5
The center indented position is unity gain. If your
connected source is a variable output and you will
be using the source (a preamplifier for example) to
control the volume, then set the Right Knob to unity
gain.
When using a fixed output source, you will use
the Right Knob to control the Volume.
To avoid
damaging headphones and ears, do not start the
MHA200 at a high volume
. If the starting volume
is above unity gain, the MHA200 will ramp up to
this volume rather than starting suddenly.
Connecting Headphones
There are three ways to connect your headphones to
the MHA200:
• 1/4” 3-conductor (stereo) phone plug
• One pair of 3-pin male XLR plugs
• One 4-pin male XLR connector (Neutrik
NC4MX)
1/4” Stereo
plug provides an unbalanced
connection. This is a common connector for
headphones (along with the smaller 1/8” plug).
The next two solutions may require replacing the
original jack.
With
3-pin XLR
connectors, there is a separate jack
for left and right. See Figure 08 for proper wiring.
The
4-pin XLR
connector uses a single plug for
both left and right channels. See Figure 09 for
proper wiring.
The Power Button and Standby LED
The Standby LED glows red when the MHA200 is
connected to AC Power and in Standby Mode. To
power the MHA200 on, press the Power Button.
The Tubes will flash green during the tube warm-up
phase. The Power Button will have no effect during
tube warm-up. When the tubes are ready, they will
glow a steady green. The Standby LED is off when
the MHA200 is on.
To power down the MHA200, press the power
button again.
If the MHA200 is being controlled by another
device through Power Control (see “Trigger Input”
on page 4), the Power Button will have no
effect.
THE MHA200 will
automatically power off
after
approximately 30 minutes of receiving no input
signal if not being controlled by another device
through Power Control.
About Those Tubes
The MHA200 features four tubes that can be seen
glowing. These tubes (two 12AT7 and two 12BH7
to be precise) are expertly incorporated into the
amplifier circuit to provide warm detailed playback.
The 12AT7s are used in the Driver stage and the
12BH7s are used for the Power stage.
Tubes should be replaced by trained McIntosh
authorized technicians. The tube locations are
shown in Figure 10.
Figure 07– Front View
STANDBY/ ON
VOLUME
STEREO
R
HEADPHONE OUTPUTS
STEREO
L
600
Ω
Ω
1
32
Ω
LOAD
V1-12AT7
V2-12BH7A
V4-12BH7A
V3-12AT7
Figure 10– Tube locations
RIGHT
LEFT
–
+
–
+
Figure 08– 3-pin XLR wiring
RIGHT
LEFT
–
+
–
+
Figure 09– 4-pin XLR wiring
PIN 1
PIN 1
PIN 4
PIN 3
PIN 2
View of XLR Jacks (not plugs)
PIN 2
12BH7
12AT7
