Burwen DNF 1201 Dynamic Noise Filter DNF. This is electrically the same unit as the DNF-1201A -- only an alteration of the enclosure (see below).
Excellent used condition. From the estate of an audiophile / vintage gear afficionado. Unit powers on and functions as intended. A beautiful example of a vintage DNF from the 1970s.
The following are the same unit (same circuit), with only a change in outer case & name. Burwen sold out to KLH, who put their own name on the later units.
Burwen DNF-1201 Dynamic Noise Filter
Burwen DNF-1201A Dynamic Noise Filter
KLH DNF-1201A Dynamic Noise Filter
MANUFACTURER'S SPECIFICATIONS "Hiss" Reduction: Up to 30 dB above 5 kHz, 5 to 14 dB total above 400 Hz, depending upon program material and control settings. Frequency Response: Minimum bandwidth, -3 dB @ 500 Hz, -10 dB @ 1 kHz, -20 dB @ 2.5 kHz; Maximum Bandwidth, ±0.5 dB, 10 Hz to 20 kHz. Input Level: 0.77 V (0 VU), adjustable to 10 dB lower level. Maximum Input: 6 V @ 0.1 dB gain. Rated Output: 2.5 V (+10 dB). Clipping Level: 6 V. Output Impedance: 50 ohms, d.c. coupled. Gain at 1 kHz: 0 dB adjustable to +10 d B. THD (Sensitivity at Maximum): 0.2 per cent at any frequency from 20 Hz to 10 kHz. IM Distortion: 0.05 per cent. Internal Noise: 100 µV rms. 20 Hz to 20 kHz. General Specifications Dimensions: 171/2 in. (44.5 cm) W x 2'/, in. (7.3 cm) H x 8% in. (21 cm) D. Weight: 8 lbs. (3.6 kg). Power Requirements: 105-125 V, 50/60 Hz, 8 W (210-250 V model optionally available).