MU-4 TUBE INTEGRATED AMPLIFIER
v1.2
Operation
1) Set BIAS TRIM switch (b) in
middle position before MU-4
amplifier power on.
2) Bias potentiometers (c) shall
be turned maximum in the „-„
direction (lowest current)
3) After power on by switch (a)
amplifier starts warm up phase
indicated by red
POWER/WARM-UP diode (d)
blinking.
4) Tubes warming up takes 30
seconds. After that High
Voltage is applied to output
tubes.
5) After following 15 seconds
operating points of all
elements becomes stabile and
output relay connects audio
signal to loudspeaker sockets. POWER/WARM-UP diode (d)
stops blinking.
6) Before first listening session output tubes bias has to be
adjusted separately for left and right channel. To do that BIAS
TRIM switch (b) shall be toggled left or right according to
description on rear amplifier panel. Adjust bias for left or right
channel by turning appropriate bias potentiometer (c). Proper
bias level (50mA) is when red bar on the VOLUME indicator (e)
reach middle position (see attached picture). When lower - bias
is too low, when higher –too high. After regulation BIAS TRIM
switch has to be set in the middle position again.
7) Now MU-4 integrated amplifier is ready to use although full sound quality is achieved after c.a.
10 minutes. During this time loud listening shall be avoided.
8) Bias adjustment shall be repeated after 1h of first listening and then every 2 or 4 weeks
depends on usage intensity.
9) Volume level and input selection can be operated by remote controller or using micro push
buttons (f) (g) located at the bottom of the amplifier. MUTE function is available only in remote
controller. It detaches loudspeakers from amplifier outputs what is indicated by blinking
POWER/WARM-UP diode (d).
Muarah
MU-4 TUBE INTEGRATED AMPLIFIER
WARM-UP / MUTE
CD
AUX
VOLUME
INPUT
PH
AUX
L
R
CD PH
RIGHT SPEAKER
LEFT SPEAKER
+8Ω
+4Ω
COM
+8Ω
+4Ω
COM
b)
BIAS TRIM
c)
a)
h)
