The Columbus model 56 was manufactured for Columbus Radio Centre Ltd by Radio Corporation of New Zealand Ltd in about 1941.

Other radios based on the same chassis:

5-valve dual-wave with bandspread short wave band. 

Appears to have been a 5-valve version of the venerable model 66 although not nearly as popular given the few examples found today. 

Noted as being similar to model 52S

Technical Information

Valves (5):
56: X65, KTW61, DH63, KT61, U50
56A: 6K8GT, 6K7G, 6B8G, 6F6G, 5Y3
56B: 6K8G, 6K7G, 6B7, 6F6G, 5Y3G

Intermediate Frequency: 455kc/s

Frequency Bands: 2

Chassis Notes(most schematics can be clicked to download a full size version)

56 service info unavailable, but it has been noted as being very similar to the 52S - see this service documentation and notes for more info:

Service information (RCNZ_-_model_52S_and_56_-_5V_DW_AC_Expanded_Shortwave_Tuning_-_1940.pdf) here

General Construction Notes for Radio Corporation of New Zealand Ltd:

The first digit of the serial number typically indicates the year of manufacture of RCNZ chassis' (although not the decade - that requires a little knowledge of the valves, construction, etc). Sets from around 1934 onwards were often (but not always) constructed in a distinctive pressed 'baking pan' style chassis, seemingly unique to RCNZ.

Model codes beginning with a 0, for example the model 051, are Osram valve versions of the model without the leading 0. Technically the 0 should be an O (for Osram), however the digit 0 was used throughout the site before this fact was discovered.

The E suffix indicates a magic eye option is fitted (in models which were available with or without, such as the model 25).

A and B suffixes appear to be simply updates to the current model, R also appears to be simply an updated model ('R'edesign, perhaps?)

P indicates either a permanent magnet speaker version of a model which also came with an electromagnet speaker (the model 26 for example), or a portable model (like the model 694P).  This suffix was used in the mid 50's when Radio Corp was changing over.

N and M indicated miniature valve versions of a model which started with all (or a mix, ie: model 5) of larger valves. One of these two codes may indicate a transitional mixture of octal and miniature - clarification is required.

S often indicates a stereo model.  It can also indicate 'self-biased' in the transition period between back-biased and self biased sets where there were models with both methods employed (53S for example)

Finally, other suffixes and prefixes make occasional appearances in the RCNZ lineup - like the 66W (a variant of the long-running model 66) and the 75XA (a 10-valve version of the model 75 with a separate amplifier chassis).

Model nicknames are often sourced from either newspaper advertising, company literature or the NZ Radio Traders Federation official trade-in price books (Particularly Courtenay models from this publication)

Other documented models using this chassis (2 in total)

1941 Courtenay model 56 'Tui'