Audio rightmark analyser - Page 2

maxpou · 26th March 2008, 04:22 AM

Hi Guys,
i want test my new preamp proto, but i have 17 Vdc between my computer gnd and my supply gnd. I don't want burn my sound card or my PS. Some body can help me please?

@ Pan,
how can i check the fft with the external signal generator?

thank you! Maxpou

Pan · 26th March 2008, 02:27 PM

OK, which software are you going to use?

Laptop or stationary PC?

Soundcard inputs XLR or RCA?

Preamp not grounded in the wall??

Preamp XLR or RCA outputs?

As long as you connect the ground first between the equipment you shouldn't need to worry but please tell some more about your set up first.

/Peter

maxpou · 26th March 2008, 04:56 PM

Thank you for reply Pan,
i use ARTA software on my stationary PC.

I have sound blaster live 24 for the moment my input/output is RCA, i will replaced it later.

My preamp is grounded in the wall i use 2 alimentation block for my PS, but I have the same problem without the earth GND on my PS.

THank you Maxpou

maxpou · 10th April 2008, 03:19 PM

Hi Guys,
i would like to know if i'm correct with the FFT mesurement of my preamp. I take my cd player with test cd for generate a sine wave at 1Khz at 0 dB. Somebody can explain to me my FFT mesurement because I do not know how to interpret it? Thank you! Maxpou

Pan · 12th April 2008, 05:38 PM

The FFT measurment is a calculation of all information in a signal. In your graph you see the 1k spike but you also see harmonic distortion at multiples of 1k.. such as 2k, 3k, 4k and so on.

The spikes that you se below the 1k is mains interference from powersupplies.

The "gras" at the bottom is the system noisefloor.

The distortion and noise of the CD player, preamp and soundcard input are all in that measurement. If you measure the signal from the CD directly without passing the preamp you can get a better view of how much the preamp contributes.

It's possible that your CD and soundcard have so much noise and distortion that there wont be a difference when you exclude the pre from the loop.. try it!

/Peter

Pan · 12th April 2008, 06:34 PM

Above I wrote "all information in a signal" well... not exactly ALL information..

/Peter

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26th March 2008, 04:22 AM	#11
maxpou diyAudio Member Join Date: Apr 2006 Location: Québec	Hi Guys, i want test my new preamp proto, but i have 17 Vdc between my computer gnd and my supply gnd. I don't want burn my sound card or my PS. Some body can help me please? @ Pan, how can i check the fft with the external signal generator? thank you! Maxpou

26th March 2008, 02:27 PM	#12
Pan diyAudio Member Join Date: Sep 2002	OK, which software are you going to use? Laptop or stationary PC? Soundcard inputs XLR or RCA? Preamp not grounded in the wall?? Preamp XLR or RCA outputs? As long as you connect the ground first between the equipment you shouldn't need to worry but please tell some more about your set up first. /Peter

26th March 2008, 04:56 PM	#13
maxpou diyAudio Member Join Date: Apr 2006 Location: Québec	Thank you for reply Pan, i use ARTA software on my stationary PC. I have sound blaster live 24 for the moment my input/output is RCA, i will replaced it later. My preamp is grounded in the wall i use 2 alimentation block for my PS, but I have the same problem without the earth GND on my PS. THank you Maxpou

12th April 2008, 05:38 PM	#15
Pan diyAudio Member Join Date: Sep 2002	The FFT measurment is a calculation of all information in a signal. In your graph you see the 1k spike but you also see harmonic distortion at multiples of 1k.. such as 2k, 3k, 4k and so on. The spikes that you se below the 1k is mains interference from powersupplies. The "gras" at the bottom is the system noisefloor. The distortion and noise of the CD player, preamp and soundcard input are all in that measurement. If you measure the signal from the CD directly without passing the preamp you can get a better view of how much the preamp contributes. It's possible that your CD and soundcard have so much noise and distortion that there wont be a difference when you exclude the pre from the loop.. try it! /Peter

12th April 2008, 06:34 PM	#16
Pan diyAudio Member Join Date: Sep 2002	Above I wrote "all information in a signal" well... not exactly ALL information.. /Peter

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