New speaker impedance tool, SimpeS - Page 2

xstreme · 4th March 2013, 09:22 PM

Quote:

Originally Posted by tvrgeek

at least it is not written in Java.

The Java compiler is one of the best compiler of the world.

i'm not talking about speed...

davidsrsb · 5th March 2013, 09:24 AM

I use Holmimpulse, driving the speaker through a 1k resistor and connecting the speaker voltage as line input. Calibration is by measuring a 10R resistor. You get a very nice graph.

xstreme · 5th March 2013, 10:41 AM

Quote:

Originally Posted by davidsrsb

I use Holmimpulse, driving the speaker through a 1k resistor and connecting the speaker voltage as line input. Calibration is by measuring a 10R resistor. You get a very nice graph.

tvrgeek · 6th March 2013, 08:16 PM

I was not getting a nice graph with a 10 Ohm resistor as I used in all my other tools. The values were quite a bit off and the phase was drooping at the high end. I switched to 200 Ohms and it is very close to the values from WT-II.

Tip, go to view and turn on the status bar. You will see it is actually doing something before it starts making noise.

tvrgeek · 6th March 2013, 08:19 PM

Quote:

Originally Posted by davidsrsb

I use Holmimpulse, driving the speaker through a 1k resistor and connecting the speaker voltage as line input. Calibration is by measuring a 10R resistor. You get a very nice graph.

They make it hard to donate and get the "save" function as they only take an European money pay thingie. If they did Pay-Pal, they would have my money now. HOLMImpulse is a very good tool.

tvrgeek · 6th March 2013, 10:00 PM

Been here too long. LIMP is where it hard to send a donation. Holm software is free. Their hardware is astronomical.

I am not sure how you do impedance measurements with HOLM, or how you could calculate the T/S parameters, which is why we are fiddling with LIMP and SimpeS.

Be aware, a "feature" of the USB protocol is some timing issues. It is packet based and was never intended for streaming audio. When you are running the test, yo hear ticks when the signal changes. Yo don't on a Firewire and probably don't on a buss sound card. SimpeS does this on my other DACs, so it is inherent to USB-2. It works fine, so don't be alarmed.

Neil Davis · 7th March 2013, 12:40 AM

Quote:

Originally Posted by tvrgeek

I was not getting a nice graph with a 10 Ohm resistor as I used in all my other tools. The values were quite a bit off and the phase was drooping at the high end. I switched to 200 Ohms and it is very close to the values from WT-II.

I've been tempted to build up a circuit with the AD5933. It wouldn't have any problems with the source resistance, as it uses a constant current source. However, if you are able to get good enough measurements using a sound card and a simple jig, there probably wouldn't be much demand for the AD5933 board. The chip itself isn't cheap--$27 in single quantities.

http://www.analog.com/static/importe...7846AN_843.pdf

geraldfryjr · 7th March 2013, 01:03 AM

I have used both Holms and REW to get impedance curves easily.
But, That is all you get is a curve.
How do you convert the db scale to to impedance?

I think a really cool method could be to use the data of a stereo sweep using Audacity in 24bit/192Khz mode and plot the curves from that using another program of some sort as there doesn't seem to be and import function using SimpleS.
Unless I am missing something.

jer

davidsrsb · 7th March 2013, 09:33 AM

If you turn the drive into a current source with a 1k series resistor and measure the voltage across resistors of 1R, 3R3, 10R and 33R, you should see a flat line at 10 dB higher level each time.
This is your calibration

geraldfryjr · 7th March 2013, 09:51 AM

Cool,Thanks I will give that a try!!

jer

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5th March 2013, 09:24 AM	#12
davidsrsb diyAudio Member Join Date: Dec 2005 Location: Kuala Lumpur	I use Holmimpulse, driving the speaker through a 1k resistor and connecting the speaker voltage as line input. Calibration is by measuring a 10R resistor. You get a very nice graph.

6th March 2013, 08:16 PM	#14
tvrgeek diyAudio Member Join Date: Dec 2009 Location: Md	I was not getting a nice graph with a 10 Ohm resistor as I used in all my other tools. The values were quite a bit off and the phase was drooping at the high end. I switched to 200 Ohms and it is very close to the values from WT-II. Tip, go to view and turn on the status bar. You will see it is actually doing something before it starts making noise.

6th March 2013, 10:00 PM	#16
tvrgeek diyAudio Member Join Date: Dec 2009 Location: Md	Been here too long. LIMP is where it hard to send a donation. Holm software is free. Their hardware is astronomical. I am not sure how you do impedance measurements with HOLM, or how you could calculate the T/S parameters, which is why we are fiddling with LIMP and SimpeS. Be aware, a "feature" of the USB protocol is some timing issues. It is packet based and was never intended for streaming audio. When you are running the test, yo hear ticks when the signal changes. Yo don't on a Firewire and probably don't on a buss sound card. SimpeS does this on my other DACs, so it is inherent to USB-2. It works fine, so don't be alarmed.

7th March 2013, 01:03 AM	#18
geraldfryjr diyAudio Member Join Date: Feb 2008 Location: Jackson,michigan	I have used both Holms and REW to get impedance curves easily. But, That is all you get is a curve. How do you convert the db scale to to impedance? I think a really cool method could be to use the data of a stereo sweep using Audacity in 24bit/192Khz mode and plot the curves from that using another program of some sort as there doesn't seem to be and import function using SimpleS. Unless I am missing something. jer

7th March 2013, 09:33 AM	#19
davidsrsb diyAudio Member Join Date: Dec 2005 Location: Kuala Lumpur	If you turn the drive into a current source with a 1k series resistor and measure the voltage across resistors of 1R, 3R3, 10R and 33R, you should see a flat line at 10 dB higher level each time. This is your calibration

7th March 2013, 09:51 AM	#20
geraldfryjr diyAudio Member Join Date: Feb 2008 Location: Jackson,michigan	Cool,Thanks I will give that a try!! jer