My experience with TDA1543 DAC

[Andypairo]

Hello,
I'm back from the first listening test of my dac.
It is mainly based on Doede's DAC, it uses a 12V battery, TL431 supplies for the CS8412 and a Mosfet regulator for the DAC itself.

I have 4 chips in parallel, Rload is calculated using Doede's document.

Vdac is 7.5V (actually I was planning to experiment a little but unfortunately I forgot my tester so... maybe next time).

The source was a cheap DVD player, connected optically with a Arcam AVR200 and to my DAC with coaxial cable, so we could switch between the 2 converters.

With great surprise we (me and my friend, the owner of the Arcam) could hardly tell the difference between the Arcam and my DAC, they sounded a bit different but frankly I can't say which was better.
The only "clear" differences were the voice, more forward with the Arcam, and the image, a bit narrower with my DAC (maybe too much).

Considering that I still have to play to get the best permformance out of the DAC this seems a good result to me!

Next session I'll bring the tester(!) and my CD931 (hoping that in the meanwhile the crystal from Elso has already arrived), and will try to get the best out of these chippies...

Cheers

Andrea

[pukka]

Which XO is it running now? I noticed after reclocking my Marantz on of the most noticeable differences was imaging...

Why did you "only" use 4 TDA's?

[Andypairo]

The DAC has no clock onboard, I made a provision for asynchronous reclocking but haven't completed it yet, partly because I was told that is better to improve the jitter at the source (changing the clock of the CD) than curing it in the DAC.
But as soon as I have a few time I think I'll try the ASR as well.

I only used 4 DAC chips for now but there's no real motivation.
I intended to experiment, I have 10 of them but before putting 8 in a row I wanted to see if my cooling arrangement was OK (BTW it works well, pics to come), so I went for 4.

But, as usual, so many variables and so few time

Cheers

Andrea

[pukka]

I see... My setup will have Guido XO's on both the CD (I already have it in my Marantz) and the 1543.

Pos pics of that arrangement! what's the highest temp. desirable on the chip tower?

[Andypairo]

For the pics... first I have to borrow a digital camera.

For the temp... the datasheet only specifies 250 mW of dissipable power but this value, as well as the thermal resistance (100 °K/W) are quoted without cooling arrangements, so don't give good info on a safe temperature.

As a rule of thumb the chips shouldn't be too hot to touch.

Cheers

Andrea

[Andypairo]

I borrowed a digital camera and took some shots...

Pic 1 - general view

[Andypairo]

Second pic.. closeup of the DAC board
As you can notice no enclosure yet...

[Andypairo]

Last one for now, showing the dac tower and the cooling arrangement. It is mathe with aluminium pieces cut to size. The blak thing that you can see near the chips is neoprene, an elastic polymer that holds the Alu pieces pressed to the chips.
This works well for me.
To take this pic I removed the 74VHC74 mounted on a homebrew SOIC to SIL adapter and intended for asynchronous reclocking (not implemented yet).

Cheers

Andrea

[pukka]

thanks for the shots Andrea!

That battery looks like a UPS one, isn't it? Same as me... I had it already...

I've been doing inventory today, and I have some doubts that maybe you can check as you have a working circuit.

Main thing is resistor ratings. Must I assume that for the battery checker circuit 500mW trimmers are ok? or should they be higher rating? What abot the rest? will 500mW suffice? What about the rest?

what kind of chips are you going to use for the reclocking?

[Andypairo]

Yes it's a UPS battery, even if it needs replacement in order to last as it should.

As far as I remember 500 mW are more than enough, the only bigger resistors are for the shunt supply of CS8412.

The reclocking chips will be 74VHC74s driven by a 100 MHz TCXO.

Cheers

Andrea