Simpson 2 Series - Measuring Decibels

Operating Instructions
MEASURING DECIBELS
For some applications, output voltages and audio frequency
voltages are frequently measured in terms of decibels. The
decibel scale (DB), at the bottom of the dial, is numbered
from —20 through 0 to +10.
To measure decibels, read the DB arc after proceeding
according to instructions for A.C. voltage measurements.
The DB readings obtained will be correct on an absolute
scale if you are using a 0 DB power level of 0.001 watt in
600 ohms, and if the voltage which you read was measured
across 600 ohms.
To obtain absolute DB values across 600 ohms:
For the 10 V. range, read the DB arc and add +12 DB
to the reading.
For the 50 V. range, read the DB arc and add +26 DB
to the reading.
For the 250 V. range, read the DB arc and add +40 DB
to the reading.
If the reference level is 0 DB - 0.006 watt in 500 ohms,
subtract (+)7 DB from the reading to obtain the absolute
value of decibels.
OHMMETER CIRCUIT
Internal batteries are used to provide power for resistance
measurements. Since the batteries are subject to deteriora-
tion over long periods of time, there is a compensating
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