[Arran]

Mr Fix;
I tend to exclude pre war battery sets with regard to speaker size due to the limitations they had, at least until the mid 1930s or so, with acquiring suitable material to produce strong permanent magnets. Even after that point the availability of larger PM speakers may have been more limited as electrodynamic speakers were in common use even in AC/DC sets, down to 4'' until the early 1940s, cost may have been a factor as well. In this case the Sparton uses an 8'' electrodynamic like most AC radios used in 1935 or 36, and they used 10''-12'' speakers in most of their other console models. I remember repairing one for a guy back in the 90s, the speaker was missing so I mounted a 10 or 12'' P.M dynamic in it, with a filter choke, it had a single ended #42 as well.
Regards
Arran