9. If a video signal is being used to trigger the MA252 on and

 

 

 

 

12. If the 12 volt trigger is being connected, use a 12 VDC

off, connect good quality short as possible video wire with a RCA

 

 

 

 

source (about 35mA) with a 3.5mm mono jack. Knoll PS1202

jack to the MA252 “Video Input”. Make sure the music sense

 

 

 

 

with a new 3.5mm jack works well. 5 VDC triggers will not work.

button is OUT.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10. If the music sense or video input is being used to turn the

 

 

 

 

Caution: Never listen to sound that is distorted. If distorted

MA205 on and off, set the “Music Sense” button to OUT. Adjust

 

 

 

 

sound is heard, turn the volume down immediately or speaker

the Sens (sensitivity) so the MA252 turns on when quieter sound

 

 

 

 

and/or amplifier damage could occur that is not covered by the

passages are playing. Adjust the “Delay” so the MA252 turns

 

 

 

 

warranty. If this problem persists, contact your dealer.

itself off 25-120 seconds after the sound has stopped.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

User adjustments and service: There are no user

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

adjustments on the MA252. Your installer may make

 

11. Individually adjust the channel gains as required. Ideally,

 

 

 

 

certain gain level adjustments on the rear panel.

 

the gains are fully on (fully clockwise).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Caution: The

MA252 REAR PANEL (condensed)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Caution: DO NOT CONNECT BRIDGED

MA252 contains

 

 

 

 

 

 

 

 

 

 

Connect the “AMP INPUTS”

AMPLIFERS or amps that do not have

no user

 

 

 

 

 

Connect these

common grounds to the “AMP INPUTS”

 

 

 

 

 

speaker level inputs to the

serviceable

Connect a composite

 

 

 

 

unbuffered stereo

as damage may occur.

 

 

 

 

whole house audio system

parts, so do not

video output from a

 

Connect stereo

line outputs to

 

 

 

 

 

 

 

VCR, plasma TV, etc.

 

other amplifier

or other amplifier outputs.

 

 

 

attempt to open

 

line level inputs

The “AMP INPUTS” pass

 

 

 

to the “Video Input” if

 

here.

inputs as needed.

directly to “TO SPEAKERS”

Connect the “TO SPEAKERS”

or repair the

the MA252 is to be

 

 

 

 

 

 

 

 

 

when the MA252 isn’t turned

to the 4-8 ohm speakers.

MA252. Refer

trigerred on when a

 

 

 

 

 

 

 

 

 

 

 

 

video signal is present.

 

 

 

 

 

 

 

 

 

on.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

servicing to a

Make sure the music

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

qualified

 

 

MA252

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TRIGGER

 

 

switched to the OUT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

technician only

sense button is

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

12VDC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

position.

 

 

Stereo Amplifier

 

 

L

Input

Output

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INPUT

 

Connect this 3.5mm

or contact the

 

 

 

 

 

 

 

AMP

 

 

 

TO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

factory for

For video triggering

 

Knoll Systems

 

 

 

 

 

 

INPUTS

 

 

SP EAKERS

 

 

 

trigger jack if the

 

Point Roberts WA USA

 

 

 

 

 

 

L

R

 

 

L

 

R

 

 

 

MA252 is to be

information.

without music sensing

 

Richmond, BC Canada

R

 

 

 

+

 

- - +

 

+

- - +

 

 

 

 

turn the “Sens” pot

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

triggered on when a

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

12 VDC signal is

 

 

fully counterclockwise.

 

Video

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

present. Polarity

 

 

 

 

Input

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sens Delay

L Gain R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

can be reversed.

 

 

 

 

 

 

 

 

 

 

 

 

Music

 

sense

 

 

 

 

 

 

 

 

 

 

 

 

 

 

It needs about

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CAUTION

 

 

 

Out = Active

 

Made in Canada

120 VAC / 1.5 A

 

35 mA.

 

 

 

 

 

 

RISK OF ELEC TRIC SHOCK

 

 

 

 

 

 

 

 

 

 

 

DO NOT OPEN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fabrique au Canada

POWER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

When using music sense only, adjust Sens so the MA252 turns on when the source music is at

amedium low volume. Sens is not used for video on or trigger on. For video sensing without music sensing turn Sens fully counterclockwise.

After MA252 is on, Delay is adjusted to turn off MA252 after the source music ends. Ideal delay adjustment is about 20-40 seconds. Delay is used with video on and music sense only.

Adjust the gain when the system is on. Best signal to noise ratio is when MA252 gains are on full (clockwise).

The music sense (auto turn on when music is present) button should be OUT (active) when the MA252 power is to be triggered either from music sense or the composite video signal.

The music sense button should be IN when the amp is turned off and on from the front panel switch or the 12 VDC trigger.

Ideal speaker impedance is 4-8 ohms.

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Knoll Systems specifications MA252 Rear Panel condensed, User adjustments and service There are no user
Page 3

MA252 specifications

The Knoll Systems MA252 is a versatile and powerful integrated amplifier designed to deliver exceptional audio performance in both residential and commercial settings. Boasting a modern aesthetic, the MA252 combines advanced technologies and high-quality components to provide an immersive listening experience.

One of the standout features of the MA252 is its hybrid design, which incorporates both vacuum tube and solid-state technologies. This combination allows the amplifier to deliver the warm, rich sound characteristic of tube amplifiers while maintaining the precision and reliability of solid-state devices. The vacuum tubes add a unique tonal quality, enhancing midrange frequencies and providing a natural, inviting sound signature.

The MA252 offers a robust output power of 100 watts per channel, ensuring it can drive a variety of speakers with ease. Its high current capabilities enable it to deliver dynamic audio performance, making it suitable for a range of musical genres. Whether listening to delicate vocals or driving bass lines, the MA252 handles every nuance with clarity.

Connectivity options are plentiful, making the MA252 a flexible choice for various audio setups. It features multiple line-level inputs, allowing users to connect a range of sources, including CD players, turntables, and streaming devices. Additionally, the built-in phono stage supports both moving magnet and moving coil cartridges, making it an excellent choice for vinyl enthusiasts.

Another noteworthy technology included in the MA252 is its advanced power supply, which minimizes distortion and enhances overall sound quality. The dual power transformers ensure consistent and stable power delivery, resulting in less noise and improved dynamic range.

The amplifier's elegant design features a brushed aluminum front panel, complemented by a classic meter that provides an analog aesthetic. The intuitive controls make it easy for users to adjust settings and enjoy their music without unnecessary complexity.

In conclusion, the Knoll Systems MA252 stands out as a premium integrated amplifier offering a harmonious blend of vintage warmth and modern functionality. With its hybrid technology, robust output, versatile connectivity, and stylish design, it appeals to audiophiles and casual listeners alike, ensuring an engaging and enjoyable audio experience. Its commitment to high fidelity makes it a worthy consideration for anyone looking to elevate their sound system.
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