History of Operadio- Dawn of High Gain Amps

[ampmadscientist]

I was surprised to learn that Operadio goes back to 1922!
But the amp I had was circa 1947.

They used to make outrageous PA speakers, and giant tube PA heads....
Besides making the "first" portable radio receivers.
Audio Pre-Amplifier 1A65 Ampl/Mixer Operadio Corp.; St.

​

Vintage Operadio Model WH7003 Speaker

Audio Pre-Amplifier 1A65 Ampl/Mixer Operadio Corp.; St.Audio Pre-Amplifier 1A65 Ampl/Mixer Operadio Corp.; St. Charles IL, build 1948 ?, 1 pictures, 4 schematics, 6 tubes, United States of America , semiconductors



View on www.radiomuseum.org

Preview by Yahoo​

These guys were the true pioneers of pro sound. The amps they built ate mesa boogies for breakfast.
(these amps grind like a chain saw on steroids)
Infinite sustain, the volume goes to 20.

(That's 10 more, isn't it?)

 

[jensvonbustenskjol]

20? And volume is logarithmic. Thats like a billion more

 

[ampmadscientist]

20? And volume is logarithmic. Thats like a billion more

It sounded like a billion more, check it out:
Model 1A45 has a master volume control.

(History from Dukane .com archives...)

1922 - Operadio Corporation is founded by J. McWilliams Stone. Product is first portable wireless radio. The plant is located at 8 South Dearborn, Chicago IL

1925 - Operadio begins developing its own line of industrial control sound systems, control panels and intercoms under the brand name "DuKane"


1927 - Operadio stops making radios and begins to make loudspeakers, amplifiers, and other sound equipment on a contract basis. Could not compete with giant manufacturer of consumer radios.

Was the giant manufacturer of consumer radios
Marconi? Or who was it?

The secret Operadio Grind = 6J7 preamp tubes, the same preamp used for Hammond B3.




(National Valve Museum)


Type 6J7 is a contemporary of the 'Magic Three' and almost as ubiquitous. Although originally designed as a detector its linear characteristic and good internal shielding (cf. 6Q7GT) made it a natural choice for audio.

It was for two decades the international standard valve for audio amplifier input stages and audio systems generally. The Mullard-Philips type EF37A, for many years the standard British low-noise audio pentode, is really a 6J7G under another name. In this exhibit we see the Mullard 6J7. The central spigot of the IO base has been broken off.

The thin metal tube envelope is 25 mm in diameter, and excluding the IO base pins, is 60 mm tall.

References: Datasheet, 1040 & 1043. Type 6J7 was first introduced¶ in 1936.


Mullards! I might have known.
Seems like Mullard had some dedicated followers, even back in those early days. The top cap is the control grid, FYI.

 

[solarburn]

Cool stuff. Sure like to hear one.

 

[LPMarshall hack]

Will this amp make me sound like Slash?

 

[Micky]

Lee DeForest was actually the person who developed tube amplifiers.
Operadio came much later...

Valve amplifier - Wikipedia, the free encyclopedia

 

[ampmadscientist]

Will this amp make me sound like Slash?

Only if your guitar has no scratches on it.

 

[ampmadscientist]

Cool stuff. Sure like to hear one.

It's unfortunate that we can't find any for sale.
But we do have the schematics and pictures of the layouts.

Good 6J7s are increasingly difficult to locate also. There's glass ones...but the metal ones are rarer there days.

 

[ampmadscientist]

Lee DeForest was actually the person who developed tube amplifiers.
Operadio came much later...

Valve amplifier - Wikipedia, the free encyclopedia

DeForest had no clue that he was giving birth to shredders. An unexpected consequence of science.
"If" he had known...do you think he would have buried the technology?
We can only guess.

 

[Micky]

Personally I think if they ALL had focused on audio amplification rather than radio or RF amplification we would be in a much different place right now...

 

[ampmadscientist]

1640
Vacuum Pumps
The first vacuum. Otto von Guericke's air pump
1643
Mercury Barometer
The barometer first demonstrated by Evangelista Torricelli
1654
Vacuum Pumps
Magdeberg Hemispheres a demonstration of the force of air pressure
1672
Air Pumps
Improved air pump and treatise on vacuum experiments published.
1716
Pressure explained?
Jacob Hermann suggests that gas pressure is proportional to density and to the square of the average velocity of the gas particles in motion
1811
Avogadro's Law
A principle stated in 1811 by the Italian chemist Amedeo Avogadro (1776-1856) that equal volumes of gases at the same temperature and pressure contain the same number of molecules regardless of their chemical nature and physical properties
1855
Geissler Tube
Johann Geissler produces a mercury vacuum pump and with it he produces the first good vacuum discharge tubes
1856
Gas Properties
Karl Kronig suggests that gas molecules in equilibrium travel in straight lines unless they collide with something
1858
Cathode Rays
Julius Plucker demonstrated that magnetic fields bend what later became known as cathode rays.
1860
Lamps
Joseph Swann patents the the carbon filament incandescent lamp that operates in a partial vacuum
1862
Vacuum Pumps
Geissler-Topler mercury vacuum pump developed
1865
Vacuum Pumps
Hermann Sprengel develops the mercury drop pump
1870
Vacuum Pumps
Sir William Crookes vacuum pumping system
1871
Cathode Rays
C F Varley suggests that cathode rays are particles
1871
Cathode Rays
Sir William Crookes advances the idea that cathode rays are negatively charged particles
1874
Photo-emission
G R Carey invents the photo-electric cell
1876
Gettering
Sir William Crookes demonstrates pumping by chemical getters
1876
Vacuum Pumps
L von Babo develops a self-recycling Sprengel vacuum pump
1876
Telephone
Alexander Graham Bell invents and demonstrates the telephone
1877
Loudspeakers
In Germany on December 14th Ernst Siemens patented the first loudspeaker.
1879
Lamps
Thomas A Edison files US patent on high vacuum carbon filament incandescent lamp
1879
Cathode Rays
Sir William Crookes develops the Crookes Tube, an early form of cathode ray tube
1879
Vacuum Pumps
Edison improves the self-recycling Sprengel-Geissler mercury vacuum pump
1880
Vacuum Pumps
Apparatus for evacuating Edison's electric lamps. Based on Crookes design
1883
Manufacturer
In May 1883 the American company Western Electric opened a small business in London. This was to become Standard Telephones and Cables (STC)
1883
Edison Effect
Thomas A Edison first observes thermionic emission in a vacuum
1883
Edison Effect
John Ambrose Fleming presents a paper on the 'molecular shadow' to the Physical Society of London on May 26
1883
Lamps
In October 1883 the amalgamation of Edison Electric Light Co Ltd and Swan Electric Lighting Co to form Edison and Swan United Electric Light Co. Ltd.
1885
Edison Effect
Sir William Preece duplicates Edison's experiment, makes quantitative measurements and presents a paper to The Royal Society
1886
Positive Ions
Eugen Goldstein observes 'canal' rays (German = Kanalstrahlen). So called because they were emitted through a hole in the cathode.
1887
Cathode Rays
Sir William Crookes performs the Maltese Cross experiment
1889
Cathode Rays
Jonathan Zenneck improves Braun's CRT and adds time base deflection
1889
Valves
The British General Electric Co. Ltd was formed
1890
Valves
A C Cossor Ltd was formed.
1891
Cathode Rays
George J Stoney suggests the name of electron for cathode ray particles
1896
Gettering
Mallgnani Corp demonstrates the use of phosphorus gettering
1896
Valves
The British Thomson-Houston Co. Ltd. was formed
1897
The Electron
Sir Joseph Thomson discovers 'corpuscles' later called electrons
1897
Radio
Guglielmo Marconi sets-up in July 1897 the Wireless Telegraph and Signal Company Limited to commercially exploit his patents
1898
Loudspeakers
Sir Oliver Lodge was granted a patent for a loudspeaker on April 27
1899
Valves
The British Westinghouse Electrical and Manufacturing Co. Ltd was formed. This later became the Metropolitan-Vickers Co. Ltd, (Metrovick)
1900
Vacuum Pumps
James Dewar builds a cryosorption pump using activated charcoal and liquid air
1900
Valves
John Ambrose Fleming becomes scientific adviser to Marconi's company
1901
X-Rays
W C Roentgen wins Nobel prize for Physics for discovery of x-rays
1901
Radio
Gugliemo Marconi transmits signal from England to North America
1901
Electron
Richardson produces an equation for the emission of electrons from incandescent metal filaments
1901
Lamps
Peter Cooper Hewitt develops the fluorescent lamp
1901
Valves
1901: valves introduced and adverts published.
1902
Lamps
Georges Claude builds the first neon lamp
1902
Lamps
E Weintraub develops the mercury arc lamp and rectifier
1902
Lamps
Charles Proteus Steinmetz files a patent on mercury vapour lamp with halide salts to improve colour
1902
Lamps
Peter Cooper Hewitt develops the mercury vapour lamp
1902
Cathode Rays
A C Cossor Ltd make the first British examples of Braun's CRT
1902
Valves
1902: valves introduced and adverts published.
1903
Cathode Rays
Harris J Ryan builds magnetic deflection CRT's
1903
Valves
1903: valves introduced and adverts published.
1904
Cathodes
Arthur Wehnelt publishes details of the oxide coated hot cathode CRT
1904
Valves
January 1904, Arthur Wehnelt patents a diode. The patent does not mention use for rectification of RF. The device is described in connection with charging accumulators
1904
Valves
October 1904, John Ambrose Fleming produces rectification of RF in a valve. Valve history begins
1904
Valves
November 16 1904, John Ambrose Fleming applies for a patent on the Oscillation Valve, later known as the Thermionic Valve and Fleming Diode.
1904
Valves
1904: valves introduced and adverts published.
1905
Cathode Rays
Philip Eduard Anton von Lenard wins Physics Nobel prize for Cathode Rays
1905
Vacuum Pumps
Wolfgang Gaede makes rotary mercury-sealed mechanical vacuum pump
1905
Physics
Albert Einstein explains the photoelectric effect
1905
Valves
1905: valves introduced and adverts published.
1906
Vacuum Pumps
W Voege and Rohn build the thermocouple vacuum gauge

1906
Valves
Lee de Forest invents the Audion (triode) as a sensitive detector!!!
(Dawn of Shredders)

(left) The first prototype Audion with the grid (zigzag wires) between the filament and plate.[11] (right) Later design of an audion tube. The grid and plate are in two parts on either side of the central filament. In both these tubes the filament is burned out.​

De Forest was granted a patent for his early two-electrode version of the Audion on November 13, 1906 (U.S. Patent

 

[Australian]

Another "I did a more exstensive Google search-therefore-you are wrong" thread.

Ha ha

 

[surfguitarkid]

Has anyone here actually heard one of these operadio amps with a guitar through it? Are there any sound clips available? I have been watching one on an auction site, and seems interesting.

 

[Ghostman]

It only works with Hipster guitars.

 

[Codeman]

It only works with Hipster guitars.

Hipster guitars? There are such things?

 

[WhaSudr]

I have a 1948 1A65 40watt, still in testing at the moment but hope to use for guitar.

 

[Geetarpicker]

Reviving an old thread! Many years ago a friend of mine got some truly great tone with a 1965 SG standard into an Operadio 1A30 and a 2x12, not unlike what one would expect from say an old NMV Marshall 50. Zoom forward a couple decades, I have two 1A30s out in my shed that someday I’m going to restore, I might even have part of the chassis chrome plated which will nicely go with the lighted front panel. One of them actually still works, and yes it kind of gets in the vague ballpark of a JTM45. The input jack is an odd antiquated threaded mic connector but there are 1/4” adapters that easily adapt the amp input for guitar use. These amps also have a few different impedance selections for the output which come in handy. One of my two 1A30 amps has stickers on the back from when it was used as a movie theater amp many MANY years ago. Pretty cool old amps!

 

[ampmadscientist]

Reviving an old thread! Many years ago a friend of mine got some truly great tone with a 1965 SG standard into an Operadio 1A30 and a 2x12, not unlike what one would expect from say an old NMV Marshall 50. Zoom forward a couple decades, I have two 1A30s out in my shed that someday I’m going to restore, I might even have part of the chassis chrome plated which will nicely go with the lighted front panel. One of them actually still works, and yes it kind of gets in the vague ballpark of a JTM45. The input jack is an odd antiquated threaded mic connector but there are 1/4” adapters that easily adapt the amp input for guitar use. These amps also have a few different impedance selections for the output which come in handy. One of my two 1A30 amps has stickers on the back from when it was used as a movie theater amp many MANY years ago. Pretty cool old amps!

GK is that YOU?
Oh master of 30 foot guitar cables?

It MUST be you, for no other could.

 

[ampmadscientist]

I have a 1948 1A65 40watt, still in testing at the moment but hope to use for guitar.

Use the phono inputs.

 

[ampmadscientist]

Has anyone here actually heard one of these operadio amps with a guitar through it? Are there any sound clips available? I have been watching one on an auction site, and seems interesting.

Prepare to throw all distortion pedals into the trash can....you have crossed the threshold.