FireFace - strange Square Wave responce, is it ok?

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Ilya

Well-known member
Joined
Feb 25, 2005
Messages
751
Location
Moscow
I never bothered to check out how my FireFace 800 handles reproducing and recording of square wave. Now, having played with it a bit  I'm really curious if this is a good responce or what? See the pic attached (1000 Hz square wave).

Just so you know, the source of the square wave is inside the computer, so for now I have now way to see when the wave gets screwed: at the input or at the output.
Any comments?

Things start to look really ugly at 20 Hz...
 

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as a guy that studied "software design for music and sound" it looks good! but does it sound good? i hope cos if you had a straight line your converter would've surpassed the designers expectations.

greetings,

Thomas
 
Thanks for your responce, guys! I've never heard of this phenomen before, and we haven't learned about it in the Academy too.
Just to make sure, this means that I can't use any digital audio interface as a test lab, at least I won't get the real world graphs for discontinued functions, right?
Now, what about digital oscilloscopes? Should they be avoided as well?
 
Ilya said:
Now, what about digital oscilloscopes? Should they be avoided as well?
I don't have one but I believe they have way higher sample rates, therefore the anti aliasing filter would be way softer in audio terms and therefore have less ringing, wouldn't it?

Michael
 
Michael Tibes said:
Ilya said:
Now, what about digital oscilloscopes? Should they be avoided as well?
I don't have one but I believe they have way higher sample rates, therefore the anti aliasing filter would be way softer in audio terms and therefore have less ringing, wouldn't it?

Michael

Real Digital scopes do not have anti-alias filters (AFAIK) so frequencies higher than the sample rate just alias down around the sample rate. Square waves still look square, and do not exhibit Gibbs phenomenon.

Using a sound card as a digital scope, who knows?

JR
 
Soundcards will have anti-alias filters.

OTOH, it might be worth the time to look at the source of the square wave. If the source is not producing an accurate waveform, there is no way that the circuit can reproduce it as you would expect.  Have you sent the source wave directly into the scope?  You might find another square wave source to try, and see how it looks.

regards, Jack
 

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