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(antique portable electron tube organ)
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Everybody knows what a pipe organ is - but did you ever hear of a tube
organ?!
This "garden grill with keyboard" is one of the very first portable full-
polyphonic electronic organs. I am not sure how rare it is - it may be
the 2nd last of its kind. On the internet I found only a single other owner
(who is missing the amplifier) and as well the release date 1946 as 1953.
Mine is a German version that according to the serial number plate was
built by "Jörgensen Electronic", licensed from René Seybold
and Harald Bode. Because it contains many common 1950th E- series tubes,
I guess that 1953 is more likely. (1940th tubes had rather round sockets
with a nipple at one glass corner instead a missing pin as the mark. Only
the EL12 look that old, but they may have been a pre- war shelf relict.)
The instrument consists of the organ itself (a black, coal- grill- like
metal construction on an collapsible iron stand) and the amplifier/ power
supply cabinet, which has the size of a large tube radio.
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This is the amplifier and its lid...
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...and
this the paper texture inside the lid and carry case. |
The organ has a wooden trunk/ carry case to transport and store it when
not in use, and also the amp is built into a similar case which has a lid
to cover the back when not in use. Unlike a Hammond and similarly
old organs, this one has a fully electronic, analogue sound generator without
any mechanical or acoustical oscillator components involved.
main features:
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36 mid- size keys (with small wire lever for contact cleaning, each key
controls 3 opener switches)
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suitcase- style portable amplifier + separate trunk for the organ itself
(and its collapsible stand?)
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18 OBS tab switches, sorted in 3 groups {16', 8', 4'} with each 6 switches.
I am not sure yet whether the switches simply set the volume of each group
in multiple steps, or if they control more complex filters (the latter
seems true, although the effect of some switches is very subtle, and some
combinations even seem to cancel out each other).
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dynamic volume control by black bakelite knee lever + preset volume (right
black knob)
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vibrato with depth and frequency control (left white front and back knob)
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treble control (right white front knob)
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tuning (left black side knob, about 2 semi-tones)
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full polyphonic, analogue sound generator with 1 tube per key. There are
12 oscillator modules for the octave tones; each module contains 3 tubes
(ECC82) for the 3 keyboard octaves (this means 36 tubes!); each octave
has different, quite complex raw waveforms (not squarewave). 1 small transformer
per module seems to generate a 4th octave as overtone. Each module has
one common tuning trimmer coil for its 3 octave outputs; I am not sure
if this functions by frequency dividers or synched oscillators.
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2 input (?) jacks for a jack plug pair at left organ side
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separate amplifier/ power supply cabinet with very heavy mains transformer,
a large loudspeaker and 2 big EL12 power output tubes.
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7 pin organ connector with 300V DC high voltage at bare jack contacts without
any touch protection and high voltage electronics easily touchable through
the knee lever hole (yikes!)
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5 Ohm and 200 Ohm external speaker outlets with mute switch for internal
speaker
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electronics mostly based on standard tubes (ECC81, ECC82, ECC83, EZ81),
those are fortunately still available.
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power consumption 183W (on type label stands 200W)
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wacky, short- circuit prone metal construction that looks very handmade
and contains many bolts and a lot of brittle, bolted pertinax circuit boards.
On
the upper left corner of the amplifier are remains of a painted brand label,
which likely once has been "Tuttivox". |
The
one at the lower right likely has been "Jörgensen". |
eastereggs:
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Each key has 3 spring wire opener contacts underneath, those touch a common
GND rail wire when not pressed. (The rail rotates by moving a lever to
clean contacts.) This way the keyboard is some kind of pressure sensitive
because the 3 switches open in a sequence and thus make 3 partial tones
of the different octaves audible one after another when a key is pressed
or released slowly. This permits interesting sound variations, although
the contact sequence of every key is different with this organ. (A Hammond
organ had even 9 separate contacts per key.)
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Due to the 12 tone generator modules are separately tuneable, it's interesting
to give the thing a POKEY tone scale instead of the boring well tempered
one. The initial tone scale I bought it with sounded anyway much more POKEY-
like than well tempered.
modifications:
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high voltage output jack touch- protected by shrink sleeve pieces.
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clear, slideable piece of sheet plastic mounted at the knee lever hole
as a rudimentary HV touch protection.
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the amplifier chassis grounding screw was oxidized and made no contact
anymore =>upgraded with a rough "spring washer" (correct term?) to improve
contact to the metal.
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black felt strip above keys added to prevent dust or other things from
falling into the electronics.
At the very right are 2 sets of jack plug outlets for external loudspeakers;
while the upper set is a normal 5 Ohms one, the lower set outputs a high
voltage signal for special tube- age speakers with external transformer.
The organ connector has (counted from left to right anticlockwise) the
following pin assignment:
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"-" 37.8V AC
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"-" 6.3V AC
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+300V DC
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audio in
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GND
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"+" 6.3V AC
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"+" 37.8V AC
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The organ tube heaters are wired in series and supplied by the 37.8V
AC output (likely to reduce the needed current on the supply cable); the
6.3V output is not used. |
The amp's serial number plate. |
Now
take a look what's inside... |
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Here you see the large loudspeaker and the 2 big EL12 power tubes on
the chassis. |
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When on, you can see the tubes glow and the bright red shine of the
pilot lamp. |
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Although this mains transformer block may look small and harmless,
I estimate that its solid, heavy iron core incorporates at least 65% of
the weight of the entire amplifier.
Above it you see the 2 EZ81 rectifier tubes; in one of the EZ81 and
one EL12 tube there is weak blue ionization visible, possible a remain
from a previously broken grid capacitor. |
The instrument can play loud enough to annoy neighbours tonight, but I
don't think that it is louder than the amp of average 1x EL84 tube radios,
despite the 2x EL12 tubes look like something as big as KT88 and by their
appearance I would expect rather 30W power than just 5W. It may be that
the ionization in one tube eats up the power, or that just the huge loudspeaker
has lost most of its magnetism (which is rumoured to happen with that old
speakers), or that a small defect in the organ makes it quieter. (Its internal
preset volume trimmer is all way cranked up.)
Through
the knee lever hole it was extremely easy to touch the high voltage electronics
of one of the tone generators; I am not sure if there ever was a protection
against this (e.g. in form of a latex rubber bellows that disintegrated
over time by oil/ bad treatment, or a brittle bakelite board that broke
and thus was thrown away) or if in 1950th they really never cared about
children safety. I covered it with transparent sheet plastic to prevent
electric shocks. (At the left corner is the hole of the power supply/ amplifier
cable.) |
There
is a mystery pair of jacks and the left side. The black knob controls pitch
in a very limited range. At the right side is a similar knob for the preset
volume control (in opposite to the knee lever volume). |
This is the back of the organ with cover cage removed. |
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There are 12 oscillator modules; each produces one tone of the octave
and contains 3 tubes for the 3 octaves of the instrument (top is the lowest). |
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To tune the organ, this row of trimmers can be adjusted with a screw
driver.
As it came, the tone scale sounded quite detuned (especially the "h");
I am not sure if this is due to broken capacitors (the main oscillators
seem to use less prone plastic ones) or if this Tuttivox was intentionally
tuned like an ancient church organ. (I read that also Arp Schnittger pipe
organs etc. often used much different tunings than the modern well tempered
scale.) The POKEY composition "One Man and his Droid" (available on the
SAP Atari XL music archive) can be played almost perfectly with this scale,
but most normal music sounds a bit strange. |
To
the right is the pre- amplifier and vibrato unit of the organ. At its right
side are 2 trimmer potentiometers; the upper one limits the maximum volume
of the organ. (Mine came fully cranked up, but I guess that is was originally
built in to prevent kids from playing too loud.) |
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Here you see the custom made special potentiometer of the knee lever.
As expected, the uncovered, dirt prone wiper contact causes some crackling
noise when moved. |
When
we remove the front cover, we can take a look at the heart of the instrument... |
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It must have been a horrible lot of work to solder all these components
together. I have no clue how expensive this small instrument was, but I
could well imagine that it costed as much as a grand piano. Unfortunately
the fully electronic tone generators contain several dozens of "explosive
candy" capacitors, and most of them already have more or less cracks in
them. Unlike the solid construction of my Tektronix tube oscilloscopes,
the 3 dimensional construction of this hardware is rather awkward to maintain,
because it consists mainly of brittle, traceless Pertinax circuit
boards those are faithlessly bolted and soldered together without removable
connectors. Also the selection of components looks rather like a collection
of post- war shelf mess than produced by a single factory.
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Beside the 2 trimmer potentiometers mentioned above, there are 3 further,
black trimmer pots simply hanging on their bare, flimsy wires among components
at a circuit board. It must be a more than unpleasant and challenging task
to adjust these during operation, because the smallest mistake can cause
things to bend, short and burn out, or makes you slip with your (hopefully
gloved) hand or screwdriver into the high voltage electronics. |
Every
tone generator module contains a small transformer (generating a 4th octave
overtone?). The modules are connected at the bottom by a main bus rail. |
main bus assignment (top to bottom):
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+297V DC
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pitch pot (+136..175V DC)
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vibrato envelope (about 2V AC, stabilized by a big "explosive candy" cap
against GND)
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GND
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32V AC
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0V (?)
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Even behind the tab switches are multiple such small transformers and
further "explosive candy" caps. |
When I examined the electronics, once the organ smoked badly and made no
sound anymore; I guess I toasted the common pitch control potentiometer
when its resistor at the 2nd bus line was accidentally bent against the
grounded case. After I bent it back, the organ fortunately still works.
Behind the keys are lots of small resistors. |
Here
you see the metal lever under a key, which plastic end presses down 3 spring
wire contacts. Behind the keys are the springs those hold them up. |
At
the right keyboard end is a small wire lever to clean the key contacts. |
The spring feathers those hold keys up have all different strengths - I
don't know if this is because it was a post- war product or because someone
incompetently tried to fix stuck keys. (Initially mine had a few stuck
keys, but the reason were bent metal levers and not too weak springs.)
On the bakelite keys are many scratches; I guess that someone incorrectly
stored the collapsed stand upon the keys when he transported the organ
in its wooden carry case.
notes:
The tone generator modules contain dozens of of more or less rotten "explosive
candy" paper capacitors those reliability is very questionable. As a safety
measure I already replaced the ones in the power amplifier, because the
previous owner said that the amp crackled and smoked a bit when he plugged
in the HV connector of the organ during operation, and because the EL12
power tubes are expensive to replace and a short in the wooden cabinet
could cause a fire. But to replace all of them in the organ would be a
tremendous lot of work. Unfortunately I not even have schematics to determine
the proper cap values for a replacement; the writing on the cracked and
dirty capacitors is partly badly readable. But I bought already new capacitors
and will repair this thing when I find time in future. This strange thing
is like a piece of ENIAC, and feels like repairing the tube operated time
machine in the movie "The Time Travelers" from 1964.
I am still not sure if the registers and tone generators sound like
intended, because they use filters made from the same old capacitors, of
those some may have a short, but replacing all "explosive candies" would
be quite a horror job and may take at least a month since it would be extremely
awkward to de-solder and dismantle the 12 tone generator units. My Tuttivox
currently sounds somewhat similar like a harmonium or plain Hammond
organ tones with almost no distortion (and no Leslie). The vibrato turns
slower and stutters/ gets a hiccup after 15 minutes of warming up; possibly
the ECC81 tube is broken.
The previous owner told me that the instrument once had been owned by
a church organist (?). I bought it used for 50 EUR. Because it had stood
at an attic for decades and according to the rusty/ calcium crusted top
of amplifier and carry case it seems to have rained upon it many times,
the instrument smelled very musty. After removing dust and cleaning it
with humid toilet papers I therefore treated the loudspeaker cloth with
fragrance- free Febreze (textile deodorizer based on a corn starch
chemical) to remove the smell, which worked quite well.
Behind
the keyboard is a row of 3 pre- punched openings those likely were intended
for an expansion unit (with a 2nd keyboard??). Also the case shape looks
like designed to place another device upon it, although on the internet
I also found info that the similar shaped case of the Clavioline
was designed to be mounted with its rear end under the keyboard section
of an acoustic piano. |
For
a size comparison you can see here my 1980th Yamaha
PortaSound PS2 in its carry case on top of the 1950th Tuttivox
amp. |
My amplifier unit has the serial number 516 and the organ itself the number
455C. On the internet I found info about a similar, but earlier (?) released
dual- keyboard instrument of the name Multimonica, which was also
built by Harald Bode, but even this one contained only a monophonic tube
organ and to play polyphonic sounds it had simply an additional accordion-
like reed organ/ harmonium built-in as its 2nd keyboard. There are still
many tube operated radios, amplifiers and also TV sets and oscilloscopes
around, but I never heard about portable polyphonic tube organs before.
I could well imagine that when the first lightweight transistor organs
came out or at least with the arise of Yamaha PortaSound many people
threw the last small tube organs away because these were neither a decorative
furniture and versatile to play like a
Hammond, nor remotely as
portable as a modern, lightweight plastic keyboard.
A monophonic and technically way less costly variant of this instrument
was released as Jörgensen
Clavioline.
removal
of these screws voids warranty... |
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