Cassette Decks: Yamaha KX-300

This is my preferred deck for recording cassettes – and was used mostly with TDK Chrome soundalike “SA90” series of tapes for best results recording either from vinyl, radio or CD. I never got into using ‘Metal’ formulation tapes – their price put me off!


The single directional tape transport of the KX-300 is soft touch controlled by switches and also an optional infra-red RS-K3 remote control (top right!) allowing easy use of the track search and phrase repeat features found more commonly on CD players. The motor drive is stable and mostly forgiving of slightly warped cassette bodies 🙂

Yamaha KX-300 Specs


Capstan – DC servo motor

Reel – Flat torque DC motor


Recording / Playback – Amorphous

Erase – Double Gap Ferrite

Wow and Flutter

WRMS – less than 0.05%

W.Peak – less than +/- 0.08%

Signal-to-Noise Ratio

(Dolby NR off) – better than 60 dB

(Dolby B NR on) – better than 68 dB

(Dolby C NR on) – better than 76 dB

Frequency Response

Normal tape (-20dB) – 30 to 17,000 Hz +/- 3dB

Chrome tape (-20dB) – 30 to 19,000 Hz +/- 3dB

Metal tape (-20dB) – 30 to 20,000 Hz +/- 3dB

Harmonic Distortion

(315 Hz, 3rd) – no more than 1%

Channel Separation

(3150 Hz) – 40 dB


(125 Hz) – 55 dB

As well as Dolby B and C Noise Reduction, this deck features a headroom extension system called ‘Dolby HX Pro’. This is a worthwhile improvement that increases the upper limit of frequencies that can be recorded on most type of tape. The Dolby HX Pro circuit does this by dynamically reducing the level of bias signal added when recording high frequencies that are known to have a self-biasing effect.

So what is this bias stuff about then? Well, in analogue tape recording a bias signal (a single frequency of roughly 100 kHz) is added to ‘help’ the magnetic particles on the tape into behaving linearly to the audio signal excitation coming off the recording head.

For good recordings the level of bias applied is important.

With too little bias, or none – as it was before this high frequency recording technique was discovered by the Germans during WWII – the tape formulation’s magnetic particles don’t properly align to represent the original signal level resulting in playback distortion. With too much bias signal, the high frequency information in the original signal is slightly erased from the recording.

Tape manufacturers generally make tapes to match different industry standardised bias presets (Type I, III, IV), and these are normally automatically selected from the identification holes present on the top of the cassette shell.

Though above these industry standards most Hi-Fi manufacturers tended to align their cassette decks to a particular cassette brand and model – and make the matching tape purchasing recommendations in their manuals, though this also could be seen as a useful marketing strategy, particularly for deck/tape products from Sony.

The Yamaha KX-300 deck was one of the few sold in the low-to-mid price range to have a variable bias control for the user to adjust the bias signal further from industry presets to match his/her preferred tape use, and a play trim control (+/- 3 dB at 10 kHz) to slightly boost or cut treble on playback of poorly recorded tapes.

A MPX (for Multiplex) filter is normally found in-use with Dolby B (or C) recording circuitry to avoid the stereo pilot tone (19 kHz) of an FM broadcast from confusing the noise reduction circuit. This deck usefully allows that low pass filter to be switched out when recording from non-radio sources.

Overall, I am pleased with this deck – I’ve thrown loads of tapes at it over the years from when I bought it in 1989. It still works fine today.

One Response to Cassette Decks: Yamaha KX-300

  1. Roseville Plumbing man…

    coolsite.Thanks for posting….

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