FREDENSTEIN F602 Multi Compressor

Variable-mu Compressor

The FREDENSTEIN F602 is a high-performance variable transconductance (often falsely called "variable mu") compressor for professional recording and mastering engineers. The FREDENSTEIN F602 features the original remote cut-off dual triode valve used in many vintage designs (Gates, Fairchild, and GE to name a few) called the 6386LGP. The signal path is very short and delivers the smoothness you would expect from a great piece of vintage gear. The innovative transformer-less input circuit provides clarity while the large Lundahl output transformer adds character.
The FREDENSTEIN F602 uses a DSP to continuously monitor the 6386 valve and optimize its operating points. This has several advantages including automatic self-test and calibration but also allows for a larger control range and much faster gain reduction.
The FREDENSTEIN F602 features rotary controls for Threshold, Ratio (2:1 to 20:1), Make-up Gain, Mix (Blend), Attack (250 uS to 15.5 mS), and Release (12 mS to 5 S). There are push buttons for Bypass (true hard bypass), Hard Knee / Soft Knee, Link (up to 10 units), and Meter Mode (VU or Gain Reduction). The LINK switch is also a standby switch which allows the tube circuit to be shut down if the F602 is not in use while the rack is still powered, thus extending tube life.
The FREDENSTEIN F602 provides exceptional attack and release times that no other "vari-mu" compressor can come close to. Usually, such fast settings would have a "thumping" side effect when the gain reduction changes, but the FREDENSTEIN F602 with its DSP regulating the valve and maintaining almost perfect balance, this problem does not occur.
The MIX control is also interesting. Fully counter-clockwise, a switch engages, sending only the compressed signal to the output. Conversely, fully clockwise, another switch engages, sending only the uncompressed signal to the output. Between these two extremes, mixing is variable, which is typically exploited to preserve some transients while increasing the level of quieter signals. Similarly, when the Release control is fully counter-clockwise, a program-dependent Auto-Release setting is activated, and when the Threshold control is fully counter-clockwise, compression is deactivated.
Gain reduction is displayed traditionally with a VU meter, and the Clip indicator lights up if the output reaches +24 dBu. The buttons illuminate when engaged.
The specifications are more than respectable for this type of compressor. Lower distortion, wider frequency response, and lower noise than much more expensive units. The high-current design and unusually low output impedance allow it to drive even the most difficult and complex loads without sonic impact.
Of course, in this small 500-series unit there is an intelligent design with a vacuum tube, DSP control, MCU, digital attenuators, high-voltage regulators, Lundahl transformer, a discrete line driver, and high-performance analog signal. It should also be noted that it is truly well-designed, using the highest quality parts - and built as solid as a tank. Expect it to be reliable and professional.
Due to the high power consumption of approximately 8W, not all lunchboxes and racks are suitable for this module. Of course, FREDENSTEIN lunchboxes and racks are well-equipped to handle these loads. Like all FREDENSTEIN products, the FREDENSTEIN F602 is designed by a German-American team and manufactured in Taiwan.

Specifications

• Reference Level: 0 db = +4 dBu (American Studio Standard) Make-up gain: 0 to +20 dB
• Threshold: -25 dB to +9 dB
• Attack Time Range: 250 to 15.5 ms
• Release Time Range: 12 ms to 5 s
• Ratio: 2:1 to 20:1
• Frequency Response: 20Hz - 20,000Hz, +/- 1dB
• Distortion: <0.01% S/N Ratio: >90dB at 0dB gain
• Input Impedance: >10KOhm
• Maximum Input Level: +24 dBu
• Output Impedance: 20 Ohm
• Max. Output Current: +/- 200 mA Max.
• Output Level: +26 dBu
• Power Consumption: +16 V +250 mA, -16V -200 mA