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11. FAQ
1. Can you operate the MRE 220 SE when no loudspeakers are connected?
Yes. The MRE 220 SE, like all OCTAVE amplifiers, is fully protected against open circuit
operation, i.e. the amplifier will come to no harm if it is operated without loudspeakers connected
and the input level is in the magnitude of normal listening levels.
2. How do you recognize a faulty tube?
See troubleshooting chap 9
3. Is there a loss of sound quality as tubes age?
No. Tubes normally sound the same throughout their service life. Our soft-start technology
contributes greatly to extending the service life of tubes. You can tell when an output tube has
reached the end of its useful life: it becomes impossible to adjust it correctly. Driver tubes cannot
be checked, but these will generally last for well over 10 years.
4. What is the significance of loudspeaker impedance and efficiency?
The impedance and efficiency of modern loudspeakers is not an issue for OCTAVE amplifiers.
The often-quoted damping factor is not normally a guarantee that an amplifier will exert tight
control over the loudspeakers. In practice, speakers of 85 dB efficiency and above are suitable
for use with tube amplifiers. The high stability of the OCTAVE power amplifier technology even
allows the use of speakers whose impedance dips as low as 2 ohms (except for EL34 with 4
ohms).
5. What cables are suitable for tube power amplifiers?
The cable manufacturers are now offering cables that have supposedly been designed
specifically for tube amplifiers. Although such cables may be of good quality, there is no need
to use special cables with tube amplifiers. Speaker cable can exhibit high values of capacitance
and inductance, and tube power amplifiers deal with such loads better than transistor power
amplifiers. The only exception would be if you needed to use a tube pre-to-power amp
interconnect cable longer than 5 meters. In that case, a low capacitance cable would be
advisable.
Status: September 2023
Summary of Contents for MRE 220 SE
Page 1: ...MRE 220 SE Owner s Manual English...
Page 3: ...4...
