Fredenstein F660 Limiting Amplifier

The Fredenstein F660 Limiting Amplifier is a valve (tube) based compressor and limiter with the same very short signal path as the famous Fairchild 660/670. It uses the exact type of tubes, the 6386 LGP, as the Fairchild. Fortunately, new production tubes are available today, since original tubes are hardly sold anymore. The four tubes form a single stage push-pull Class A amplifier and the whole signal path consists only of a T-type input attenuator, input transformer, Class A amplifier and finally an output transformer. At this point the similarities end. The F660 uses a DSP to control the operating points of the tubes, guarantying perfect working conditions all the time. The side chain amplifier is designed with semi-conductor components since it ÌÕonlyÌÒ generates the control voltage for the tubes. The final result is a compressor with the compression characteristics of the Fairchild, but with an extended frequency response, lower noise and lower distortion. The perfect buss compressor is for today's high resolution audio.