Designing And Constructing Direct-Coupled A.F. Amplifiers Part 1 - 1933 - Here is part one of a 1933 article from Radio Craft on designing Direct Coupled amps. http://itishifi.blogspot.com
Thursday, January 12, 2012
Western Electric 12a and 13a combination..
So I have this book.. Sound-Picture Recording and Projection... it is from around 1931... and for quite some time now I have been fascinated how it just refers to a high flying 12a and a floor mounted 13a as a "system"... yeah, right! I mean who has BOTH of these horns???
I have studied the horns... and how they are referenced in this book.. and I dig the thought behind the "system"... the 12a is shorter.. it leans to the high side of the spectrum... upper midrange heavy... and the 13a is longer... more low frequency loading.. so the air mass rolls the top end a bit more and the length extends the bass down a bit... so it is more midbass... and when used in tandem, you can now see the "system"...
and the 12a is flown up high... your brain will follow the upper frequencies more for "image source"... and the nice touch of the 13a out in front of the 12a as its path length is longer - time alignment, eh?
and I would go into the control system.. how the 200A works.. and all the impedance charts in this text, but I mean, really, who has *multiple* pairs of these??
so then a few months back our Music Maker of the Month sent me these shots... I have been blown away ever since...
and now in a new home: