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Old 4th July 2003, 01:22 PM   #41
dddac is offline dddac  Germany
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Hi Fedde,

thanks for answering... This moderation drives me nuts. I give an answer and it take ages. If the administrator reads this: Please get me off the hook. Check my WEB SITE and you can see for your self I am a serious DIY'r .........

OK, Fedde is right. you NEED to halve BOTH Rload as well Rref when you pggiback 2 chips. If you do 5 chips, divide all by 5, do n chips and divide by n .........

just give it another try

doede

PS: check your power supply... each chip draws aprox 50mA. Can drive a tl431 to go haha!
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Old 4th July 2003, 01:24 PM   #42
dddac is offline dddac  Germany
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Correct, actually there can be found an optimum for any combination the 3 main parameters of the 1543 DAC:

1. The Rref
2. the Rload
3. The VB

In the 1st picture the combination was 1k38 2k2 and 8,00 Volt

Easy to check with a FFT anlyzer (real one or S/W and your soundcard in the PC) and a test CD which contains a 1kHz 0dB sine wave...... in stead of a fix resitor I used a 25 turn trimmer, just turning till you see the d2 and d3 disapearing almost !! no magic, no rocket sience

These values were both achieved by measurements as well later with listening tests, which were done blind. I used trimmers for Rref and the VB and found the best position (well best, I prefered this position) I checked the values later on and came up with 1350 Ohm ( !! ) and 8,5 Volt for VB

Just try yourself !!!

by the way, more to come. I still have some ideas which need to be checked

Doede
PS: hope I will be left "out of jail soon"
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Old 4th July 2003, 01:24 PM   #43
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Just another question:

My TDA1543 has significant background noise.

I reported this before but no one could confirm it. I have a pre-amp/DAC combination with 4 different style DAC's inside. The TDA1543 has by far the most background noise, you can hear it from listening position... does anybody else have the same experience?

Regards,
Thijs
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Old 4th July 2003, 01:33 PM   #44
fedde is offline fedde  Netherlands
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Quote:
Originally posted by tschrama
Hi Fedde,
Damm .. I make no sence today..
That's not right, you make no sense! (damn...)

(just kidding!)
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Old 4th July 2003, 01:36 PM   #45
fedde is offline fedde  Netherlands
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Quote:
Originally posted by tschrama

My TDA1543 has significant background noise.
I reported this before but no one could confirm it. I have a pre-amp/DAC combination with 4 different style DAC's inside. The TDA1543 has by far the most background noise, you can hear it from listening position... does anybody else have the same experience?
I share the opinion that the TDA1543 is somewhat noisy. If I really turn up the volume I can hear some noise. But it's not extremely bad and doesn't worry me. It could well be that using a larger I/V increases the SNR...

Fedde
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Old 4th July 2003, 01:38 PM   #46
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Need I say more? This week has been too long for me.....
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Old 4th July 2003, 02:37 PM   #47
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Talking Clairvoyant?

Quote:
Originally posted by fedde


Let's answer for Doede:

Doede uses the TDA in passive mode, with 2.2k I/V and 8V supply. In that configuration, the correct Vref setting is essential!!!
Theoretically the DC output level should be at 4.3 V, but Doede says he gets minimal distortion between 3.7 V-4.1V or so. Doede seems to use 1k38, I use 1k26 (4.25V).

Fedde
Hi Fedde,
Are you clairvoyant knowing in advance what Doede is going to answer??
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Old 4th July 2003, 02:40 PM   #48
fedde is offline fedde  Netherlands
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Sure... You should meditate more often !

May the power be with you,

Fedde
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Old 4th July 2003, 05:46 PM   #49
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Lightbulb Vref Setting TDA1543

Hi, I just put a 5k pot at Vref and played a bit. Low setting gives a distorted sinewave on the scope, especially at the top. Higher setting is OK. With a little safety margin in the setting the pot measured 3k2.
So Philips might be right using 3k3 in there players. This is with +5V supply and active (opamp) IV-conversion.
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Old 4th July 2003, 06:38 PM   #50
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Default Re: Resistor at Vref

Quote:
Originally posted by Elso Kwak



After some time your posts are displayed immediately. Newcomers are first subjected to some kind of "filtering", taking some time in the process.....

I took Doede off moderation, so Fedde doesn't have to predict anymore what Doede meant to say
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