Quad (Acoustical Manufacturing) · Quad valve era

QCII

The control unit that accompanied the Quad II - made in two runs (about 2,001 in 1953 to about 20,419 by 1965 per the official serial table).

Catalogue code: QCII
Years: 1953–1959
Type: valve control unit
Valves & speakers: Mono valve control unit (preamp) for the Quad II, 20,000 units built
Lifecycle: retired
Confidence: High

Specifications

Technology: tube
Channels: 1
Inputs_outputs: radio, pickup (multiple equalisation)

Safety

UK valve chassis: mains-derived HT rails stay charged after switch-off; original Hunts/TCC/Erie capacitors and the mains transformer are the two failure points. Value is set by untouched transformers and original cosmetics (silver/black livery), not by the valves fitted.

01 / Witnesses

What applies here

Marks that can be entered for this maker: Serial number, Model / catalogue number, British capacitor code (Hunts, Mullard), Japanese capacitor code (Nichicon, Chemi-Con, ELNA), EIA component code, Version & era marker.

02 / Bounds

The model year is a floor

Nothing predates 1953; components only push the date later.

03 / Value

What moves the price

Sold-price aggregates are not collected yet, so the archive gives no figure — condition, originality of the transformers and a documented recap move this model more than any list price.