Q-tron Audio
Q-tron Audio
Manual PA34B4R1
Page
9(9)
If adjustments are necessary these will be performed automatically and when these
values are correct the amplifier will switch off. The values for bias are stored in non-
volatile memory.
When the amplifier next time is switched on, the stored values for bias will be applied.
If the power tubes start to get worn so that they need very different bias voltage an
orange "Service" LED will be lit at the back panel, the amplifier can then still be used but
will not be optimally tuned.
If any value is completely out of specification even after adjustments, (as in the case that
a tube catastrophically has failed or got too weak) there will be a red "alarm" LED lit and
the amplifier can then not be used for playing music, (the inputs and outputs will be
shorted) until the fault has been corrected.
6.1 Automatic bias tuning of new power tubes
The bias auto calibrator also automatically sets the correct operating parameters for new
power tubes.
Procedure:
1. Switch off the amplifier completely, also with the switch on the rear.
2. Set the amplifier in tuning mode by connecting the tuning plug to the connector
on the rear panel
3. Put a new balanced set of 4 power tubes in the channel where they should be
replaced
4. Note all other tubes must be installed in the amplifier
5.
Note! the new power tubes must be matched to within 2V difference in grid
bias at 200mA anode current and 160V anode voltage, e.g. 2 tubes that
need -55V and -57V are OK. The grid voltage of power tubes must be in any
case between -55 and -65V.
7.
Performance data:
Output power in 8 ohm load
80W at 1% distortion at 1kHz
Output power in 4 ohm load
60W at 1% distortion at 1kHz
Output impedance
<0.4ohm
Harmonic Distortion
0.01% at 1kHz and 2W output power
0.1% at 1kHz and 25W output power
Power bandwidth
10 – 150000 Hz -3dB
Noise and hum
90 dB below 80W output power, (10 – 200000Hz)
100 dB below 80W output power, A-weighting filter
