Nearly all the domestic models in the Ferrograph range, were available as YD models. Since these were designed for and marketed to industrial scientific users.  YD models had some subtle changes to the design to suit the needs of specialist customers.
  • All YD models were housed in substantial metal cases.
  • YD recorders all had 600 ohm input /outputs. This allowed recorders to be connected to professional Public Address amplifiers or broadcasting equipment.

Some YD series machines were specially designed and built to perform a certain task.

  • Language laboratory use.
  • Auto-reverse play only machine for continuous message relay.
  • Low speed logging machines, designed for 24 hour monitoring of radio broadcasts.
  • Two channel, with staggered heads. Used for scientific measurement purposes.

During the 1960's a lot of ex government equipment came onto the surplus market, including many of these special YD machines.  Some were not suitable for normal domestic use, particularly the extremely low speed logging machines, which had non-standard record / play equalisation, making them incompatible with existing hi-fi equipment.

Domestic Recorders were in Wooden Cabinets.

YD Recorders always had Metal Cabinets.
MODEL "D" & G100
  • No counter or tape guides
  • Meter with half-round fascia
  • "V" head cover
  • Polished Wooden Cabinet. (not G100)

  • Speed change by lift-up lever behind

    head cover. Single idler used.

  • Circular Control Knob.

  • Deck mouldings that set lower tape level.

  • No pause control.

  • No deck lifting handle on early machines.

 

  

  • Still retained deck moldings, these were discontinued when adjustable tape guides were fitted.
  • Recording equalisation automatically switched by tape speed switch.
  • Aux Socket available by removing the dummy volume control on the extreme left of the amplifier panel. This socket uses a standard octal valve base and can provide ht voltage.

SERIES 2.

  • No tape counter on early version. introduced as optional extra later, decks which catered for this had cut-out to take a counter that was available in kit form.

  • The tape counter had a black bezel.

  • No tape guides on early models, introduced just before it became the Series 3.

  • Level Meter with half-round fascia.

  • "V" head cover.

  • Speed change switch in centre of deck behind head cover.

  • Circular Control Knob.

YD MODELS HAVE METAL CABINET & 600 OHM INPUTS/ OUTPUT SOCKETS.

SERIES 3

  • "V" Head cover

  • Tape Counter fitted (Chrome Bezel)

  • Tape guides fitted.

  • Square fascia Meter

  • Speed change switch as Series 2

  • Circular Control Knob.

  • Recording EQUALISATION automatically switched by tape speed switch.

  • Colour scheme was either black/Grey or Bronze / Cream.

 
  • Aux Socket available by removing the dummy control on the extreme RIGHT of the amplifier panel. 

YD MODELS HAVE METAL CABINET & 600 OHM INPUTS/ OUTPUT SOCKETS.
SERIES 3S.
  • As Series 3, but with a Stacked in-line stereo replay head fitted.
  • Stereo replay, with optional Stere-Add unit.
  • Normal Series 3 deck, with counter, tape guides.
  • Colour scheme was Bronze deck / Cream knobs & switches.
  • The stereo replay head was only wired to the rear sockets for use with the Stere-add unit. This allowed monaural recording twin track, but twin track playback of stereo pre-recorded tapes.

The above announcement was made in 1959, with the introduction of the Series 4 range.
SERIES 4 - 4S
  • One piece hinged head cover
  • Pause Control on head cover
  • New Style Control Knob.
  • Square Fascia Meter (except 420)
  • Tape Counter fitted ( Chrome Bezel)
  • Aux Socket available by removing the dummy control on the extreme RIGHT of the amplifier panel. 
  • On stereo 422/4 this socket is located on back panel.
  • Stereo-Add option also available with 4S model which came with a Stereo Playback head fitted as standard
  • Colour scheme two tone Grey.

 

Colour scheme standardised from Series 4 onwards to two tone Grey.

YD MODELS HAVE 600 OHM INPUTS/ OUTPUT SOCKETS

Model 422 : Half track record / playback.

Model 424 : Half track record / half and quarter track replay with height adjustable replay head mechanism.

SERIES 420 - Consisted of the 422 & 424 models.
  • Standard Series 4 tape deck.
  • No amplifier stages, needed external amplifier.
  • New smaller flush type Record Level meter.
  • Mixing Mic / Line inputs.
  • Three heads, monitoring off tape.
  • Wooden Cabinet.
  • Series 5 tape deck was added later in the Series.
  • Pause control on head cover.
SERIES 5
  • One piece hinged head cover
  • Pause control incorporated with Run lever
  • New smaller flush Level Meter.
  • Record EQUALISATION now on separate rotary switch on amp panel. Needs to be set to the same speed as the speed selector or deck will not run.

The small flush mounted level meter first appeared on late Series 4 machines.

Record EQUALISATION now on separate rotary switch on amp panel. Needs to be set to the same speed as the speed selector or deck will not run.

 SERIES 631.
  • Identical to Series 5, but with three speed tape deck
  • Locking pause control incorporated in with the run lever.
  • Angled Tape Counter.
  • Mono only, half track.
  • New style cabinet. lighter fibre case with aluminium trim.
  • Lockable "PAUSE" control incorporated into "RUN" lever

 

SERIES 633.

  • Three speed tape deck. As 631.

  • Half track mono only

  • Three heads. Monitoring off tape.

  • Mixing of line / Mic inputs.

  • Wooden cabinet.

  • Input / Output level adjustment for accurate monitoring.

  • Angled Tape Counter.

  • Lockable Pause control on RUN lever

Record EQUALISATION now on separate rotary switch on amp panel. Needs to be set to the same speed as the speed selector or deck will not run.

 

Model 632: Half track record / playback.

 

Model 634: Quarter track Record/Playback.

 SERIES 632, 634.
  • 3 speed deck, as 631 - 633.
  • Smaller flush meter as Series 422 & 5.
  • Lockable Pause control on RUN lever
  • Record Safety Switch on Control Knob.
  • Record EQUALISATION now on separate rotary switch on amp panel. Needs to be set to the same speed as the speed selector or deck will not run.

 

SERIES 66
  • An early Series 3. 
  • No counter or tape guides.
  • No output stages / speaker.
  • No pause control.
  • Designed for installation in cabinet in home hi fi system.
  • Colour scheme, Bronze deck plate, Cream knobs / switches.

SERIES 88 -- As Series 77 except
  • Full Stereo Record / Replay
  • Two speeds 7 1/2 & 15 ips
  • Series 3 Deck.
  • No power Amps
  • No internal speaker
  • Colour Bronze deck / Cream knobs & switches.
  • Unsuited for monaural only recording, unless both tracks in parallel to give full track.
SERIES 808 ( 1960 )
  • Normal Series 4 deck.
  • Stereo Record / Play
  • Half Track
  • No amplifiers / speakers
  • On some models the first tape guide appears to be missing. Could it be an early series deck?
  • Used extensively in Language Laboratories.

SERIES 77
  • Mono record / play
  • Stereo (replay only)
  • Two speeds 3 3/4 & 7 1/2 ips
  • Series 3 tape deck, incl. tape guides.
  • No amplifiers, needs external amp.
  • Colour Bronze deck / Cream knobs & switches.
  • Discontinued in 1958, and replaced by Model 3S.

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