Noise Reduction Unit KDB1

The KDB1 Noise Reduction Unit from Kellar Electronics is designed for use with home tape recorders to improve the signal-to-noise ratio during playback. It implements the Dolby B noise reduction system, a consumer adaptation of the professional Dolby A system.

Function:

• The KDB1 applies level adjustments during recording and playback to reduce tape hiss, particularly in quiet passages.
• During recording, the KDB1 boosts mid and high-frequency signals.
• During playback, the KDB1 attenuates the boosted frequencies, restoring the original signal balance and reducing tape noise by approximately 10 dB.

Compatibility:

• The KDB1 is designed for tape recorders with a combined record/replay head.
• A separate model, the KDB2 for machines with separate record and playback heads.

Operation:

• The KDB1 requires a simple calibration for proper level matching with the tape recorder.
• A record/playback switch allows selecting the appropriate mode for recording or playback of Dolby B encoded tapes.
• The KDB1 can also be used for playback of commercially available Dolby B encoded cassette tapes.

Construction:

• The KDB1 is housed in a metal cabinet with a black, simulated leather finish and a brushed aluminum fascia panel with control knobs.

Additional Notes:

• A later model, the KDB3, offers a simplified Dolby B noise reduction circuit with the addition of an FM notch filter.

Here you find 7 models, 7 with images and 1 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Kelly Acoustics Ltd.; Enfield