Specifications

Internal Adjustments continued

• Initial Setup.

See the previous page for the location of the trimmer pots. Set all

front panel switches (except for the PWR obviously) to the UP

position. Set the GAIN knob fully anticlockwise. The MA 2.2 should

be powered up for 1 hour before making adjustments. All

measurements are referenced to 0dBu = 0.775V RMS, (sometimes

called 0dBm).

• Maximum Gain Adjustment.

Connect an audio voltmeter to the channel output to be adjusted.

Apply a –50dBu 1kHz balanced sine wave signal to the channel input.

Turn the GAIN knob fully clockwise and adjust the MAXIMUM GAIN

trimmer to obtain +15dBu at the output. This sets the maximum

gain of the MA 2.2 to 65dB.

• PK LED Threshold Adjustment.

Connect an audio voltmeter to the channel output to be adjusted.

Apply a –20dBu 1kHz balanced sine wave signal to the channel input.

Adjust the GAIN knob to obtain +18dBu (or your desired threshold

level) on the audio voltmeter. Adjust the PK LED trimmer so that the

front panel PK LED just lights.

• Low Frequency and High Frequency CMNR.

CMNR is the Common Mode Noise Rejection, the ability of the

amplifier to reject noise common to both “legs” of the balanced

input.

Connect an audio voltmeter to the channel output to be adjusted.

Apply a +10dBu approx 1kHz square wave signal to both PIN 2 and

PIN 3 of the channel input connector. Set the GAIN knob to the

51dB marked position. Adjust the LOW FREQ CMNR trimmer for a

minimum reading (dip) on the audio voltmeter.

Change the input frequency to 10kHz adjust the HIGH FREQ CMNR

trimmer for minimum reading on the voltmeter. Return to the 1kHz

input frequency and check the LOW FREQ adjustment, re adjust as

necessary. Finally, check the HIGH FREQ adjustment null whilst still

applying a 1kHz square wave input.

• Problems ?

Contact your dealer or Buzz Audio.

MA 2.2 USERS MANUAL VERSION-1 PAGE 9