mikeaj
Headphoneus Supremus
- Joined
- Jan 10, 2010
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Load impedance = headphone impedance, yes. In this system, the load is the headphone.
The system is the amp (voltage source) connected to the resistor (in the adapter) and headphones, as well as the amp's own output impedance, in series—all that for a single channel. It looks identical on the other channel.
As a result, the total load from the amp's perspective is the sum of its own output impedance, any impedance from cables or adapters or whatever else, and the impedance of the headphones. So 232 ohms, around. From the headphone's point of view, it's being driven by an amp with ~200 ohms output impedance (everything else connected in series that's not the headphones itself). The voltage the headphones get is proportional to its impedance compared to the total amount: so 32 / 232 = 13.8% of whatever comes out of the amp.
Yes, you could attenuate the input in the way the picture shows, but 200 ohms wouldn't be enough for that. As you said, input impedance is ~10,000 ohms, so to reduce the level in half you'd need 10,000 ohms there. And really, you'd want to reduce it by significantly more than half. There are other configurations you could do too.
The system is the amp (voltage source) connected to the resistor (in the adapter) and headphones, as well as the amp's own output impedance, in series—all that for a single channel. It looks identical on the other channel.
As a result, the total load from the amp's perspective is the sum of its own output impedance, any impedance from cables or adapters or whatever else, and the impedance of the headphones. So 232 ohms, around. From the headphone's point of view, it's being driven by an amp with ~200 ohms output impedance (everything else connected in series that's not the headphones itself). The voltage the headphones get is proportional to its impedance compared to the total amount: so 32 / 232 = 13.8% of whatever comes out of the amp.
Yes, you could attenuate the input in the way the picture shows, but 200 ohms wouldn't be enough for that. As you said, input impedance is ~10,000 ohms, so to reduce the level in half you'd need 10,000 ohms there. And really, you'd want to reduce it by significantly more than half. There are other configurations you could do too.