Just a note for anyone interested in this sort of thing. Given the sorry state of current "pro" audio periodicals (even the good ones assume we have no interest in how things work.....), you might be surprised at just how much great info is available in old issues of "Audio Engineering" magazine and the "Journal of the Audio Engineering Society." The first, "Audio Engineering" only last about 6 years, from about 1947 to 1953 or 1954. It then changed its name to "Audio" and it's focus to home hifi in deference to the new "Journal of the Audio Engineering Society." (I guess they thought that the pro audio biz was only big enough for one magazine?). And for anyone scared off by the current Journal of the AES, which reads more like a math textbook these days, take comfort in the fact that it was different back in the pre-digital days. Up through the mid-sixties or so, the JofAES was a much more practical, hands-on kind of magazine.
Between the 6 or 7 years of AE and the first couple of decades of the JofAES, you could spend the next decade or so doing nothing but reading great articles taking you from the very birth of audio recording up to the modern era (ca '68 or so...) I have picked up bound volumes of an entire year of issues of AE for as little as $9 on Ebay! Individual issues form the 40's and 50's show up for as little as $2. And as a bonus, the 50 year old advertisements (U47, $349, or even better, second hand listings for just absurd prices) will keep you amused for hours.