Hellp with AudioTester 2.1

[a007udio]

Hello.

I would like to measure some T/S parameters with audioTester but i have problems.

I wire all exectly the same like it must be but when i measure impedance or T/S the impedance curve is strange (no piks and dips, jusr one rise and then strait curve).

Is the use of amplifier a must?

Any hint?

Regards.

 

[bzdang]

Yes, use an amplifier, as the line out of your sound card is not good for low impedances. It is very easy to set up but the amplifier (or receiver) should have a volume control.

bzdang

 

[a007udio]

Thanks, but how i protect my sound card from high voltage from amplifier?

What kind of setup i must make? Do i need any special output level to drive speaker?

Sorry for all that questions but im a novince in this.

 

[bzdang]

Ah yes, I forgot about that.
I use a test jig made from plans by one Eric Wallin, called his 'Jig II", you can find it here
http://mysite.verizon.net/tammie_eric/audio/jig2/jig2.html
It has built in protection for sound card inputs when using an external power amplfier, and is very convenient and worth building.
http://www.vikash.info/audio/sw_jig/

There is a simpler cable setup by Claudio Negro at this link http://www.claudionegro.com/swsetup/cables/cables.html
and he has much useful information on his webpages. He describes adding a dividing network to the simple cables but claims to be able to make impedance measurements with amp by being careful with level setting of the amplifier. It is true that the impedance can be measured at very low power levels, also true that you can kill your sound card very quickly if an accident happens on unprotected inputs!

bzdang

 

[a007udio]

OK, i made the jig II and drive speaker throu amplifier.
And it works!!

So i was measouring T/S parametres but the resoults are quite different from factory T/S.
Only the Fs is almoust the same.

Are there (clio, praxis...) more accurate programs for measuring or the diference from factory T/S is normal?



Thanks for all help.

 

[bzdang]

You are welcome for the help!
I have found that Audiotester does impedance measurement very well, very accurately, but I have not used the TS measurement yet. May I suggest that you make a test box of accurate volume, and get a test mass accurately weighed, and test the same driver with both methods. Also respect the need to clamp the driver firmly vertical with no obstacles in front or behind the cone, I read this somewhere but can't remember where. Lastly, if the driver is new, it's TS parameters may change as it accumulates some hours-weeks-months of use. I don't know if manufacturers publish TS for new unused drivers or 'broken in' parameters. Interesting to measure before use and at intervals after the driver is put to use.
Cheers from Toronto!
bzdang

 

[Tyimo]

Calibration question

Hi!
I have the AudioTester 2.2 and after a couple of hour I could make some impedance and TS parameter measurements.
Every thing is fine and the results was very near to a reference professional made measurement.
But! I am not 100% sure that I understand well the calibration process.
Could somebody help me and to tell me what and where I need to adjust?
In the manual it is a bit "dim" where and which pot I need to adjust in the windows mixer. Play or record mixer? Master volume or input line volume etc.
I use SB LIVE 5.1 sound card and it can drive the speaker very well.
Now I have 549mV output voltage and full open input volume.
One more question: what is the best value for the serial resistor?
10 or 33 Ohm?? Now I use 21 Ohm......


Greets:

Tyimo