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M-203 AM p l i f i e r
(p e r Mo n o AMp)
Sp e c i f i c A t i o n S
In p u t s :
tr u e Ba l a n c e d (Xlr)
In p u t Im p e d a n c e 36kOh m
sI n g l e -en d e d (rca)
In p u t Im p e d a n c e 18kOh m
In p u t se n s I t I v I t y :
4.34 vp p @ 200W
(hI g h ga I n +28d B )
8.68 vp p @ 200W
(lO W ga I n +22d B )
cO m m O n mO d e ra n g e :
+/- 20 v
ma X . lI n e a r In p u t ra n g e :
10 vp p
ma X . In p u t vO l t a g e :
20 vp p
tr a n s I s t O r s :
al l BI-pO l a r
M203
Users
Fe e d B a c k :
0 ne g a t I v e lO c a l Fe e d B a c k
0 ne g a t I v e gl O B a l Fe e d B a c k
da m p I n g Fa c t O r :
80
sI g n a l t O nO I s e ra t I O :
>120 dB
pO W e r ra t I n g :
>200 Wa t t s a t 8 Oh m s
ca p a B l e O F d r I v I n g
a 1 Oh m l O a d
st a t I c pO W e r cO n s u m p t I O n :
250 Wa t t s
FI l t e r ca p a c I t a n c e :
220,000 µ f
tr a n s F O r m e r s :
du a l 600W tO r O I d a l
tr a n s F O r m e r s .
dI m e n s I O n s :
13” d I a m e t e r X 18” t a l l
100 lBs
sh I p We I g h t 120 l B s , 24 X 20 X 20
Manual
Rev 1 (7/12)
cO n t r O l Fe a t u r e s :
- sW I t c h F O r Ba l a n c e d
O r sI n g l e -e n d e d O p e r a t I O n .
- pO W e r On /st a n d B y /OF F
- re m O t e pO W e r cO n t r O l
- hI g h a n d lO W BI a s mO d e
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M203 Amplifier Users Manual
A Simple Approach
The M203 monoblocks provide a simple but effective approach to good sound. An amplier does two things, it increases the voltage
of an audio signal and it increases the current. Class A ampliers completely overlap the positive and negative signals providing great
performance but with huge power losses. Class A-B overlap only a little with much lower power use but compromised performance.
The MSB amplier uses a fully CLASS A stage to increase the voltage signal, and a CLASS A-B stage with no voltage gain to increase
the current supplied. This unique hybrid gives the best of both - a great performance with reduced power requirements.
Setup and Quick Start
This is easy. Plug it in and go. The power switch has three
positions:
ON =Green, Standby = Amber, and OFF = Red.
Power - The power requirement depends on the speakers
being driven. The ampliers will both run off a single 120V,
20A circuit easily with a standard 8 ohm speaker load.
With a 4 ohm load, they will still run off a 20A circuit, but
with a 2 ohm load, each amp must be on a separate 120V,
20A circuit.
Inputs - The amplier will accept a single-ended or balanced
input.
Outputs - Connect to your speakers.
Burn-In
The concept of burn-in is little understood. Does it take your ears
some time to get used to the incredibly detailed and life like sound
of an MSB product or is something actually changing. The feedback
we receive leads us to recommend at least 100 hours of burn-in on
this amplier. Customers generally recommend one month.
Heat and Bias Setting
These ampliers will get quite warm. They should be used in an open air-conditioned
room with nothing covering them. Operation in extreme conditions will cause failure.
Heat is not reduced in stand-by mode. If your listening room is subject to high
temperature when you are not using these ampliers, please turn them off when not
in use.
The Bias switch on the cover allows you to use the amps in two modes. In high bias
you get the best performance but the M202 will be warmer to the touch. Normal bias
sounds almost as good and runs quite a bit cooler.
Fuse and Voltage
To meet the world-wide AC power specications, three different input power modules
are available. These are not switchable so Ampliers cannot be moved between regions
without changing the input module. The rest of the Amplier is identical.
• USA Model requires 120VAC +/- 10V, 50 or 60 Hz
• Japan Model requires 100VAC +/- 10V, 50 or 60 Hz
• International model requires 240VAC +/- 20V, 50 or 60 Hz
The amplier uses a 15A SLOW BLOW fuse. It is an input fuse only. The
amplier does not have output fuses.
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If the signal is pulled low:
Unit will turn off.
If the signal is pulled down with a 50K resistor:
Unit will go to standby.
If the signal is left oating:
Unit will remain on.
If the signal is driven with 12 V:
Unit will turn on and switch will be ignored.
12 Volt Remote Trigger wiring.
12 Volt Remote Trigger
This power supply is equipped with a remote trigger for use with other MSB
products. The trigger uses a headphone jack. When any MSB product is
turned off, the other products connected will also turn off and vice-versa.
The connector is wired as shown. If you connect “signal” to “ground”,
all MSB products will turn off. If you let the signal oat (12 V), all MSB
products will turn on.
Power Supply LED Color Table
Green: The unit is on and operating
Amber: The switch for the unit is on, but the 12V trigger has turned it off, OR, the switch for the unit is on, but the protection
has shut if off because of overheating or over voltage.
Red: The switch is in the Off position.
Off: The switch for the unit is off but the 12 V trigger has turned the unit on, overriding the switch, OR, there is no power
due to a blown fuse or no power connection.
Input Details and Ground Issues
A toggle switch by the inputs selects between three modes. The RCA and XLR are connected together.
The signal of the RCA input is connected to the non-inverted input of the XLR. The RCA case is
connected to the XLR inverted input.
The toggle switch changes the ground connections and gain as follows:
• Top position is the RCA mode. In this case the amp is in the normal gain mode. The RCA connector case is connected to
the AMP ground. This is the normal RCA input setting.
• Middle position is a special mode. The gain is still in the normal gain mode. The RCA connector case is NOT connected
to the XLR ground pin. This setting can be used with either the RCA or XLR input as follows. When the RCA input is
used, both the case and signal pins are oating. An external ground must be hooked up to the ground pin of the XLR. This
can be handy in solving some ground hum problems. If the XLR input is used, the gain is twice what one would expect.
This mode is handy when your output levels are very low.
• Lower position is the XLR mode. In this mode the ground connections are the same as the middle position but the output
is reduced by 6 db, making this the normal input mode for balanced inputs.
For best results, do not plug in both cables at the same time.
Warranty
All MSB products carry a one year warranty in the country of origin. No returns accepted without an RMA. Upon
receipt, MSB will repair or replace any defective product. All product shipped FOB Aptos. Shipping and shipping
damage is the responsibility of the consignee.
The M203 Amps are a key part of
a complete MSB system and can be
finished to match any color scheme.
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