Last Friday at lunch, I was telling the well-known---and very San Francisco centric---story of Jack Mullin and the WWII origins of high-fidelity magnetic tape recording. One account of the events is here:
My only quibbles with this account are
- it claims that we don't know the identity of the German engineers who developed the Magnetophon,
- frequently refers to the use of wax recordings for radio transcription,
- omits the fact that Crosby wrote a no-strings-attached check to Ampex for $50K (over $600K in 2022) that allowed them to purchase the parts and set up production of the first 24 Model 200 machines. Ampex, in return, appointed Bing Crosby Enterprises (BCE) to be the US distributor of their products west of the Mississippi.
The first is simply wrong, the key innovator was Walter Weber at Reichs-Rundfunk Gesellschaft (RRG). RRG commissioned AEG to build the machines for the use of the German military and radio broadcasting networks. They also commissioned the infamous IG Farben (later BASF) to make the tape. Magnetic tape transfer expert, Richard Hess has translated into English this account of Walter Weber's work at RRG:
Weber and his manager, Hans Joachim von Braunmühl, also invented the variable-pattern, dual-diaphragm condenser microphone, known as the "von Braunmühl and Weber" design. RRG commissioned Georg Neumann to build them, resulting in the M7 capsule and U47 and M49 microphones. The Neumann U67, U87, as well as the AKG C12 and C414 are also based on this design.
Second, transcriptions were 16-inch aluminum discs coated with lacquer. During WWII, glass was substituted for aluminum. No wax involved.
Back to Mullen, et al., here is the most detailed account of the whole thing that I've found -- first hand from Mullin's #2 guy at Bing Crosby Enterprises, Robert Phillips:
and this account by Peter Hammer, who was the curator of the Museum of Magnetic Recording at Ampex in Redwood City:
The AES Historical Committee has an Ampex History project:
Ampex's version of this history appeared in the December 1977 and January 1978 issues of dB magazine. I recall reading it at the time. It was written by Harold Lindsey, who lead the development of the audio tape recorder at Ampex.
More details in a talk he gave at Foothill College in 1974
Mullin's account of the events appeared in High Fidelity magazine and an AES talk/interview:
I've seen reference to a movie "Sound Man: WWII to MP3", but can't find a copy anywhere:
The Audio Engineering Society has a history of magnetic recording
One of my lunch companions asked what became of Jack Mullin after Ampex started making audio tape recorders. I had to admit that I didn't know, which lead to finding and reading Robert Phillips' account, linked above.
The short version is Mullin was Crosby's chief engineer in the electronics division of BCE, where he worked on building a video recorder. After Ampex beat them (and RCA, the BBC, and Telefunken) to producing a practical video recorder in 1956, Crosby sold off the electronics division of BCE to 3M. Mullin went with the sale and ended up at 3M's instrumentation recorder division in Mtn. View, working on military contracts.
His tape collection is at the Stanford Libraries, digitized by my friend Richard Hess:
My own exposure to Ampex audio and video recorders starts in 1975, when I joined WRPI, Renssselaer Polytechnic Institute's student radio station. I was soon appointed Director of Studio Engineering where one of my weekly duties was cleaning, degaussing, and checking and touching up the alignment of the station's two Ampex 351 stereo recorders. In 1976, the station bought a pair of Ampex AG-440Cs, and keeping those in correct alignment became my responsibility as well.
In 1978, I took a year off school and worked as second-shift engineer at the local PBS affiliate, WMHT. The workhorse video recorders there were an Ampex VR-1100 (the first transistorized model) and a VR-1200 (the first high-band color model). The former had been donated to the station by WRGB and converted from low-band monochrome to high-band color. There were some low-band tapes in the library of programs from the early 60s that could be played on that machine with appropriate settings. The Ampex VR-1200 had been retrofitted with a crude punch-in editing system, called the Edit-Tec, that I used to assemble the following days promo reel. These were behemoths that used 2-in tape running at 15-inches/second. A one-hour program needed about a mile of tape on a 14-inch reel and weighed over 30 lbs. If you were not careful when mounting the reel on the machine, you could trap your fingers underneath which was quite painful. The machines were cleaned and aligned before every recording and playback [1]. The training tape for a VR-2000 is on YouTube:
Part 1 Part 2 Part 3
While I was there, the station purchased a pair of AVR-2s, which were the first machines to use digital timebase-error correction. They also had Tektronix "HR" precision monitors, which produced beautiful images compared to the fuzzy, anemic Ball Brothers monitors on the other machines (yes, the same company that makes canning jars and star-trackers for satellites).
All the Ampex machines came with extensive documentation, theory of operation, schematics, alignment and troubleshooting procedures, which I studied in my free time. For example, I learned that the A/Ds in the AVR-2s ran at 4x subcarrier and comprised two four-bit TRW flash converters, in a two-stage successive approximation topology.
Lastly, I note that while Ampex's location on Broadway, south of Woodside Road, in Redwood City was well known from the large sign right on 101 [2], their original location in San Carlos was a mystery (to me anyway) for a long time. A couple of years ago, I found an online copy of a maintenance manual that has the address "Howard Ave at Laurel St." That's a short block west of El Camino Real. One of our frequent lunch spots, The Office, is a few blocks south of there.
In his talk, Lindsey says 1155 Howard St., but notes that their very first location was on Old County Rd in Belmont.
- On the original VRX-1000 machines, Ampex had not yet solved the compatibility problem, so tapes had to be played with the same head assembly they were recorded with. If a tape was being sent to another station, the head assembly was shipped along with it.
- The Ampex campus is now occupied by Stanford. The sign was demolished a few years ago. It's location was at the north end of the parking structure.
Comments