How much quality of a microphone do you need for simple measurements
Simple measurements can tell you something
How much quality of a microphone do you need for simple measurements? As David explained in his last blog simple distortion measurements. It is of course possible to extract relevant insights from simple measurements. David showed this with several measurement results especially on distortion measurement. For those measurements he used a simple microphone. For distortion measurements of loudspeakers one would rather choose an anachronic chamber. David demonstrated also reasonable results taken at listening position in a living room.
For simple measurements the key success factor is to know what you are looking for. Secondly you must stay within the boundaries of the limiting factors of your measurement setup. As long as the insights you are looking for are big enough to be detected within the tolerances of your measurement set up, it is of course possible to gain very relevant insights.
There are plenty of unpleased effects on the listening experience, like acoustic room influences, harmonic distortion of the whole system, peaks and drops in frequency range at the listening position, stereo effects and many more.
Surprisingly, when doing listening room measurements it is impressive how huge even simple peaks and drops in frequency range of many many systems are. Especially in rooms without or with only minor acoustic treatment.
Also for time and phase coherence, results taken with simple measurement setups deliver very impressive insights.
Many issues at listening positions are bigger as you would think
An audio system setup in your listening room delivers sound quality which is the sum of all of the components including the source material. You might have a vinyl setup with pure analog signal chain until your speakers or a complete digital signal chain until your speakers. Behind your speakers your sound is drastically influenced by your room setup including or excluding special acoustic treatment.
Somewhere in that room is your listening position and at this listening position you might want to know what you receive there as sound that you experience. Exactly there you might want to put a microphone to get some visual support to help you to interpret what you hear and what you potentially should improve.
Frequency range, time and phase coherence between left and right as well as frequency groups of more way speakers or distortion are information of interest.
Impacts on sound, that you hear might be very small in measurement results. For such small impacts, that are detectable with our ears, you would need a very high quality measurement setup. Especially if you want to locate the origination of such impacts to special components of your system setup. Most drastic impacts at the listening position usually don’t come form your hifi system, they usually are caused by the room influences.
I am still very often surprised how much effort and money people invest in optimizing they audio system components. Also how much people debate about differences of analog vs digital. Seeing them listening in a room without any acoustic treatment.
Microphones are the frontend of measurements
The same people are than overly surprised when they see some simple measurement results taken with a smartphone. They are even more surprised how simple measurements taken are visible in smartphone measurements. Simple measurements are manipulating the audio system setup or taking some simple room acoustic measurements. More important of course, they hear those differences and can easily connect to what they see in the measurement results.
The first comment, most of the time, “Wow, and this can be measured with a smartphone, I had never guessed this. The microphone is good enough for such measurements, wow.”
The god father of microphones
Source material used to playback the music influences a lot of the sound. The quality of the source material is heavily dependent on the recording, of course. There are many more influences in addition, but one thing is true here as well, garbage in, garbage out.
The recording is very depending on the microphones used for the recording. The setup of the microphones also influence the recording drastically. There is a hole science around the microphones. Here is a little story about a very high quality and very rare microphone with some extraordinary quality characteristics.
Here you find some photos of a C12 tube microphone, that was completely build by Markus Sauschlager, a mic-freak in Vienna, a friend of mine and a member of the Vienna Audio Labs. The images show the microphone in its unfinished prototype state. The brass metal parts are to be nickel plated. Then it also looks like an old AKG C12.
He build it completely himself, no replica housing parts involved anymore. But he also had to manufacture the fixtures, molds and stamps necessary to form the grille and various metal brackets.
Markus visited Neumann GmbH headquarters in Berlin. He really enjoyed to show them what the Austrian microphone making heritage has to offer 😀
Also he gave the mic to a studio owner who is very familiar with an old C12 specimen to test it over the weekend. The studio owner wasn´t too happy when time had to return the mic …
That particular CK12 capsule was a new challenge, as Markus wanted to get basically the behavior of the 1960´s version that had 9µm diaphragms, while actually using 6µm diaphragms. That meant he had to change the backplates´ parameters to compensate for the lower diaphragm mass. A direct comparison to a perfectly preserved vintage original showed same behavior in level and balance in all polar patterns.
This is an impressive piece of work and dedication.