Hummel's origin is the development and manufacturing of very high quality
studio equipment. Many parts and units found in the hifi gear are derived
from the professional equipment. Many output transformers are of outstanding
quality. Later they made a legendary hifi tuner, FM 2002.
The VS70 or VS71 is maybe the best German Stereo amp
made in the 60s (do not forget the Melpic 35). Frequency response and tech
data is state of the art. Using the "Fernregler" connector the unit can be
used as preamp or power amp without any modification.
This amp uses 6 ECC83s in the
preamp section and 2 ECF80s as drivers. The output tubes are 4 EL36 tubes.
It sounds very nice.
The output transformer is grounded between the 0 and 4 Ohms tap - so be
careful when switching or testing!