First, I'm thrilled to hear of another member (Hal Davis) who has/had a
Novachord.  Is/was yours playable, all the way down through the bottom
octave?  Because of the octave-divider system used, once a given note
mis-plays, all the octaves of that note below also go out.

Mine uses all octal tubes except for the power amp's 2A3s, 5Z3, and
76s.  Mostly 6W7G, similar to 6K7, but the master oscillators use 6C8G
dual triodes.

I can imagine early models using the 5, 6, or 7-pin tubes (Philco
kept using these until 1936 or 37), and if the Novachord had stayed in
production (or did stay in production) into 1941, it could have been
redesigned with Loktal tubes, which were quite an improvement over
Octal, and spearheaded by Philco.

A few tubes in the instrument could have been retrofitted with 7-pin
sockets, or forward-fitted with Loktal, but nobody could have replaced
*every* tube in a Novachord -- the war lasted only four years, and it
would take a technician longer than that! :-) Remember, two tubes per
note, 6 octaves ... But the chassis is designed to be easy to work on.

I've seen photos of an early prototype whose chassis rose up vertically
behind the keyboard, like an upright piano or Orchestrelle or telephone
switchboard from the HA-des exchange.  I guess the player could
instantly reach up and change a bad tube during a performance.

Seriously, the tubes are run at reduced voltage and current, and
they last and last.  And I have two boxes of brand-new spare 6W7s
(or 6W8s?).

Mike Knudsen

 [ The Hammond 'synth' I saw must have been very early production.
 [ Could there be another name for it?  Lots of rotary switches (no
 [ drawbars) and 6E7 (I believe) 7-pin tubes with grid cap.  -- Robbie