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Impedance matching for DACs and Amps? - Page 2

post #16 of 22
Quote:
Originally Posted by 00940 View Post
 

 

It can... badly. Have a look here, fig. 4.32, 4.33. And that's 3Vrms into 1K.

That's still around 0.01% THD, which isn't audible, and its worst at extremely high frequencies (where it really, really isn't audible). Sure, it's pretty mediocre by modern electronics standards, but you aren't going to hear any serious flaws in your music just because the preamp is adding 0.005%THD to most of the spectrum and 0.02% to the top octave.


Edited by cjl - 5/8/14 at 6:02pm
post #17 of 22
Quote:
Originally Posted by 00940 View Post
 

 

It can... badly. Have a look here, fig. 4.32, 4.33. And that's 3Vrms into 1K.

 

Take a look at the scale bars! This is given as a log plot of the percent THD and all values are much less than 0.1 %.

 

 

I'm not sure that would be audible at all.

 

Cheers

post #18 of 22
Quote:
Originally Posted by 00940 View Post

It can... badly. Have a look here, fig. 4.32, 4.33. And that's 3Vrms into 1K.

Into 600 ohms, it would likely hit about 0.02% at 20kHz. That wouldn't even bring it into the realm of audibility.

se
post #19 of 22

Quote:

Originally Posted by ab initio View Post
 

 

Take a look at the scale bars! This is given as a log plot of the percent THD and all values are much less than 0.1 %.

 

Wow, I would never have figured out by myself how to read those graphs  :rolleyes: 

 

I don't have the time to get into yet another debate. When I wrote a significant increase, I had in mind an increase by an order of magnitude. When he read significant increase, Steve Eddy had in mind an audible increase. Not the same thing and let's leave it at that.

 

 

Quote:
Originally Posted by Steve Eddy View Post


Into 600 ohms, it would likely hit about 0.02% at 20kHz. That wouldn't even bring it into the realm of audibility.
 

 

It's already 0.025% with a 1K load in Self's setup (3Vrms @20khz). I suppose you mean 0.02% at 2Vrms, a standard dac output ?

 

S. Groner has the measurements at +20dBu btw, if you're interested.

post #20 of 22
Quote:
Originally Posted by 00940 View Post

It's already 0.025% with a 1K load in Self's setup (3Vrms @20khz). I suppose you mean 0.02% at 2Vrms, a standard dac output ?

No, I meant 3 VRMS. And I erred, I meant to say about 0.03% THD, not 0.02%. And again, that's at 20kHz. What's the second harmonic of 20kHz? Can you hear 40kHz?

Sure, if you're just wanting to play the numbers, the TL071 doesn't fare as well as others into 600 ohms. But outside the numbers, is it really meaningful?

Quote:
S. Groner has the measurements at +20dBu btw, if you're interested.

Thanks, but I think these numbers make my point just fine.

se
post #21 of 22
Thread Starter 
What have I done... (@, @ )!
post #22 of 22
Quote:
Originally Posted by Audio Jester View Post

What have I done... (@, @ )!

This is what you get for asking questions here. :evil:   Hope you learned your lesson.  

Yup, you created this ambiance.  :evil:  kidding.  :D


Edited by SilverEars - 5/9/14 at 1:44pm
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