Audio Valve RKV - Mark II, Manual, Page: 10 / 14

RKV – MARK II RKV – MARK II _________________________dynamic headphone amplifier____________ _________________________dynamic headphone amplifier____________
8. Use of the IMPEDANZER
In case headphones with impedances below 100 Ohm are to be connected, it is recommended to
use the so-called Impedanzer for a better match between amplifier and load impedance. This
device allows to connect headphones with impedances between 8 – 64 Ohm.
Also high efficiency loudspeakers can be connected through the two pairs of connectors at both
sides of the front. The rotary switch selects the right amount of impedance matching. In case of
doubt optimal matching can be established by ear.
At the middle of the front plate two headphone jacks can be found. Again, optimal matching can
be selectec by the switch.
The backside of the Impedanzer has a cable connector that is to be connected to one of the
headphone jacks of the RKV.
If you like to use two headphones of the same load impedance please select a matching
impedance at the Impedanzer that equals half the impedance of each headphone. Example: Both
headphones have a 32 Ohm load impedance and both are connected. Please select the 16 Ohm
setting for a proper matching.
The two pictures show the frontplate and a photograph of the Impedanzer and visualize the
various control elements.
(Upgrading Febr. 2004)
The Impedanzer is equipped with a bypass switch that completely removes the built-in
transformer from the circuit, a so-called true bypass. This feature allows the RKV owner to hook
up headphones such as the AKG K-1000 directly to the speaker binding posts of the
Impedanzer using the headphone's standard cables and without any need for custom
terminations. At the same time the RKV's output impedance remains unchanged, resulting in a
perfect impedance match between RKV and headphone.
When the bypass switch is facing upwards, the Impedanzer's impedance selector is activated and
may be adjusted to loads of 8, 16, 32 and 64 Ohms. When the bypass switch is facing
downwards, the impedance selector is bypassed, and the RKV will work best into loads of
approximately 100 Ohms or higher.
A word of warning: The volume control of the RKV should always be turned all the way down
before operating the bypass switch. Bypassing the Impedanzer will otherwise result in a
considerable jump in volume, which may damage your hearing or your equipment.