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Signalyst DSC1
Signalyst DSC1
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Old 6th January 2016, 12:45 AM   #201
mcluxun is offline mcluxun  United States
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Quote:
Originally Posted by abraxalito View Post
Those plots all look very noisy to me - you have an effective measurement bandwidth of 1.46Hz and the noise levels are in the -100 to -110dB region. Which if you integrate to the full audio bandwidth turns into -60 to -70dB noise.
All of them are tested with 32768 FFT size, it would look "cleaner" with 1/2 the FFT size, like this:
http://i.imgur.com/CffGQ4k.png

Under the same condition:
closed form 11.2m
http://i.imgur.com/FfoXO22.png

Last edited by mcluxun; 6th January 2016 at 12:49 AM.
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Old 6th January 2016, 12:52 AM   #202
abraxalito is online now abraxalito  United Kingdom
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Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Sure, that's looking much cleaner because you've set the software to average 30 passes. Does not change how noisy the circuit is though
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Old 6th January 2016, 02:45 AM   #203
bibo01 is offline bibo01  Italy
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Given that DSC1 board is based on Amanero, I have some news about it and how it plays on Linux -

I have just finished talking on the phone with Domenico, the producer of Amanero USB boards.
We had a very friendly chat, also because he comes from a town 60Km away from me.
He explained that it already exists a firmware capable of DSD512 under Linux, but he just offered the tools to designers and at the moment it is up to each one of them to patch OS in order to work in DSD natively.
I suggested to contact ALSA maintainer to make such patch public as part of Linux next release.
He will do so and keep me informed.
So sooner or later Amanero board will be able to play DSD in bitstream (non DoP) on Linux.
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Old 6th January 2016, 07:12 AM   #204
zaum is offline zaum
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Quote:
Originally Posted by bibo01 View Post
Given that DSC1 board is based on Amanero, I have some news about it and how it plays on Linux -

I have just finished talking on the phone with Domenico, the producer of Amanero USB boards.
We had a very friendly chat, also because he comes from a town 60Km away from me.
He explained that it already exists a firmware capable of DSD512 under Linux, but he just offered the tools to designers and at the moment it is up to each one of them to patch OS in order to work in DSD natively.
I suggested to contact ALSA maintainer to make such patch public as part of Linux next release.
He will do so and keep me informed.
So sooner or later Amanero board will be able to play DSD in bitstream (non DoP) on Linux.
Wow, thats a great news! So i can simple embed a Beaglebone board into DAC.
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Old 6th January 2016, 10:28 AM   #205
Signalyst is offline Signalyst  Finland
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Originally Posted by mcluxun View Post
Hats off to the new closed form filter outperformed others by a big margin.
Just curious, which modulator was used for this? I recommend trying with HQPlayer 3.12 and ASDM7 (note that 3.12 fixes one bug in ASDM7 initialization).

What is resolution of the ADC used for the measurement?

Last edited by Signalyst; 6th January 2016 at 10:39 AM.
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Old 6th January 2016, 02:17 PM   #206
mcluxun is offline mcluxun  United States
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Originally Posted by Signalyst View Post
Just curious, which modulator was used for this? I recommend trying with HQPlayer 3.12 and ASDM7 (note that 3.12 fixes one bug in ASDM7 initialization).

What is resolution of the ADC used for the measurement?
It was ASDM7 under 3.11. I'll test again under 3.12 soon.

ADC is QA400 https://www.quantasylum.com/content/Products/QA400.aspx

For the reference:
AD-DA loop of QA400
http://i.imgur.com/Ydio4eY.png

1k sine soekris R-2R
http://i.imgur.com/1gN8HCh.png

Last edited by mcluxun; 6th January 2016 at 02:30 PM.
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Old 6th January 2016, 02:42 PM   #207
mcluxun is offline mcluxun  United States
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under 3.12, ASDM7 it's indeed better.
http://i.imgur.com/xE4dYsM.png
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Old 6th January 2016, 11:55 PM   #208
Signalyst is offline Signalyst  Finland
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I did some measurements with dScope III today too. Still without case, just boards on a table with open wire hassle.

dScope gives me -90 dBr noise level at DSD128 including PSU hum, which is still better than most power amps ref 0dBW. Background noise is pretty much white noise without any correlated or spurious tones/peaks. The background noise shape peaks at 7.5 kHz and I believe it is PSU related so that's one of the areas to be improved. I just regret the opamp choice and wish I would have stick to the ones I used before. But IMO, still not bad for rev.A board.

Good thing is also that Jtest24 spectra is quite clean, only visible side bands are PSU related +-100 Hz somewhat below -120 dB level.

1k wide spectrum:
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IMD spectrum:
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1k at -96 dB level:
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PCM 0-input upsampled to DSD128:
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R2R ladders tend to generate forest of correlated discrete tones throughout the spectrum, which I personally consider more audible than white noise.

For comparison, Metrum Musette discrete R2R:

1k wide spectrum:
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IMD spectrum:
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And 1k wide spectrum with upsampling to 352.8k:
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Old 7th January 2016, 01:44 PM   #209
mcluxun is offline mcluxun  United States
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That IMD plot of Metrum wow almost like you were doing two tests at the same time.
I'm really confused about the test result of my DSC1 the first harmonic seems to be consistent with your but there's at least 15db difference of noise floor. Maybe it's some error on my part.
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Old 7th January 2016, 11:51 PM   #210
mcluxun is offline mcluxun  United States
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Jussi are those measurements taken with any USB conditioners?
I try different ways to get a better measurements apparently using a USB hub gives me better measurements around 1k (shorter "grass")
Also better PS definitely helps a lot, Reflector-D works wonders with DSC1
http://i.imgur.com/A2BIAL5.png
I'm still not able to get it below -120 like you did, however -110 is definitely doable.
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