DDAC Clone - 12-way parallel TDA1543

Hi all,

For a few reasons, some time ago I decided I'd build myself a DDDAC-1543 MKII clone, or at least the parts I need. Most important reason I guess is I wanted to design my 'own' PCB having no real electronics experience (a PPA v2 headphone amp was my first project, a few weeks ago). In addition, I found Doede's DDDAC design not-so-practical with the tower cooling, so I wanted something more suited to my wishes. More on cooling later, though...

There's two parts to my DAC: (1) USB to I2S, based on TI PCM2706/7 (currently 2706 because the 2707 is not available anywhere). (2) I2S to audio (non-oversampling) board. Again, both are based heavily on Doede's prior art.

In summary, this DAC feeding into my PPA v2. I am STUNNED!:

1. By the SOUND of this thing!! Coming from playing via PC soundcard, obviously I expected an improvement, but this...! I am very happy. (wonder how long it will be before I want to know how this compares to other DACs...) Bass, treble, mids, it's all there!! At this moment, I can not believe a DAC can sound better than this one. You may wake me up ;-)
2. By myself, that I managed to design, based on Doede's work, have this fabricated etc. etc. etc. build this :-) Heh!

Costs? € 20 for the PCBs, € 8 for the PCM2706, € 10 for the TDA1543, say another € 10 for the other parts. In all, € 48... (sauf the power supply, which currently is a simple wall-wart, will be moving to a TREAD. Current draw is 0.66A @ 15 V.

So, the picture:

• The mini-heatsinks are insufficient for TDA1543s running @ 8 volt. So Doede (obviously) was right to build the cooling tower running @ 8 V. I am quite convinced that as the chips get to their steady state temperature at this voltage and cooling, noise is introduced. When just having started up, all nice and cool, the DAC is (almost) dead silent. I'll reduce the voltage to 7V, 6 and see if that alleviates the heat dissipation while keeping sonic qualities.
• There's a slight hum when turning my PPAv2 headphone amp to the max. The hum is not there when I disconnect the DAC / disconnect another source, so hum must be coming from the DAC.
• Coupling caps are 'el cheapo' nichicon muse caps. Basically, I don't have a clue yet what I'm doing in this area, I basically used what I had on hand. Still have to learn a lot, but is sounding great already.
• I had the PCBs made at batchpcb. They work, but I somehow feel the stop mask is very thin. It comes off (too?) easily.
• This being my first PCBs ever, there's tons of mistakes, will-do-different-next-time comments to make. Trace widths, just enough edge clearance to mount, a socket for an optional Tent clock which will not fit, 90 degrees angles in (signal) traces, mirrored text on silk screen : you name it, I've made the mistake I guess. Still, the board works and is sounding great already.
• CLEAN your boards after soldering... Really... Have been troubleshooting a horrible hiss, not getting audio at all, for quite some time. After a good rub of the I2S interconnects (the three silver wires) on both boards with IPA the DAC worked!

OK, that's it for now! Comments, questions welcome!

Quote:

Originally Posted by smellofpoo 

Great Job, really! I´m impressed, especially as you are on the finishing straight where I haven´t yet started. I´m about to tap out the i2s signal from my Squeezebox Receiver and found that the TDA1543 is a perfect match as the Receiver´s DAC is clocked with 11.289 MHz. I´m very interested in your schematics and pcb layouts, would love to buy your surplus boards. And for the mistakes: It could have been me as well, no doubt. I find that charming, somehow ... Where did you source the 1543s?

 

Keep on tinkering!

 

Cheers,

 

Gerd

Thank you for the compliments! Maybe this will indeed inspire others to pick up work in this area as others have inspired me!

• Schematics are below, I can not find a way to attach the board layout/gerber files to this message...? I am planning to do a second version, though, correcting the mistakes + adding some enhancements (I have managed do build a DIR9001-based coas/spdif to I2S receiver board, will probably bring tread onboard as well, different heatsinks..)
• To give credit where credit is due: original DDDAC schematics, PCB layouts are here and here.
• I got the TDAs off of e-bay, here for example. These are used chips, but you can also buy new for a few dollars a piece.
• I am willing to sell the boards to you. I have already soldered additional parts on these boards. If you are interested let me know and I will check what's already on there and we can agree on a price.
   

@Pricklely Peete:

TREAD is in, and indeed silent now, only humming when maxing out PPA amp. Will try battery power, see if this eliminates humming.

Thanks for pointing me to the valab chameleon, I missed that. I will tidy up the I2S interconnects when mounting in the box. Now I have the SPDIF->I2S board ready I should be able to box up soon.

Hi, just sent you an e-mail that the board is on it's way. Just to be sure, also posting them here!

Very curious about your results, please share them here! 

Quote:

Originally Posted by Dynobot 

With much trepidation I will suggest that you use a ADum device for your USB input.

Thanks, very good suggestion. I am working on a new version of this DAC and for sure will seriously consider including this IC. For sure will have an SD-card reader + player + USB interface included (also optical, coax via WM8805)

If, BTW, you have any suggestions for alternatives for the PCM2706/7 I'd be much obliged: would be nice to at least be able to do 96kHz/24 bi (which is a payload bitrate of 4,6 Mbps, USB2.0 is rated for 12 Mbps). However, no matter how hard I search, I can't find alternatives to the PCM2706/7 (I2S output is a requirement!)