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Stereo Tool 7.20 Release

Just a quick reply to my old post about sound cards.

I have a booth at the IBC (European version of the NAB) in Amsterdam this week, and I have borrowed some professional measurement equipment to demo things at our booth. We only had 4 hours to set things up, and there were some issues with the pc (with Marian card) that I wanted to use, so I decided to try out my laptop.

To my big surprise, after setting the level such that a 1000 Hz tone shows 75 kHz deviation, and after performing tilt correction, this is what I see:
- 1000 Hz sine: 75 kHz
- 60,000 Hz sine: 74 kHz
- 30 Hz sine: 75 kHz
- 30 Hz square wave: 75 kHz
- 15 Hz sine: 75 kHz
- 15 Hz square wave: 75-76 kHz
(Without tilt correction the 2 square wave values are 82 and 88). There's a highpass filter at around 30 Hz in all FM presets so the 15 Hz square wave isn't an issue.

I've been playing music with these settings for two days now and I haven't seen a single peak above 76 kHz during that time. So, right now I wouldn't hesitate anymore about putting this built-in laptop sound card (Realtek ALC269) on-air on a real FM station. (I'm not too sure how reliable a laptop is in the long run, but at least the signal that comes out looks good - it is definitely usable as a backup solution).

(If you're at the IBC and want to chat or see a demo of new features, please come by at booth 8.C94 in hall 8.)


hvz said:
The best one I know is the Marian Trace Alpha (or Trace Pro if you want digital AES/EBU input). The ESI Juli@ is very close, but it's not DC coupled (it has a highpass filter in the output which, if not compensated, can cause some peaks above 75 kHz modulation if it's not compensated). Stereo Tool has a tilt correction filter to compensate for this - but if you have the choice, not needing to compensate is always better.

If you just want to test it, even some on-board sound cards can work pretty well - I have a Realtek ALC269 in my laptop that I use for FM tests (it generates a reasonable quality composite signal). The biggest difference between this sound card and the Marian cards is that with the Marian, if I measure the signal with an FM analyzer, it shows over 90% of all measured values at 74 or 75 kHz and maybe 2% at 76 kHz (and 0% at 77), while with the Realtek I get 60% at 74-75 and some sporadic peaks upto 79 kHz (and no guarantee that there won't be higher ones). Which is probably good enough for doing some tests with a low power transmitter - it gives you a reasonable impression of how Stereo Tool will sound on-air.
Click to expand...

PS: Sorry for using a different user name. I suddenly couldn't login anymore and password recovery fails as well.
 
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