Teac A-3340S - Page 31

SIGNAL-TO-NOISE RATIO
PLAYBACK
1. Thread a blank SCOTCH 203 tape on the vvyv Vv Vv
unit leaving the tape outside the cap- S/N See tle hag TAPE erate uence im 8)
stan and pinch roller. z2 One
+
4
2
agence
BS
PEAK
REC
LEVEL
(3%)
z
2. Place the unit in the PLAY mode (BP) o- +648 ——— 5S
(the tape will not move using PAUSE). a = neg
(REFERENCE )
3. The Test Set connected to the OUTPUT
jacks should indicate -50 dB or less.
This represents a signal-to-noise
ratio of 50 dB (1% THD). Residual
tape noise is below this at 54 dB.
4. For a 3% THD signal-to-noise ratio, |
-6 dB is added (3% THD is 6 dB above oS
1% THD level), giving 54 dB, or the | | me ie |
residual noise level of the tape. ee ae Hee ie am a
(See the chart to the right.) sg BESO, NO,
DU:
OILVd SSION OL TWNDIS
AV NIT
g
pat RESIDUAL NOISE Sas. me
WHEN LEVEL METER
NOISE READS
T- O77
Fig. 11-8 Signal/Noise Conputation
OVERALL
IMPORTANT: Clean and demagnetize the heads before proceeding.
It is extremely important that all tests described in the pre-
ceding paragraphs have been completed and that all controls
are left at their specified settings.
1. Thread a blank Test Tape SCOTCH 203 on the unit.
2. Remove the AF oscillator from the LINE IN jacks.
3. Piace the unit in the RECORD mode with "no signal" applied.
Note the point on the index counter where recording begins.
4. Rewind the tape to the beginning point and play it back.
5. The noise level as indicated on the Test Set should be -55 dB
or less.
NOTE: Bias, erase and playback amplifier noise are all include
in this measurement. All frequencies between 40 Hz and 15 kHz
are measured unweighted.