Corey Bailey
Audio Engineering
USEFUL INFORMATION
TIME CHARTS
The charts on this page are provided to give you an idea of running times for
various reel-to-reel audio tapes and records. Starting with analog tape, the chart
below from the box of an old reel of Irish brand tape, is calculated for 7” reels.
The lengths shown on the left of the chart represent the different thicknesses of
audio tape.
The Single Track listing is for recording in one direction. This column can be used
for full track mono or any format for stereo recording, recorded in one direction.
The Dual Track listing is for recording in both directions. 1/2 track mono was the
available consumer format when this tape was produced. The same “Dual Track”
column can be used to calculate 1/4 track stereo recorded in both directions.
This tape is from the late 1950’s. Notice the price stamped just below the brand
logo. It’s barley readable, but it is $2.88. Pretty pricey for 1958.
1200’ is 1.5 mil thickness (1 mil = one thousandth of an inch)
1800’ is 1 mil thickness.
2400’ is 0.5 mil thickness.
My deepest sympathies if you have any audio tape that is 0.5 mil (1/2 mil). It was
fragile in its day, and it is incredibly fragile now. The tape in this particular box is
1.5 mil acetate, and it played just fine. There is a picture of the reel here if you are
interested.
RECORDS
The running times listed above represent the approximate maximum time
available.
The average running time for a 10” Dia. 78 RPM record is about 3 minutes.
The average running time for 12” Dia. 33-1/3 RPM micro-groove records varies
from about 18 minutes to about 22 minutes.
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© Corey Bailey Audio Engineering
DO IT YOURSELF?
ANALOG TAPE
BAKING AUDIO TAPE
LUBRICATING AUDIO TAPE
MOISTURIZING ACETATE
TAPE
RECORDS (DISCS)
RECORD CLEANING
ARTICLES
A Little About Sound
Bit Depth
Optimizing your PC
Packing Records for
Shipment
People I have Known
Playing Records Wet
Sample Frequency
Defined
Saving Your Family
Video
Time Charts
Your Digital Data is at
Risk
Wire?
