Knoll Systems MA-205 Owners manual

MA205

Stereo Power Amplifier

INSTALLATION
AND OPERATION

MANUAL

Version 1.1

Congratulations and thank you for choosing the Knöll
MA205 power amplifier. The MA205 is designed to meet
the amplifier needs where high quality sound is a specific
requirement.

Key Features:

1. Manual and Automatic Power On and Off.
The MA205 stereo power amplifier is designed to be
turned on when a video signal is detected, music inputs are
sensed, a 12 volt trigger is activated or the front panel
power switch is pushed on. Power off is automatic in all
modes except the front panel power button.

2. Whole house music override. In homes, yachts,
businesses and motorhome applications (typically with
plasma or large screen TV's) the MA205 features
amplifier inputs so that whole house music system can be
heard on the local speakers (without the MA205 turned
on). When the local source (TV, dish, etc.) needs amp
power, the whole house music is automatically switched off,
the MA205 amplifier turns on and plays the local source.

3. Automatic protection circuitry. Each MA205
channel is individually and fully protected against low
impedance, overheating, overloading, overvoltage and
undervoltage. The protection circuitry automatically
restores the amplifier channel as soon as its parameter
returns to the safe operating area.

4. Individual input gain adjustment. Each channel
features an input gain adjustment pot to adjust each
channel for gain and speaker sensitivity variations. The
gain adjustments are on the rear of the MA205 so
installers normally set the gain.

5. Stackable 17" chassis. Two MA205's can fit side
by side and stacked for applications requiring more than
two amplifier channels.

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Installation

Installing the MA205 should be relatively easy. With a bit of
planning, the MA205 will give trouble free service for years.

1. The most important consideration when installing the MA205
is cooling. When installing it in an equipment stack, it should be the

top component. It needs at least 3"-5" of space above the amplifier
to allow for adequate convection cooling.

2. When installing the MA205 in a rack we suggest adding a
3-1/2" blank above and below the MA205. In multiple MA205
installations, plan for a 3-1/2" blank (double) between each MA205
and a 3-1/2" blank on the top and bottom. Amplifiers should always
be the top components in a rack system.

3. If MA205 channels frequently shut down due to overheating,
install a fan directed up from the MA205 bottom center.

4. Never operate the MA205 on its side, as the cooling potential
drops significantly when operated on the side.

5. Connect the MA205 inputs to the source component outputs with
good quality, short as possible RCA jack cables.

6. Connect the MA205 speaker outputs to speakers using good
quality speaker wire. Minimum 16 gauge copper wire is recommended
with 14 gauge minimum for runs over 30' (10m).

Note: Ideally the MA205 is operated into 4-8 ohm speaker
loads. The MA205 will not operate into 2 ohm loads.
Do not attempt to mono bridge the MA205

installation continued...

11. To use the 12VDC trigger to turn the MA205 on/off, connect the

trigger to the 3.5mm trigger jack. Set the music sense switch to "IN".
The front panel power switch is normally off (out position).

12. Individually adjust the channel gains as required. For best noise
and hum cancellation, all MR205 gains should be on full (fully cw).

MA205 2 Channel Power Amplifier

Inputs: Gold RCA style with adjustable gain
Input impedance: 20 k ohms
Outputs: Gold 5 way Binding posts
Output power: 50 watts RMS per channel (8 ohms)
Peak output power: 70 watts RMS per channel (4 ohms)
Ideal impedance: 4-8 ohm speakers
Freq. response: 10 Hz - 40 kHz +/- 1 dB (1w)
S/N ratio: over 95 dB A weighted 50 watts
THD distortion: <0.1% 20 Hz to 20 kHz
IMD distortion <0.01% 60 Hz 7 kHz 4:1 (SMPTE)
Trigger control: 12 VDC 35mA (3.5mm input jack)
Power: 140 watts 117 VAC
Dimensions: 8.5" x 3.5" x 10.5"
Weight: 8 lbs (3.6 kg)

7. Make sure the speakers in each room are connected in phase with
the amplifier + going to the speaker + . Out of phase speakers give
unstable imaging and poor bass response.

8. If connecting the MA205 to the whole house sound system,
connect the whole house amplifier outputs to the MA205 speaker
terminals labeled "AMP INPUTS" using good quality speaker wire.

9. If you are planning to use a video signal to trigger the MA205
power on and off, connect a good quality video wire with an RCA
jack to the MA205 input labeled "Video Input". Make sure the music
sense button is in the "OUT" position.

10. If the music sense or video input is being used to turn the
MA205 power on and off, switch the music sense button to the
"OUT" position. Adjust the "Sens" itivity pot on the MA205 so the
amp turns on when quieter passages are playing via the RCA line level
inputs. Adjust the "Delay" pot so the amp turns off a reasonable time
after the music has stopped.

Caution: Never listen to sound that is distorted. If

distorted sound is heard, turn the volume down immediately
or speaker and/or amplifier damage could occur that is
not covered by the warranty. If this problem persists,
contact your dealer.

User Adjustments and Service: There are no user

adjustments on the MA205. Your installer may make
certain level and delay adjustments on the rear panel.

Caution: The MA205 contains no user serviceable parts,

so do not attempt to open or repair the MA205. Refer
servicing to a qualified technician only or contact the
factory for information.

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