3-Manual Theatre - 1962
Blue Book says
· 2 61 -Key Manuals (this model has even 3...)
· 32 Pedals
· 3 Tremolos
· 3 Vibratos
· External Speakers Gyrophonic Projector
· Memory Pistons
This organ was build in 1962 and for me this was a total different experience compared to the mainstream organs I saw before. The console is made of massive wood, it weights about 200kg. It has wooden keyboards, and those huge comb relays, which were also found in large pipe organs with electric tractures from the same era.
Allen started replacing vacuum tubes by germanium transistors in their models by 1959, keeping the basic circuits the same. Thus the sound is comparable to the earlier tube models from Allen (an exception is the solid state power amplifier).
Allen calls it a unit duplex organ. The oscillators are reused for several tabs and footages. It has three single tone tone generators each producing sine waves: Flute/Reed Generator, String- and Celeste-Generator. The reeds sounds are provided by an additional wave shaping circuit after each sine oscillator. And by the way, the reeds really sound great. One uniqueness: the so-called Hartley tone oscillators are silent when no key is played. When a key is pressed, the supply voltage is send over the keying/relay matrix to the appropriate oscillators and only they start making sound. RC filters at these individual power supply inputs result in a smooth attack phase of the waves.
The three tone generators. The
discreet electronic parts are housed into solid metal cases. On top the
oscillator coils and individual potentiometers to adjust the volumes of each
tone. The cases can be turned around to access additional pots for tuning and
opening the lids.
One tone generator opened.
Each oscillator has a tuning and volume potentiometer . All components
individually wired and soldered; was this fly-by-wire already?
. All components individually wired and soldered; was this fly-by-wire already?
Back side of the manual. Each tab has its own coil which moves a key contact to the keying matrix behind each key (12 per keyboard) and enables the addressing of the matching oscillators.
Additive Synthesis! There is a Clarinet tab. I was surprised not to hear an ordinary rectangle wave sound. Instead, the clarinetish sound is synthesized by adding several attenuated odd overtones on top to the sinus 8' tab. Nice. The Flute tabs are come up with real sinus sounds, but without the spirit of the tone-wheel organs. A unique „Flutes become Tibia“-tab adds an attenuated fifth footage by engaging another comb relay to the flute which brings more life.
for each pedal tab s
There are also different bell tabs like Glockenspiel that engage several footages together. Some comb relays connect electrolytic caps to the oscillator supply inputs, resulting in sustain and chiff effects. This is also the basis for percussive instruments like bells.
. Buttom view: Diode matrix for
pedals keyers. All circuit boards are no printed circuit boards, but each piece
is mounted on nails and individually wired.
Circuit board on top: relays and caps for the sustain circuit for flute voices on Solo Manual
. Buttom view: Diode matrix for pedals keyers. All circuit boards are no printed circuit boards, but each piece is mounted on nails and individually wired.
What's that? A Crescendo Roll – like in pipe organs!
A theatre organ needs drum tabs, so did the developers at Allen think and integrated Taps Generators. The organ sends the control signals to a separate speaker box, which includes the drum circuits, amplifier and speakers.
There are two extensive rotating speakers, an invention by Allen and somehow different to the well-known Leslie principle. The speakers are mounted on a spinning disk, thus the direction of the sound remains always the same. The resulting effect is more subtle compared to a leslie.
I had to exchange all electrolytic caps, as they were in the power supply, the oscillators and the sustain unit. Some germanium transistors had to be replaced, and some relays needed cleaning with a glassfiber pencil. That was all for this 50 years old proud lady.
My personal ranking
**** (4 Stars of 5)
Impressing technology of 1962.
Good trumped voices, strings.
Complex sound by 3 Generators.
almost noise free
Not so many possibilities compared to a Rodgers