PK Fc 7000 Hz Gain -8 dB Q 5.8
Filter: ON PK Fc 7700 Hz Gain 6 dB Q 11.9
Filter: ON PK Fc 8400 Hz Gain -4 dB Q 10
Filter: ON PK Fc 10000 Hz Gain -1 dB Q 7

Also, if you'd add/modify/delete any filters, let me know.

Here's the resulting EQ curve:
View attachment 228476
Hello & welcome! Congrats on your first "audiophile" headphone. As Jimbob says in the post above mine - how do you know the measurements don't tally with your particular unit you've got there? You can't really know without measuring them on the same style of device that Amir or Oratory use. Which measurement have you based your EQ on - Amir's or Oratory's? To save me the trouble of comparing them, what changes did you make from Oratory's EQ?

EDIT: you can always quickly try an Oratory EQ to see if it's instantly better or not, K712 is one of the headphones at the following link:
 

bartosso

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Hello & welcome! Congrats on your first "audiophile" headphone. As Jimbob says in the post above mine - how do you know the measurements don't tally with your particular unit you've got there? You can't really know without measuring them on the same style of device that Amir or Oratory use. Which measurement have you based your EQ on - Amir's or Oratory's? To save me the trouble of comparing them, what changes did you make from Oratory's EQ?

EDIT: you can always quickly try an Oratory EQ to see if it's instantly better or not, K712 is one of the headphones at the following link:
Thank you for the link and a warm welcome!
I was actually looking for this oratory index, been seeing screenshots from it around. Thanks again.

The sound is very similar but the oratory EQ seems better and less jagged indeed. I am very sensitive to high treble, but so far it seems OK, I'll maybe dial it down a little bit down the line.

Do you know what the harmonic distortion on the k712 is with this setting?

How do you know?
I tried to equalize with some headphone frequency tests on youtube :D Didn't hear a couple of the dips and peaks visible in the measurements (EDIT: and I heard other peaks and dips elsewhere in the spectrum), especially the rtings measurement seemed off to me.
 
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Robbo99999

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Thank you for the link and a warm welcome!
I was actually looking for this oratory index, been seeing screenshots from it around. Thanks again.

The sound is very similar but the oratory EQ seems better and less jagged indeed. I am very sensitive to high treble, but so far it seems OK, I'll maybe dial it down a little bit down the line.

Do you know what the harmonic distortion on the k712 is with this setting?


I tried to equalize with some headphone frequency tests on youtube :D Didn't hear a couple of the dips and peaks visible in the measurements, especially the rtings measurement seemed off to me.
Hi, well I reckon you should stick with the Oratory EQ and try to fine tune that one, considering you're saying it sounded better straight off the bat. One good thing about his EQ's is that he offers a few "customisation filters", which the user can tweak to change the sound to their own preference - and it might help counter some unit to unit variation too. The Customisation Filters are literally just a few wide filters (filters that effect a wide broad range of frequencies) that can be used to broadly influence the main different parts of the frequency range. So there's always a Customisation Filter for the bass, always one for the Treble above 10kHz (he calls "airiness"), and oftentimes one somewhere between 1-3kHz which he often calls "shoutiness", lol, but that is an accurate terminology for the effect. Following is a screenshot of Oratory's EQ for the K712, you'll notice the Customisation Filters are listed on the right hand side of that screenshot:
K712 customisation filters.jpg

So, probably best thing to do as a first step for customising this EQ is to pay attention to how the bass sounds in some of your bass heavy tracks that you know well, and hopefully some of those tracks will include some other stuff going on apart from just the bass so you can feel out the whole balance of how increasing the bass can negatively affect the whole experience if you increase it too far. So for your K712 you would adjust the Gain of Band 2 to adjust the bass. Currently it's at 5.5dB, if bass was too heavy then you'd dial this down by 1dB and see if you like it better.........or if there's not enough bass then you'd increase it by 1dB and listen again......and you'd keep increasing or decreasing until you felt the bass was being properly represented.

Second thing you'd do for this particular headphone given you say you're sensitive to treble, then you you'd probably adjust Band 3 which Oratory calls "Treble Balance" in this EQ (you can see in the right side of the screenshot). This particular filter is very wide acting as it pivots the whole response above 690Hz up or down, so this filter will change tonality of the headphone far more than the Bass filter we were talking about in the previous paragraph - therefore with this "Treble Balance" filter I suggest you change that in 0.5dB increments up or down, if treble is too bright you'd lower it by 0.5dB.....and keep on going from there until it's right.

Lastly, you'd think about changing Customisation Filter #10 (airiness), which is influencing the High Treble above 10kHz. You'd probably change this in 1dB increments. Now, you did say you were sensitive to High Treble, but I don't know if that means above or below 10kHz for you. If it means above 10kHz for you, then you might consider experimenting with manipulating this filter before you make any changes to Customisation Filter #3 (which was topic of previous paragraph) - because you might find that your piercing treble problems are above 10kHz rather than below it. However, given the way the frequency response looks, it doesn't look very peaky above 10kHz, so any treble that's bothering you is likely to be happening below 10kHz, so therefore it's more likely that Customisation Filter #3 in the previous paragraph would be the one to adjust before tweaking Customisation Filter #10. You can of course experiment with changing one & not the other though to try to identify where any peaky treble issues might lie.

So far, my best EQ results for one of my headphones (HD560s) has been based on using the Oratory EQ and then adjusting his Customisation Filters to finetune it. For some of my other headphones I've had better results doing my own EQ's from scratch using his or other people's measurements, but for my HE4XX and HD560s my best results were using his EQ's and then tweaking his Customisation Filters to taste.

Regarding your question on distortion, Oratory's EQ emphasises 30Hz / 1500Hz and 3000Hz (he boosts those areas in this K712 EQ). Amir's review shows that there is some bass distortion at the loudest levels and also at around 1300Hz. The distortion shown at 1300Hz is not relevant because you won't be listening above the red peak in the following graph (104dB) at 1300Hz, even accounting for the +6dB boost in that area within the EQ - simply because music doesn't contain as much energy in that area (it's mostly in the bass) and you would blast your ears out if you were listening to 98dB at 1300Hz, the headphone is not gonna be producing that much energy in that area.
index.php

Regarding the bass distortion, the Oratory EQ is boosting 30Hz by about 9dB, this could become more problematic. If you were listening loudly using his EQ you could have bass peaks around 100dB or so, and given that the bass is also being boosted by 9dB then this could mean the relevant distortion line to look at in the above graph would be around 109dB or so - in other words somewhere between the red line and the green line. The red line is fine in the bass, no issues. You'd probably want to keep it below 5% distortion in the bass if possible, and you can see the green line is shooting above 5% in the bass. I'd said you could find yourself inbetween those two lines. I would wager you'll just about be ok for distortion in the bass after using the Oratory EQ and listening at loud levels as long as you're not a person that is known for listening at super loud levels. It's not ideal that bass distortion, but I think you'll be ok.

EDIT: if you increase the bass level, then you'll also want to lower the negative preamp too, in order to make sure you don't get any digital clipping. Currently Oratory has a +8.5dB boost in the bass and therefore a -8.5dB Negative Preamp......so if you increase the bass above 8.5dB in the EQ then you'll need to lower the Negative Preamp by the same amount..........so if you add another 1.5dB to Oratory's bass then you'll need to run a -10dB Negative Preamp for example.
 
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bartosso

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Lastly, you'd think about changing Customisation Filter #10 (airiness), which is influencing the High Treble above 10kHz. You'd probably change this in 1dB increments. Now, you did say you were sensitive to High Treble, but I don't know if that means above or below 10kHz for you. If it means above 10kHz for you, then you might consider experimenting with manipulating this filter before you make any changes to Customisation Filter #3 (which was topic of previous paragraph) - because you might find that your piercing treble problems are above 10kHz rather than below it. However, given the way the frequency response looks, it doesn't look very peaky above 10kHz, so any treble that's bothering you is likely to be happening below 10kHz, so therefore it's more likely that Customisation Filter #3 in the previous paragraph would be the one to adjust before tweaking Customisation Filter #10. You can of course experiment with changing one & not the other though to try to identify where any peaky treble issues might lie.
I'd say my sensitivity begins around 6-7 kHz. K712 has a big peak in that range and on my EQ this range was tuned down more aggressively (in the stock oratory preset the reduction is insufficient imo). There is this track called Uviol (on Confield from Autechre) which has this persistent high gain peaking sample in the 12 kHz range, throughout the whole song, that made me extremely uncomfortable to listen to on headphones that boost upper treble (like CAL! for instance)
Regarding the bass distortion, the Oratory EQ is boosting 30Hz by about 9dB, this could become more problematic. If you were listening loudly using his EQ you could have bass peaks around 100dB or so, and given that the bass is also being boosted by 9dB then this could mean the relevant distortion line to look at in the above graph would be around 109dB or so - in other words somewhere between the red line and the green line. The red line is fine in the bass, no issues. You'd probably want to keep it below 5% distortion in the bass if possible, and you can see the green line is shooting above 5% in the bass. I'd said you could find yourself inbetween those two lines. I would wager you'll just about be ok for distortion in the bass after using the Oratory EQ and listening at loud levels as long as you're not a person that is known for listening at super loud levels. It's not ideal that bass distortion, but I think you'll be ok.
Thank you for this, distortion measurements is one of the topics I struggle to translate into real-life applications. I still can't really measure how loud I actually listen to music, but I'm rather sensitive to loudness (at rock/metal/electronic concerts I often stand way back to make the experience bearable) so I'm probably on the quieter side of things. All in all, your explanation helped me understand distortion graphs more.
I reckon you should stick with the Oratory EQ and try to fine tune that one
Yeah, I already messed around with it a bit, because, as I said, the measurements do not seem to match exactly with my unit (I think). For instance, the 3-4 kHz dip comes around 3200 Hz on my unit and hits the bottom around 3600hz. The Oratory EQ boosts the 2800-3300 range which makes the whole 2-5 kHz range quite uneven with my unit (Peak around 2900, then a big dip). Moving the boost a little "to the right" makes it sound more even and well, "harmanish". Besides, with the stock ora EQ, I can still hear a considerable peak in the 6-7 kHz range which I tuned down a little bit more.
 

Robbo99999

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I'd say my sensitivity begins around 6-7 kHz. K712 has a big peak in that range and on my EQ this range was tuned down more aggressively (in the stock oratory preset the reduction is insufficient imo). There is this track called Uviol (on Confield from Autechre) which has this persistent high gain peaking sample in the 12 kHz range, throughout the whole song, that made me extremely uncomfortable to listen to on headphones that boost upper treble (like CAL! for instance)

Thank you for this, distortion measurements is one of the topics I struggle to translate into real-life applications. I still can't really measure how loud I actually listen to music, but I'm rather sensitive to loudness (at rock/metal/electronic concerts I often stand way back to make the experience bearable) so I'm probably on the quieter side of things. All in all, your explanation helped me understand distortion graphs more.

Yeah, I already messed around with it a bit, because, as I said, the measurements do not seem to match exactly with my unit (I think). For instance, the 3-4 kHz dip comes around 3200 Hz on my unit and hits the bottom around 3600hz. The Oratory EQ boosts the 2800-3300 range which makes the whole 2-5 kHz range quite uneven with my unit (Peak around 2900, then a big dip). Moving the boost a little "to the right" makes it sound more even and well, "harmanish". Besides, with the stock ora EQ, I can still hear a considerable peak in the 6-7 kHz range which I tuned down a little bit more.
You know what, you mention 2900Hz peak that you seem to have identified (I guess by playing sine tones), what you could do is experiment with tuning another of Oratory's filters - he actually has a wide filter at 2900Hz which is Filter #6. I actually did the same thing when I was finetuning my HD560s - I chose to tweak one of his wider filters that weren't in his "Customisation List" (to the right of that earlier screenshot I showed you), except that was a wide filter at 7000Hz - but the idea is the same I identified a weakness in my headphone (not using sine tones, but listening to music whilst watching the spectrum analyser in real time - I think I linked it to various drum strikes and s tones in voices) and there was a wide filter in Oratory's EQ that covered it - he could have listed his 2900Hz wide filter on the K712 EQ as a customisation filter too, but he didn't. Yeah, so you could try lowering that Filter#6 if you're detecting a peak there.

But one thing to be certain on before you go down the route of trying to tune by identifying peaks from sine tones - your hearing can have localised peaks & dips throughout the frequency range "in real life" when listening to sounds that don't come from headphones, therefore you wouldn't correct such personal hearing anomalies in your headphones, as that would be unnatural. For instance, I know I've got a massive peak in my hearing between 8-12kHz which I first noticed in headphones, but then I tested to see if I had the same peak when listening to perfectly flat anechoic EQ'd speakers (ie my 308p Mkii speakers) and I have the same large natural peak in my hearing between 8-12kHz, therefore I don't correct that peak in headphones. So you have to be careful about using sine tones in headphones as a means to decide whether you EQ them - as you don't want to EQ down a natural peak in your hearing for instance. I don't really use listening to sine tones to EQ my headphones, but I have used them at times to check a few things.

Have a think about what I've said in relation to what you're doing, and go from there. Of course you can still try to optimise Oratory's EQ by manipulating his customisation filters if you've not done so already.
 
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