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Old 3rd April 2011, 02:35 PM   #851
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Quote:
Originally Posted by 4pyros View Post
Can I cheak the resonance of the TH sub by cheaking the AC current with a DVM and looking for a Dip? Andy
Suggestion: Get a WT3 and use it to measure the impedance response of the TH. It will tell you all you need to know, including the resonance points, AND if there are any sections that need more bracing.
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Old 3rd April 2011, 06:30 PM   #852
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Suggestion: Get a WT3
Ya I dont think I want to go that far to test one speaker, maybe I would measure the voltage across a resistor if I had to. Andy
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Old 3rd April 2011, 06:36 PM   #853
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Originally Posted by 4pyros View Post
Ya I dont think I want to go that far to test one speaker, maybe I would measure the voltage across a resistor if I had to. Andy
Believe me, once you starting building speakers, a WT3 is probably one of the best, if not THE best tool you can have in your toolkit.

You can take the long way around and hook a resistor in series with the speaker, and then use voltage measurements across that to calculate impedance at varying frequencies. A WT3 will do the same for you in seconds. It's worth the $$.
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Old 3rd April 2011, 08:26 PM   #854
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Believe me, once you starting building speakers, a WT3 is probably one of the best
I believe you, But I am only making one speaker.
Quote:
You can take the long way around and hook a resistor in series with the speaker, and then use voltage measurements across that to calculate impedance at varying frequencies.
Cant I do the same thing by measuring the AC current with a DVM?
Andy
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Old 3rd April 2011, 08:31 PM   #855
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Originally Posted by 4pyros View Post
I believe you, But I am only making one speaker.

Cant I do the same thing by measuring the AC current with a DVM?
Andy
Sure, if your DVM has an internal impedance of zero and it can measure current accurately for frequencies from 0 to 200 Hz or so .
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Old 4th April 2011, 12:27 AM   #856
djk is offline djk
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The woofer tester has an AC constant current source that drives the speaker and an AC voltmeter to measure the resulting voltage drop and then calculates the impedance from this data.
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Old 4th April 2011, 02:14 AM   #857
Djim is offline Djim  Netherlands
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Old 4th April 2011, 03:15 AM   #858
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No, put a 10KΩ in series with the driver and measure the voltage across the driver with a true RMS AC voltmeter.
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Old 4th April 2011, 03:25 AM   #859
tb46 is offline tb46  United States
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Hi 4pyros,

I'm with djk, but a 1000 Ohm resistor is large enough. Then you can use the precision 10 Ohm resistor in place of the speaker for an initial calibration. If any of this is unclear, get a WT3 :-).

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Old 4th April 2011, 03:46 AM   #860
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