Harman Kardon EQ8. Very highly-regarded analogue 10-band stereo graphic equalizer. Immaculate face plate. Part of this brand's higher-quality separates range. With subsonic filter, which is particularly valuable for vinyl playback.

Read my feedback and bid with complete confidence. Almost 1,500 transactions and not a single negative feedback.

Can be well packed and posted for €15 extra at buyer’s expense.

Approx 435mm wide, 318mm deep and 100mm high (from bottom of the feet to top of casing).

Key features include:

x10 frequency bands per channel: 31.5Hz, 63Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz and 16kHz.

±12dB adjustment on each band.

Variable subsonic filter adjustable between 5Hz and 30Hz., ideal for turntables (see below)

Input level controls with overload indicators

Tape-monitor loop and flexible connection options.

Excellent published specifications: 105dB signal-to-noise ratio and 0.01% THD.

The EQ8 has a variable subsonic filter (5Hz-30Hz), which is unusual and quite sophisticated for a domestic equalizer. This is useful with a turntable because records often generate very low-frequency signals below the audible range (typically below 20Hz) that don't originate in the music.

These unwanted signals can come from: 1) Warped records causing the cartridge to move slowly up and down; 2) Tonearm/cartridge resonance, usually around 7-12Hz; 3) Slight bearing rumble from the turntable; and 4) Footfall and vibration reaching the deck.

Although you can't hear these frequencies directly, your amplifier and speakers still try to reproduce them. This matters for the protection of woofers. You may notice bass drivers "pumping" in and out dramatically when playing slightly warped records. That's often subsonic energy, not music. The EQ8's variable filter can remove it before it reaches the speakers.

Adding the EQ can also give you clearer audible bass. If an amplifier is wasting power reproducing 5-15Hz rubbish, it has less headroom available for actual bass notes. Filtering the infrasonic content can make bass sound tighter and cleaner.

Finally, the sub sonic filter will offer better handling excessive subsonic energy that can sometimes feed back through suspended floors, especially with speakers close to the turntable.

For example, with a well-set-up Rega, Linn, Thorens or Technics deck, you might set it around 10-15Hz.
With warped records or a very compliant cartridge, 15-20Hz may work better.

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