This is a companion to the article “A Brief History of Delayed Programming.”
Like many stations in the late 1940s and beyond, WTOP in Washington, D.C., was faced with the problem of delaying CBS network feeds. It was a CBS O&O until mid-1948 and likely assisted the network in providing regional delays.
Assuming that at least 10 hours of network program time-shifting was required for each day of the five month-long periods of Daylight Saving Time in the late 1940s, this probably amounted to some 1,500 hours of recordings. (ABC reported their time-shifting operation ran 16.5 hours per day on average and that more programming was fed out on a delayed basis than went live.)
Expensive proposition
As disc recording gear was in universal use at radio stations then, WTOP certainly could have used this technology for delaying programs.
However, in examining the cost of such an undertaking, it would have been very expensive. One source, the Allied Radio Corp., advertised 16-inch “Audiodisc” professional recording blanks at $3.40 each, or $31 in today’s money. Purchased in quantity they cost some $2.04, about $26 now.
Each disc was good for about 15 minutes of recording time, with four sides needed for a one-hour show. Assuming that a backup copy was also made and both sides of the discs used, the cost of the four blanks would amount to more than $100 when adjusted for 75 years of inflation.
This cost-per-hour figure does not include the salary of the technician who made, labeled and played out the recording, nor does it include the cost of another consumable, the recording stylus. A “high-end” sapphire stylus was good for perhaps 10 hours, and came with a price tag of nearly $5 when purchased in quantity — more than $60 today. Using disc recording technology for program delay was not cheap.
WTOP wisely elected to handle program delay with six Brush Soundmirror tape recorders. When introduced in 1947, the machines sold for $250 (about $3,200 now), and were a real bargain when compared to the cost of acquiring Ampex’s first production machine, the 200A; it initially carried a price tag of $5,000 (nearly $7Kk now), with a later reduction to $3,000 ($38K). A 1/2-hour tape (1,200 ft.) could be purchased for about $2.50 ($32), driving the cost of delaying an hour-long show (with protection copy) to around $125 in 2024 currency.
Credit: Granville Klink Jr. collection
While it might appear that tape was more expensive than ETs, it actually was far, far cheaper, as it could be erased and reused many times — something not possible with discs.
Recorder/space heater
The downside of using Brush machines for delay was that they were designed as a consumer product and intended only for occasional use, certainly not for operation hours on end.
The big problem was Brush’s cramming of nine heat-producing vacuum tubes (some models used 10) and three motors into slightly more than 1.2-cubic feet of cabinet space. Exacerbating things even more was the heat buildup in the take-up reel motor due to its being slowed down in pulling the relatively slow-moving tape. The machine ran so hot that it could double as a space heater!
Credit: James O’Neal. Brush Soundmirror is from Gary Alley collection
Brush recognized the heat issue in its service manual, and the Scotch (3M) recording tape manufacturer went a step further, warning against the use of plastic tape reels in all Soundmirror applications.
As the WTOP machines had to run continuously throughout the broadcast day, the heat problem was resolved by relocating the chassis units containing recorder DC power supply and power tubes to an overhead shelf. A wall-mounted fan supplied additional cooling for the “hot chassis” units.
