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13. FREQUENTLY ASKED QUESTIONS (FAQ)
1.
Can you operate the V70 when no loudspeakers are connected?
Yes. The V 70, 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.
2.
How do you recognize a faulty tube?
There are 3 different symptoms indicating a faulty tube:
1. Broken heater filament. The tube stops glowing
2. Defective cathode layer. The tube glows, but no current can flow. You can confirm this fault
using the bias display panel - no amount of adjustment will be able to extinguish the minus
LED.
3. Internal short circuit. Normally, the electronic protection cuts in and the red Off LED illumi-
nates, or the tube will not respond to bias adjustment (the display keeps returning to the
red area).
With faults 1 and 2, the amplifier will still operate, although the channel containing the faulty
tube will be quieter than normal. At low listening levels, the fault may not be obvious, but dis-
tortion will become evident at higher listening levels.
If fault 3 occurs, the protection circuits will normally switch the amplifier off. You may also hear
loud background noises just before it switches off, although these are not harmful to the ampli-
fier.
3.
Is there a loss of sound quality as tubes age?
No. Tubes normally sound the same throughout their service life and 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 can-
not be checked, but these will generally last for well over 10 years.
4.
Does the V 70 have to have all tubes fitted?
In principle, the V 70 will also operate without tubes. It is sometimes useful to do this when
testing the operation of the switching functions such as the selector switch, remote control,
etc. Of course, it is not possible to play music under these circumstances.
For test purposes, a channel may also be used with a single output tube, although its power
output will, of course, be reduced. The amplifier will come to no harm if it is operated continu-
ously like this.
Operation without driver tubes is also possible for test purposes, although, for obvious rea-
sons, music playback is not possible.
5. 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 with a sensitivity of 85 dB and higher are
suitable for use with tube amplifiers. The high stability of the OCTAVE power amplifier tech-
nology even allows you to connect speakers that dip as low as 2 ohms.
Summary of Contents for V70
Page 1: ...V 70...
