Graaf WFB-One all tube preamp
Fabulous sounding tube preamplifier from legendary Italian amp maker Graaf, with musical, revealing MC/MM phono section. Can compete with the very best! Rarely available. There are 3 gain settings for phono. There are also 3 input impedances for phono: 100 ohms, 500 ohms and 47000 ohms. Works with MM or MC cartridges without the need for a transformer. All tube gain.
7 sets of RCA inputs including phono and tape, 2 sets of RCA outputs and a tape output. Balance and Volume controls.
I bought this amp in Europe and had the voltage conversion done by tube technician Blackie Pagano in New York. It is currently wired for US electricity. He just had to use different wires on the original transformer. He also checked out the unit, found that the original PC900 tubes tested weak and replaced them. He gave the unit a clean bill of health. It functions perfectly. The cost to get this done was $262.39 (bill attached) and this was done in February 2019.
The new four PC900 tubes are NOS Toshiba. The four 6922 are Sovtek so can be rolled for even better sound. Both sets of tubes (8 tubes total) have been tested by Blackie Pagano, test great and are matched (test results attached). I will also include two good quads of Telefunken branded PC900 that might have been made by Siemens bought on eBay.
I have the original packaging including the red cloth bag, manual, and info sheet. The unit is in very good cosmetic shape. I will include a generic power cord.
You can see and hear the unit by clicking on the link below:http://youtu.be/HF_GZGU4yLE
Anyone is welcome to hear this preamp in Brooklyn, NY.
I will pack very carefully and the unit will need to be insured.
Any questions, please ask. No returns.
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 RIAA 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.
Tubes: 4 PC900 (4HA5) , 4 6922 (E88CC)
Gain: line stage 16 dB, line + phono MM 45 dB , line + phono MM/MC 55 dB, line + phono MC 66 dB
Input Impedance: line stage: 100 Kohms , phono stage: choice of 100, 500, or 47000 ohms
Output Impedance: 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, currently configured for 115V, internally convertible to other voltages
Dimensions (w x d x h): 41 x 31 x 9.5 cm
Any questions, please ask. More photos available upon demand.
Asking Price: $1600 + shipping + Paypal fees. I might be interested in partial trades for a Miyajima mono cartridge or suitable SUT.