SRS 830 Lock-in Amp Help

Thread Starter


Joined Oct 28, 2011
We are rather new to this device and have been getting to know it better that we might use it for the 3-omega technique in research, however, we have come across a stumbling block.

As a test, we set the lock-in in such a way that it takes the internal frequency it produces, transfers that frequency to a speaker, which then is relayed to a microphone, the signal from which returns to our lock-in through the A input.

We know that the voltage produced should be about .08V, but the voltage measured on the return is a laughable .008V! Any ideas on why this is happening?

Our setting are at 0 Degree Phase, 1 kHz, 1 V Amp, 1 Harmonic.

Any and all help would be appreciated, and thanks in advance!


Joined Jul 17, 2007
SRS has a tech support hotline; you will find it on this page:

You can talk to one of their engineers immediately to get your questions answered.

You should have documentation available as to why you think that the voltage should be 0.08v instead of the 0.008v that you are measuring. It could be that your speaker or microphone is misaligned, or some other problem that is not related to the SRS equipment.

It would be best to peruse their collection of application notes first:


Joined Jun 6, 2011
Our setting are at 0 Degree Phase, 1 kHz, 1 V Amp, 1 Harmonic.
Are you assuming 0 degree phase? Or is that where the amp output peaks? It would surprise me if the signal from the mic is in phase with that of the LIA. As a matter of fact, the phase should change with respect to the distance between the speaker and the microphone.

This is one of the reasons I prefer quadrature detection to synchronous detection when possible.