Measuring T/S with audioTester amp or no amp

[diy1995]

Hello,
so I finally recieved 10ohm 1w 1% resistor and proceed with the measuring.

I measured without amp (directly from sound card) and with amp
And I got totaly different curves and T/S parametres.

No amp:


With amp (30w EQ to flat and volume at 15/30 -at this volume I get speaker about equaly loud as with only sound card):


I`m totally lost right now.
Should I use measurement measured directy from soundcard?

Thank you for help

 

[TBTL]

Seas uses a 2 Vrms signal, as measured at the drivers terminals. I suggest you try the same level with your amplifier.
DATASHEETS

 

[turk 182]

can you supply more details about the amp your using?
setting volume by ear is suspect.
you've got the resistor why can you use it to set the level?

if it's an 8 ohm speaker wouldn't 3v be closer to 1 watt?

 

[diy1995]

Seas uses a 2 Vrms signal, as measured at the drivers terminals. I suggest you try the same level with your amplifier.
DATASHEETS

Well I can`t do that. Max input of Line In on my sound card is 1.1V, 0.2V for mic.

 

[diy1995]

can you supply more details about the amp your using?
setting volume by ear is suspect.
you've got the resistor why can you use it to set the level?

Hy,
I`m using Sony micro hi-fi component system, rated at 2x30w
I don`t understand what you mean by setting level with resistor.

 

[turk 182]

i was suggesting using the resistor as a substitute for the speaker as a load so you can establish a 1 watt level for testing.

if your sound card's input is listed as 1.1v max setting a 1 watt level may be a problem.

what software are you using?

quick look at Sony micro components systems suggest they may not go low enough in frequency for what you want to do.

 

[TBTL]

Well I can`t do that. Max input of Line In on my sound card is 1.1V, 0.2V for mic.

You could build this circuit if you want to measure at higher signal levels: http://www.artalabs.hr/AppNotes/AP1_MeasuringBox-Rev4Eng.pdf
Remove all microphone related stuff if you don't need it (J3, R5, SW1). It works really well.

 

[turk 182]

i feel shame after looking at that artalabs box!
my jig isn't as pretty but is functionally the same.
i'm still looking for an amp with a better low frequency reponse (i keep saying i'm gonna build one but we know how that goes...maybe someday.)