Hello!  I haven't been writing some time now, but now I'm bit irritated
by this posting about electronic fairground organs...

Paul Allen wrote in Digest 960813:

> I was interested to hear from Robbie that Andy LaTorre has built a
> similar organ to mine.  As requested here are a few more lines.
>
> My organ also uses real percussion, only the organ tones are
> electronic.  The percussion instruments are played by electromagnets,
> I have used pipe organ pallet magnets for the glock.  Two in tandem for
> each of the side drum beaters.  A home made giant solenoid type is used
> for the bass drum, this is driven from a 120v dc supply to give the
> required mechanical power.

So, there are no pipes in it?

> The tone generators are Hartley oscillators which are arranged with an
> appropriate wave shaper for the required voice.   Waveforms generated
> are sine, half sine and sawtooth.
>
> Organ specification as follows, using standard 48-key system
                                                 ^^^^^^
Let me see...

> Melody
>  22 8ft flutes.  The trumpet is borrowed from this rank on Forte.
>  22 8ft violins 1
>  22 8ft violins 2 tuned sharp of 1
>  22 2 2/3ft
>  44 note rank, can play at 8ft, 4ft and 2ft.  Flutes or violins can
>  be produced.

Well, this seems normal to me, beside this being about 4 (?) registers...
How do you control them?  There is place for 3 registers in a standard
48-key plus one "off"-key...

> Accompaniment
>  12 8ft flutes
>  12 4ft flutes
>  12 8ft violins on Forte

Now, this is what I'm wondering about the most.  Perhaps its just a
little fault by you, but: do you really have "12" of each?  In 48-key
systems there are 11 accompaniment-lines [channels] ...

> Bass
>  8 16ft Bourdons.  16ft Trombone on Forte.
>  8 8ft flutes
>  8 4ft flutes
>
> There are a total of 192 independent oscillators, attack times are
> arranged as required, i.e., bass notes start slower than the higher
> notes.  Only two voices are borrowed on Forte, a total of twelve 35-watt
> amplifier and loudspeaker channels are used.  Speakers range from 15
> inches down to 4 inches in size.  I have no idea how much the beast
> weighs!

Hmm... One oscillator per "pipe"?  12 loudspeakers?

Well, I do prefer instruments built up as electronic and driven by
mechanics, to instruments built up as mechanics driven by electronics,
but, wouldn't a standard organ be about the same weight?  And you would
have a natural tone there...

This is no criticism, but I wonder why someone would construct
somethin' like this ... just 'cause of the possibility to do so?
Adjustable volume of the organ?

And one thing that always disturbs me: you need electricity for it.  :-)
Is it at least provided by solar-cells?

> Paul Allen
>
> [ 192 oscillators -- I'm impressed!  Ray DeVault, proprietor of
> [ Devtronix, advised me that the independent "free phase" oscillators
> [ yield a warmer and more natural sound than the ubiquitous master
> [ oscillator and divider chain.  As always, the challenge is to create
> [ a realistic sound of the violin pipe; DeVault said, "More filters!"
> [ Are recordings of your organ available?  -- Robbie

What's the problem with the sound?  Am I mixing things up or isn't this
system built up on waveform samples?

Seems I need lots of info to get this to make some sense.  :-)

greetings by(e) InK - Ingmar Krause
ERlanger drehORGEL-Trio, Familie Krause, erorgelt@erlangen.franken.de


 [ Editor's note:
 [
 [ Ah, welcome again to Spring (almost Summer) at MMD, Ingmar !
 [ Paul Allen explained, in Digest 980612, that he is experienced in
 [ the building of electronic organs, which usually have a full-length
 [ division of N*12+1 notes, e.g., 13, 25, 37...  So he comes from the
 [ world of theater organs, but he has adapted his instrument to play
 [ from keyless music books.
 [
 [ A separate amplifier and loudspeaker for each "pipe rank" doesn't
 [ cost much, and it gives much better sound quality than does a single
 [ amplifier and 'speaker.  The tones are generated by simple sine-wave
 [ oscillators and wave-shaping filters, one for each "pipe"; it's not
 [ a wave-table synth organ.
 [
 [ Why did he build it?  Why did the bear go over the mountain ??!!
 [ To see if he could!  :-)
 [
 [ Ingmar, I'm happy to tell you that I have begun lessons on how
 [ to crank the Drehorgel.  Yesterday, at the AMICA/MBSI Organ Rally,
 [ Jody and I practiced turning the crank on a beautiful 41-key keyless
 [ organ built by Johnny Verbeeck, with music arranged by Tom Meijer,
 [ and owned by Ron Wolf of San Diego CA.  I would love to own such
 [ a crank-organ myself !
 [
 [ -- Robbie