Extract from 1960 DeArmond Amps Catalog.
R5 Example 1, Ser. No. K0457:DeArmond-R5-amp (B0428):
R5 Vacuum tubes Layout and Serial No. label.
Chassis interior. Two photos.
Jensen Speaker Type SP-5403. EIA code (220026) shows 26th week of 1960 as speaker manufacture date.
Amp logo – 1st. version: Plastic, approx. 2″ (50mm.) wide:
Example 2, Ser. No. MH0390: Martin M110 amp (photos copyright David Boltz B0012).
Front View of Amp.
Back of amp. Speaker is not original.
Chassis Views – 2 photos.
Mains Transformer, Ref. No. PT5200
Output Transformer, Ref. No. T-706 549-6026