Hi all,
Having gotten very interested in hi-q audio recently, I have set out to build my own digital transport. The main reason is that I could not find a transport which
- plays losless from SD card (WAV and eventually FLAC)
- does not require a PC/Mac/Linux whatever to work
- adds quality to the average livingroom CD/DVD-player
- has on on-board non-oversampling DAC
- accepts 4 S/PDIFs (2 optical, 2 coax)
- accepts USB for streaming audio (so NOT to connect a hard disk)
- has a user friendly interface with just the absolutely necessary buttons
- is somewhere in the € 500 - 600 pricerange, which excludes the true audophile end of the spectrum (?)
None of the players I have seen before combine all of the above:
- SDTrans; looks nice, but have trouble understanding what it covers and what not. For sure, it does not cover all the items listed above.
- Traxmod; nice, but 'only' the SD component
- SD2; very nice looking, great build quality, but limited in functionality and selling for roughly € 1,200. Seems to be in the true audiophile section.
- Ultimate Source V2 from koonlab.com. 'only' SD component, though, and development seems to have stalled a bit.
So I decided to start from scratch, trying to combine all the objectives above...
Now, I have an early prototype sittig at my desk, and I have to tell you it SINGS!!! I am (rather: was, see below) listening it via a PPAv2 and HD-555 cans. Using the SD-player makes listening to my regular crystal-clocked PCM2707 USB-fed 12-way TDA1543 a joke. Crispness, deepness are overwhelming to me. (sorry, am no poet so forgive the choice of words).
Can't wait for someone else with more 'high-end' listening experience to evaluate this unit. (see 'how could you help')
The imminent 1.0 version should be able to do the following:
- SD+SDHC card support, FAT16/32 incl. LFN support
- S/PDIF (2 x coax, 2 x optical) (WM8805)
- TDA1543 12-way onboard DAC (inspired by Doede Doedema's DDDAC)
- PCM2706/7 based USB streaming support
- High quality clocks for SD playback (an independent 11.2986MHz for 44.1/176.4kHz and one 12.288 MHz for 48/96/192kHz)
- SD player plays WAV, 16/24 bit 44.1/48/96 kHz samplerates up to 24 bits resolution (I know, the TDA1543 only looks at the 16 MSBs).
- Fits on euro-size PCB (to fit this http://www2.conrad-uk.com/goto.php?artikel=522953 casing. This casing selected because of the integrated cooling ribs)
Version 1.1 tentatively will have
- USB support based on Tenor TE7022L (to support 96kHz sampling rate)
- Choice between 12-way TDA1543 and PCM1794A DAC implementation
- SD player plays WAV, FLAC 16/24 bit 44.1/48/96/176.4/192 kHz samplerates.
- Optional integrated PPA/M³-inspired headphone amp (integrated as 'in the same case').
- Firmware flashing possible
- Consider adding ADUM device for USB connection isolation
- Modularity: leave out the PCM2706/7, S/PDIF, one clock etc. etc. according to the user's need
- I2S out
- ...?
I have identified the following areas which need progress. If you feel like it, please contact me to discuss where you could help out. The list is in order of descending priority:
- First and foremost: I know this device meets my personal demands. However, I have no clue if it meets the demands of others. Your opinion on the (planned) feature set of this device is very welcome.
- Evaluating the sound quality of this system. I am planning to make one available for evaluation by a selected head-fi member. Please PM me if you are interested to review the unit.
- Create SPI library to control the WM8805.
- Cleaning the PCB layout: having only 6 months experience, I can imagine there is a LOT to be improved in the area of the PCB.
- Help in enabling support for FLAC decoding (FYI: on-board MCU is dsPIC33FJ256GP710A). This still has to be done from the ground up (rest of the code is written in C30).
- Any help on getting a Tenor USB streaming chip TE7022L... GFED is playing a bit hard to get at the moment... :-)
- Suggestions for the two masterclocks for the SD section. I have experienced low-jitter is absolutely critical to good sound. I have been using this clock which I *think* is good, but the price is realitvely quite hefty. Especially considering the unit needs two of these. Also have considered Tent clocks, but these are, I think, too much for this pricerange. For now, I will stick with the e-bay clocks, but additional advice would be appreciated: currently, I am considering this for n x 48kHz and this for n x 44.1kHz
I am planning on eventually making available both kits + fully finished and cased units. Also, it should be allowed, for personal use, to be building this project.
Furthermore, I have attached the following to this post:
- LJ-A.png: a screenshot of the PCB v 0.2 currently being made;
- LJ-A.JPG: a picture of the v 0.1 prototype. This was taken after I accidentally applied an overvoltage. I had already removed the dsPIC (=IC32) and a few other components before taking this picture. It is a true prototype, having taken much abuse ;-)
- panels.pdf: front and backpanel design for the case. (just figured out I cannot create attachments, please find document here.
- A link to the parts list on mouser is here. Note that the parts list is not 100% complete. 'Missing' are a.o.:
Case
TDA1543 ICs
clocks
C9/10 capacitors (still have these on stock, 1000uF)
there could be a few more parts missing, but nothing big.
- UPDATE: parts list above no longer accurate. Please see BOM posted here.
I have not included the schematics, code for the MCU because these really are still too messy.
Note that the picture of the populated board is version 0.1, not the new version 0.2 which is depicted in the png of the v 0.2 PCB.
Last but not least: I think this post and project complies with the DIY board rules. If not, I am sure a moderator will be in touch shortly.
Edited by Koen - 11/1/10 at 3:52pm
I listen to the TDA1543 also. It's very good with a good transport.
