Basically as the title states. How do you know for sure that your measurements are correct? I've got a Dayton measurement mic with a calibration file and all that jazz running into REW, but how do I know for sure that it's correct and calibrated properly for measurements? I.E. How do I know for sure that the graph my eyeballs are seeing in REW is the same response as my earballs are hearing?
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Hello:
You are way ahead of those how think they know and don't.
Two ways to find out:
1. Find someone to sit under and learn from them.
2. Take the red pill and learn yourself.
The best way to approach #2 is with Syn-Aud-Con, easily the best audio training organization in the world. Their online courses are worth far more than they cost, as are the live training events if you can manage them.
Online Audio Training | Pro | Prosoundtraining.com
You are way ahead of those how think they know and don't.
Two ways to find out:
1. Find someone to sit under and learn from them.
2. Take the red pill and learn yourself.
The best way to approach #2 is with Syn-Aud-Con, easily the best audio training organization in the world. Their online courses are worth far more than they cost, as are the live training events if you can manage them.
Online Audio Training | Pro | Prosoundtraining.com
Try to measure some reputed very reliable and consistant loudspeaker manufacturer loudspeaker drivers and compare them to their measurements.
I've measured some loudspeakers drivers of the same model but coming form a batch sparated from 2 years, and the two measurements traces wre literally superposed and extremely close to the manufacturer datasheet.
PS : Take the whole box of red pills and learn yourself with others.
Another way if it is a multiway speaker is to measure drivers individually (including impedance) and then measure with the crossover in place (don't move anything) for all of the measurements.
Then simulate the crossover in something like PCD or XSIM using the individual measurements.
If your simulated curve is very close to the measured curve (with the crossover) then you are doing fine with your measurements.
Note this won't tell you if your calibration is accurate, but it will tell you if you are doing your measurements properly
Tony.
Then simulate the crossover in something like PCD or XSIM using the individual measurements.
If your simulated curve is very close to the measured curve (with the crossover) then you are doing fine with your measurements.
Note this won't tell you if your calibration is accurate, but it will tell you if you are doing your measurements properly
Tony.
I'll have to dig up my measurements on my laptop some evening for screenshots, but I've measured both an Alesis powered monitor, and a pair of C-Notes with a Parasound Zamp. Both have published response curves. My measurements kinda reflect each other, but are definitely not close to the published curve, or what my ears are telling me. Same story inside and outside on a calm day with gains set up correctly and all that fun stuff.
My mic is calibrated by professionnals that use some mysterious very confidential professionnal brand stuff (Brüel & Kjaer, 3M Quest...)
This mic is calibrated by a mic that have been calibrated by a calibrator and i use a calibrator in order to calibrate my calibrated mic each time i use it... Ok ?
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It's not so much that the measurement itself is or is not correct. With a recently calibrated microphone and soundcard based system there is very little chance that the measurement is in error. These days any trained semi-evolved monkey can connect a microphone to some recording device and produce a "measurement".
What is more important is this: Do you understand what the measurement is telling you, e.g. what have you actually measured with your microphone and how that relates to the loudspeaker?
What is more important is this: Do you understand what the measurement is telling you, e.g. what have you actually measured with your microphone and how that relates to the loudspeaker?
@ Silverprout: In case there is some confusion on your part, the above use of "trained monkey" was not meant as an insult to anyone. In English there is an expression that "[something] is so simple that a trained monkey can do it". I was adapting that expression to mean that the procedure of making a measurement is pretty simple and anyone can do it.
I find that lots of people make all kinds of measurements on their loudspeakers but very few of them seem to know how that relates to the loudspeaker's "soundfield" and what it means about how the loudspeaker sounds. Most people, in my opinion, make far too few measurements and only measure "on axis", or even worse "in room at the listening position". A measurement made by a microphone is NOT the same as the ear+brain system of "hearing" of a human. This is where the "knowledge" part comes in - knowing what your microphone measurements are telling you about what you are hearing, and knowing what measurements to make so that you can draw some meaningful conclusions from the data you have collected.
Well, any trained monkey can "get a measurement", but how does the monkey know the result is correct is my question.
I'll try to cross-check if I can find another calibrated mic somewhere in the Kansas City area, but my measurements (with calibrated mic and outside on a quiet day) are nowhere close to published measurements. I've tuned a couple speakers to be 'flat' using active eq methods, but they sounds hollow and nasally when the graph looks flat and I'm not just a bass head used to stupid amounts of bass. Flat speakers, such as the C-Notes and Alesis powered monitors, sound fairly good to my ears, but my measurements aren't anywhere close to lining up with my ears. I'll post some measurements hopefully tonight when I get home from work.
I'll try to cross-check if I can find another calibrated mic somewhere in the Kansas City area, but my measurements (with calibrated mic and outside on a quiet day) are nowhere close to published measurements. I've tuned a couple speakers to be 'flat' using active eq methods, but they sounds hollow and nasally when the graph looks flat and I'm not just a bass head used to stupid amounts of bass. Flat speakers, such as the C-Notes and Alesis powered monitors, sound fairly good to my ears, but my measurements aren't anywhere close to lining up with my ears. I'll post some measurements hopefully tonight when I get home from work.
What do you mean above when you say "correct"??? I am asserting that the measurement system is very likely working perfectly. It's not all that surprising if a loudspeaker or driver measures differently than the MFG data. Did you use exactly the same measurement conditions that they did? Although you have not said it outright, I get the idea that you do not believe the data.
This could be a result of you not fully understanding what the data means or doesn't mean, whether your measurement is really measuring what you think it does, and what it "tells you" about your system. Understanding what any particular measurement, or set of measurements, "means" about how your system "sounds" can be quite a deep subject.
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They correlate well with what I'm hearing.
Boomy bass = big ol' peak somewhere <80Hz.
Something weird going on high up = in one case, a 6dB narrow spike at 7kHz.
Rough upper midrange = lots of peaks and valleys all the way through.
I do a lot of work in ProSound, though, so I know my frequencies quite well.
Chris
You don't, there are inaccuracies and discrepancies all along the way at every turn particularly at the transducers on your head
I'm sorry if i've humilated the monkeys
I'm still searching for a measurement procedure and Dr Gedlee have pointed to me a way to calculate the the sound fiedls transistions (Pierce Acoustics), pehaps my embryonary mathematic brain will be able to draw the radations patterns with the soudfields delimitations in 3D (and therefore etablish a pertinent measurement procedure)
I'm trying to grab the money to buy the book...
Nice experience regarding this topic:
How do you know the guy calibrating your cheap 50 bucks mic didn’t mix up the serial numbers while he was sweeping 500 a day??
Out of trust... I’ve send mine to an engineer for individual calibration.
And oops, was a lot different. And this weird peak at 18k every speaker had disappeared...
Cheers
Josh
How do you know the guy calibrating your cheap 50 bucks mic didn’t mix up the serial numbers while he was sweeping 500 a day??
Out of trust... I’ve send mine to an engineer for individual calibration.
And oops, was a lot different. And this weird peak at 18k every speaker had disappeared...
Cheers
Josh
Unfortunately no-one can hear what a microphone hears or what REW or other compatible software converts into graphs etc.
Everyone hears differently (shape of ear,age,gender,eg)
Speaker manufacturers driver only and off the shelf completed ready to listen too boxes can manipulate there measured response, using 20db 15db 10db inclement graphs
make it look pretty and even include smoothing to a greater extent 1/3rd example.Thankfully a great deal of information regards reputable speaker manufacturers measurements is on the net.
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