Re: Pianocorder Information
By Will Dahlgren
Reply to::
> Date: Wed May 17 00:17:06 PDT 1995
> From: kravitz@foxtail.com (Jody Kravitz)
> To: automatic-music@foxtail.com
> Subject: Pianocorder Information
>
> Mike Jardin asked some questions about the Pianocorder. First, I'm curious
> where Mike is getting the parts. I don't believe these have not been in
> production for a long time. There's a lot of these systems in the LA area
> maintained by a technician who bought the rights to use the DBA
> Universal Piano Co. His name is Randy Cox and he can be reached
> at 714-283-4242.
The major resource for Pianocorder parts is: Bob Baker ; Electric Orchestras, Inc @ (708) 367-7996.
> I cannot speak for the mechanical difficulty of installing one of these
> systems (talk to Randy), but I've had some experience with the electronics.
> The most notable point w/r/t the electronics is that it structured very
> similarly to pneumatic reproducing pianos. In particular, there are
> two D/A converters for expression control -- one for the bass cleff and
> one for the treble cleff. I don't recall there being any support for
> cresendos, just discreet levels. I don't remember if there are 3 or 4
> bits going to each converter. This arrangement makes transcribing
> pneumatic rolls into Pianocorder format straightforward (except for
> the cresendo issue), but it makes the MIDI conversion a problem because
> MIDI assigns a velocity value to EACH note. It is possible to play
> notes in the base and treble cleff simultaneously with differrent velocities,
> it is not possible to play notes in the same cleff simultaneously with
> differrent velocities. This makes the job of the MIDI converter box hard.
This is true. For those interested, I will try go give a nutshell view of the Pianocorder data method:
Your TV images are transmitted at 30 "frames" per second. It is not possible for your TV to "update" an image quicker that the 1/30 pe rsecond transmission rate for a frame. The same situation occurs in the way the Pianocorder system works. The information encoded on a Pianocorder tape is "updated" every 27 milliseconds". Every 27 ms. a new "picture" occurs which tells the piano what notes are on or off, etc. The Pianocorder frame has the following:
Soft pedal: on/off
Sustain pedal: on/off
5 bits of bass intensity: (32 levels)
Bass notes: on/off
Control bits: Micro controls which mid range notes get the bass or treble
intensity info.
5 bits of treble intensity: (32 levels)
Treble notes: on/off
Sync byte: Used to determine if the previous 120 bits were is OK
The Pianocorder system can only time notes to a 27 ms. interval, and during any interval when a note goes on, any of the bass or treble velocity ON infos must be assigned to ALL of the notes in either the bass or treble group.
The MC-2 system I developed, does pretty well in converting Pianocorder to MIDI, but the above limitations must apply.
The MC-2 is sold by:
Bob Baker ; Electric Orchestras, Inc @ (708) 367-7996.
> Frankly, this also makes conversion of MIDI performances to pneumatic
> reproducing piano format difficult as well. Mike Ames has made an Ampico A
> available to me for experiments in this area, but there's only so much
> time in the day...
>
> A word of caution w/r/t the Pianocorder's electronics (and probably
> some of the other systems which I've not seen the insides of yet). The
> Pianocorder systems I've seen did NOT have isolation transformers. This
> results in the possibility of line voltage to be present where you think
> there should be "ground", including wiring to the cassette recorder. They
> use plastic knobs for a reason!
Yes,yes! There is 165 VDC on many Pianocorder exposed boards. This can kill you!. Both Pianomation and PianoDisc use isolated DC supplies that limit the DC voltage to about 45 VDC on potentionally exposed boards. ( I don't know the situation with Yamaha Diskclavier - anyone know?)
> I've only seen (and tried) one commercial MIDI converter design for the
> Pianocorder. It worked pretty well and _seemed_ to have the necessary
> circuit isolation.
The MC-2 is completely opto-isolated from the Pianocorder electronics.
> I talked to the engineer that designed it a couple of
> years ago. It turns out that he's the same engineer that designed the
> Pianomation electronics for QRS.
Jody is referring to my MC-2 - please see previous answers.
Will Dahlgren (WillWiz@aol.com)
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