Impedance Measurement with rew

[goginux]

Hi, does anyone have a diagram or link, for cables with resistors, in the audio card, measuring with the amplifier, calculate the Thiele-Small parameters?
I made a cable directly in the audio card
sound blaster audigy fx pcie,with 100ohm resistor, but it doesn't measure well or I don't know how to set parameters

 

[Antonio Di Motta]

Hi, the impedance curve you attached seems to be correct, only the impedance values seem wrong.
Did you do the calibration procedure regarding the impedance?
The procedure involves three tests, open circuit with short circuit and with a resistance of known value.
After you have performed the tests the system will be calibrated.

Greetings

Antonio

 

[goginux]

yes I did,the calibration,with 33 ohm rezistor.

 

[Antonio Di Motta]

So the system is calibrated, did you re-measure the 33 ohm resistor after calibration?
You should have a graph with a straight line with a value at 33 ohms and phase at 0 degrees
If the result is as I told you, the system is functioning and calibrated.

 

[Antonio Di Motta]

One of the problems when using a low level signal output such as the line out of a sound card is that the speaker is driven with too little power and you risk getting it to work properly, and the system is sensitive to noise. environmental. It is always better to use a power amplifier to have an adequate signal level.

 

[goginux]

how to do with power amplifier, for example, I have one in class d, I need a diagram!

 

[Antonio Di Motta]

I do not recommend the use of class D amplifiers, as they are often in bridge configuration and have high powers. If you are capable in electronics you could build one, I use the integrated LM3886 for the power section but you can also use the TDA7294 with the scheme suggested by the Hardware & Tools manual of the ARTA software. To build the amplifier you need to be able to assemble the power supply and the power amplifier in a box. Otherwise you have to use a ready-made amplifier, a 10W amplifier is enough as all the measurements are normally carried out at the power of 1W.
If you go to my post Make a good measurement system with REW and Raspberry you will find the amplifier schematic with LM3886 and more.


Greetings
Antonio

 

[goginux]

ok,thankyou for answers!

 

[goginux]

succes!!! on linux peppermint 10 with atomic pi! work perfect with rew,arta/limp on wine.
rew is linux,no wine.

 

[Antonio Di Motta]

I have been using Arta on windows for a long time and also using wine on linux, but since using REW I feel no need to go back to Arta.
REW has everything that is available in ARTA in a single program and also has some more things such as the simulation of the Room
response, the calculation of the VAS with two different methods and the measurement of the LRC components, in short, a program complete
with everything you need and above all multi-platform.
From my point of view REW is better than Arta also as a measurement method.

 

[goginux]

it's true, rew is the best, but i was a little disappointed in the windows, with the speaker impedance measurement, on linux work perfectly.

 

[pi77]

I see there are users that come from ARTA here. Can you tell me if the ARTA measuring switch box (see attached manual) can be used with REW. I think so but I'd like to know your feedback
P

 

[Antonio Di Motta]

Certainly yes, the circuit reported in the documentation is perfectly functional also with REW.

 

[pi77]

Thanks Antonio, I'm not really sure how to use it with an amplifier as suggested by the REW documentation... it's a bit confusing for me... but I'll try

 

[Antonio Di Motta]

If you feel like wasting some time you can read my post on how to use raspberry to create a good measurement tool with REW.
There you can find some suggestions on how to do it all.

Make a good measurement system with REW and Raspberry

I am an electronic technician who has been a HiFi enthusiast and speaker loudspeaker for many years. I have always felt the need to have a reliable and precise instrument to perform electro-acoustic measurements, but the various systems on the market had a prohibitive cost for a non-professional...

www.avnirvana.com

If you have any doubts, ask, I will be happy to help you.

A greeting

Antonio