TDA1543 DAC issues and observations.

[IpsilonSound]

Overall very happy with the results.

The NonozIII schematics is great, I experimented with quite a few things to test the changes and in most of the returned to the original specs.

The voltage regulators were LM78xx and i replaced them with Panasonic AN8008/AN8005M series. I noticed a big improvement in battery life using those regulators. The sound became better, more refined using AN80xx regulators. The DAC is now powered from the battery supply(12AAA 700mAh cells) since the regulators are getting very hot when running from 24V regulated power supply. This is a supply used for my PPA and both PPA and DAC will eventually be powered from it or the battery. The DAC will be using 2 or 4 2N5486 jfets to clean some ripple and provide rail isolation from the PPA ground.

Question:
What would be the best solution to adapt the DAC for 12-24V supplies and avoid AN80xx heat issue? They don't have the heatsink like the LM78xx ones and may be destroyed over time, I think. I was thinking about aditional regulator to bring the output voltage to 12V first but that would affect battery runtime. Transformers are not practical, since I targeted for a portable solution.

For the passive I/V stage I tried using a trebble correction circiut

but didn't like it compared with non-polar BG passive circiut by Fedde. The 3k resistors sound a bit too loud, i replaced them with Riken 1.8k. Riken does make a big difference, more pleasant sound, especially voices are rendered better, bigger soundstage.

One more question:
For phase inverting problem, I'm looking into transformers now. Does anyone have experience which type i can use here? Jensen make some pretty good ones, but they are not easy to find. Also, how much would it affect the sound if I put a lineout transformer on each channel to invert the phase?

And the last question:
Does using SN75179B really imrove the CS8414 jitter handling and the sound? I haven't tried this driver/receiver chip yet, but very tempted to order it from Newark after reading Peter Daniel posts. Peter uses SN75179B in combination with CS8412 chip which is not exactly the same as CS8414, the latter has better error handler as far as I know.

[Peter Daniel]

I didn't really compare the circuit with and without SN75179B, so I can't comment on actual improvement. However, comparing to my previous DACs without that buffer, the one using it sounds as good or better.

As to the voltage level before AN800x regulators, I'm dropping some of it with passive CLCRCRC filtering. So I'm ending up eith 12V before AN8008 reg and 8V before AN8005. They stay pretty cool this way. You might attach small heatsink to TO-92 case or in case of lack of such glue a piece of aluminum (to the case) using 2 part epoxy.

The resistors are on order of 10ohms and caps are approx 3300u.

[Audiofanatic]

Hi guys,

Can one of you tell me where to buy the AN8005 reg in europe?

Thanks in advance,


Audiofanatic

[Elso Kwak]

Hi ,
I tried the AN8005 in place of my triple Darlington regulator circuit with a LM329 and a constant current source.
I was not impressed by the AN8005. There was a lack of inner voices and bass slam.

[Audiofanatic]

Originally posted by Elso Kwak
Hi ,
I tried the AN8005 in place of my triple Darlington regulator circuit with a LM329 and a constant current source.
I was not impressed by the AN8005. There was a lack of inner voices and bass slam.

Hi Elso,

Thanks for the warning
I wasn't gona use it in my DAC PSU.
It is for my CD80 PSU and for testing, to see (listen) if the sound of the CD80 can get better with this AN80xx

Thanks anyway.


Audiofanatic

[Peter Daniel]

Originally posted by Elso Kwak
Hi ,
I tried the AN8005 in place of my triple Darlington regulator circuit with a LM329 and a constant current source.
I was not impressed by the AN8005. There was a lack of inner voices and bass slam.

What bypass caps (values) did you use?

[setmenu]

Hi IpsilonSound
Are you enjoying the sound of the dac?
I like mine ,especially since implementing Peters[cheers] recommendations
regarding caps and Rikens.
It is sensitive to recordings though, whether the top end sounds
'all there' seems on a bit of a knife edge at times...

I have also noticed when doing a 20-22k frequency sweep , [nothing sophisticated, just a test CD] that as the higher frequencies pass by there are some 'birdies' to be heard
phasing in an out as the frequency changes .
Spot frequency checks reveal all kinds of differences
compared to My Arcam CD23..

Are these intermodulation products ?

Though I can still enjoy the sound of this unit, as long as I don't
think about it too hard.

Here,s a pic of my little dac in bed with its partnering amp for the
portable headphone setup.


Cheers


Setmenu

[Elso Kwak]

Originally posted by Peter Daniel


What bypass caps (values) did you use?

Hi Peter, The same as with my triple Darlington regulator, to make things comparable.

[IpsilonSound]

Using 2N5486 to isolate the power from the DAC ground doesn't work. I burned a few 2N5486 transistors last night trying to connect V- V+ from the PPA to the DAC power thru them. My PPA power rail cascodes could've been destroyed this way, but survived I noticed that AOS Electronics using the same approach on his Ally DAC which works in combination with PPA. No idea why mine doesn't work when it should (

Maybe the only way to isolate the DAC ground from the PPA is using the 1:1 transformer?

Anyone can suggest isolation 1:1 transformers in the region of 15-30V suitable for this task? I would need to use a small one to reduce the weight of DAC and save batteries as much as possible.

[setmenu]

When i tried running my dac and amp off the same battery pack
I did not connect the dac ground to the amp pot ground.
merely connected the L+R dac outputs.
I preferred the sound of separate supplies though.

Any comments on the birdies?
Elso?



Setmenu