Early Tabletop Stereo

Nowadays it is easy to purchase a boombox or Bose Wave Radio and have a full-fledged stereo table radio. But, back in 1962 when multiplex stereo broadcasting was first standardized, there were few tabletop stereo radios to choose from.  Several companies offered matching tabletop multiplexors with their table radios. This section is dedicated to early tabletop stereo and their descendants. 

[Advent] [Granco] [Heathkit] [KLH] [Sony] [Zenith]


The Advent 420s is perhaps the first integrated tabletop high fidelity radio.  Henry Kloss introduced the KLH Model 8 (see below) when he was with his partners at KLH.  He moved to Advent and introduced the Advent Model 400.  The Model 420s was introduced after Kloss left Advent.  The Model 410m (mono) and this model 420s a stereo retained the modern look and excellent sound of the 400.



Granco 603 and SC-3

  Granco 604 and SC-4

Granco developed a reputation for FM table radios in the 1950's.  The Granco Model 603 is one of the earliest radios to offer a matching multiplexor, the Granco SC-3 "Companion."  The Granco Model 604 and SC-4 are similar in design and operation.  The Model 603 is a FM-only table radio that can be used by itself for monophonic listening.  The Model 603 and the Companion work together to provide stereo using a division of labor most common in early stereo.  The 603 has two rear RCA-style phono connectors.  One connector is the demodulated, unfiltered FM signal; the other connector is a low-level audio input.  The Companion demodulates the multiplex signal and amplifies one channel.  A speaker in the Companion plays sound for that channel.  The audio for the other channel is routed from the Companion back to the audio input of the 603 to play the other stereo channel.  The phono connector of the audio input has a switch to disable the normal (mono) audio of the 603.  It is interesting to look inside the two Granco units.  The 604 and SC-4 use the same chassis (but populated with components very differently) in an obvious effort to hold down manufacturing costs.  Although the Granco Model 603 had a "Companion", the later Granco 603, Model 603b, did not have connections for a Companion.  One might infer that the Companions did not sell very well.



heath_gr21_with_gra21.jpg (11916 bytes)

Heathkit introduced the Model GR-21 and its matching Multiplexor, Model GRA-21-1 contemporaneously.  The GR-21 is an excellent-sounding FM table radio with a "magic eye" tuning indicator.  The GRA-21-1 was a somewhat primitive multiplexor.  It provides a "separation" control on the front panel that is difficult to adjust properly.  The two radios connect together much like the Granco and KLH pairs. 




klh_8_and_13.jpg (19857 bytes)


The KLH Model 8 vacuum tube radio set the standard for tabletop FM high fidelity.   This no-compromise radio has been imitated by KLH itself (KLH Model 21) and others (Advent Model 400, Lafayette Criterion IV) over the years.  The Model 8, designed by Henry Kloss, used an external, matching speaker.  It was designed to work with a stereo adapter.   However, a matching tabletop adapter was not produced immediately.  When the KLH Model 13 stereo adapter was introduced (also designed by Kloss), it looked like the Model 8, but was transistorized.  It connects to the Model 8 much like the Granco 604 connects to the Granco Companion SC-4.  Together the Model 8 with its speaker, and the Model 13 with its speaker, the desktop arrangements places 4 matching boxes on the table. The arrangement in this picture is backwards.  The Model 13 should be on the right!  See more at the KLH 8 page.



Sony provided a matching multiplexor for a number of their FM radios.  The Sony model TFM-9000 (on right) is a push-button operated FM only solid-state table radio with very nice sound.  It can be converted into a small stereo Hi-Fi by adding the STA-9000 multiplex adapter (on left).  There are rear inputs selected by the pushbuttons on the top of the multiplex adapter.



zenith_mh910_2.jpg (24477 bytes)

The Zenith Model MH910 is a unique solution to tabletop FM stereo.  The MH910 can receive monophonic FM, or either LEFT or RIGHT stereo channel.  That is, each MH910 comes with a complete stereo demultiplexor inside, but has only one amplifier and one speaker.  These must have been expensive sets.  Moreover, to received true stereo, the consumer needs two MH910's tuned to the same radio station.  A look at the owner's manual hints at a classic confrontation between the engineering and the marketing departments at Zenith.  Rather than sell the MH910 as a full stereo solution, the manual suggests that the listener can get a "stereo effect" by using one MH910 with his old, mono, FM radio.  With a regular radio on the right side of your table, and the MH910 one the left side of the table (and set to the LEFT stereo channel), the user could hear stereo sound.  This ugly arrangement probably reflected that fact that Marketing did not expect to sell the MH910's in pairs.



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Last updated 24 February 2004

Original site located at http://www.somerset.net/arm/fm_only.html by Andrew R. Mitz ; copied with permission.
(Mirror maintained by Mark Sherman)
All text, photographs, and other graphics are copyright (c) 1998-2004 LTJ Designs.