My DAC for the Raspberry Pi

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#61
A question I am almost embarrassed to ask . If using CD's with the Raspberry how does one get the best sound ? I am thinking I will use a solid state hard-drive soon . I will see if I can store the files jitter free . There might be a possibility to make it real time CD playing . Also to process LP's in near real time ( my girlfriend laughed at me for not having a scratch filter when her old stereo did , I did say how much music should I throwaway in reply ) . How would one best hook up a conventional CD player for best sound ?

I am of an age where many already draw a pension so please forgive .
 
#62
I connected a USB hard drive to my Raspberry Pi, and ripped my CD collection to it as FLAC files using a CD ripping program. (I started out with Exact Audio Copy on my old PC laptop, and ended up with XLD on a Mac.)

Not sure if it's possible or advisable to have the thing play back CDs directly from a CD drive.
 
#63
It would e great to do vinyl real time . My brother copied an old 1950's RCA recoding for my mother . Both using processed and simple 16 bit encoded . After sometime she preferred simple 16 bit . The sound of the processed was not unlike MP3 and rather good . BBC Radio 2 seem to use similar for playing 78's . The pop of the microphone clearly heard even on 1930's recordings . Virtually no evidence of a 78 record except some rather nice rumble of the cutting lathe . If that was removed I would feel uneasy , so glad they leave that choice to me . If you have never heard 78's played correctly with correct EQ you might be astonished at the voice quality . If you were to filter at 80 Hz and 6 kHz a modern recording I doubt it would be as good . Mostly this is down to excellence of technique which might be a dead art . It is almost like with cooking where too many ingredients spoil the cake . Also recording engineers deliberately make their world seem complex so as to exclude those who can read and play music ( sorry to be so blunt , the old world tests for the job was to play 4 instruments and be able to instantly play a score , George Martin can ) . A dreadful ( de )eveolution .

Vinyl Recording Software - free download suggestions
 
#66
Hi,

I'm not sure what you are looking for. Do you want to have a phono input an the Raspberry or do you want to do RIAA equalization in software?

Doing RIAA equalization in software is not a very good idea, because you will loose 40dB dynamic range on the upper end (20kHz) and even 20dB dynamic range in the mids.

Daniel
 
#69
usul27 said:
I didn't notice yet, that the DSP of the 5142 is fully programmable. I will have a look into this. However, this will take some time, as my DSP software is still in development.

Regarding an I2S standard connector. This will be quite difficult, because different people will have different requirements. For this project, the space is limited, therefore I do not want a very large connector. I will think about it an present a proposal in another thread. Let's see, if we find a common standard.
Click to expand...

Regarding the connector it migh be better to use a 50 mil one like on LPCLink2 (Embedded Artists JTAG debugger / development target board), this is one example:
M50-3551042 - HARWIN - HEADER, EJECTOR, THT, 1.27MM, | Farnell Suomi
 
#70
mhelin said:
I think PCM5142 is as powerful as the ADAU1701 part, haven't compared them though but TI data sheet tells "The miniDSP can run up to 1024 instructions on every audio sample at a 48kHz sample rate." That's exactly the same 50MIPS as with AD part, right? Only difference is that audio performance for the DAC is better on the PCM5142.
Click to expand...

I had a look at this now. While the datasheet says "up to 1024" instructions, the coefficient memory is limited to 2x256 coefficients. Also the FIR filtering seems to work only up to 128taps. Therefore it is nice for IIR filtering, but not powerful enough for larger FIR filters.
 
#74
PicoPlayer

PicoPlayer.jpg

https://sites.google.com/site/picoreplayer/home
 
#75
Gents,

just discovered this thread. looks like really interesting stuff.
I'm the systems definition engineer responsible for the PCM51xx family at TI... it's awesome (personally) to see this family getting picked up in DIY! 😀

Where possible, I always recommend a PCM512x or PCM514x over the PCM510x. The package is a little bigger, but the flexibility to do extra configuration via I2C is worth it... even if you don't plan to play with the miniDSP.

It's also a lot of fun to change the digital interpolation filter options. There's a lot of opinions and fun discussion around the FIR/IIR/Ringingless FIR etc.

Cheers

Dafydd Roche
 
#76
Interesting project, with good economy.

TI's PCM5122 is also interesting in and of itself, being low-cost to boot ... which is unlike ESS. That said, the PCM5122 does not seem to be able to do DSD, let alone double DSD.

Haven't looked into the latest and greatest from WM, Cirrus, AKM, etc. Double DSD needs to be std., IMO.
 
#79
usul27 said:
It is still based on the PCM5102.
Click to expand...
Good enough!
Okay, now the BIG question. How exactly (or roughly) is the power of the Rasp. Pi -- AS A DEDICATED AUDIO COMPUTER -- used for this project? Or is only a portion of the Rasp. Pi computer REALISTICALLY avail. for audio (i.e., technically feasibly)?
That is ... one now has a powerful CPU (SoC) -- potentially the whole thing -- AVAILABLE to process audio. But the skilled programmer has to program/config. it to devote its "entire" Rasp. Pi self to audio. Not sure this is possible.
Head-Direct and AK and Cypher Labs have their own, mini stand-alone devices that can do the same thing.
Can Rasp. Pi -- with a ckt like one in this thread -- pull off similar "class acts"?
 
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