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Headphone amp K712pro

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Headphone amp K712pro

Postby Dave Rowles » Sun Jan 17, 2021 4:27 pm

I’ve searched and read, but still none the wiser, so thought I’d ask here.

I’ve been using the K712s with my focusrite clarett and it’s going ok, but I still seem to be running my mix loud in the box, so I’m wondering if a suitable headphone amp would be a good idea, and if so what?

I could get a mojo but wondering if there’s anything I could rig my Clarett into so I can keep a single cable into the Mac.
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Re: Headphone amp K712pro

Postby Martin Walker » Tue Jan 19, 2021 8:15 pm

Hi Dave,

Not totally sure what you're after - like you I've got AKG K712 Pro's and with a quoted impedance of 62 ohms is it that your Focusrite Clarett headphone output isn't giving enough volume for your purposes without running your mix close to 0dBFS?

I run mine from the heapdhone output of my Lavry DA10 converters, which has an output impedance of just 0.69 ohms, so they are driven easily (I find it's generally recommended that you plug in headphones with a nominal impedance of at least ten times that of the headphone amp, to avoid any frequency response variations).

However, I tend to avoid plugging the K712's into my RME Fireface UC headphone output, as its output impedance is 30 ohms and therefore I could get compromised frequency response variations. Instead, I plug in my old faithful Sennheiser HD650's, whose impedance of around 300 ohms is more compatible.

If you want to get into all the technicalites, there's a good article here: https://nwavguy.blogspot.com/2011/02/he ... dance.html


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Re: Headphone amp K712pro

Postby James Perrett » Tue Jan 19, 2021 10:52 pm

Martin Walker wrote:(I find it's generally recommended that you plug in headphones with a nominal impedance of at least ten times that of the headphone amp, to avoid any frequency response variations).

There's an interesting article at

https://www.stereophile.com/content/bet ... nes-page-4

where it mentions that the IEC measurement standard is to feed headphones from a 120 ohm source impedance. This probably reflects that fact that many headphone outputs on hifi amps are (or were in the past) taken from the speaker outputs and simply fed through a 100 ohm resistor to attenuate the output sufficiently for headphones.
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Re: Headphone amp K712pro

Postby Dave Rowles » Tue Jan 19, 2021 10:53 pm

Hi Martin,

Thank you for the response. I guess I just need to work more at it. It seemed to distort when I ran the volume high enough when mixing at -18/-14 peak in logic, but I've just gone a re-listened now, and maybe it was ear fatigue that was the problem, not the gear.

Thank you for allaying my fears!
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Re: Headphone amp K712pro

Postby Martin Walker » Wed Jan 20, 2021 1:05 am

Dave Rowles wrote:Hi Martin,

Thank you for the response. I guess I just need to work more at it. It seemed to distort when I ran the volume high enough when mixing at -18/-14 peak in logic, but I've just gone a re-listened now, and maybe it was ear fatigue that was the problem, not the gear.

Thank you for allaying my fears!

My pleasure.

One thing that I do to combat potentially low headphone levels while mixing with plenty of headroom is to place my most transparent buss compressor on my master channel (in my case the most excellent yet reasonably-priced Tokyo Dawn Labs Kotelnikov GE), and then add a gain boost plug-in prior to this that just causes the final output to 'graze' the threshold of that compressor. The more basic Kotelnikov can also be downloaded free!!!

Typically I can add anywhere between 12dB and 18dB of clean gain (my headroom) prior to the compressor before it starts applying any gain reduction, which means that I can listen much louder on headphones without worrying about audio interface clipping, since it will never exceed 0dBFS.

I personally also tend to push the master track gain a tiny bit more to tweak the compressor for a tiny amount of 'buss glue' (typically 1 or 2dB, and never more than 3dB), and that gives me a much better idea of how my final mix is going to sound before the mastering stage.


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Re: Headphone amp K712pro

Postby Martin Walker » Wed Jan 20, 2021 1:09 am

James Perrett wrote:
Martin Walker wrote:(I find it's generally recommended that you plug in headphones with a nominal impedance of at least ten times that of the headphone amp, to avoid any frequency response variations).

There's an interesting article at

https://www.stereophile.com/content/bet ... nes-page-4

where it mentions that the IEC measurement standard is to feed headphones from a 120 ohm source impedance. This probably reflects that fact that many headphone outputs on hifi amps are (or were in the past) taken from the speaker outputs and simply fed through a 100 ohm resistor to attenuate the output sufficiently for headphones.

That makes perfect sense James - thanks for the interesting link!


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