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Old 22nd October 2012, 07:52 AM   #18621
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Originally Posted by Ben Hanke View Post
Hey guys, I've built my first separate PSU for the DAC analogue supplies using a 7VA transformer (2 secondaries @ 3.5VA), some Schottkys and some mondo smoothers. Here I go with another noob question: What do I do with the ground? Anything different? Do the ground pins become separate or the same ground as the rest of the player? I only just realized how clueless I am about this part.
I believe you are talking about the ground connection of the secondaries. I don't think you need to earth this to the PCB or the casing. when you have finished with the 5V regulator just fix the +5V to the DAC and connect the 0V to the PCB's common ground.
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Old 22nd October 2012, 09:52 AM   #18622
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I used the star point near C813 negative terminal as my gnd point for everything. Can get a bit busy tho!!
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Old 22nd October 2012, 02:50 PM   #18623
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This method of direct coupling the output works here because there is 0v DC offset after the 2nd Opamp stage.

You should always check with a meter set to the mV range before you direct couple. DC into your amp could damage the amp and speakers!!!
Hi UV101,
I am hearing a kind of distortion after did the direct coupling of output. Initially I didnt hear this kind of distortion for last 2 days. Can you please tell me what will happen if DC go into amp and speaker? What should be the value if i measure DC?

Thanks
Badri
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Old 22nd October 2012, 03:17 PM   #18624
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Thanks guys. The output of each of my 5v regulators is currently wired to both terminals of a 470uF local decoupling capacitor close to the chip. It sounds as though I can leave those connections in place until I upgrade my regs to lower noise types.

Just searched the forum for info on badrisuper's question and saw that Brent had 22mV/24mV DC offset and that went down to 2mV per channel when he moved to a star earthing scheme (for his regs?)

@badrisuper - the DC should measure as close to zero as possible. I have about 30mV offset per channel at the speaker terminals of my amplifier, which is a little on the high side. Depending on your amp/pre-amp, any DC present at the output of your player could get amplified my the same amount as the music signal. In the short term this could result in distortion and popping of the speakers, but it could also fry your voice coils and/or your amp. Did you measure it before you hooked it up?
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Old 22nd October 2012, 03:57 PM   #18625
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Default Grounding?

Hi,
I taken signal output straight away from U210 and U214. But where to ground?

Thanks
Badri
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Old 22nd October 2012, 04:45 PM   #18626
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Mine are wired to the original IEC socket ground, but I find I get a fuller sound if I also don't use the internal insulator rings on the RCAs and screw them nice and tight to the chassis.
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Old 22nd October 2012, 05:11 PM   #18627
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Originally Posted by badrisuper View Post
Hi,
I taken signal output straight away from U210 and U214. But where to ground?

Thanks
Badri
Take gnd from the original point that fed the output phonos. Where are you taking gnd for now? This could be the reason for distorted output??
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Old 22nd October 2012, 05:14 PM   #18628
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Originally Posted by Ben Hanke View Post
the DC should measure as close to zero as possible. I have about 30mV offset per channel at the speaker terminals of my amplifier, which is a little on the high side. Depending on your amp/pre-amp, any DC present at the output of your player could get amplified my the same amount as the music signal. In the short term this could result in distortion and popping of the speakers, but it could also fry your voice coils and/or your amp. Did you measure it before you hooked it up?
For me at the speaker terminals I got 10mV DC on the Right speaker and 20mV on the Left speaker irrespective of volume setting of my amplifier and with or without the CD63 being turned on/off. It seems that the amplifier's input has built-in DC blocking capacitors. As to the CD63 RCA output, the measurement are both just less than 30mV DC. I did not hear any distortions at all.

Last edited by higlander; 22nd October 2012 at 05:16 PM.
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Old 22nd October 2012, 05:14 PM   #18629
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I didnt take the ground. Can you please tell me the position number fromt he scematic if it is there?

Thanks
Badri
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Old 22nd October 2012, 05:21 PM   #18630
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Seriously, if you cannot identify the original output gnd connection, you really shouldn't be poking around in the player.

Why don't you have a look and the PCB and point it out to me and then I'll help!!!!
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