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Measurement Microphones [message #81119] Sat, 14 February 2015 17:28 Go to next message
jshupe is currently offline  jshupe
Messages: 31
Registered: January 2014
Location: Austin, Texas
Baron
I decided to measure my speakers today, Pi 4 mains with Pi 3 subs. I used a Pyle Pro PDMIC58 (Shure SM58 clone) that I have laying around the house for drunken karaoke nights, so I knew going in that these measurements may not be accurate.

They ended up having a slope to them that I haven't seen on other Pi speaker measurements.

index.php?t=getfile&id=1664&private=0

After doing a little reading, I found this chart for the SM58 (bottom) that looks quite familiar...

index.php?t=getfile&id=1666&private=0

So as someone who does not measure speakers very often (I'm actually only measuring them now because I plan to rebuild my cabinets in the next couple of months and would like before/after measurements) I'd like to know what microphone(s) I should be looking at. I've seen several units that claim to be measurement microphones starting around $40 online. Or am I barking up the wrong tree?
Re: Measurement Microphones [message #81127 is a reply to message #81119] Sun, 15 February 2015 11:44 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

You can definitely see the influence of the microphone superimposed on the measurements. Your charts look right considering the microphone response curve has rolloff down low, up high and a peak between 3kHz and 5kHz. If you were to account for the microphone chart with a conjugate curve, and then apply that curve to the measurement charts, you'd have a chart that accurately showed loudspeaker response.

Re: Measurement Microphones [message #81128 is a reply to message #81119] Sun, 15 February 2015 12:52 Go to previous messageGo to next message
jshupe is currently offline  jshupe
Messages: 31
Registered: January 2014
Location: Austin, Texas
Baron
I found the following SM58.cal file out on the internet, and loaded it.

20 -15
50 -7
100 -1
120 0
1000 0
2000 +1
4000 +4
5000 +5
7000 +3
7500 +2
9000 +3
10000 +4
15000 -5
20000 -15

index.php?t=getfile&id=1667&private=0

My microphone is knockoff, so I don't expect those figures to be exact. And my room is terrible: 16' ceilings, ceramic tile floors, very few treatments. I think the measurements look pretty good all considered, but I'm not entirely sure what they're expected to look like in my case.
  • Attachment: speakers.png
    (Size: 15.27KB, Downloaded 2254 times)
Re: Measurement Microphones [message #81132 is a reply to message #81128] Sun, 15 February 2015 23:26 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

There you go! That's what I'd expect to see.

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