Posted on Thursday, 8th February 2007 by Jimmy Auw

Due to the raise of resampling problem of most consumer sound card (most likely Creative, prior X-Fi), some people claimed to use the “udial” test tone to check whether they have resampled sound card or not (or having intemodulation distortion problem or not). I’ll explain a little bit more.

You can search around the Internet with keyword “udial” and one of the links is:
http://www.hydrogenaudio.org/forums/index.php?showtopic=9772

You can download the “udial.zip” from that link. I’ll give you direct link to download the file:
http://www.hydrogenaudio.org/forums/index.php?act=Attach&type=post&id=3

If the link is broken, you can download from my website:
http://www.jimmyauw.com/wp-datajim/junk/udial.zip

Read carefully before you play the tone. I will have no responsibility for any damage on your speakers!

As I’ve told you, some people claimed that this file can be used to check whether your sound card has any problem or not (resampling, IMD distortion, etc). But IMO, this is more likely to be a “virus” to blow up your tweeter. As you can see from the picture above (click to enlarge), the sound only has tone at 555-1400 Hz with intensity around -35 dB. But check the upper band. You can see huge amount of power (around -4 dB) on the 19.5-20 kHz. Normally, you will hear a sequence of dialling tones (tone at the 555-1400 Hz area). Some people say that on a “bad sound card”, the tone will be distorted like a laser gun.

Most likely, you will pump up more volume to check the noise, etc (to make sure that your sound card has no problem), but you don’t realize (or can’t hear) the upper band (19.5-20 kHz tone). This tone will clip you tweeter whether you hear it or not. Some people around the net have claimed to destroy their tweeters!

I decide to check whether we can use this “udial method” to detect the resampling in a sound card. I launched up my Foobar, activated the SSRC at 48 kHz and played the “udial.wav”. All sounded ok. I could hear the dialling tone sequence. I disabled my SSRC (and back to 44.1 kHz). Both sounded ok, no distortion or laser gun distortion.

Photo above is just to make sure that I’ve switched my sound card to 48 kHz when playing the “udial.wav”. From this moment, I confirm that this “udial method” can’t be used to detect whether your sound card is a resampled one or not. Perhaps it can detect the IMD distortion, but it’s another case.

Same like photo before this one, I switched back my sound card to 44.1 kHz and both played the “udial.wav” completely with no laser gun distortion or whatsoever.

Conclusion:

1. This “udial method” is a very dangerous file. Don’t play it if you are not sure what you are doing!

2. This “udial method” can’t be used to detect whether you have resampled card or not. In my test, udial could be played perfectly with or without Foobar SSRC (44.1 and 48 kHz).

3. Watch out for any sound file that you have downloaded around the Internet (especially on a test tone file like this). You don’t even realize that you’ve just blown up your own tweeters

Posted in DIY Audio | Comments (5)

5 Responses to “Udial Explained”

1. Willy Says:
   April 26th, 2008 at 04:13

   Is there a way to check if there is no incorrect 44.1 > 48 Khz conversion?

   
   
   
2. Jimmy Auw Says:
   April 27th, 2008 at 19:52

   What do you mean? I don’t understand what you are talking about? Please explain.
   Thank you.

   
   
   
3. AstralStorm Says:
   February 20th, 2009 at 03:27

   Udial is meant to detect bad resamplers, not all of them.
   It will certainly detect simple linear and cubic interpolation.
   It can even detect low-quality sinc interpolation libsamplerate can do at low settings.
   Good quality resamplers don’t introduce intermodulation artifacts - Foobar’s polyphase resampler (PPHS) is one.

   
   
   
4. Octoploid Says:
   February 28th, 2009 at 22:04

   Here is a spectrogram of udial.wav:

   http://www.mypicx.com/uploadimg/1456787709_02282009_1.png

   
   
   
5. XoR Says:
   March 4th, 2009 at 03:13

   U’re testing if udial.wav is good on E-MU 1820? This is just plain retarded…

   It can damage tweeters but this happen if someone think distortions won’t be easily audible. Laser sound are louder than dialing tone, as high frequencies are louder.

   And it’s meant to sound bad on onboard audio codecs and on Live!/Audigy, not on E-MU… My Live! 24-bit sounded good, but onboard audio performance was horrible.

   It ofcourse can damage tweeters and caution is needed. To hear that “laser sound” volume should be very low as this sound is louder than dialing sound. It habe volume of that

   ps. Udial will always sound good on Vista/Win7 cause those OSes have much better audio stack with highest quality resamplers.

   
   
   

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