Saturday, January 20, 2007

Early days of loudspeaker audio

The horn arrangement is a familiar one, taken from nature and also from the shape and construction of various wind instruments, like the tuba. Edison used a conical horn for his very first cylinder phonographs, followed later by more esthetically pleasing morning glory shaped horns and finally internally fitted horns placed inside the gramaphone cabinet. The external horn got its reprieve in the late teens and early twenties when radio first started making its way to the well-to-do and to experimenters. Manufacturers fitted bell shaped horns to simple electromagnetic reproducers that were little more than large headphone elements in order to produce loudspeaker volumes.

The radio shown here is a battery operated tuned RF type nicely enclosed in a sloping front cabinet. The excellent lighting and photographic composition, and the appearance of the gent in the photo suggest that this is a well posed shot of someone of note - perhaps a radio pioneer - enjoying the fruits of his labor. Please comment if you know who this is.

The horn is a directional impedance matching device which can greatly improve the efficiency of a small driving membrane, but it has its limitations. Today any audio through a horn like this is considered to be "telephonic" or worse, and it has been difficult to produce horn like loudspeaker systems with adequate bandwidth in the past, though the horn is still very much a part of the auditorium and public address technology mix used today, and is still being improved.

I think he needs a sub.


Anonymous said...

I have two of these ancient horn loudspeakers. It is interesting how the makers tried to deal with resonances in the horn. One of the speakers is constructed with a steel throat to about 3/4 of the distance and the large diameter bell is made of aluminum. The other horn is completely formed of hard rubber. The sound is not very good by modern standards but if you were living in 1925 and wanted to listen to the new radio the whole family could listen if they were quiet.

Bob Crowley said...

I'll bet it was amazing.

That picture was probably taken later than the 20's, judging by the posed look of it, and the lighting. I thought that might have been E Alexanderson himself in front of his invention, a multistage TRF (tuned radio frequency) receiver. Then Armstrong came along with the regenerative and then the superheterodyne.

I can't seem to find a picture of Alexanderson in his later years.

Manufacturing methods used in the 20s may have been fairly primitive and you can imagine that these old horns were hand made and/or assembled. The radio evolved so rapidly during the 20's and by 1930 AC console sets with enclosed speakers were common, then just six or so years later the superhets completely took over. During the 30s and 40s millions of radios were sold. TV came in during the late 40s and early 50s and radio went into the background. The golden age of radio was only about 20 years.

Anonymous said...

The man in the picture is not Ernest Alexanderson. At this time I do not think it is Reginald Fessenden either. My best guess is that it is an advertisement photo from the 1920's that epitomized the good life at that time which would have included a radio with a loudspeaker.