3577084 (Google)Computer Sound Generator May 4 1971 Singer-General Precision 327/107; 84/659; 327/134; 341/147; 377/51; 377/112; 984/389; 984/DIG1
3696201 (Google) Digital Organ System 84/648; 84/659; 84/660; 984/382; 984/DIG1 (Wurlitzer) -
4018121 (Google) Method of synthesizing a musical sound Filed: May 2, 1975, Pub: April 19, 1977 John M. Chowning 84/696; 84/101; 84/659; 984/309; 984/324; 984/389; 984/DIG1 - Basis of the Yamaha DX-7 Synthesizer.
Patents calling 4018121 -
4813326 Method and apparatus for synthesizing music tones with high harmonic content, Yamaha, Filed: Jul 16, 1984, Pub: - Fig 22 block diagram of an operator
4922795 Tone signal forming device, Yamaha, Filed: Nov 17, 1987 -
5025702 Electronic musical instrument employing time-sharing frequency modulation and variable control of harmonics,Yamaha, Filed: Jul 3, 1975, Jun 25, 1991 - FM synth (filed a month after Chowning)
5191161 Electronic musical instrument including waveshape memory and modifiable address control, Yamaha, Filed: Jul 3, 1975, Pub: Mar 2, 1993 - variable color with same pitch from table entries.
I had one of these synthesizers. After adding on a small PCB (Grey Matter E! ?) the capabilities were greatly increased and not only could it be controlled by my Radio Shack Color Computer it also could remember an arrangement. I think it had a complex rendition of "The Entertainer" built-in. If you know the maker and/or model number of this add on board let me know.
Wave of the Future - History of Chowning's development.
With the introduction of micro controllers and home computers the age of digital sampling (Wiki) allowed the production of sound that matched that of an actual instrument. The samples could be played back at different speeds and modified using the same signal processing methods used for analog music synthesizers. So analog synths fell out of favor and the digital synths took over.
But in the late 1990s an interest in analog synths came back. Part of this is related to the availability of Eurorack (Wiki: Doepfer_A-100)modules, most of which are reasonably priced. PAiA (home, Wiki) has been making low cost music synth modules since 1967 and still offers them.
rack mount box version of the DX7. Requires external MIDI controller.
YouTube: Yamaha TX802 Demo - Yamaha TX802 - A few performance patches -
Dave Benson's DX7 Page - many documents
YouTube, cellarseer: Yamaha TX802 Service Mode - walks through the 8+9+On mode.
Hold number pad 8 and 9 while turning on power.
Firmware V1.0 22-APR-87
Fig 2 Op Sys chip in upper right
just below TX802, marked: XB223 
New chip marked: TX802, XB224 OS V 1.5
I installed the V1.5 chip at the top left, but it should have been
installed in the upper left.
Fig 3 with Ver 1.5 op sys:
The top LCD row is all black dots.
Got this to go with the Korg M-20, but also used it with the Yamaha DX-7 (borrowed) and TX802.
This is a hand held unit that can be powered either by three AA batteries or by a USB-A to USB-A cable that's included. It's a mono amp, but comes with a stereo 3.5mm - stereo 3.5mm cable.
I got this as an alternative to the Radio Shack 277-1008.
The box has the word "Bluetooth" but that's marketing hype. Also note the brown and Black wires from the USB socket to the main board means that only DC from the USB is supported, not audio.
The speaker seems much more substantial than what I remember of the Radio Shack 277-1008, so this may sound better.
100k Ohms Left to ground
100k Ohms Right to ground
20k Ohms Left to Right
I'm hoping to use this as a replacement for the Radio Shack 277-1008.
Note The new version 277-1008 has a Positive center 9VDC input. It runs on 9V (battery or external wall wart) and has 3.5mm input and ext speaker/headphones output jacks.
The prior 277-1008 Micro-Sonic unit runs only on a 9VDC battery (no external 9VDC input). Also there is no headphone/speaker output. (See: Radio Museum: Microsonic)A similar unit was the Telephone Hearing Assist Amplifier Archer 43-229 that ran on a single 1.5 V "N" cell.
K4CHE - Knock Off BC-611 - Schematic of the 277-1008C -
Found this on eBay for a good price. Poor packaging, but these seem to be made to take a beating and keep on ticking.
Fig 1 Styrofoam peanuts (crushed) and popped
air pillows inside box, should have used bubble wrap.
See Packing for shipment.
Fig 2 Front
Fig 3 Back Controls are for Guitar effects (Wiki)
I started by looking at the PCBs based on the PAM8403 (datasheet.pdf) These are nice and run from 5.0 VDC max, or 3ea Alkaline batteries or a single 18650 cell. Some come with a volume pot built-in. There is also a PAM8406 and PAM8610
For lowest harmonic distortion many of the PAM amplifiers like 8 Ohm speakers better than 4 Ohm speakers, but the 4 Ohm speakers offer twice the power.
large holes on left
for mounting PCB
or 3.5mm terminal block
50k pot + knob
2.5" 4 Ohm
4" 8 Ohm 10W Spkr
Speakers from Marlin P. Jones
14618 SP 4 Ohm Mini Speaker- 2" 4 Ohm, 400 - 8k
Gento P/N ZSP99023A 33056 SP 8 Ohm Mini Speaker, 3W, 2in. - 2" 8 Ohm 3W
33055 SP 4 Ohm, 3W, 2in. Mini Speaker- 2" 4 Ohm 3W
35607 SP 2-3/8" 8 Ohm MINI SPEAKER - 2-3/8" 8 Ohm 20W
Onkyo 580213-1001 36939 SP Pack of 6 - Multi Sized Micro Speakers Speaker small horn - 8 Ohm 1W
This introduced me to expressive music controllers. Each key is sensitive for pressure (Z axis), pitch bend (x axis) and a third parameter like filter setting (y axis) allowing for very nuanced performance.
There are a number of other expressive controllers such as:
The Eigenharp family of instruments (Wiki) from EigenLabs - patent 8934088 Sound-creation interface - uses a custom switch that has variable outputs for x, y and z based on modulating a light beam or using a breath controller.
These allow performing electronic instruments with the same expression as actual instruments, fantastic!
At first glance this appears to be an acoustic guitar. But it has an internal DSP based (Wiki) processor that adds special effects then used a force actuator to shake the sound board so it acts as a loudspeaker.
7812243 Stringed instrument with embedded DSP modeling for modeling acoustic stringed instruments, Peter J. Celi,Michel A. Doidic, Marcus Ryle, Yamaha Guitar Group Inc, 2010-10-12 - The actuator might make use of
Magnetostrictive material, i.e. be something like the Sound Bug.
Korg MS-20 Mini Synthesizer
Teenage Engineering PO-16 Factory "lead synthesizer for keys melodies. sequencer with parameter locks, play styles and punch-in effects. pocket operators are small, ultra portable music devices." - User Guide - pdf -
While looking for an analog music synthesizer that might be used with the Linnstrument came across the 1978 MS-20 (Wiki) and the modern MS-20 Mini version that includes MIDI (Wiki).
Note that the M-20 is a monophonic (one note at a time) synth and so is not suitable for use with the Linnstrument.
Very capable device, but has a steep learning curve.
Note there are LEDs above each button 2 and 12 are on in this photo.
Home Theater - 7.1 Surround Sound
Sound Powered Telephones & Early Loudspeakers
The Player Piano (Wiki)Patents by Kenneth B. Caulkins related to this topic.
eBay: user: kenquienenquien -
Ragtime Automated Music - Catalog.pdf
Page created 22 June 2003.