GRAAF WFB-1 Tube Pre-Amp MC/MM

Fabulous sounding tube amplifier with musical, revealing MC/MM phono section.  Can compete with the very best!  Rarely available.

The four PC900 tubes are Telefunken.  The 6922 are Sovtek so can be rolled for even better sound.

Original packaging and red cotton drawstring bag.

Email:  [email protected]

Description :
The Graaf Graafiti WFB One uses a tube circuitry design in both line and phono stage, and realized in total absence of feedback. In order to obtain the best quality of the digital sound, the line inputs circuit uses two 6922(E88CC) double triode tubes for each channel. Thanks to the phono section which uses a particular input configuration "cascade" and SRPP(shunt-regulated push-pull), the sound coming from the turntable is more natural and pure. This circuit is made up of two PC900(4HA5) low noise single triodes and a part of the 6922 double triode, followed by a passive R1AA and by the other part of the 6922 used in buffered configuration. This allows a low output impedance to be obtained. This circuit is able to amplify moving-coil cartridges with low signal. To ensure that all cartridges are able to feed the Graaf WFB One, the user can select three different gain levels for moving-magnet or moving-coil types, through impedances of 100, 500, 47000 ohms. The power supply has been studied in such a way that the unit decouples from the AC line and is able to work with line voltages varying by as much as +/-10% with respect to the normal AC voltage. With its high filtering effect of the power supply, the voltage leaps do not compromise the quality of sound reproduction. High quality potentiometers have been chosen for the gain control. The Graaf WFB One produces very detailed, warm and engaging sound, along with a significant body and a fantastic soundstage.

Specifications :
Tubes.............................................PC900(4HA5) x 4
         .............................................6922(E88CC) x 4
Gain...............................................line 16 dB
      ................................................line + phono MM 45 dB
      ................................................line + phono MM/MC 55 dB
      ................................................line + phono MC 66 dB
Input Impedance..............................line 100 Kohms
                        ..............................phono 100 - 500 - 47000 ohms
Output Impendance..........................250 ohms
Maximum Output Voltage.................60 VRMS
Total Harmonic Distortion(THD).........0.4% (10 V)
Signal Noise Ratio...........................line 103 dB A at max output
                           ...........................phono MM 78 dB A
                           ...........................phono MM/MC 80 dB A
                           ...........................phono MC 76 dB A
Frequency Response.......................4Hz - 80 KHz (-3dB)
EQ-RIAA.........................................20Hz - 20KHz(+/-3dB)
Power Supply..................................105-120V / 210-240V
Power.............................................45W
Dimensions (w x d x h).....................41 x 31 x 9.5 cm
Weight............................................5kg