Violectric DHA V590² Pro Headphone Amplifier, Preamp, and DAC - Manual (Page 18)

18
Too loud? Too soft? The PRE-GAIN method
The VIOLECTRIC DHA V590 is specially designed to drive headphones. To do so it is placed between
up to three analogue or up to four digital sources and the headphones. Headphones however can
present load impedances from 8 to 2000 ohms and efficiency ratios from 85 to 115 dB per Milliwatt.
The sources may have output levels between 0.5 Volt up to 10 Volt. Thus, it can be quite tricky to
fulfil all demands, since...
… owners of high-efficiency headphones will rarely set the volume control higher
than 9 o'clock in order to exclude hearing damage, while
... the maximum setting may still be too soft for low-efficiency headphones, but
… all users expect highest quality at lowest noise and distortion.
Thus, the
circuitry must adapt itself as the headphones will not do and the sources will seldom do!
WE CALL THE SOLUTION TO THIS PROBLEM PRE-GAIN
A single amp of DHA V590 has no gain (gain = 0 dB = factor 1). In case a balanced headphone is
connected two amps are active with a combined gain of +6 dB (factor 2).
By this measure the amps will produce an extremely low self-generated noise which can hardly been
heard even with highest sensitive in-ear-monitors (IEM).
On the other hand, the amps of DHA V590 with very powerful transformers and with their high
operating voltage are able to drive low efficiency or high impedance headphone to the full with ease.
You will be unable to find a headphone driving DHA V590 to its limits. This effortless action will save
your precious headphones as they will never see a distorted signal from the amp.
The alignment between amplifier and headphone is provided by the preamp stage, which can boost
or attenuate the input signal in seven steps of -18 / -12 / -6 / 0 / +6 / +12 / +18 dBr. For this purpose,
two switching devices are located on the rear panel for left and right channel individually.
HOW TO OPTIMIZE THE PRE-GAIN SETTING:
Connect your source to VIOLECTRIC DHA V590 and plug in your headphone. Listen !!
Your amp is adjusted best by the individual PRE-GAIN setting when the volume control for “normal”
listening is positioned around 12 o´clock.
So it is provided that there is enough attenuator travel to boost the signal through lower level
passages or to listen with higher volume. On the other hand, the attenuator travel is optimized to
reduce the self-generated noise from the amp.
In case you cannot reach the 12 o´clock position because the input signal is too loud, feel free to
reduce the signal with the PRE-GAIN steps -6 / -12 / -18 dBr.
In case the signal is too
soft even with volume
settings above
12 o´clock please use
the PRE-GAIN settings
+6 / +12 / +18 dB to
achieve more gain.
Other than the above
settings are not useful
but harmless.