25W version + 2x4700 Power Humpty (50W each). 220V. Mint condition. Slightly used. Purchased from the official dealer. Perfect working order. Original packaging. MSRP $6850.
I can provide local pickup in Bonn (Germany).

Extreme simplicity ----- minimum circuitry

The heart of sound lives in the point of contact where musician and instrument meet. To trace this point-of-contact sound wave, Model 4706 utilizes a filter/condenser with the smallest possible capacity and a minimum number of parts, and the shortest signal pass length ever. All the parts (except attenuators) are mounted on a circuit board measuring 45 x 30 m/m per channel.

Powerful voltage regulation
If energy supply depends on the capacity of filter/condensers, you can easily lose the freshness of sound. The high capacity transformer of Model 4700 (170 VA) regulates enough energy to support the extremely small filter/condenser (1000 F) of Model 4706, enabling it to trace avalanches of fff.

True values of NFB
Today's amplifier design trend tends to eliminate the use of NFB in circuitry. However, for those speakers with long strokes, NFB is still an effective device. But the length of NFB loop creates a time delay between the original and the return signals and allows noises to enter. To take full advantage of NFB, we shortened the length of the feedback loop on Model 4706 to 9m/m, which includes the length of the resistor. We achieved this breakthrough by utilizing power IC and intricate point-to-point hand wiring.

Rigid and compact chassis structure
The Model 4706 chassis is constructed from two tubular aluminum frames (40 x 80 m/m section) and front and rear panels of 10m/m thick machined aluminum plate. Each left and right channel circuit is encased in a separate chassis to eliminate interference between them and to achieve dual mono structure. Model 4700's chassis is also made out of 130 m/m aluminum tube and has 10 m/m thick front and rear machined aluminum panels. Both models contain no damping materials at all.

Gaincard with 2 x 4700 Humpty Power Supplies is complete mono block operation.

Compatibility:
Gaincard is capable of driving most of the speakers as long as their impedance stays over 4 ohms.
Gaincard can be used with any pre-amplifier of your choice.

Features:

  • World's smallest number of parts - 9 parts per channel( excluding attenuators )
  • World's shortest signal pass length - 32 m/m ( including the length of parts )
  • World's shortest NFB loop length - 9 m/m ( including the length of the resistor )
  • World's smallest filter/condenser - 1000µF, (50W version - 2200µF)
  • Dual mono construction with each channel in a separate chassis.
  • Rigid and compact aluminum chassis construction to release vibrations smoothly.
  • Separate 12-position attenuators for each channel.

    Specifications:

  • Output power: 25W+25W ( 8 ohms)
  • Input impedance: 22k ( unbalanced only )
  • Attenuators: 12 steps for each channel
  • Output on and off switches for each channel
  • Dimensions: Model 4706 170(w)x40(h)x100(d)m/m