1 Topic by dir (edited by dir 2018-04-23 20:55:48)

  • dir
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Topic: Weird deviation on the top of the frequency response

i was measure outputs of DAC and Pro via Adi-2 Pro Input
24/44 & 24/48 mode in RMAA
DA and AD filters are switched to SD Sharp

both devices are shows similar light (+-0,07 dB) pulsing on the top of the frequency response

when i route RME's to the my old LynxTwo input - it shows worse noisefloor of cource, but curve are smooth. Below you can see compare between ADC section of LynxTwo and RME Adi-2 Pro
http://i.piccy.info/i9/74c10d5557cc0126fdc12feeecdc9840/1524504888/14144/1239453/Spectrum.png


if i try to measure any other devices via ADI-2 Pro input i get the same deviations of the curve response((
any chance to fix it in the next firmware?

2 Reply by MC

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Re: Weird deviation on the top of the frequency response

It would be nice if people research their questions a bit instead of just posting. This deviation is well documented, even in several reviews of the Pro and its own manual. It is just a matter of zooming in. Every AD and DA has it , some more, some less, so depending on your zoom you notice it or not. This is from the AD chip itself and can not be changed.

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Matthias Carstens
RME

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  • dir
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Re: Weird deviation on the top of the frequency response

both curves was made in the same scale and has a same zooming
why there is no deviation on the LynxTWO?
it means response of the old AK5394 has a better linearity than 5574?

4 Reply by MC

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Re: Weird deviation on the top of the frequency response

Answered in post number 2.

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Matthias Carstens
RME

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  • dir
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Re: Weird deviation on the top of the frequency response

its like a "signature" of 5574's response, ok, i understand it
but its seems not like just 'zooming' point of view

all measured devices via ADI-2 will have same specific deviations from 5574's chip, so next time i must compensate it in RMAA reference slot

6 Reply by MC

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Re: Weird deviation on the top of the frequency response

I prefer to measure such things at 384 kHz sample rate, if possible, as there is no such effect anymore, so one does not need compensation. Unfortunately RMAA can not handle such a sampling rate (yet).

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Matthias Carstens
RME

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7 Reply by MC

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Re: Weird deviation on the top of the frequency response

> This is from the AD chip itself and can not be changed.

Well, it can:

https://www.forum.rme-audio.de/viewtopic.php?id=27295

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Matthias Carstens
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  • dir
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Re: Weird deviation on the top of the frequency response

wow, thanx-a-lot!