GreenDac TDA1541A from Analogmetric




Lampizator's journey is very close to an end. In the years of my search for perfect sound forever, which Philips advertised 29 years ago - I came full circle and I arrived at .....
the Philips basic datasheet implementation of their magnificent TDA1541A DAC.
How is it possible?

Well, in my opinion, with which I fully agree by the way, I found out beyond reasonable doubt that there is NOTHING AT ALL that money can add to a pure,  simple implementation of a naked DAC chip. Be it TDA1541, 1540, PCM63, PCM1704, CS4397, AD1862, Pulseflow P2028B, CS4327, PCM1794, or ESS Sabre  or any other good one out there. No amount of "engineering" and marketing, marble, gold, opamps and other stuff can IMPROVE the signal coming out of a DAC. So we DON'T NEED any of the stuff. Meaning - expensive gear has nothing to offer. No added value. The pure signal can only be damaged in one way or another.

Simply speaking - to make a perfect DAC we need this:
1. DAC chip which plays well
2. Power supply within specification - usually just 5V DC.
3. Digital input of data which was not manipulated in ANY WAY - no oversampling, no upsampling, no reclocking, no DSP. Nothing at all.
4. Final amplification in the form of a one stage voltage amplifier. A perfect device to do this is a triode, a FET transistor, or maybe sometimes a very good opamp - just one.
That is all.
To accomplish this we need something that holds this bunch of parts together - a good PCB.

Why not a player but DAC ? well, the TDA1541A were mounted inside players produced in the period of 1985-1995 so they are getting long in the teeth and there are all possible problems with laser, drawer etc. Investing in a DAC frees us from these problems.

Enter Analogmetric GreenDac

(I call it GreenDac for no better name I can think of)

Analogmetric is a Hong Kong business that sells parts , kits and counterfeit PCBs of famous designs. This particular PCB which I present does not seem like a counterfeit of any famous design. EVERY PCB for TDA must by definition be similar to fulfil requirements of Philips concept. There is no patent on this design, as there is no patent on recipe for bread.
We could say that the mother of all TDA designs is Philips CD304-MKII CD player and its schematics. EVERY product using TDA later (hundreds of CD players and DACS) was a variation on the same theme.

http://www.analogmetric.com/store/category.php?id=21


So what Analogmetric did was to make the most beautiful, most gorgeous PCB which has provision for the great TDA DAC and all parts, some really needed - some not.
Analogmetric offer this PCB in multitude of variants - from empty and naked to fully working. Choice is yours. The price goes from 15 USD for the PCB to 270 USD for the whole working product. Any price point in between is possible - so your purchase is lean meat - only what you need and nothing you don't need.
Nice idea, isn't it ?

Why Greendac is probably THE ULTIMATE product in all high end commerce?

Well, providing that you have most basic soldering skills - this DAC can be all you make it. YOU are responsible for its sound. You control every part, and whether a success or a failure (sonically) - you are the owner of that process.

So no more tweaking, no more part swapping of the original commercial product - finally we can put the parts WE WANT, and have zero waste.  This DAC is designed for LEAN and 6 Sigma.

No more variables we don't control. No more guessing. No more fighting with the original designer - we are GOD of this project.

When I ordered this PCB, it seemed like the SATCH without a box. But it is not. The PCB is MUCH more solid, thicker laminate, better silk-screen, simpler layout, better look and feel.
I SIMPLY ADORE the quality, I have not seen such good PCB in any player I ever examined.  The feel is as if Krell was preparing it to be proudly displayed in CES Las Vegas.

How does GreenDac relate to the SATCH ?

On paper the schematics is almost identical, but SATCH uses 5 PCB boards, GreenDac is just one. SATCH costs 600 USD, and fully loaded Greendac - only 270. If we make it ourselves, it costs in a range of 200 including a decent cabinet and transformer. The Greendac is definitely easier to build from scratch than the SATCH is to be tweaked and optimized.  Honestly, if you can not solder the GreenDac - you should seriously change your hobby. My own SATCH is the same as GreenDac because I modified SATCH very deeply. So my final SATCH and final Greendac are electrically identical.

PART COMPLETION


If you don't buy the parts from Analogmetric, you save some money because some parts in their kit are unnecessary, because we are not building op-amp analog stage. We can stop at DAC. We also do not need SAA7220p/B chip for digital filtering and oversampling.

So as you see below - I just bought two sets of Shottky diodes for rectification, three sets of LM317 type of regulators to provide three voltages:
+5, -5 and -15V needed by TDA chip.
The decisions which will impact sonics are mainly: the choice of electrolyte which stands between DAC power inputs and regulator. I used OS-CONS, but of course Black Gates are an option, as well as Tantalums, Elna Cerafine or Duorex or Nichicon Muse.
Another important decision is decoupling caps - the famous 14 small caps around DAC. Since I tried tantalums, MKP, etc.before in my tweaking projects,  this time around I decided to try OVERSIZED MKP - namely 0,56 uF Manti. The biggest MKP that I could squeeze there.
The role of these caps is not clearly known, but I allow myself to be different and use what others would never use (because of "too long antennas". So sue me.

Another interesting option used by my TDA Guru is to try the smallest possible oscons there - like 2uF. The minimum voltage rating of these caps is 10 V.

So far the damage is: 15 USD for PCB, 5 USD for postage, 5 USD for regulators, 20 USD for OSCONS, and the most expensive part is Mister TDA himself. Depending on how you buy it, it may be a fake one, or S1 fake print, or damaged one, or a good one. Safest way of buying is to buy a CD player with TDA inside and a broken laser - that should cost circa 20 Euro.
A good practice is to solder a socket not the TDA directly.
There is a provision for heat sinks for regulators, but in my opinion the power consumption is so low - you can get away without heat sinks. Or a simple beer bottle cap will do.

The exact voltage is adjustable by precision pots - it regulates with incredible precision of 1/100 V !!!

The last missing part is the SP/DIF receiver. Analogmetrics suggest CS8412 which needs adaptor board. They sell this complete set for 25 USD.
I decided to recycle a CS8414 from one Lampucera dac with broken DAC chip connected by I2S three wires.






















































On the above photos you see my prototype ready to go. Big part of the PCB is un-populated. That is all I need before I hook up the missing parts: receiver, lampizator and 15 V transformer.
I have not yet played this DAC but the result is pretty easy to guess. There is nothing that can go wrong. This will be the TDA at it's best. The finest analog-like DAC that I can imagine, able to compete with the other two contenders which belong in the TOP THREE - the Buffalo and the AudioNote DAC4.

The final comparison is scheduled for february.

I've had enough - I go on vacations now.
Till next time.