Asimov wrote:>
I have a small MONO portable German made machine with track switching
similar to that. It is a SABA TK125. When it was given the person said
it was used by a missionary in Africa, whatever... Anyways, there is
only one output tube and only one speaker but it plays back 2 tracks
at a time in MONO. There is a switch to select between 1-2 or 3-4.
The only odd thing is the DIN speaker socket has both speaker I and II
labeled. BUT it is MONO, no doubt about it. After cleaning all the
axles and relay contacts it works nicely now. It is very
pre-transistor 50's looking, in modern green plastic not bakelite.
A*s*i*m*o*v
... That was a fascinating period of time for electronics
Most 4 track mono reel to reels have a selector switch labelled 1-4,
3-2 and PAR (parallel). Position 1-4 (or 3-2), does *not* mean you hear
both track 1 and 4 (or 3 and 2) together. It means that track 1 and 3
are the two tracks you use on side one, and after turning the reels
over you still have 4 and 2 to use on the other direction. (On a stereo
model, 1 would be left and 3 right. same for 4 and 2 on the second
side).
Labelling of the positions can be different depending on manufacturer
(grundig for example, often used the terms 1-2 and 3-4, but in reality
they meant tracks 1-4 and 3-2, same quarter track system but i think
they just simplified the names a bit for the end-user)
Quarter track r2r is not like cassette, there is a grerater space width
between the heads:
_______________
Track 4
Track 3 --Head
Track 2
Track 1 --Head
_______________
Unlike the stereo decks, It is not generally possible to record on both
1 and 3 at once on a mono deck as there is only one set of recording
circuitry, which was coupled to either the upper or lower head
depending on track selector position.
However, On playback, if the switch is set to PAR, it will feed the
upper and lower head signals to the head amp, and hence play both
tracks 1 and 3 (or tracks 2 and 4 if we're talking about side 2 of the
tape). It is thus possible to hear left and right (together!) of a
stereo tape on a mono quarter track deck.
Many mono decks had more than one speaker output, depending on how
beefy their amps were. I have some mono tandbergs like that. Some also
had a "free head output" which was an unamplfied signal from whatever
head was not being fed through the deck's internal amp at the time,
theoretically enabling you to connect an auxiliary second head amp (and
power amp, speakers etc) and get stereo.
hope some of that made sense ;-)
Ben