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Measuring impedance with oscilliscope

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JonB67 View Drop Down
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    Posted: 30 March 2017 at 8:02am
I've been offered an oscilloscope (two actually)

Am I right on thinking I can use this to tune the box by using it to measure impedance?

If so it's not a piece of equipment ive used before, and im at the point of needing to tune my ports, how do i use it?

Jon

Edited by JonB67 - 30 March 2017 at 8:06am
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odc04r View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 30 March 2017 at 10:44am
Well you could, if you have a sine wave generator and feel like writing down lots of numbers and drawing a graph. Or you could just use PC software with a standard soundcard and a 10 Ohm resistor. Which is a lot easier.

E.g. https://www.roomeqwizard.com/help/help_en-GB/html/impedancemeasurement.html
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 30 March 2017 at 6:32pm
Hey, if someone wants to give you two oscilloscopes for nothing, get them...if nothing else it will make your workshop look really cool. LOL
Studio45 - Box Builder Commotion Soundsystem -Mobile PA
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JonB67 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 30 March 2017 at 7:38pm
Ok ok, point taken!

Never learn if you don't ask though. I'll use REW as you suggest.

Cheers.

Edited by JonB67 - 30 March 2017 at 7:38pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 30 March 2017 at 9:24pm
You can also use your sound card as generator. One oscilloscope parallel to speaker second parallel to resistor in series with speaker.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 31 March 2017 at 9:29am
No reason why you can't do it with your oscilloscope if you want to, it'll give you a good appreciation of the process. It's how people used to do it before automated measurements came along! See if you get the same results with both techniques.

Also if you have the chance to get a scope for free as said do it anyway, they have many applications. You can even check your car timing with them if you are inclined to! Diagnose broken equipment, etc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 31 March 2017 at 4:11pm
The one thing I will add is that osciloscopes are very good for getting a picture of what's going on but aren't good for accurate measurements of Voltages.  You'll be able to get a picture of where the impedance peaks and dips are but you won't be able to measure accurately what the impedance is.

If you're going to do it manually, a true RMS multimeter is probably better.  Incidentally I still often do impedance measurements using a resistor, a multimeter and a spreadsheet!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 31 March 2017 at 6:30pm
ocsilloscopes are handy but there is a much simpler way of tuning a port - stick a piece of paper in front of it and see when it flaps about most.
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