Analog Delta-Sigma interpolation DAC

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#342
And when going on a logarithmic scale from 14K to 40 K as you did, this is how the result should look like.

Hans
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#343
kokoriantz said:
I don't understand why you delay the original samples by 15.5 samples and why the clock ck is reversed by delaying 11us. All I see from the FFT the OS to be this.
View attachment 924917
Are you sure mine was wrong? I make the OS to be first the 16th on the positive, as the sampler acts on the rise, and switch to the midpoint on the negative.
Click to expand...

It’s working properly, isn’t it?
That’s all that counts.
I could have taken a sample from your delay line, but this was more flexible, and for the anogue delay I needed a separate delay line anyhow.
It’s beautiful weather here, like spring.
And I preferred to sit in the sun instead of behind a PC.
That’s why I didn’t take the time to check things as I normally try to do.
But the last .asc file is right.

Hans
 
#344
Markw4 said:
OT Warning:
Some people say Chord DAVE sounds more like real music than the $100,000 complete dCs Vivaldi setup. One guy who said that owns both of them. In addition, Chord has a 'prescaler' for use with DAVE and Hugo TT 2 that adds a million tap preprocessing filter before the dac. People say both dacs sound better with the prescaler. Don't know about Stereophile in every case, but have it on good account that sometimes they can't say what they know or they will lose advertising revenue they need to survive. Only the German hifi magazines are willing to tell it like it is.

Anyway, longer filters do seem to be preferred by many.
Click to expand...

Hi Mark,
Nice friends that you have.
Do you happen to remember which German magazine it was that tested the Chords?

Hans
 
#347
Hayk,

I saw that you did not download the Sinc Hamming 2.asc file from #341 ready to run the Impulse Response.
The impulse response is the ultimate test to check the correct working of the model.
Or did you alter E31’s gain from 1.15 to -1, and do you now get the correct FR with 20K input as in #342 ?

Hans
 
#351
kokoriantz said:
The only thing I needed to change to be similar to yours is the rise and fall of the clock ck. With 0 rise, fall.
View attachment 925141
With 0.05u rise fall.
View attachment 925142
How strange?
With -40db image, my interpolator is a excellent.
Click to expand...

You are close but still not perfect.
Look at the image in #342 at 0dB with the first mirror at -37dB.
Yours is at -25dB for a 0dB signal.
Try to sim an impulse response, that’s the easiest way to find out if everything is O.K. Image should be flawless like in posting #334

Hans
 
#359
kokoriantz said:
adjusted to 44.1khz it needs 8.3% extra gain. To say that the clock has half the period on but 0.05us rise and fall. If I subtract the rise from the on time to have it 50% duty cycle, I get lot of parasite pulses.
View attachment 925538
Click to expand...

That’s why you should better use the sample input instead of the clock input of the S&H.
That relieves you from calculating 50% dutu cycle.

Hand
 
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