I have an LG-V30 cellphone, which has an integrated headphone amp with two modes for audio reproduction depending on the headphones you plug in.
- Normal mode for headphones under 50 ohm, low output, amp disabled.
- High impedance mode for headphones over 50 ohm, high output, amp enabled.
I'm using Takstar 82 Pro headphones which according to the specs are 32 ohm (plus-minus 15%).
These headphones have a detachable cable, and I have two different cables, a short cable (1m) and a long cable (2m). When I plug the headphones with the short cable, the cellphone detects them as under 50 ohm, but when I use the long cable they're detected as over 50 ohm and the amp gets enabled, resulting in higher sound level and just better sound overall.
I have measured the apparent resistance of the cable by measuring the ohm between the tips.
- Short cable: 0.4ohm
- Long cable: 1.5ohm
Questions:
- Is it possible that the higher resistance of the longer cable is somehow fooling the phone into thinking the headphones are of higher impedance?
- Can I somehow add in-line resistors to the short cable to simulate the resistance of the longer cable, so I can use the headphones in high-impedance mode with the short cable?
- If so, which values would those resistors be?
- Will this mess up audio quality the way inline capacitors would?
Notes:
- I am aware there are other headphones with higher impedance, but I want to use these specific model.
- The behavior of the cellphone cannot be changed by the user.
- My knowledge in electronics is somewhat basic, so be gentle 🙂
Best Answer
You can try putting two 2.2 ohms resistors in series with the left-audio the right-audio connections - likely it will do the trick for you and should be pretty simple to do.