An uncompromising version of a class A headphone amplifier.The amplifier is built according to the well-proven Lehmann Audio Black Cube circuit, but unlike the original, the board has protection that will protect the headphones 100% in any emergency, there is a switchable tone compensation, and the weekend transistors are mounted on a common heat sink, which adds linearity to the device. The transistor balanced circuit with a buffer on a high-quality op-amp is a time-tested "classic".
The key to great sound is the selection of extremely high quality components in the signal circuits:
-ОУ - LME49860 or OPA2134 (optional)
- BD140 / BD139 Philips output transistors, vintage in gray case with copper feet
-Driver transistors BC546 / BC556 Philips, vintage with a silver "muzzle"
- Polypropylene film capacitors WIMA, MKP series with shunting by mica capacitors KSO (silver-plated mica)
-Metal film resistors Vishay DALE (US military acceptance)
An adjustable gain (Ku) from 0 to 20dB makes the amplifier universal and allows you to adjust the comfortable volume control for almost any headphone.
Loudness is built on a passive filter that cuts the midrange, while at the same time not adding any "gag", which is observed with loudness on active filters.
Power supply voltage 2x16 ... 20V