Reference

No. 6. sets the reference for the calculation of the impulse/frequency response.

As a reference you can select from the types below

If you select Right ch. input, the input signal from channel 2 is used as reference for computing the impulse response. This setting should work for all sound cards (with stereo input). The response and delay of the sound card will automatically be corrected using this method.

If you have selected External source in nr. 4, Right channel input is automatically selected as reference.

If you select Generator, you are not using an input channel as reference and you can thus measure using all input channels. This means that you can measure the impulse/frequency response of two microphones simultaneously using a standard stereo sound card. With a standard 2-channel soundcard this is impossible if you use Right channel input as reference, since then one channel is used for the reference signal.

Note: that Generator will not give optimal results if your sound card does not have exactly the same sampling rate on the input as the output (an example of such a card is the Sound Devices USB Pre).

The last choice No reference is meant only for error-checking since it does not compute the impulse/frequency response but only displays the input signal.