Fixing driver imbalance on akg 712 pro some questions and suggestions

Hello dear readers I recently bought the 712 pro cans and am loving them.
but there is one small problem…

you see on some songs I would notice that my left driver is a tad bit louder then the right,
so I went out to test why that is.

I got my multimeter and measured the resistance on the cable and mini xlr pins on the headphones
the cable was ok but the pins showed a resistance difference of 1 ohm one had 55 ohms and other 56
I then confirmed that the difference is there after I plug the cable(note I don’t know witch one I was measuring but I would guess that the lower ohm one was louder …),

then I opened the headphones to check if there are any faulty looking cables or solder and it all seemed to check out.
My head theory is that the headphones came out of the factory like that and that the 1 ohm difference might be because they use the metal headband construction to connect the left and right driver and not copper cables like normal.

Now I don’t know squat about electronics but hear me out…
The cable I get with the phones is like 3 m long and I have been thinking about getting a new one so my logic goes like this:
What if I cut the cable to the length I desire but I leave more cable on the line that has lower ohms enough to make up the one ohm difference …?
I don’t know how it would affect the signal if at all and if it will fix the slight difference or how much cable is needed to make up one ohm for now I want to see if this is plausible and if there are any different ideas I can try that might be better?
Thanks a lot in advance for reading and commenting your thots I look forward to reading them.

For any tests photos experiments and the like I should do or try just comment and Il get to it.

K712 owner here. Mine have a mismatch of ~0.4 Ohm (half ass measured on the quick).

Make an adapter/extension.
Leave the headphones and everything that came with it aswell.

Get a big jack plug (example: Neutrik NP3X) and a socket (example: Neutrik NJ3FD-V or Neutrik NJ3FC-BAG)

Get a 1 Ohm Resistor (1%, ≥1W, Wirewound or Thinfilm, NOT carbon!). Wire that in series with the Tip connection.
That way, resistance on both sides should be the same. And the “mod” is removeable at any time.


TRS pinout:

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That is much smarter than my crude caveman idea,
Il get right on that.
Thanks a million mate :slight_smile:.

Also if I may dig your brain a bit.

I want know if this will affect the sound or not other than getting rid of the imbalance and of the two Wirewound and thin film witch one is better for my purposes I have also read this and dont really get it if you dont mind helping me out : "There are a number of considerations for what composition resistor to use in each position. Many will disagree and that is just the way it is (IMHO).

Metal Film (MF) are the lowest noise in signal path applications. Here I mean Dale Vishay types and all those designer resistors. And they are available in high tolerances.

Carbon Film (CF) is a little more noisy but impart a different flavor than MF.

Thick film MF, are good for plate loads in tube amps where there is some current to be seen.

Carbon composition, while trendy, are both noisy and the values drift with time and heat. They are great for grid stoppers and plate stoppers in tube amps where the exact value doesn’t matter. But carbon composition are good for nothing else today.

Wire wound (inductive) have limited proper use in audio applications due to the problems with induction. Non-inductive wire wound are great for crossovers (power required here) and cathode resistors in tube amps.

For solid state circuits I use a lot of MF thin film, Dale Vishay, types. Heat is not a factor and neither are the power ratings. I used a bunch of these in the LO/HO/MC phono pre and the CNC phono preamps I built.

I hope this helps." Thanks a lot in advance ?

technically, yes. In Practice, probably not much

I agree with most of that. Except carbon film is to be avoided for anything except signal LEDs. They are electrically noisy. This video touches on that briefly.

If you wanted to go nuts, get a Manganin Resistor. Those are normally used in measurement applications because of the mostly flat thermal coefficent and lack of any other wierdness. These are considerably more expensive than any other type.

As either of the sensible options costs the same (= nothing), why not get one of each resistor type (or several from various brands) to try? The soldering will be the most annoying part and the connectors the majority of the cost.