REW for the first time

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arivel

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Is there a way to check the correct functioning of the bass reflex port?
 
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arivel

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hello everyone .
i want to use the method described in the following two web pages to measure the small-thiele parameters of my speakers .
a non-inductive resistor is recommended but there are many types of resistors with this characteristic . can you recommend the right one ?.
bye thanks
 
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dcibel

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Any resistor is fine really. REW's calibration process will compensate for the resistor and test lead inductance, so I'm not sure why the recommendation is for a "non-inductive" one. Besides, a standard low resistance wirewound 10W sand cast resistor has an inductance in the 0.001mH range, not very significant in the context of speakers and crossovers. My test jig uses a normal 5W sand cast 10 ohm resistor, and it's perfectly fine.

My jig is made for use with a power amp, as well as loopback for speaker measurements:

Dual Channel Measurement Jig - HTGuide Forum

Here's a schematic for a simple dual channel measurement jig, which can be used with ARTA, REW, or SoundEasy.
www.htguide.com

On the port measurement topic, of course "there is a way", multiple ways in fact. One would be to measure nearfield response of the woofer output, and port output. These two measurements can be combined for a total response similar to the software cabinet model. Alternatively, the speaker low frequency response can be obtained using a "mix in box" method. This method can provide a good detail of the total low frequency response output, but won't be able to separate the woofer output from the port output.
 
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arivel

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interesting your system.
going back to the link I posted, it seems that in reality on the REW page 3 measurement methods are proposed.
1) direct use of the audio card outputs with a 1KOhm resistor
2) use of a headphone amplifier with a 100 Ohm resistor
3) use of a power amplifier with a 33 Ohm resistor
but the image on the page only shows connection diagram number 1).
where are the other two connection diagrams?.
 
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dcibel

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1 and 2 are the same, 3 I have provided for you, it is the same but with a voltage divider at the soundcard input to step down the signal to "line level".

REW it a tool, how you use it is up to you. All methods of connection that produce a signal at the soundcard input for analysis are possible. Impedance measurement is simply to create a voltage divider between the driver and a known constant resistance.
 
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arivel

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if instead I decide to use the sealed box method how many liters should the total volume of the box be for 12" ,15", 18" speaker drivers?
thanks
 
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