Can I hook a 50 Ohm Variable Attenuator To This Circuit?

[Bigredbloke]

The is the Output circuit of a microphone I'm using to look at photoacoustic signal, is just an Op-Amp, connected to a high pass filter which is using a 30 Kohm resistor. Sadly, the signal the microphone gives is too strong for the lock-in I'm using to read the signal, and overloads it. I want to buy an attenuator in order to lower the signal without disturbing the waveform. When I measured the output resistance of my microphone it was 30 kOhms, which matched the circuit diagram, so I know that is correct.

My question is can I buy an 50 Ohm Attenuator and hook it up to the output of the mic, will it still properly attenuate the signal? If not do you have any other possible solutions? I am trying to attenuate the signal by at least 10 dBV. Thanks for the help!

 

[anorlunda]

Ping @Baluncore, @berkeman. Another HAM question. This one about impedance matching.

 

[berkeman]

The is the Output circuit of a microphone I'm using to look at photoacoustic signal, is just an Op-Amp, connected to a high pass filter which is using a 30 Kohm resistor. Sadly, the signal the microphone gives is too strong for the lock-in I'm using to read the signal, and overloads it. I want to buy an attenuator in order to lower the signal without disturbing the waveform. When I measured the output resistance of my microphone it was 30 kOhms, which matched the circuit diagram, so I know that is correct.

My question is can I buy an 50 Ohm Attenuator and hook it up to the output of the mic, will it still properly attenuate the signal? If not do you have any other possible solutions? I am trying to attenuate the signal by at least 10 dBV. Thanks for the help!

You can just terminate the output of the microphone in 50 Ohms and parallel tap that into the input of your lock-in amplifier. The 50 Ohm termination of the 30 kOhm source should give about 55 dBV of attenuation. Is that too much? If so, you could just make your own attenuator that is matched to the 30 kOhm output impedance and the input impedance of your lock-in amplifier. It sounds like your signals are all in the audio range, so making your own resistive attenuator should be fairly straightforward.

 

[Baluncore]

Welcome to PF.

I think there are better ways of attenuating 10k impedance signals than using a commercial 50 ohm attenuator. You should be able to make a suitable attenuator from a couple of resistors.

We need to know more about the setup you are using before we can advise you of the easy solution.
A block diagram of your system would help us understand your application and requirements.
Can you please post some links to the circuits you are using.
You can also drag and drop files onto your next post.