Violectric DHA V226, User Manual

User´s Manual DHA V226, November 2021, F. Reim         

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a small one, manufacturers like Noble or Panasonic don't offer these 
anymore. A current sample of top of the line pots is the RK27 by ALPS, 
which is used inside DHA V226. 

Why a low output impedance is essential? 
When actuated, electro-dynamic systems respond with a counterforce. 
When the voice coil of a headphone has been displaced by the signal, an 
(error-) current will be induced when it swings back to its initial position. 
This current must be suppressed as far as possible, which is affected 
best if the amplifier's output impedance is the lowest possible. The 
damping factor describes nothing but the ratio between the output 
impedance of an amplifier and a given load. 
Since there is no known technical specification, we define the load 
(voice coil impedance) as 50 Ohms. With DHA V226 having an output 
impedance of < 0,5 ohms in balanced mode and < 0.25 Ohms in 
unbalanced mode this results in a damping factor of 100 (balanced) and 
a damping factor of 200 (unbalanced). 
Due to general recommendations the output impedance of an amp shall 
not be higher than 5 % of the headphone impedance, that means a 
minimum damping factor of 20.   

Why are high supply voltages essential? 
A headphone doesn't really require high power, but from the equation  
P = U

2

 / R we can see that the square of the supply voltage determines 

the power into a given load resistance. The higher the headphone's 
impedance, the more voltage will be needed to achieve high listening 
levels. But this deals with the achievable loudness to a limited extent 
only: Technically spoken, music lives on fast transients which put high 
demands on signal processing. And thus, a fast transient can easily push 
an average amplifier with +/-15 volts supply to its limits (95 % of all 
headphone amps in the market are operated with these or even lower 
supply voltages). Due to the high supply voltage and the balanced 
operation mode of DHA V226 you will benefit from far over two times 
more output voltage swing capability compared to single ended amps