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7. TUBES
7.3. BIAS measurement facility
The BIAS measurement facility makes it easy for you to check and adjust the idle current of the
output tubes. Getting the BIAS setting right for all four tubes is critical for both the sound of the power
amplifier section and for the service life of the tubes. This feature guarantees consistent sound quality
over the entire lifetime of the output tubes.
That is why we have built this BIAS measurement facility into the MRE 220 SE – to allow you, the
user, to carry out the adjustment yourself without the need for test equipment. The use of precision
op amps makes it possible for you to set the BIAS to accuracy within 0.2%, making it superior to any
other method.
Using selected output tubes only makes sense if the idle current is adjusted accurately, as is clearly
shown in Fig. 1 Technical Data.
Please turn the trimmers (they look like little screws) carefully and slowly
The bias adjustment should be made only when the tubes are heated. If the
tubes are still cold, you will set wrong values.
The LED display
:
Ecomode LED
indicates the status of the Ecomode Electronic
Yellow - LED
indicates that the BIAS is Low
Green OK LED
indicates that the BIAS has the correct value
LED
indicates that the BIAS is too high
Red OFF LED
indicates that the Protection Electronic has turned off the Power supply of
the Tube section
Summary of Contents for MRE 220 SE
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