Frequency Response of a Microphone

This is a Ribbon Microphone. I have two. Made for and sold by Studiospares as S300 Ribbon Microphone. I asked for a Frequency Response chart - but they do not have one. What is the best way to check these Microphones and get a chart of the result? I have downloaded HOLMImpulse but this seems it's for Speaker and room acoustics.
 
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Michael Gamble
17:56 (3 minutes ago)
to diyAudio

Thanks for this. I have some E-V RE55's - dynamic Omnis - flat from 50cps - to 20KHz. It's not a 'measurement' Microphone as such - just . . . flat. My trouble is, I simply cannot get my head around the Principle of how to go about doing it.

BTW - the 'Link' ergo posted is 'broken' at the moment. Michael
 
Thank you Simon7000 for these concise instructions! I shall use an E-V RE55 as the 'loudspeaker' with just a few m/w of power and the S.300 placed on the same axis within a few mm 'Head-to-Head' in a 'Very Quiet Place' for this test! It may be a little while before this is done as I need to come to terms with my DAW and down-load the HOLMImpulse programme to it first! I do have a pair of Electro-Voice Sentry 100A Studio Monitor Speakers which are quite flat - what do you think would be best?
 
Thank you, Simon7000. We have three E-V RE55's and two of the S300 ribbon. Also have some E-V RE20's. All the E-V Microphones are a 'known' factor and we have their specs. It's just the two S300 which are unknown. If, as you say, the idea is to use two of the same Microphones (and we do have these two S300's), I am to use them in a way with which I am unfamiliar and have to establish a 'learning curve'. So, from the above 'posts' you know what I have, how do I set about this, please? Michael UK
 
That depends on the gear you have. You could download a sample copy of Smaart and use the internal converters in a computer for both send and receive. Just keep the send level
Low enough you can hear the test signal but it needs to only be 15 dB above the background noise.

I presume others here are more familiar with the sample or shareware software.

In the old days one would use a test oscillator, preamp and meter and graph it by hand.

To measure frequency response you don't need a lot of precision. 8 bits of resolution would actually be enough. As most gear does at least 14 bits accurately that should not present a problem.
 
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You use one as a loudspeaker and the other as a microphone. Just be sure they are close to each other and on axis in a very quiet space.

Send mic power should stay under a few milliwatts.

:yikes:

The right way to do this is to record a sweep through a speaker (any speaker with enough extension will do) through both mics. Mics must be in exactly the same position and orientation. Subtract the flat reference mic's response from the unknown mic's and you have the unknown mic's response.
 
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Thanks for this 'projectwhite' - - Ah-Ha! So these two Microphones are NOT the same - One could be the Behringer 'reference mic' and the other the mic under test, but their orientation will then be side-by-side facing the speaker? I can use a Stereo Bar for this. The speaker will be an E-V Sentry 100A Studio Monitor. Michael UK
 
Thanks for this 'projectwhite' - - Ah-Ha! So these two Microphones are NOT the same - One could be the Behringer 'reference mic' and the other the mic under test, but their orientation will then be side-by-side facing the speaker? I can use a Stereo Bar for this. The speaker will be an E-V Sentry 100A Studio Monitor. Michael UK

Yes they can be different mics as long as one of them has a known response.

You can do one measurement followed by the other, with the mics being swapped out of the same stand. This will slightly improve the accuracy too.

In case you want an app to help with this, Holmimpulse is free and can do the whole process, including subtracting the reference response from the mic under test.
 
Testing Microphones for Freq. Response using HOLMImpulse

I now have HOLMImpulse on the StudioDaw which has Analog and Digital inputs. What is the simplest setup using: an Electro-Voice Sentry 100A Studio Monitor, the Behringer ECM8000 Measurement Condenser Microphone to test and an unknown Microphone for its frequency response?
 
A friend brought around a pair of these mics and below are the graphs.

Berhinger reference mic using Tannoy 611 as the sound source.

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Best wishes

David P
 

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My friend tells me that these microphones were not as bought from Studio Spares, but had been gutted and the Mic transformers replaced with bespoke Ribbon transformers because of the unacceptable base noise level from the FET input.

But clearly they're a good starter for modification in such a way.

Best wishes

David P