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ES9038PRO VS AK4497 FIR Filter
ES9038PRO VS AK4497 FIR Filter
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Old 30th October 2016, 07:49 AM   #1
diyinhk is offline diyinhk
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Default ES9038PRO VS AK4497 FIR Filter

I just do a quick test on the default FIR filter using the latest ES9028PRO and AK4497, i.e. the default sound output look like.
The ideal output should be a square wave.
The test file is Left channel 1KHz Right channel 2KHz square wave PCM 48kHz sampling rate

AK449X DAC series can output ideal square wave like those NOS R2R DAC when SSLOW=1, (although there is a small overshoot when comparing to ad1865 nos)

es9028pro010
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ak4497sslow0sd1slow0
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ak4497sslow1sd0slow1
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ad1865nos
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Old 30th October 2016, 12:51 PM   #2
JensH is offline JensH  Denmark
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ES9038PRO VS AK4497 FIR Filter
What output level did you use? Was it at or close to maximum?
It looks like the filters are clipping the output, especially with the ES9028PRO.
The title says ES9038PRO, but the measurements seems to be on the ES9028PRO.
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Old 30th October 2016, 01:18 PM   #3
Zoran is offline Zoran  Serbia
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It is not strange thing,
1. actually if You emulate passive n times RLC netwotk filter (like Zanden style for the ex.) You will get the similar or same results.
2. IF You plot the (Sin(x))/x function You will get the same or sim. results.
.
In these chips that is done by the software. Other Question is what is more friendly to the ear? Personally I prefer passive way, with no-dsp in the dac-s.
.
DiyHk is right older dacs (r2r) have not present this kind of "phenomenon". For instance I measured almost perfect square @ 20KHz (Yes You reading right 20KHz ) with NOS TDA1540 philips 14bit R2R dac...
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Old 30th October 2016, 01:23 PM   #4
Zoran is offline Zoran  Serbia
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Another Q is that almost 100% music "recorded" captured, recently, is from the same sound signature hand-writened by the contemporary ADCs, DSPs, "remastering" etc. etc.
When You play - the output result is squared to worse... .
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Old 30th October 2016, 01:24 PM   #5
Zoran is offline Zoran  Serbia
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Diyinhk, could You please post the square of 10KHz od 20KHz from the same dacs?
Thanks
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Old 3rd November 2016, 06:27 PM   #6
themystical is offline themystical  United Kingdom
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These tests are really interesting especially the AK4497 ones. Was the difference in the different FIR filter settings audible in your tests?


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Old 3rd November 2016, 07:22 PM   #7
scott wurcer is online now scott wurcer  United States
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Quote:
Originally Posted by Zoran View Post
It is not strange thing,
True, a plus to minus full scale transition in one clock period violates Nyquist.
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Old 3rd November 2016, 07:56 PM   #8
TNT is offline TNT  Sweden
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Quote:
Originally Posted by scott wurcer View Post
True, a plus to minus full scale transition in one clock period violates Nyquist.
Isn't it > one full scale transition but not =< ?

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Old 4th November 2016, 12:39 AM   #9
chris719 is online now chris719  United States
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ES9038PRO VS AK4497 FIR Filter
It's a step function. You couldn't have sampled it in a band-limited system. People love to see that "clean" square wave, but if you have a proper reconstruction filter you will never get it. As Jens mentions, it does look like the Gibbs ringing is clipped.

What do you get from the other filter settings on the ES9028PRO?
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