Goldmund SRM250 User manual

USER MANUAL
GOLDMUND SRM250 Power Amplifier

INTRODUCTION
The GOLDMUND SRM250 Power Amplifier
User manual - SRM250 Power Amplifier
Goldmund was founded in 1978 and has ever since been dedicated to the accurate reproduction of sound
and image.
At Goldmund, we strive to lead in the creation, development and manufacture of the industry’s most
advanced technologies, including audio and video systems, home - networking and music distribution.
The guiding principle at Goldmund is to produce a precise sound with the least possible loss of quality
through the different stages. Goldmund will never adopt a technology before it is sufficiently developed to
satisfy the high quality standards we set. This is why Goldmund has often rejected mainstream technologies
and developed its own.
Congratulations.
Thank you for purchasing the Goldmund SRM250 Power Amplifier.
You have acquired the best Analog Power Amplifier ever made for professional and domestic uses. Please
take some time to read this manual. It may provide you with useful information to make your pleasure of
listening to the SRM250 even higher.

No connection or manipulation must be
done before reading these instructions.
Damage to the amplifier may result if the
following instructions are not consciously
understood and applied.
This extremely high quality amplifier
possesses new technical features which are a
necessity for accurate sound reproduction in
the best audio systems.
Only careful installation and use can provide
the satisfaction you are expecting.
The installation instructions must be carried
out in full and the mentioned precautions
taken to get the expected result and to avoid
impairing the amplifier’s performance.
WARNING
!
GOLDMUND SRM250 Power Amplifier
User manual - SRM250 Power Amplifier

1UNPACKING p 4
2CHOICE OF AMPLIFIER LOCATION AND COOLING p 4
3LINE VOLTAGE ADJUSTMENT p 5
4CONNECTIONS p 5
5AMPLIFIER CONTROLS p 6
6SOUND QUALITY OPTIMIZATION p 6
Warm-up sonic effect.
Speaker polarity.
Mains line phase inversion.
7SAFETY AND PRECAUTIONS p 7
Protection against DC.
Protection against short-circuits.
8MAINTENANCE p 8
9TECHNICAL DATA p8-9
Power
Frequency response
Analog input sensitivity
Group delay
Distortion
Speed
Noise
Operating temperature
Power supply
Size and weight
Warranty
CONTENTS
User manual - SRM250 Power Amplifier

UNPACKING
You will find in the GOLDMUND SRM250 box:
❑The amplifier
❑The power cord
❑This manual and the warranty card
❑Accessories and spare fuses
WARNING
PLEASE KEEP THE PACKAGING IN CASE YOU NEED TO TRANSPORT THE
AMPLIFIER AT A LATER DATE OR IF YOU HAVE TO SEND IT FOR MAINTENANCE.
THIS PACKAGING HAS BEEN DESIGNED SPECIFICALLY TO PROTECT THE
SRM250 IN TRANSIT. USE OF ALTERNATIVE PACKAGING IS LIKELY TO RESULT
INDAMAGE, INVALIDATING WARRANTY COVER.
CHOICE OF AMPLIFIER LOCATION AND COOLING
The Goldmund SRM250amplifier, as all the high quality amplifiers generates a lot of heat if
driven at high power.
To ensure adequate cooling of the heat sink the SRM250 must operate in a well-ventilated
location. Avoid putting other equipment on top of the amplifier.
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LINE VOLTAGE ADJUSTMENT
Avoltage selector is provided inside the amplifier.
If your line voltage is not adapted to the voltage indicated on the serial plate of the amplifier,
please consult your local GOLDMUND dealer for assistance.
ATTENTION
At the 220V position, the GOLDMUND SRM250 amplifier will function properly
for main line voltages in between 200V and 240V.
At the 110V position, the main line must deliver between 105V and 125V. If
your ACline is usually outside of these tolerances, please consult your
GOLDMUND dealer.
Please check the value of the main line fuse. This fuse is located in the power
cord receptacle.
Use a 5A delayed fuse for 220V and a 8A delayed fuse for 110V.
CONNECTIONS
Make sure the volume control is set to zero on the preamplifier.
If used with an analog signal, connect the interconnects between the preamp/processor and
each of the power amplifier inputs.
If you are using a Goldmund Universal Preamplifier,connect a lineal digital cable between
one of the preamplifier outputs and the amplifier digital input, then change the amplifier
switch on the rear panel to digital input.
Connect the speaker cables to the red and black terminals accessible at the back of the
amplifier.
You may notice that the ground of the input and the black speaker terminal are of the same
polarity. The amplifier is non-inverting in phase.
Then, connect the power cords to the back of the amplifier and plug it in the nearest wall
plug. Use a 3 pin grounded plug, for safety reasons. To get the best sound of the amplifier,
avoid multiple plugs or extension cords.
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AMPLIFIER CONTROLS
On the front panel of the GOLDMUND SRM250 amplifier you will find only one switch and
two Leds. To start playing the amplifier, turn the power switch ON. The amplifier is operative
immediately and the green Led indicates it is operating normally.
It is normal for a slight sound to be heard from the speakers when the amplifier is turned
ON or OFF. The SRM250 is self-protected and the sound heard is corresponding to the
charging and discharging of the capacitors. The yellow Led indicates that the digital signal is
locked on a source when the digital input is in use.
SOUND QUALITY OPTIMIZATION
❑Warm-up sonic effect
If the power amplifier has been powered OFFfor some time, the optimum sound quality
may only be reached after 15minutes. The critical circuits must warm to around +55degrees
C(+131 degrees Farenheit) for optimum performance. If in recent use, the optimum
temperature may take only 1 or 2 minutes.
❑Speaker polarity
Even if you have an absolute phase inverter on your preamplifier (as on the GOLDMUND
Mimesis 2 or Mimesis 22M), and you have carefully selected the proper line phase, there is
apossibility to further increase the sonic quality of your speakers by reverting the polarity of
the speaker cable amp termination. Line phase and speaker polarity interfere to each other
however. We therefore recommend careful experimentation with all the combinations in
order to arrive at the best one for your installation.
If your preamplifier has an absolute phase inverter, this will interfere too. If it has not, don't
forget that the result will depend on the source, as most sources (vinyl CD or DVD) are
recorded without care for the absolute phase. Be patient…
❑Mains line phase inversion
The sonic quality of your GOLDMUND SRM250 can be greatly improved if the main line is
properly connected. Try to invertthe mains plugs of both your amplifiers, using special
adapters.
We recommend careful experimentation in this area. This should be in combination with the
speaker polarity and/or with absolute phase switching tests to be sure of finding the best
result for you.
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7SAFETY AND PRECAUTIONS
The GOLDMUND SRM250 is an extremely high speed amplifier. Any bad ground connection
can generate high frequency oscillation which is dangerous for tweeters.
It is also generally dangerous to run analog input cable and speaker cables in parallel for a
long distance. If these cables are not of high quality or badly shielded, an “antenna-effect”
can generate dangerous high-frequency oscillations.
❑Protection against DC
The GOLDMUND SRM250 is a DC-coupled amplifier. Without protection and if the associated
analog preamplifier is badly designed or defective (often true for tube preamps and some 5
channel processors), the speakers could easily be damaged by amplified DC. The SRM250
protects itself from this danger via a feedback DC control loop that limits DC amplification.
This protection circuit is totally transparent and has no sonic effect.
❑Protection against short-circuits
If one output is short-circuited by accident, the amplifier output has self-limiting protection
to prevent the current becoming too high. Steps should be taken however, to avoid this
happening over protracted periods as excessive heat build-up may still occur over time. In
extreme cases, such mishandling could destroy the amplifier,which is not covered by the
warranty.
There is no risk in leaving the speaker terminals unconnected when the amps are on.

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8MAINTENANCE
The GOLDMUND SRM250 amplifier usually requires no maintenance.
Always turn the power off before cleaning your amplifier. Use only a clean, soft, damp
cloth. Dampen with water or a mild detergent solution. Avoid abrasive or harsh cleansers
(eg. products containing sodium carbonate).
TECHNICAL DATA
POWER
• Nominal power before clipping: 200 W RMS (2 - 8 Ohms).
120WRMS(1 - 16Ohms).
• Maximum power: > 400 W RMS (3 Ohms).
• Maximum voltage: 55 V peak. Maximum current : > 15 A peak.
• Maximum current: > 15 A peak.
FREQUENCY RESPONSE
These figures are valid for the circuit alone, at any level between 0 and nominal power.
• +/- 0.1 dB, 10 Hz - 1 MHz.
• +/- 1 dB, 6 Hz - 1.2 MHz.
• +/- 3 dB, 3 Hz - 1.4 MHz.
ANALOGUE INPUT SENSITIVITY
•Nominal level:0.75 V.
• Input impedance: 50 kOhms.
GROUP DELAY
Propagation delay < 100 ns stable with frequency from DC to 200 kHz.
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9TECHNICAL DATA
DISTORTION
Figures valid for all levels from 0 to 20 V / 8 Ohms.
• Dynamic: TID < 0.01 % (- 80 dB).
• Static: THD < 0.01 % (- 80 dB).
SPEED
• Slew rate: > 250 V/us
• Rise time: < 250 ns.
NOISE
• Weighted ASA A: > 100 dB.
OPERATING TEMPERATURE
• Room temperature: -30 to +40 degrees Celsius ( -22 to +104 degrees Fahrenheit).
• Internal temperature: +45 to +65 degrees Celsius ( +113 to +149 degrees Fahrenheit).
POWER SUPPLY
•Nominal line voltage:117 or 234 V.
• Input voltage range: +/- 15 %.
• Maximum power consumption: 300 W.
SIZE AND WEIGHT
• 22 cm W x 38 cm D x 8 cm H. Weight : 13 kg net.
• Weight: 10 kg net.
WARRANTY
•3years parts and labor.