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My DAC for the Raspberry Pi
My DAC for the Raspberry Pi
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Old 24th October 2013, 12:07 PM   #21
Turbon is offline Turbon  Sweden
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Quote:
Originally Posted by usul27 View Post
@smallangryboy: There are 2 eval boards of the prototype, these are already reserved for 2 guys. There might be another 2 eval boards of version 2. The phono sockets will be parts of the kist, however, you do not have to solder them on the board.

@Turbon: This is not a USB DAC, it connects directly to the I2S port of the SoC.
Ok, rephrase - so we have a solution to get good sound outta the PI? I want one! Sign me up and let me see the bill!

Brgds
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Old 24th October 2013, 01:22 PM   #22
nigel pearson is offline nigel pearson  United Kingdom
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Any idea what the - 60 dB distortion is ? It seldom is better than 4% . I have been trying to devise a test for this . Perhaps record via an excellent CD burner like TEAC at - 60 db and use it for comparison tests . It should mean something to test the whole chain . An early Denon test disc was of a piano at 0 db - 20 dB and - 40 dB . Doubtless the disc as much as anything at fault . 0 db ( seldom used ) strong and clear . - 20 dB simlar but bleached out detail . - 40 dB like a Kazoo . Denon said construct an attenuator to test at identical levels . I did and didn't have to . From that I conclude pre 1990 CD had a real dynamic range of 20 db at best . Worse still is engineers were told not to go into the 0 to - 20 d range . To an extent dither added 20 dB to that ( 30 % THD became 3 % with dither ) . 4 % THD espeailly if not the higher harmonics at - 60 dB would be excellent . As someone recently said , analog recording fades to noise . Digital if dithered does also . If not one has to ask extra questions as noise is a full register of harmonics if white noise , 7 th and 9 th harmonics are not a great replacement no matter how small . One 24 bit chips maker said " no need for dither " . I wonder ?

Proof that - 20 db was typical is the input sensitive of tape deck inputs works fine with CD . In principle it is about 15 dB too high . Even knowing tape decks peak at + 6 dB doesn't account for it all . Build to the 2 v spec and CD will be too quiet . Not true of a pick up amp built with 6 dB spare gain . It is obviously loud .

Last edited by nigel pearson; 24th October 2013 at 01:24 PM.
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Old 24th October 2013, 01:33 PM   #23
usul27 is offline usul27  Switzerland
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Hi Nigel, there is no -60db distortion. The D2 peaks is at about -90db.
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Old 24th October 2013, 02:00 PM   #24
nigel pearson is offline nigel pearson  United Kingdom
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That's great to know . I will do the chain one day as like vinyl one needs benchmarks . I said to a German guy . " Why do we insist on getting RIAA correct to 0.05 dB when the pick up might be + 7 dB 14 kHz " ? " We get right what we can " was his answer . It sounds right but is mathematical nonsense . The big picture often brings surprises . Doing the detailed study says sometimes why despite evidence one thing sounds different in a way where 0.05dB could not matter . Worse still if 0.03 dB becomes a quest . I get people tell me the NE 5532 is a rubbish op amp . It can be and often is . It is a great op amp with a few problems that need considering . It can go unstable due mostly because it is a high current device . Put in an OP 2604 will often sound better . The reason is it is more tolerant . DAC's might almost be op amps when saying this .
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Old 28th October 2013, 01:46 PM   #25
rezbit is offline rezbit  Croatia
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Any possibility of just SPDIF output, without DAC? I'm most certainly interested in this but since I already have DAC that I like, some mean of hooking my raspberry to it would be perfect.
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Old 30th October 2013, 07:18 AM   #26
usul27 is offline usul27  Switzerland
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I'm also working on SP/DIF out. However this will be a completely different device. It will be more complex than the DAC. You will find more information about it here: http://www.crazy-audio.com/projects/hifiberry-digi/. Note that it is still in the design phase. I hope to get the prototype running this year, but the device will not be available before 2014.
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Old 31st October 2013, 07:41 AM   #27
kalinowski is offline kalinowski  France
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This is a great project! I'll be interested in a prototype pcb if you decide to make them available
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Old 2nd November 2013, 05:27 PM   #28
BRN is offline BRN  United States
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My DAC for the Raspberry Pi
I'm really interested in this DAC. What music server/player are you using with it?
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Old 3rd November 2013, 06:00 PM   #29
pidesd is offline pidesd  Canada
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hi,

just stopping by to say that i like what you do and your website.

if i were a computer engineer, i d be all over the Pi. What is not to like from such a tiny cheap computer?

Really cool that you successfully tapped from the I2s for the HifiBerry. Makes me want to buy a Pi, upgrade the regulators and try it with my upcoming 1794 dac just to see what quality it outputs...maybe it could replace my hiface,who knows!

keep up the good work!
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Old 4th November 2013, 06:07 AM   #30
usul27 is offline usul27  Switzerland
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@BRN: I'm using it with RaspyFi, but it should work with every player software.
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