Согласование и мостовое соединение импедансов в звукотехнике.

the amplifier configuration
In audio engineering and sound recording, a high impedance bridging, voltage bridging, or simply bridging connection is one in which the load impedance is much larger than the source impedance. The load measures the source's voltage while minimally drawing current or affecting it.

Impedance bridging is typically used to avoid unnecessary voltage attenuation and current draw in line or mic level connections where the source device has an unchangeable output impedance ZS. Fortunately, the input impedance ZL of modern op amp circuits (and many old vacuum tube circuits) is often naturally much higher than the output impedance of these signal sources and thus are naturally suited for impedance bridging when receiving and amplifying these voltage signals. The inherently lower output impedance of modern circuit designs facilitate impedance bridging. For devices with very high output impedances, such as with a guitar pickup or a high Z mic, a DI box can help with impedance bridging by converting the high output impedances to a lower impedance so as to not require the receiving device to have outrageously high input impedance (which would suffer drawbacks such as increased noise in long cable runs). The DI box is placed close to the source device, so any long cables can be attached to the output of the DI box (which usually also converts unbalanced signals to balanced signals to further increase noise immunity).

As explained in , the efficiency η of delivering power to a purely restive load impedance of RL from a voltage source with a purely restive output impedance of RS is:This efficiency can be increased using impedance bridging, by decreasing RS and/or by increasing RL. However, to instead transfer the maximum power from the source to the load, impedance matching should be used, according to the maximum power transfer theorem.