Measuring ClassD with Audigy 2 Value

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Done. I didn't take a photo, but the noise is between 60 and 300 kHz.



No external input is enabled for playback. Only wave out is enabled.



It would have make an audible noise, but this is not. And 3 of 3 independent PC with the same, incredibly strong GND problem is very unprobable.

Don't guessing, the source of the noise is obvious already, only the quantity (the way to make it less) is questionable.
Sounds like you feel you know all about it, so why the need to ask here?:confused:
 
How does looks 10kHz sinewave from your sound card in oscilloscope? Is it not aliased? If you play 192kHz/24bit file, it does not mean, that soundcard will output it using exactly same format. Usually there is some resampling in digital path, which affects the output strongly... :(

It's not aliased even at 80 kHz, but the noise is always there. (Actually I played 192/16, but I don't think it's important.)
 
Sounds like you feel you know all about it, so why the need to ask here?:confused:

I asked what I didn't know. Please read what I wrote! I don't know everything about it, but the source. And when I started the thread I was not sure about it, and I didn't know if it's a common problem, or an individual, but since then I could check other sound cards, so now I know it's a common problem (and I shared this info with others). I also don't know if there's a hidden possibility to switch the DAC to fast roll-off filter mode. Do you think if somebody asks, then he must be (and stay) completely ignorant?
 
Last edited:
I asked what I didn't know. Please read what I wrote! I don't know everything about it, but the source. And when I started the thread I was not sure about it, and I didn't know if it's a common problem, or an individual, but since then I could check other sound cards, so now I know it's a common problem (and I shared this info with others). I also don't know if there's a hidden possibility to switch the DAC to fast roll-off filter mode. Do you think if somebody asks, then he must be (and stay) completely ignorant?
Well, whatever I can tell, you think the problem is with the DAC. I don't think so. I've used the Audigy 2ZS notebook, and the only problem I get from that is clock jitter. However, it does not create a noise problem in measurements. Some of the SB cards let you set the sample rates, but not all. Anyway, if you have to be so defensive in your replies, I will just step aside. Good luck.

BTW, if you want more control, possibly there is a Kx project driver available. Try to look it up.
 
Last edited:
Hi,
Pafi, I did not really understand it, just that you have 60 and 300kHz noise. (If this measure is directly oscilloscope card's output), then it is normal to see beyond the audio band signals and these depend on the samples / rate / bit.
It is not clear how to use the Audigy 2 drivers and no software for it.
PC sees it as the default audio? . you can download the software and drivers are very important to use good card. (You can see that the noise and peak frequency change depending on the settings).
 
AP2!
Pafi, I did not really understand it, just that you have 60 and 300kHz noise.

No, I don't have 2 noises at 60 and 300 kHz, but I have a noise spectra between 60 and 300 kHz! It's not periodic, it looks like a band-limited pink noise. (As you can see on fehrudi's picture.)

(If this measure is directly oscilloscope card's output)

Sorry, but I don't understand this sentence!

these depend on the samples / rate / bit.

Maybe it depends, but I can't adjust it.

it is normal to see beyond the audio band signals

I don't understand why do you say it's normal. I have never seen such noise on older cards. Of course always there is some noise, maybe a whole mV, but not 80 mV!

It is not clear how to use the Audigy 2 drivers and no software for it.

Simply: I got a CD with a file SBAX_PCDRV_LB_2_18_0011.exe and I installed it.

you can download the software and drivers are very important to use good card

Please tell me wich is that specific software, and where can I get it from, and maybe I will install it. (If I don't have to follow a 5 pages long guide to do it.)
 
Last edited:
Well, whatever I can tell, you think the problem is with the DAC. I don't think so. I've used the Audigy 2ZS notebook, and the only problem I get from that is clock jitter. However, it does not create a noise problem in measurements. Some of the SB cards let you set the sample rates, but not all. Anyway, if you have to be so defensive in your replies, I will just step aside. Good luck.

BTW, if you want more control, possibly there is a Kx project driver available. Try to look it up.

If you have an Audigy 2 then please could you answer to my question? Is there a noise at high freq on analog output or not? Have you ever checked it with a high bandwidth device (for example oscilloscope)?
 
now I understand (you could write 60 to 300KHz) instead 60 and 300KHz.
no problem, I can guarantee that audigy 2 has-108dB SN / R flat up to 46KHz (samples = 96kHz/24bit). no noise, then you module Have a problem or mistake on setting parameters.
audigy on the web, download and install driver + Configure Panel (exe), simple, without guides or see page long.
This panel have set for f-sample(44 to 192KHz) and bit (16/24).
 
Last edited:
That is ,perfectly the normal behavior for low bit modulator, high order noise shaping chips like those cheap cirrus DA's.

Also its fast roll off filter isn't really that steep , because these chips are optimised for low latency, and can't use many FIR taps like for example ESS sabre does.

You can count somewhat on the switched capacitor output stage. Looks like , not that much.
...BTW , ever saw how sacd output spectra looks ?
 
Last edited:
So I don't have to type it again, here's my rant:
AudioKarma.org Home Audio Stereo Discussion Forums - View Single Post - Is the $50 Creative X-Fi worth it for my PC to Amplfier connection?
Hello!

Yesterday I measured on an other card, EMU1212, and it has the same issue, so it's not unique.

I measured it with oscilloscope. FFT is not neccessary, however useful. You can't check the sound card with itself, since there is a low pass filter on input with ~40 kHz corner freq.
Looking at this article on E-Mu Systems (owned by Creative Technology, maker of Audigy) under the "Non-Creative sound cards" section:
E-mu Systems - Wikipedia, the free encyclopedia
it could be the common "core DSP" in these cards that's the culprit.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.