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The audio input level jumpers (J1, J2) control the amount of gain applied 
to the input audio signals.

The microphone level setting has the highest gain for the onboard 
microphones (U2, U5), the line level setting has less gain and is appropriate 
for the line level audio interface (for example, CD players, MP3 players, 
and so on).

These settings will affect the gain of the external audio source and should 
be left in the line level setting if an external microphone or audio source 
is used at audio stereo input port (U10), described in the 

 section. Table 2-2 shows the possible audio 

input level settings.

Ensure that line level audio signals are not connected to the audio input when the 

NI SPEEDY-33 is configured in the microphone level setting. It is possible to damage the 
audio input circuitry by overdriving the input.

Table 2-2.  Audio Input Level Jumpers (J1, J2) Settings

Audio Input Level, 
Left Channel (J1)

Position 1

Position 3

Audio Input Level, 
Right Channel (J2)

Position 1

Position 3

1

2

3

1

2

3

1

2

3

1

2

3