Flying higher and higher with the Doede Dac

[Lucas_G]

Many people have already built a Doede Dac with 8 TDA 1543's.
I would suggest to share experiences on building and finetuning this DAC in this thread...

There are already a couple of other threads concerning aspects of the Doede DAC. One of them deals with the question to reclock or not: Doede DAC..reclocked or not?

On his site, Fabian has a lot of interesting information: http://www.geocities.com/tdac1543/

And there is of course Doede own excellent site: http://www.dddac.de/

I hope many will post their findings on modding and finetuning the DAC.

[Lucas_G]

After building the DAC in an enclosure, using better cabling and connections, I started to finetune the Vref.

Using a spectrum analyzer, I found that the best setting was at 3,50 Volt DC at the left output, and 3,46 Volt DC at the right output.

I got the followong result:

The bottom level in yellow is when the DAC gets digital silence.
The upper level in red is when the DAC receives a 1 kHz sinuswave at -6dB.

This was the best attainable spectrum. I could not see a significant difference between reclocking or no reclocking.

[Lucas_G]

Note in the previous picture the relatively high distortion at 44.1 kHz
For the rest I don't think this spectrum is bad at al.

Here is the frequency plot when feeding the dac with whitenoise:

[Lucas_G]

After finetuning Vref, the DAC sounds ten times better than before. It does make a huge difference!

There is a better definition of ambience and less glare.

At this moment I use a Mundorf standard MKP of 8.2 uF, bypassed with a 1 uF Wima MKP and a 0.1 uF Mundorf Supreme Cap. This gives a pleasant sounding combination, but I will order some Blackgate NP's to try them as well.

I removed the 50k resistors at the output. I found them making the sound much duller. I hope I will not run into oscillation.

The Dac is very dynamic indeed, and it has a nice detailed midrange. What is still missing is a more refined treble. I hope this will improve with Blackgates...

Regards,

Lucas

[Lucas_G]

As a comparison, here is the same spectrum for my Philips DVD 963 SA player:

The line in yellow is when playing digital silence.
The line in blue is when playing a 1000 Hz sinuswave without upsampling.
The line in red is when playing a 1000 Hz sinuswave with upsampling to 24 bit 96 kHz by the AD 1895A.

Funny to see those differences between upsampling or not

[Lucas_G]

And here the frequencyresponse when playing white noise...

The Philips is completely flat here, where the Doede Dac has its -3 dB at 20 kHz, and a lot of rubbish in the 30 to 50 kHz region.

[Bernhard]

Lucas,

I can not understand why people built DACs with TDA1543.

This chip is declared by Philips as "economy" and used in their el cheapo players.

It is the very worst of all.

THD is -75dB in the data sheet, your measurements are very accurate

By comparison, the 1541 has -95dB.

Does the distortion noise floor provide tube sound ?

Had a CD614 with this chip. Sounded lower middle class.


Bernhard

[Audiofanatic]

Originally posted by Bernhard
Lucas,

I can not understand why people built DACs with TDA1543.

This chip is declared by Philips as "economy" and used in their el cheapo players.

It is the very worst of all.

THD is -75dB in the data sheet, your measurements are very accurate

By comparison, the 1541 has -95dB.

Does the distortion noise floor provide tube sound ?

Had a CD614 with this chip. Sounded lower middle class.


Bernhard

Why do you trust the philips data, trust your ears, if you never listen to the TDA1543, with an active 627 output opamp, you'll forget about the philips data!

Audiofanatic

[jean-paul]

Originally posted by Bernhard
Lucas,

I can not understand why people built DACs with TDA1543.

This chip is declared by Philips as "economy" and used in their el cheapo players.

It is the very worst of all.

THD is -75dB in the data sheet, your measurements are very accurate

By comparison, the 1541 has -95dB.

Does the distortion noise floor provide tube sound ?

Had a CD614 with this chip. Sounded lower middle class.


Bernhard

Oh oh, another spec hunter Trust the Philips data but let your ears be the judge please.

Try the TDA1543 in non os just for the heck of it. It will cost near to nothing so building one DAC with it won't hurt your wallet. Big chance you'll forget about the 4 x TDA1541A thingie.

Your CD614 had oversampling which makes quite a difference. IIRC it had an even more crappy digital filter than SAA7220 too. And the power supply could have been better too and... well you know what I mean.

To be honest I think TDA1543 is one of the better DAC chips soundwise but TDA1541A and TDA1545A I like more *when implemented right*. It is those last words that make building a DAC with 1543 so nice. Only one supply voltage and passive I/V, not much that can be screwed up except for PCB layout and a decent supply. I'll leave the comments about stacking TDA's and running them on near maximum allowable voltages to others.

[Bernhard]

The measurements confirm the Philips specs.

I had some friends in school who had motorcycles of which the specs said 25 km/h.

My diy friends were very clever, they made it go 75 km/h.